Fender 5E3 Tweed Deluxe / 5E5 Tweed Pro Hybrid Amp - resistor question
Ether
I'm building a hybrid Tweed Deluxe/Pro amp, using the 5E3 preamp stage
and the 5E5 output stage. If you look at the two output-stage
schematics, there are two pertinent differences (besides the tubes &
transformers, of course):
1) The 5E3 has a 5000 ohm resistor in the power stage, while the 5E5
has a 2500 ohm resistor.
2) The next resistor is 20,000 ohms in the 5E3, while the 5E5 has a
10,000 ohm resistor.
The lower resistor values in the 5E5 allow higher plate currents for
the 6L6 tubes, of course. (I plan to start with 6L6 tubes and a 5AR4
rectifier. And yes, I will boost the filter cap values.)
So here are my questions:
1) If I want to be able to go back to using 6V6 power tubes and a 5Y3
rectifier, is it safe to use the 5E5 Pro's lower resistor values, or
will that fry these lower-output tubes?
2) If the Tweed Pro current levels are too high for the 6V6 & 5Y3
tubes, what do you think of wiring in both resistor values, and using
a selectable switch?
Thanks for your input.
P.S. I'm also considering using the fixed bias network from the 5E5-A
output stage. Would this make enough of a difference in the amp's
sound to be worth trying? The 5E5-A seems to be hard to get
information on.
Walter Campbell
<et...@x-mail.net> wrote:
> Here's one for Lord Valve, Ned, and other experts:
>
> I'm building a hybrid Tweed Deluxe/Pro amp, using the 5E3 preamp stage
> and the 5E5 output stage. If you look at the two output-stage
> schematics, there are two pertinent differences (besides the tubes &
> transformers, of course):
>
> 1) The 5E3 has a 5000 ohm resistor in the power stage, while the 5E5
> has a 2500 ohm resistor.
>
> 2) The next resistor is 20,000 ohms in the 5E3, while the 5E5 has a
> 10,000 ohm resistor.
>
> The lower resistor values in the 5E5 allow higher plate currents for
> the 6L6 tubes, of course. (I plan to start with 6L6 tubes and a 5AR4
> rectifier. And yes, I will boost the filter cap values.)
>
> So here are my questions:
>
> 1) If I want to be able to go back to using 6V6 power tubes and a 5Y3
> rectifier, is it safe to use the 5E5 Pro's lower resistor values, or
> will that fry these lower-output tubes?
Are you going to have a bias adjustment/fixed adjustable bias setup on
the power tubes? If yes, then your can switch to 6V6s, reabias and be
alright.
If you leave the amp cathode biased then you'll need to change the
cathode resistor value (probably) when you switch tubes.
Remember, it's max plate dissipation that really counts, so when plate
voltage goes up, bias it colder to keep it under mpd.
>
> 2) If the Tweed Pro current levels are too high for the 6V6 & 5Y3
> tubes, what do you think of wiring in both resistor values, and using
> a selectable switch?
>
> Thanks for your input.
>
>
> P.S. I'm also considering using the fixed bias network from the 5E5-A
> output stage. Would this make enough of a difference in the amp's
> sound to be worth trying? The 5E5-A seems to be hard to get
> information on.
My 2¢ worth....
Walt Campbell
Campbell Sound
www.campbellsound.com
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Ether
(And if anyone has info on the Tweed Pro 5E5-A, don't hold back.)
Walter Campbell <wa...@starstream.net> wrote in message news:<171120031114276055%wa...@starstream.net>...
> In article <c9d2eb15.0311...@posting.google.com>, Ether
> <et...@x-mail.net> wrote:
>
> > Here's one for Lord Valve, Ned, and other experts:
> >
> > I'm building a hybrid Tweed Deluxe/Pro amp, using the 5E3 preamp stage
> > and the 5E5 output stage. If you look at the two output-stage
> > schematics, there are two pertinent differences (besides the tubes &
> > transformers, of course):
> >
> > 1) The 5E3 has a 5000 ohm resistor in the power stage, while the 5E5
> > has a 2500 ohm resistor.
> >
> > 2) The next resistor is 20,000 ohms in the 5E3, while the 5E5 has a
> > 10,000 ohm resistor.
> >
> > The lower resistor values in the 5E5 allow higher plate currents for
> > the 6L6 tubes, of course. (I plan to start with 6L6 tubes and a 5AR4
> > rectifier. And yes, I will boost the filter cap values.)
> >
> > So here are my questions:
> >
> > 1) If I want to be able to go back to using 6V6 power tubes and a 5Y3
> > rectifier, is it safe to use the 5E5 Pro's lower resistor values, or
> > will that fry these lower-output tubes?
>
> Are you going to have a bias adjustment/fixed adjustable bias setup on
> the power tubes? If yes, then your can switch to 6V6s, rebias and be
> alright.
I'm planning on using cathode bias (at least for now).
> If you leave the amp cathode biased then you'll need to change the
> cathode resistor value (probably) when you switch tubes.
The cathode resistor value is the *same* (250 ohms) in both the 5E3
and 5E5; just the wattage rating is higher (10 watts) in the 5E5.
It's the two filter-stage resistors that are different.
I have heard that 6L6 tubes can run fine using the stock 5E3
filter-stage resistor values. But I imagine that 6V6 tubes might burn
up in the 5E5 circuit, even if I subbed a 5Y3 for the Pro's 5U4
rectifier.
> Remember, it's max plate dissipation that really counts, so when plate
> voltage goes up, bias it colder to keep it under mpd.
Yes, I know... But I want to use cathode bias so I won't have to
worry about bias adjustments when I change tubes.
I'm still thinking of wiring in both sets of filter-stage resistor
values, so I can have a stock 5E3 or 5E5 at the flick of a switch.
> >
> > 2) If the Tweed Pro current levels are too high for the 6V6 & 5Y3
> > tubes, what do you think of wiring in both resistor values, and using
> > a selectable switch?
> >
> > Thanks for your input.
> >
> >
> > P.S. I'm also considering using the fixed bias network from the 5E5-A
> > output stage. Would this make enough of a difference in the amp's
> > sound to be worth trying? The 5E5-A seems to be hard to get
> > information on.
>
> My 2¢ worth....
Thanks for taking the time to respond!
Mike Schway
et...@x-mail.net (Ether) wrote:
> The cathode resistor value is the *same* (250 ohms) in both the 5E3
> and 5E5; just the wattage rating is higher (10 watts) in the 5E5.
> It's the two filter-stage resistors that are different.
>
> I have heard that 6L6 tubes can run fine using the stock 5E3
> filter-stage resistor values. But I imagine that 6V6 tubes might burn
> up in the 5E5 circuit, even if I subbed a 5Y3 for the Pro's 5U4
> rectifier.
>
>
> > Remember, it's max plate dissipation that really counts, so when plate
> > voltage goes up, bias it colder to keep it under mpd.
>
> Yes, I know... But I want to use cathode bias so I won't have to
> worry about bias adjustments when I change tubes.
>
> I'm still thinking of wiring in both sets of filter-stage resistor
> values, so I can have a stock 5E3 or 5E5 at the flick of a switch.
Just a wild idea...what about just using the 5E5 supply resistor values
and putting a couple 470/1W screen stopper resistors mounted on the
sockets. You'd get the additional current limiting to the screens while
maintaining a higher preamp/p-i voltage. I don't think the tone will
suffer much while in "pro" mode. No switch necessary. Hopefully plate
voltage will be low enough for the 6V6.
--Mike
--------------------------------------------------------------------
Mike Schway | [Picture your favorite quote here]
msc...@nas.com |
--------------------------------------------------------------------
Ether
> Just a wild idea...what about just using the 5E5 supply resistor values
> and putting a couple 470/1W screen stopper resistors mounted on the
> sockets. You'd get the additional current limiting to the screens while
> maintaining a higher preamp/p-i voltage. I don't think the tone will
> suffer much while in "pro" mode. No switch necessary. Hopefully plate
> voltage will be low enough for the 6V6.
As I understand it, these resistors would go from pin 4 of each power
tube socket to the junction of the two power supply resistors. Is
that right? (Correct me if I'm wrong.)
What effect do screen-stopper resistors have on the sound of a Deluxe?
> Hopefully plate voltage will be low enough for the 6V6.
If they're not, I'll know soon enough!
Thanks.
Mike Schway
> Mike Schway <msc...@nas.com> wrote in message
> news:<mschway-22F1C6...@netnews.attbi.com>...
>
> > Just a wild idea...what about just using the 5E5 supply resistor values
> > and putting a couple 470/1W screen stopper resistors mounted on the
> > sockets. You'd get the additional current limiting to the screens while
> > maintaining a higher preamp/p-i voltage. I don't think the tone will
> > suffer much while in "pro" mode. No switch necessary. Hopefully plate
> > voltage will be low enough for the 6V6.
>
> As I understand it, these resistors would go from pin 4 of each power
> tube socket to the junction of the two power supply resistors. Is
> that right? (Correct me if I'm wrong.)
True. Mount the stoppers directly on the sockets from pin 6 (normally
unused) to pin 4. Run what would have been your normal screen supply to
pin 6.
>
> What effect do screen-stopper resistors have on the sound of a Deluxe?
Not much, I'd think. My first 5E3 build had 'em and it sounded great.
> > Hopefully plate voltage will be low enough for the 6V6.
>
> If they're not, I'll know soon enough!
>
> Thanks.
--------------------------------------------------------------------
Ether
> >
> > > Just a wild idea...what about just using the 5E5 supply resistor values
> > > and putting a couple 470/1W screen stopper resistors mounted on the
> > > sockets. You'd get the additional current limiting to the screens while
> > > maintaining a higher preamp/p-i voltage. I don't think the tone will
> > > suffer much while in "pro" mode. No switch necessary. Hopefully plate
> > > voltage will be low enough for the 6V6.
> >
> > As I understand it, these resistors would go from pin 4 of each power
> > tube socket to the junction of the two power supply resistors. Is
> > that right? (Correct me if I'm wrong.)
>
> True. Mount the stoppers directly on the sockets from pin 6 (normally
> unused) to pin 4.
Hmmm... my 5E3 layout diagram has a 1500 ohm resistor between pins 5
and 6 on each power tube. But when I look at the schematic, it seems
that nothing else comes between the 1500 ohm resistor and the 220k ohm
resistor. So, as you say, pin 6 is not used -- it's just being used as
a binding post for the 1500 ohm resistor.
> Run what would have been your normal screen supply to
> pin 6.
So, if I do that, I will have to disconnect the 1500 ohm resistor from
pin 6, correct? (The 1500 ohm resistor would go from Pin 5 directly to
the 220 ohm resistor / .1 uF cap junction.)
As I look at this, it's similar to what Doug Hoffman did on his 5E3
board, right? (Except that Hoffman runs his 470 ohm screen-stopper
resistors from pin 4 to the junction of the two power-stage resistors.
He leaves the 1500 ohm resistor conencted between pins 5 and 6 of each
power tube.) I guess there's more than one way to do this.
Can you give me a rundown of what the power tube pins are? (7 is the
heater filament, of course.)
Thanks.
P.S. 5E3 schematic is available at www.ampwares.com/ffg (Narrow Panel
Deluxe.)
Mike Schway
> Mike Schway <msc...@nas.com> wrote:
>
> > >
> > > > Just a wild idea...what about just using the 5E5 supply resistor values
> > > > and putting a couple 470/1W screen stopper resistors mounted on the
> > > > sockets. You'd get the additional current limiting to the screens
> > > > while
> > > > maintaining a higher preamp/p-i voltage. I don't think the tone will
> > > > suffer much while in "pro" mode. No switch necessary. Hopefully plate
> > > > voltage will be low enough for the 6V6.
> > >
> > > As I understand it, these resistors would go from pin 4 of each power
> > > tube socket to the junction of the two power supply resistors. Is
> > > that right? (Correct me if I'm wrong.)
> >
> > True. Mount the stoppers directly on the sockets from pin 6 (normally
> > unused) to pin 4.
>
> Hmmm... my 5E3 layout diagram has a 1500 ohm resistor between pins 5
> and 6 on each power tube. But when I look at the schematic, it seems
> that nothing else comes between the 1500 ohm resistor and the 220k ohm
> resistor. So, as you say, pin 6 is not used -- it's just being used as
> a binding post for the 1500 ohm resistor.
Right. You'll have to put the 1500 ohm resistor from pin 1 to pin 5,
and the feed from the p/i (junction of the 220K and 0.1uF cap) goes to
pin 1. Pin 1 is normally unused (or sometimes tied to cathode).
That'll leave pin 6 open for the tie point from the 470/1W resistor to
the screen supply.
This is the way all (well NEARLY all) Blackface and Silverface fenders
are done. Check out the layout diagrams for these amps.
>
> > Run what would have been your normal screen supply to
> > pin 6.
>
> So, if I do that, I will have to disconnect the 1500 ohm resistor from
> pin 6, correct? (The 1500 ohm resistor would go from Pin 5 directly to
> the 220 ohm resistor / .1 uF cap junction.)
>
> As I look at this, it's similar to what Doug Hoffman did on his 5E3
> board, right? (Except that Hoffman runs his 470 ohm screen-stopper
> resistors from pin 4 to the junction of the two power-stage resistors.
> He leaves the 1500 ohm resistor conencted between pins 5 and 6 of each
> power tube.) I guess there's more than one way to do this.
There's a good reason to mount these resistors directly to the socket,
it has to do with oscillation supression. Both the 1500 and 470
resistors should be on the socket.
>
> Can you give me a rundown of what the power tube pins are? (7 is the
> heater filament, of course.)
Hmmm....methinks you might be getting over your head??? (no offense
intended, of course). You should get used to reading a tube data sheet.
You can find 6V6 and 6L6 anywhere, but an easy online source is at
duncanamps.com.
OK:
Pin 1 (unused, unless you use it as a tie point for the grid feed)
Pin 2: Heater
Pin 3: Plate
Pin 4 Screen
Pin 5 Control grid
Pin 6: Unused (unless you use it as a tie point)
Pin 7: Heater
Pin 8: Cathode.
>
> Thanks.
>
> P.S. 5E3 schematic is available at www.ampwares.com/ffg (Narrow Panel
> Deluxe.)
Use this source to check out the chassis layout for any blackface (well,
maybe not the Princeton). Pay attention to the output tube sockets.
Regards,
--Mike
Ether
> In article <c9d2eb15.03111...@posting.google.com>,
> et...@x-mail.net (Ether) wrote:
>
> > Mike Schway <msc...@nas.com> wrote:
> >
> > > >
> > > > > Just a wild idea...what about just using the 5E5 supply resistor values
> > > > > and putting a couple 470/1W screen stopper resistors mounted on the
> > > > > sockets. You'd get the additional current limiting to the screens
> > > > > while
> > > > > maintaining a higher preamp/p-i voltage. I don't think the tone will
> > > > > suffer much while in "pro" mode. No switch necessary. Hopefully plate
> > > > > voltage will be low enough for the 6V6.
> > > >
> > > > As I understand it, these resistors would go from pin 4 of each power
> > > > tube socket to the junction of the two power supply resistors. Is
> > > > that right? (Correct me if I'm wrong.)
> > >
> > > True. Mount the stoppers directly on the sockets from pin 6 (normally
> > > unused) to pin 4.
> >
> > Hmmm... my 5E3 layout diagram has a 1500 ohm resistor between pins 5
> > and 6 on each power tube. But when I look at the schematic, it seems
> > that nothing else comes between the 1500 ohm resistor and the 220k ohm
> > resistor. So, as you say, pin 6 is not used -- it's just being used as
> > a binding post for the 1500 ohm resistor.
>
> Right. You'll have to put the 1500 ohm resistor from pin 1 to pin 5,
> and the feed from the p/i (junction of the 220K and 0.1uF cap) goes to
> pin 1. Pin 1 is normally unused (or sometimes tied to cathode).
In the 5E3 layout diagram, Pin 1 is tied to Pin 2 (heater filament),
and then grounded. So, to do what you're suggesting, I would have to
just ground Pin 2, and then use pin 1 as a binding post for the 1500
ohm resistor.
Wouldn't it be easier to do this?:
1) Leave the 1500 ohm resistor between pins 5 and 6 (as is stock 5E3).
2) Disconnect the lead between pin 1 and pin 2 (grounding only pin 2).
3) Connect the 470 ohm screen-stopping resistor between pins 4 and pin
1 (and then on to the grid feed / resistor junction.
That would accomplish the same thing, with fewer changes from stock.
(Unless there's a problem having the 470 ohm screen-stopping resistor
stretched over the tube socket -- but having the 1500 ohm resistor
between pin 1 and pin 5 would be a similar stretch.)
Side question: Why does the stock 5E3 schematic bother to ground the
unused pin 1 on the power tube socket? (Does it make any difference?)
> That'll leave pin 6 open for the tie point from the 470/1W resistor to
> the screen supply.
True, but as I said above, it's easier just to use pin 1 for this
purpose.
> This is the way all (well NEARLY all) Blackface and Silverface fenders
> are done. Check out the layout diagrams for these amps.
> >
> > > Run what would have been your normal screen supply to
> > > pin 6.
> >
> > So, if I do that, I will have to disconnect the 1500 ohm resistor from
> > pin 6, correct? (The 1500 ohm resistor would go from Pin 5 directly to
> > the 220 ohm resistor / .1 uF cap junction.)
> >
> > As I look at this, it's similar to what Doug Hoffman did on his 5E3
> > board, right? (Except that Hoffman runs his 470 ohm screen-stopper
> > resistors from pin 4 to the junction of the two power-stage resistors.
> > He leaves the 1500 ohm resistor conencted between pins 5 and 6 of each
> > power tube.) I guess there's more than one way to do this.
>
> There's a good reason to mount these resistors directly to the socket,
> it has to do with oscillation supression. Both the 1500 and 470
> resistors should be on the socket.
> >
> > Can you give me a rundown of what the power tube pins are? (7 is the
> > heater filament, of course.)
>
> Hmmm....methinks you might be getting over your head??? (no offense
> intended, of course).
That's why I'm asking *you* for help! But really -- I'm familiar
enough with the circuit to put it together successfully from the
schematic, even without an in-depth knowledge of every component's
exact function. (I suppose that's what separates a hobbyist from an
amp tech.) And yes, I know enough to keep from frying myself, too.
(Hey -- what's that burning smell?)
> You should get used to reading a tube data sheet.
> You can find 6V6 and 6L6 anywhere, but an easy online source is at
> duncanamps.com.
>
>
> OK:
> Pin 1 (unused, unless you use it as a tie point for the grid feed)
> Pin 2: Heater
> Pin 3: Plate
> Pin 4 Screen
> Pin 5 Control grid
> Pin 6: Unused (unless you use it as a tie point)
> Pin 7: Heater
> Pin 8: Cathode.
Just what I was looking for! I have looked at several tube data
sheets, but it's always good to have confirmation from a real-live
person. (Data sheets can have errors. I have a borrowed I-177B tube
tester that has a manual full of them!)
> > P.S. 5E3 schematic is available at www.ampwares.com/ffg (Narrow Panel
> > Deluxe.)
>
> Use this source to check out the chassis layout for any blackface (well,
> maybe not the Princeton). Pay attention to the output tube sockets.
Will do. However, I think I may just try the stock 5E5 circuit
without the screen-stoppers first. If I have problems with 6V6 tubes,
or with oscillations, I'll add the stoppers later.
Let me know if I'm taking an undue risk with that approach. (Blowing
the output tubes may harm other components, of course.)
>
> Regards,
> --Mike
Thanks again!
Mike Schway
et...@x-mail.net (Ether) wrote:
> In the 5E3 layout diagram, Pin 1 is tied to Pin 2 (heater filament),
> and then grounded. So, to do what you're suggesting, I would have to
> just ground Pin 2, and then use pin 1 as a binding post for the 1500
> ohm resistor.
>
> Wouldn't it be easier to do this?:
Well, sort of, though it's generally a quieter design to not use the
chassis as one of your heater conductors (even though Leo did it in the
50s). If your heater supply has a center tap, ground the CT, otherwise
use a resistor balance network (two 100 ohm resistors with the junction
going to ground).
Just run one of the filament leads to pin 2, leaving pin 1 open.
>
> 1) Leave the 1500 ohm resistor between pins 5 and 6 (as is stock 5E3).
> 2) Disconnect the lead between pin 1 and pin 2 (grounding only pin 2).
> 3) Connect the 470 ohm screen-stopping resistor between pins 4 and pin
> 1 (and then on to the grid feed / resistor junction.
>
> That would accomplish the same thing, with fewer changes from stock.
> (Unless there's a problem having the 470 ohm screen-stopping resistor
> stretched over the tube socket -- but having the 1500 ohm resistor
> between pin 1 and pin 5 would be a similar stretch.)
Whichever seems easier... I generally go with the stock BF layout (1500
ohm between pin 1 and 5, 470 ohm between 4 and 6). Just make sure
nothing is touching what it shouldn't...and be sure to leave some slack
in the middle for the tube key.
>
> Side question: Why does the stock 5E3 schematic bother to ground the
> unused pin 1 on the power tube socket? (Does it make any difference?)
Grounding unused pins is generally done, though probably not crucial if
the pin isn't connected internally to anything. On a 6L6, the pin isn't
even inserted! Definitely, if you were wiring only one half of a dual
triode (12AX7, e.g.), you should ground the 3 elements in the unused
half.
>
> > That'll leave pin 6 open for the tie point from the 470/1W resistor to
> > the screen supply.
>
> True, but as I said above, it's easier just to use pin 1 for this
> purpose.
And in either case, be VERY careful about pin 1 if you ever decide to
run an EL34 instead of a 6L6. (pin 1 gets tied to cathode!).
>
> ...And yes, I know enough to keep from frying myself, too.
> (Hey -- what's that burning smell?)
That would be my dinner.... :-)
>
>
> > > P.S. 5E3 schematic is available at www.ampwares.com/ffg (Narrow Panel
> > > Deluxe.)
> >
> > Use this source to check out the chassis layout for any blackface (well,
> > maybe not the Princeton). Pay attention to the output tube sockets.
>
> Will do. However, I think I may just try the stock 5E5 circuit
> without the screen-stoppers first. If I have problems with 6V6 tubes,
> or with oscillations, I'll add the stoppers later.
But the extra resistance the screen stoppers give will provide some
current limiting for the screens when running 6V6s...that's what you
were initially asking about.
OTOH, the 5E5 is a great amp too.
>
> Let me know if I'm taking an undue risk with that approach. (Blowing
> the output tubes may harm other components, of course.)
Hey, it's only money. Main thing is to make sure your B+ is low enough
when you do run 6V6s. 350-375V under load is about right for cathode
biased operation. Of course, the 6L6s will draw more current which in
turn will load down the power supply further. If you're getting 375V
with 6L6s, you can be sure you'll have more when you pop in 6V6s.
Finally, the output transformers for 6V6s and 6L6s optimally are a
little different (aside from power handling). 6V6s ideally want to see
a higher impedance. Shouldn't be fatal, though.
My gut level feeling is that you probably are best off building the best
5E5 you can make using the right transformers (PT and OT). The best 5E3
you can make will involve a different PT and OT. Anything else is a
compromise.
Good luck.
Ether
> Well, sort of, though it's generally a quieter design to not use the
> chassis as one of your heater conductors (even though Leo did it in the
> 50s).
I will definitely be running my heater supply returns back to a ground
lug.
> If your heater supply has a center tap, ground the CT, otherwise
> use a resistor balance network (two 100 ohm resistors with the junction
> going to ground).
I've seen this described, but I can't recall which PT leads to attach
the resistors to. Can you refresh my memory?
> > Side question: Why does the stock 5E3 schematic bother to ground the
> > unused pin 1 on the power tube socket? (Does it make any difference?)
>
> Grounding unused pins is generally done, though probably not crucial if
> the pin isn't connected internally to anything. On a 6L6, the pin isn't
> even inserted! Definitely, if you were wiring only one half of a dual
> triode (12AX7, e.g.), you should ground the 3 elements in the unused
> half.
Well then, if I use 6L6's only, I won't bother grounding the phantom
pin!
> And in either case, be VERY careful about pin 1 if you ever decide to
> run an EL34 instead of a 6L6. (pin 1 gets tied to cathode!).
Will do. (But I don't plan to use EL34's.)
> > Will do. However, I think I may just try the stock 5E5 circuit
> > without the screen-stoppers first. If I have problems with 6V6 tubes,
> > or with oscillations, I'll add the stoppers later.
>
> But the extra resistance the screen stoppers give will provide some
> current limiting for the screens when running 6V6s...that's what you
> were initially asking about.
Ok. I'll keep that in mind. Maybe someday, some manufacturer will
come up with a decent RCA black plate 6V6 clone, so we won't have to
worry about it so much.
> OTOH, the 5E5 is a great amp too.
That's what I hear. What I can't seem to find out, though, is how the
5E5 (cathode-biased) sounds different from the 5E5-A (fixed bias). Or
a description of how the 5E5 Pro is different in character from a
5F6-A Bassman. The Fender Field Guide should have a section
describing the sound of these amps.
> Finally, the output transformers for 6V6s and 6L6s optimally are a
> little different (aside from power handling). 6V6s ideally want to see
> a higher impedance. Shouldn't be fatal, though.
>
> My gut level feeling is that you probably are best off building the best
> 5E5 you can make using the right transformers (PT and OT). The best 5E3
> you can make will involve a different PT and OT. Anything else is a
> compromise.
That's the bit of wisdom I'm really looking for.
What I think I'll do is gear the transformers for the 5E5, and not
worry about using 6V6's. I could then put in a switch that would
allow the amp to go from cathode-bias (5E5) to fixed-bias (5E5-A).
That's certainly feasible, as these two circuits use the same output
tubes and transformers.
Another side question: Do you know how to substitute a 1N4007 diode
for a selenium rectifer in the 5E5-A? I have read that more than one
1N4007 may be needed, but I can't find anything specific on the
subject.
Thanks.
Mike Schway
>>
> > If your heater supply has a center tap, ground the CT, otherwise
> > use a resistor balance network (two 100 ohm resistors with the junction
> > going to ground).
>
> I've seen this described, but I can't recall which PT leads to attach
> the resistors to. Can you refresh my memory?
The green leads (heater supply) go to both free ends of two 100 ohm 1/2W
resistors in series. The junction of the resistors goes to ground. If
you have a green lead with a yellow stripe, that's most likely a heater
center tap and it should be grounded. If you have a (grounded) center
tap, there's no need for the balance resistors.
>
>[snip]
>
>
> > OTOH, the 5E5 is a great amp too.
>
> That's what I hear. What I can't seem to find out, though, is how the
> 5E5 (cathode-biased) sounds different from the 5E5-A (fixed bias). Or
> a description of how the 5E5 Pro is different in character from a
> 5F6-A Bassman. The Fender Field Guide should have a section
> describing the sound of these amps.
*in general*, cathode biased amps sound a little "sweeter", perhaps a
bit more compressed and less clean headroom. The 5E5 (non-A) also has no
NFB loop which would also aid earlier breakup. The 5E5-A has a presence
control in the NFB loop which will give you some control over the upper
midrange Fixed bias amps sound tighter and you can get more power out
of it.
The 5F6 Bassman has a totally different tone stack...separate bass and
treble for more tonal variation. It really is an entirely different
beast. The choice between the three amps depends entirely on your
tastes. I would suppose the 5E5 (non-A) is somewhat like a 5E3 on a
small amount of steroids. A little more clean headroom than the Deluxe.
The -A version will have more clean headroom yet and a tighter sound.
The Bassman gives you more kinds of sounds (3 tone controls). Of course
the speaker complement is hugely different for the two amps..
>
> > [snip]
>
> What I think I'll do is gear the transformers for the 5E5, and not
> worry about using 6V6's. I could then put in a switch that would
> allow the amp to go from cathode-bias (5E5) to fixed-bias (5E5-A).
> That's certainly feasible, as these two circuits use the same output
> tubes and transformers.
Perhaps so, but to ideally take advantage of the incease in power that
fixed bias allows, you probably should have a higher voltage.
Crazy idea #2: Maybe switching rectifier tubes may do this...a 5AR4 for
the fixed bias version and a 5U4 for cathode biased. Dunno if the
difference in voltage will be right on the money, though.
IMO, amps which have all sorts of switchable architecture really can
only nail down one thing at a time. The absolute worst offender is the
Mesa Triple Rectifier. You can switch output tube types and between
tube and SS rectifier. Unfortunately, it'll only work best for one of
the 4 possible configurations due to a non-optimized bias level. You
may get it to operate OK for EL34s with a SS rect, but once you switch
to a tube rect, it'll be biased WAY WAY cold. (sorry for the rant.)
>
> Another side question: Do you know how to substitute a 1N4007 diode
> for a selenium rectifer in the 5E5-A? I have read that more than one
> 1N4007 may be needed, but I can't find anything specific on the
> subject.
It's not necessary to series two diodes for the bias supply. If you are
subbing a 1N4007 for a HV rectifier tube, you'll need to put 2 of them
in series on each HV leg, but for a mere bias supply, the PIV is well in
the range of a single diode.
>
> Thanks.
Happy T'giving.
Ether
> In article <c9d2eb15.03112...@posting.google.com>,
> et...@x-mail.net (Ether) wrote:
>
> >>
> > > If your heater supply has a center tap, ground the CT, otherwise
> > > use a resistor balance network (two 100 ohm resistors with the junction
> > > going to ground).
> >
> > I've seen this described, but I can't recall which PT leads to attach
> > the resistors to. Can you refresh my memory?
>
> The green leads (heater supply) go to both free ends of two 100 ohm 1/2W
> resistors in series. The junction of the resistors goes to ground. If
> you have a green lead with a yellow stripe, that's most likely a heater
> center tap and it should be grounded. If you have a (grounded) center
> tap, there's no need for the balance resistors.
I now see that Doug Hoffman recommends connecting one 100 ohm resistor
to each terminal of the pilot light socket (and then grounding the
other ends). I supposed that's still wiring these resistors in series,
even though they're in parallel with the pilot light.
I'm going to use the balance resistors even if my PT has a grounded
center tap--for the extra protection against power tube shorting.
> > > OTOH, the 5E5 is a great amp too.
> >
> > That's what I hear. What I can't seem to find out, though, is how the
> > 5E5 (cathode-biased) sounds different from the 5E5-A (fixed bias). Or
> > a description of how the 5E5 Pro is different in character from a
> > 5F6-A Bassman. The Fender Field Guide should have a section
> > describing the sound of these amps.
>
> *in general*, cathode biased amps sound a little "sweeter", perhaps a
> bit more compressed and less clean headroom. The 5E5 (non-A) also has no
> NFB loop which would also aid earlier breakup. The 5E5-A has a presence
> control in the NFB loop which will give you some control over the upper
> midrange Fixed bias amps sound tighter and you can get more power out
> of it.
Since I'm using a 5E3 chassis, I don't have the extra hole for a
Presence pot. (Or for separate Bass and Treble pots, for that
matter.) Would the 5E5-A circuit be workable without the NFB/Presence
circuit and a single Tone control? If not, I'll just stick to the 5E5
schematic, since it has the same Tone/Volume/Volume pot layout as the
5E3.
> The 5F6 Bassman has a totally different tone stack...separate bass and
> treble for more tonal variation. It really is an entirely different
> beast. The choice between the three amps depends entirely on your
> tastes. I would suppose the 5E5 (non-A) is somewhat like a 5E3 on a
> small amount of steroids. A little more clean headroom than the Deluxe.
> The -A version will have more clean headroom yet and a tighter sound.
> The Bassman gives you more kinds of sounds (3 tone controls). Of course
> the speaker complement is hugely different for the two amps..
The reason I started on this 5E3/5E5 project is that, a couple of
years ago, I played through a vintage '59 Bassman. It sounded
fantastic, of course, but I wanted to see if I could get close to the
Bassman tone in a smaller package. That's why I chose the Tweed Deluxe
project, and then decided to use the 5E5 power section for a little
more clean headroom.
Then, when I studied the schematics a little more, I realized that the
5E5-A, being a fixed-bias circuit, might sound a little more like the
Bassman than a 5E3 or 5E5. This was conjecture, of course. It would
have been great to have had someone around to tell me either (1) "The
5E5 will sound nothing at all like the Bassman", or (2) "The 5E5 will
sound enough like the Bassman that you won't be disappointed". Or
perhaps (3) "If you use a choke instead of the 2500 ohm resistor in
the 5E5, you'll get closer to a Bassman sound". But alas, I've been
pretty much left in the dark!
I actually prefer the sound of a Bassman with two 12" speakers,
instead of the normal 4 x 10" complement. It has a little better
definition in the low end. (However, I'm basing this comparison on a
Tweed Bassman reissue and a recent Fender Custom Shop Bassbreaker 2 x
12", so that might not be a valid assessment.)
> > What I think I'll do is gear the transformers for the 5E5, and not
> > worry about using 6V6's. I could then put in a switch that would
> > allow the amp to go from cathode-bias (5E5) to fixed-bias (5E5-A).
> > That's certainly feasible, as these two circuits use the same output
> > tubes and transformers.
>
> Perhaps so, but to ideally take advantage of the incease in power that
> fixed bias allows, you probably should have a higher voltage.
The voltage will vary somewhat depending on what transformer I choose.
Right now, I'm leaning toward using Dave Allen's Deluxe Reverb upgrade
transformer ($69), which is rated at 325-0-325 V (and 180ma).
> Crazy idea #2: Maybe switching rectifier tubes may do this...a 5AR4 for
> the fixed bias version and a 5U4 for cathode biased. Dunno if the
> difference in voltage will be right on the money, though.
I have three different rectifiers that I am going to try: a 5AR4, a
5R4GY, and a 5U4GB (stock), in decreasing order of voltage. I'll just
see how they sound, and pick one accordingly. (That's the great thing
about cathode bias: I won't have to adjust anything when I change
tubes.)
My power tubes are NOS Sylvania 6L6WGB's, so I don't think that I will
exceed their voltage ratings, no matter which rectifier I use.
If I bother with the switchable 5E5-A option, I will put in a bias
pot. (But without the space for the extra tone controls, I may forget
about the fixed biasing.)
> IMO, amps which have all sorts of switchable architecture really can
> only nail down one thing at a time. The absolute worst offender is the
> Mesa Triple Rectifier. You can switch output tube types and between
> tube and SS rectifier. Unfortunately, it'll only work best for one of
> the 4 possible configurations due to a non-optimized bias level. You
> may get it to operate OK for EL34s with a SS rect, but once you switch
> to a tube rect, it'll be biased WAY WAY cold. (sorry for the rant.)
The reason that the switchable 5E5/5E5-A option appealed to me is that
the 5E5 side is totally stock, and it should sound fine, and not need
any adjustment. Then I could set the bias on the 5E5-A side of the
switch, and that too should sound good once it's adjusted, and not
need to be adjusted each time I switch to the fixed-bias side. (As
long as I keep the rectifier the same, that is.)
The only problem is that I would need a 4-pole switch for all the
connections!
> > Another side question: Do you know how to substitute a 1N4007 diode
> > for a selenium rectifer in the 5E5-A? I have read that more than one
> > 1N4007 may be needed, but I can't find anything specific on the
> > subject.
>
> It's not necessary to series two diodes for the bias supply. If you are
> subbing a 1N4007 for a HV rectifier tube, you'll need to put 2 of them
> in series on each HV leg, but for a mere bias supply, the PIV is well in
> the range of a single diode.
So, you're saying that I just need to put a single 1N4007 diode where
the 5E5-A schematic has a selenium recitifier, and that's all. A
one-for-one substitution, correct?
(I don't know anything about the specs of the selenium rectifier
Fender used, so I'm a little unclear on how to use the diode.)
>>>>> Just a wild idea...what about just using the 5E5 supply resistor
values [*snip*]
I should have asked this before, but...when using a 5E3 preamp stage
and 5E5 output stage, do I need to change *both* power supply
resistors to the 5E5 spec? (Or just the 5000 ohm one?)
> Happy T'giving.
> --Mike
You too!
Mike Schway
> I now see that Doug Hoffman recommends connecting one 100 ohm resistor
> to each terminal of the pilot light socket (and then grounding the
> other ends). I supposed that's still wiring these resistors in series,
> even though they're in parallel with the pilot light.
Yup, it's just that the junction is connected to ground. This is the
standard arrangement. BTW, it can be done anywhere, but on old fenders,
it's convenient to do it at the lamp socket which is usually the first
place the filament supply goes.
>
> I'm going to use the balance resistors even if my PT has a grounded
> center tap--for the extra protection against power tube shorting.
If you do this, don't connect the center tap to ground.
> Since I'm using a 5E3 chassis, I don't have the extra hole for a
> Presence pot. (Or for separate Bass and Treble pots, for that
> matter.) Would the 5E5-A circuit be workable without the NFB/Presence
> circuit and a single Tone control? If not, I'll just stick to the 5E5
> schematic, since it has the same Tone/Volume/Volume pot layout as the
> 5E3.
You could, I suppose, just pick a value for a resistor and don't use the
pot. or just eliminate the feedback loop, but it will sound different.
> The reason I started on this 5E3/5E5 project is that, a couple of
> years ago, I played through a vintage '59 Bassman. It sounded
> fantastic, of course, but I wanted to see if I could get close to the
> Bassman tone in a smaller package. That's why I chose the Tweed Deluxe
> project, and then decided to use the 5E5 power section for a little
> more clean headroom.
>
> Then, when I studied the schematics a little more, I realized that the
> 5E5-A, being a fixed-bias circuit, might sound a little more like the
> Bassman than a 5E3 or 5E5. This was conjecture, of course. It would
> have been great to have had someone around to tell me either (1) "The
> 5E5 will sound nothing at all like the Bassman", or (2) "The 5E5 will
> sound enough like the Bassman that you won't be disappointed". Or
> perhaps (3) "If you use a choke instead of the 2500 ohm resistor in
> the 5E5, you'll get closer to a Bassman sound". But alas, I've been
> pretty much left in the dark!
>
> I actually prefer the sound of a Bassman with two 12" speakers,
> instead of the normal 4 x 10" complement. It has a little better
> definition in the low end. (However, I'm basing this comparison on a
> Tweed Bassman reissue and a recent Fender Custom Shop Bassbreaker 2 x
> 12", so that might not be a valid assessment.)
The Bassman is NOTHING like either the Pro or the Deluxe. Much more
headroom, perhaps a little brighter tone (but not as bright as a
blackface tone stack. If you want a bassman, build one. A Deluxe or
Pro isn't a "bassman with fewer knobs". It'll be a fine sounding amp,
but isn't really recommended for a first build.
BTW, I built a couple of 5F6A bassmen with 2-10s. They KILL!!! :-)
> > > Another side question: Do you know how to substitute a 1N4007 diode
> > > for a selenium rectifer in the 5E5-A? I have read that more than one
> > > 1N4007 may be needed, but I can't find anything specific on the
> > > subject.
> >
> > It's not necessary to series two diodes for the bias supply. If you are
> > subbing a 1N4007 for a HV rectifier tube, you'll need to put 2 of them
> > in series on each HV leg, but for a mere bias supply, the PIV is well in
> > the range of a single diode.
>
> So, you're saying that I just need to put a single 1N4007 diode where
> the 5E5-A schematic has a selenium recitifier, and that's all. A
> one-for-one substitution, correct?
Yup. Just make sure the polarity is as per the prints.
>
> (I don't know anything about the specs of the selenium rectifier
> Fender used, so I'm a little unclear on how to use the diode.)
>
> >>>>> Just a wild idea...what about just using the 5E5 supply resistor
> values [*snip*]
>
> I should have asked this before, but...when using a 5E3 preamp stage
> and 5E5 output stage, do I need to change *both* power supply
> resistors to the 5E5 spec? (Or just the 5000 ohm one?)
I think just the 5K. Try it and see. It'll be easy enough to change
back.
Ether
> In article <c9d2eb15.03112...@posting.google.com>,
> et...@x-mail.net (Ether) wrote:
>
> > I now see that Doug Hoffman recommends connecting one 100 ohm resistor
> > to each terminal of the pilot light socket (and then grounding the
> > other ends). I supposed that's still wiring these resistors in series,
> > even though they're in parallel with the pilot light.
>
> Yup, it's just that the junction is connected to ground. This is the
> standard arrangement. BTW, it can be done anywhere, but on old fenders,
> it's convenient to do it at the lamp socket which is usually the first
> place the filament supply goes.
> >
> > I'm going to use the balance resistors even if my PT has a grounded
> > center tap--for the extra protection against power tube shorting.
>
> If you do this, don't connect the center tap to ground.
Right.
>
> > Since I'm using a 5E3 chassis, I don't have the extra hole for a
> > Presence pot. (Or for separate Bass and Treble pots, for that
> > matter.) Would the 5E5-A circuit be workable without the NFB/Presence
> > circuit and a single Tone control? If not, I'll just stick to the 5E5
> > schematic, since it has the same Tone/Volume/Volume pot layout as the
> > 5E3.
>
> You could, I suppose, just pick a value for a resistor and don't use the
> pot. or just eliminate the feedback loop, but it will sound different.
I think I'll just wait on the 5E5-A circuit until I have another
chassis that will accomodate it.
[SNIP]
> The Bassman is NOTHING like either the Pro or the Deluxe. Much more
> headroom, perhaps a little brighter tone (but not as bright as a
> blackface tone stack. If you want a bassman, build one. A Deluxe or
> Pro isn't a "bassman with fewer knobs". It'll be a fine sounding amp,
> but isn't really recommended for a first build.
I just read a comment from a 5E5-A Tweed Pro listing on eBay that said
the 5E5-A sounded very similar in tone to a 5F6-A Bassman. (I
wouldn't expect a 5E5 to sound at all similar to the Bassman, of
course.) Have you ever heard a 5E5-A Pro?
The added headroom of the Bassman is at least partially due to the
fixed bias. The 5E5-A also uses fixed bias, so I would expect it to
have more headroom than the cathode-biased 5E5. (No?) The 5E5-A also
has a Presence control/NFB loop, as does the Bassman. There are so
many design similarities that I would find it odd it they *didn't*
sound something alike.
Anyway, the 5F6-A circuit will be my next project. (But I'm going to
use 2 x 12" alnico speakers in a Tweed Twin cabinet.)
> BTW, I built a couple of 5F6A bassmen with 2-10s. They KILL!!! :-)
What kind of speakers did you use? That's a lot of wattage to pour
into two 10's. And what sort of cabinet?
[SNIP]
> > So, you're saying that I just need to put a single 1N4007 diode where
> > the 5E5-A schematic has a selenium recitifier, and that's all. A
> > one-for-one substitution, correct?
>
> Yup. Just make sure the polarity is as per the prints.
I'll keep that in mind for my next 5E5-A or Tweed Bassman project.
Thanks.
> > I should have asked this before, but...when using a 5E3 preamp stage
> > and 5E5 output stage, do I need to change *both* power supply
> > resistors to the 5E5 spec? (Or just the 5000 ohm one?)
>
> I think just the 5K. Try it and see. It'll be easy enough to change
> back.
Looking at the schematic, you must be right. The 22k ohm power-supply
resistor mainly affects the preamp. (Anyone else out there with a
definitive word?)
Thanks for your patience, Mike!
--E
Mike Schway
et...@x-mail.net (Ether) wrote:
>
> I just read a comment from a 5E5-A Tweed Pro listing on eBay that said
> the 5E5-A sounded very similar in tone to a 5F6-A Bassman. (I
> wouldn't expect a 5E5 to sound at all similar to the Bassman, of
> course.) Have you ever heard a 5E5-A Pro?
I haven't heard one, but since the tone controls are way different, I
doubt they sound that similar.
>
> The added headroom of the Bassman is at least partially due to the
> fixed bias. The 5E5-A also uses fixed bias, so I would expect it to
> have more headroom than the cathode-biased 5E5. (No?) The 5E5-A also
> has a Presence control/NFB loop, as does the Bassman. There are so
> many design similarities that I would find it odd it they *didn't*
> sound something alike.
But the tone stack is different. Also the way the NFB and presence works
in the pro is very different than the Bassman. The P/I is also very
different. It's a Cathodyne on the Pro and a Long Tail on the bassman.
I would expect the Bassman to have more headroom than the Pro, and any
distortion in the Bassman will be from the output tubes and not
necessarily from the p/i.
>
> Anyway, the 5F6-A circuit will be my next project. (But I'm going to
> use 2 x 12" alnico speakers in a Tweed Twin cabinet.)
>
> > BTW, I built a couple of 5F6A bassmen with 2-10s. They KILL!!! :-)
>
> What kind of speakers did you use? That's a lot of wattage to pour
> into two 10's. And what sort of cabinet?
Weber C10N (now called 10F150). Actually, I used a "mismatched"
pair...one C10N and one C10N-Q. The Q cone has a little more high end,
but the same voice coil. The cabinet is a Tweed cabinet built by Rick
Sisney of Tulsa. Rick builds GREAT cabinets.
Best-
--Mike
Recruiterman
news:c9d2eb15.03112...@posting.google.com...
> I now see that Doug Hoffman recommends connecting one 100 ohm resistor
> to each terminal of the pilot light socket (and then grounding the
> other ends). I supposed that's still wiring these resistors in series,
> even though they're in parallel with the pilot light.
>
> I'm going to use the balance resistors even if my PT has a grounded
> center tap--for the extra protection against power tube shorting.
Using the 2 - 100 ohm resistors is a smart move. Even if my PT's have a CT,
I'll just tape it off and coil it out of the way and will still use the 2 -
100 ohm resistors to create an artificial CT. I was checking some voltages
on my power tubes, and was using the standard probes instead of my insulated
alligator clips, as I was just going to do a few quick reads. I must have
had too much coffee or something because my probe accidentally touched an
adjacent pin, and a nice arc (fire) developed, along with a bit of a
"sizzle" sound. Those 2 - 1/2 watt carbon comps that I had set up as the
artificial CT started to smoke, then burnt in half, within just a second or
two. Those 2 resistors saved my PT. If they weren't there, I'd probably be
replacing a $50.00 PT instead of .50c worth of resistors.
> > > > OTOH, the 5E5 is a great amp too.
> > >
> > > That's what I hear. What I can't seem to find out, though, is how the
> > > 5E5 (cathode-biased) sounds different from the 5E5-A (fixed bias). Or
> > > a description of how the 5E5 Pro is different in character from a
> > > 5F6-A Bassman. The Fender Field Guide should have a section
> > > describing the sound of these amps.
Obviously, the best thing would be to hear them for yourself. But, to give
you an overall idea, cathode biased amps generally sound more compressed,
they tend to give the smooth, singing type tones and overdrive. They're less
efficient (about 30%) than fixed biased amps, so the volume will go down.
You'll be cranking the volume to get the same volume level, which will then
give you more overdrive. I personally like both cathode biased amps, as well
as fixed biased, they both have their place and different tones. Fixed
biased amps are more efficient, usually offer more volume, and generally
offer more clean punch and/or headroom. If you build the 5E5-A circuit, you
can set the amp up to switch between the fixed bias and cathode bias.
Hopefully, you'll be using a 3-prong grounded AC cord, so you won't need the
"ground" switch in the chassis. You can use that location to wire in a
cathode-bias/fixed-bias switch instead. Then, you'll be able to switch
between both modes and hear the differences for yourself.
> Since I'm using a 5E3 chassis, I don't have the extra hole for a
> Presence pot. (Or for separate Bass and Treble pots, for that
> matter.) Would the 5E5-A circuit be workable without the NFB/Presence
> circuit and a single Tone control? If not, I'll just stick to the 5E5
> schematic, since it has the same Tone/Volume/Volume pot layout as the
> 5E3.
The 5E5 and the 5E3 are basically the same circuit, there's a few minor
resistor values that are different, and there's an extra 16uF electrolytic
in parallel with another on the 5E5 to create 32uF of B+ filtration for the
first stage. The 5E5 rectifier is a 5U4, the tubes are 6L6's and the PT
would be larger as well, so the extra first stage filtration is needed. But
otherwise, the circuits themselves are almost the same. There is also an
additional preamp tube in the 5E5. Both inputs of channel 1 run directly
into V1a & b, and channel 2's inputs have V2a & b, looks like the preamp
tubes are running in parallel. If you have a 5E3 chassis, you have holes for
only 2 preamp tubes, and the 5E5 requires 3, so you would have to drill an
additional hole to accomodate the additional preamp tube. It would probably
be better/easier to use the 5E3 circuit, and just beef it up more like the
5E5, to be able to handle a higher voltage PT, 6L6's and the 5U4 rectifier.
You could probably replace the first 16uF cap with a 40uF, since you don't
have the layout on the 5E3 board to parallel 2 - 16uF's for the first stage.
You may also want to consider removing the 5K power resistor connecting the
first and second power cap stage, and inserting a choke in it's place. A
choke, IMHO, gives smoother tones, smoother overdrive. Lot's of guys seem to
like adding a choke in the 5E3 circuits.
The 5E5-A circuit is workable without the feedback circuit. Disconnecting
the feedback will increase the volume of the amp, and will definitely
improve the "fidelity" of the amp, giving up much more harmonics, but it
will be somewhat uncontrollable/raw. I initially used the ground switch,
which is unused on the DRRI, to disconnect the negative feedback loop in my
rebuilt DRRI, and when I removed the feedback, the volume increases and the
harmonics are jumping. The amp feels more "alive" and responsive, but it is
uncontrollable and somewhat "raw". Eventually, I inserted a 100KL pot in
series with the loop, so that I can dial in exactly how much negative
feedback I want, this has been referred to elsewhere as a "soul" switch.
Also, you don't even need a Presence pot to get Presence. If you want to add
Presence to an amp that has negative feedback, but no Presence pot, locate
the negative feedback resistor. That resistor will connect to another
resistor that goes to ground. Place a 1uF/250V cap across/parallel to that
resistor. That will act like a Presence pot that's turned all the way up. I
didn't have a 1uF cap at the time, so I used a .68/250V cap on mine, so it's
like a Presence pot that's a little more than halfway up. You can try
different cap values to "season" your Presence to your personal taste.
> The reason I started on this 5E3/5E5 project is that, a couple of
> years ago, I played through a vintage '59 Bassman. It sounded
> fantastic, of course, but I wanted to see if I could get close to the
> Bassman tone in a smaller package. That's why I chose the Tweed Deluxe
> project, and then decided to use the 5E5 power section for a little
> more clean headroom.
I'm currently doing a scratch build of a 5F6 59' Bassman. I picked up a 4x10
custom Tweed Cab loaded with Jensen P10R's at a really good price on eBay.
If you want to get the 59' Bassman tone in a smaller package, why don't you
just consider building the 5F6 circuit, and get a smaller cab with either
2x10's or 2x12's? You can get a smaller PT and OT if you want lower power,
but IMHO, it would be a much more cleaner build and much easier to go this
route, than to try to combine various circuits from different amps to try to
accomplish the same thing. There's much more probability of having problems
and troubleshooting nightmares when you start messing around with combining
this circuit and that circuit. I would suggest that you start with the
proven design of the 5F6, and just get a smaller cab and lower power PT and
OT. I think you'll be much happier going this route in the long run.
> Then, when I studied the schematics a little more, I realized that the
> 5E5-A, being a fixed-bias circuit, might sound a little more like the
> Bassman than a 5E3 or 5E5. This was conjecture, of course. It would
> have been great to have had someone around to tell me either (1) "The
> 5E5 will sound nothing at all like the Bassman", or (2) "The 5E5 will
> sound enough like the Bassman that you won't be disappointed". Or
> perhaps (3) "If you use a choke instead of the 2500 ohm resistor in
> the 5E5, you'll get closer to a Bassman sound". But alas, I've been
> pretty much left in the dark!
There's numerous differences between the 5E5-A and the 5F6 Bassman circuit.
Just because a circuit is fixed biased, doesn't mean that it's going to
sound like another circuit that's also fixed biased. The layout/design of
the circuit, cap values, resistor values, type of PT, type of OT, type of
rectifier, etc. all contribute to the final tone's of the amp, as well as
the type/size of the cab and speakers used. Instead of trying to take a
circuit that's not a Bassman, and trying to make it a Bassman (like trying
to put a round peg through a square hole), why don't you just build the
Bassman circuit, put it in a 5F6 chassis, get lower powered PT and OT if you
want, and a smaller cab with 2 speakers. THAT will probably be the closest
that you're going to come to getting the tone's that you want. Without have
the 4x10's, it won't sound exactly like the 59' version, but it will be as
close as you probably can get. At least you'll be using the SAME circuit of
the amp who's tone's you're trying to cop. My .02
Mikey
>
Ether
[5E5-A Tweed Pro vs. 5F6-A Bassman discussion]
> But the tone stack is different. Also the way the NFB and presence works
> in the pro is very different than the Bassman. The P/I is also very
> different. It's a Cathodyne on the Pro and a Long Tail on the bassman.
> I would expect the Bassman to have more headroom than the Pro, and any
> distortion in the Bassman will be from the output tubes and not
> necessarily from the p/i.
I see. Thanks for pointing out the pertinent design differences.
By the way, do you know how the term "Long Tail" came about? What does
it refer to? (I assume it has to do with the extra 12AX7 in the
Bassman preamp stage.)
> > > BTW, I built a couple of 5F6A bassmen with 2-10s. They KILL!!! :-)
> >
> > What kind of speakers did you use? That's a lot of wattage to pour
> > into two 10's. And what sort of cabinet?
>
> Weber C10N (now called 10F150). Actually, I used a "mismatched"
> pair...one C10N and one C10N-Q. The Q cone has a little more high end,
> but the same voice coil. The cabinet is a Tweed cabinet built by Rick
> Sisney of Tulsa. Rick builds GREAT cabinets.
The 10's would sure be easier to carry around...
I was thinking of ordering a Weber 12F150T (the old C12NQ) for my amp,
but I ended up acquiring a few other used speakers, including a Weber
Chicago. (I did order my 5E3 chassis From Ted Weber, and he has been
very responsive and helpful.) I have a Jensen P12Q with a ratty cone
that will be heading to Weber VST as soon as the snowstorm lifts!
It's great to have people like him around.
Now I've gone and bought an early silverface Pro Reverb chassis
(non-master volume), so I've got yet another project to work on.
Thanks again for your brain time.
Ether
> Using the 2 - 100 ohm resistors is a smart move. Even if my PT's have a CT,
> I'll just tape it off and coil it out of the way and will still use the 2 -
> 100 ohm resistors to create an artificial CT. I was checking some voltages
> on my power tubes, and was using the standard probes instead of my insulated
> alligator clips, as I was just going to do a few quick reads. I must have
> had too much coffee or something because my probe accidentally touched an
> adjacent pin, and a nice arc (fire) developed,
Wow--good thing I don't drink coffee!
> > > > > OTOH, the 5E5 is a great amp too.
> > > >
> > > > That's what I hear. What I can't seem to find out, though, is how the
> > > > 5E5 (cathode-biased) sounds different from the 5E5-A (fixed bias). Or
> > > > a description of how the 5E5 Pro is different in character from a
> > > > 5F6-A Bassman. The Fender Field Guide should have a section
> > > > describing the sound of these amps.
>
> Obviously, the best thing would be to hear them for yourself.
True. But I seem to have a hard time finding vintage Fender Tweeds at
my local Guitar Center! (But they did have a few old tweed Champs.)
> But, to give
> you an overall idea, cathode biased amps generally sound more compressed,
> they tend to give the smooth, singing type tones and overdrive. They're less
> efficient (about 30%) than fixed biased amps, so the volume will go down.
> You'll be cranking the volume to get the same volume level, which will then
> give you more overdrive. I personally like both cathode biased amps, as well
> as fixed biased, they both have their place and different tones. Fixed
> biased amps are more efficient, usually offer more volume, and generally
> offer more clean punch and/or headroom.
That's as good and succinct a summary as I've read on the subject.
> If you build the 5E5-A circuit, you
> can set the amp up to switch between the fixed bias and cathode bias.
I was thinking about that, and it would require something like a
4-position dual-throw switch. The cathode-bias / fixed-bias switch
would have to:
1) Remove the 250 ohm cathode bias resistor (and 25-25 cap) from the
circuit.
2) Ground the cathodes of the power tubes.
3) Lift the junction of the two 220k ohm screen grid resistors
from ground.
4) Connect the bias circuit to the junction of the two 220k ohm
resistors.
5) Connect the bias ciruit to ground. (Or maybe it could just be left
grounded even while in cathode-bias mode?)
> Hopefully, you'll be using a 3-prong grounded AC cord, so you won't need the
> "ground" switch in the chassis. You can use that location to wire in a
> cathode-bias/fixed-bias switch instead. Then, you'll be able to switch
> between both modes and hear the differences for yourself.
I'm using that position for a standby switch (which I will need if
using a 5AR4 rectifier). So I'd have to put the switch on the bottom
of the chassis by the power tubes.
> > Since I'm using a 5E3 chassis, I don't have the extra hole for a
> > Presence pot. (Or for separate Bass and Treble pots, for that
> > matter.) Would the 5E5-A circuit be workable without the NFB/Presence
> > circuit and a single Tone control? If not, I'll just stick to the 5E5
> > schematic, since it has the same Tone/Volume/Volume pot layout as the
> > 5E3.
>
> The 5E5 and the 5E3 are basically the same circuit, there's a few minor
> resistor values that are different, and there's an extra 16uF electrolytic
> in parallel with another on the 5E5 to create 32uF of B+ filtration for the
> first stage. The 5E5 rectifier is a 5U4, the tubes are 6L6's and the PT
> would be larger as well, so the extra first stage filtration is needed. But
> otherwise, the circuits themselves are almost the same.
Yes--I noticed that very quickly. So, if using the 5E3 preamp stage
and the 5E5 power stage, do you have to change the 22k resistor to the
5E5 value (10k), or do you leave it as is because you still only have
one preamp tube.
> There is also an
> additional preamp tube in the 5E5. Both inputs of channel 1 run directly
> into V1a & b, and channel 2's inputs have V2a & b, looks like the preamp
> tubes are running in parallel.
Great if you have two guitars plugged in at the same time, I suppose.
Each gets its own preamp tube. But if you've only got one guitar
plugged in, it's extraneous.
> If you have a 5E3 chassis, you have holes for
> only 2 preamp tubes, and the 5E5 requires 3, so you would have to drill an
> additional hole to accomodate the additional preamp tube.
Nah. I have been told that the extra 12AY7 would just add more noise,
which makes sense to me, so I'm going to stick with the single 12AY7
in the 5E3 preamp stage.
> It would probably
> be better/easier to use the 5E3 circuit, and just beef it up more like the
> 5E5, to be able to handle a higher voltage PT, 6L6's and the 5U4 rectifier.
> You could probably replace the first 16uF cap with a 40uF, since you don't
> have the layout on the 5E3 board to parallel 2 - 16uF's for the first stage.
That's what I was thinking. The second power stage resistor in the
5E3 circuit is the one I still have questions about in this kind of
mod.
By the way: Would a 22uf cap as in the *preamp* power filter position
change the way the amp sounds (versus the schematic's 16uf cap)? I
notice that Bruce Collins' "Tweedy Deluxe" keeps this cap at 15uf
while using higher values in the other filter positions. (I already
have some 22uf 450V caps.)
> You may also want to consider removing the 5K power resistor connecting the
> first and second power cap stage, and inserting a choke in it's place. A
> choke, IMHO, gives smoother tones, smoother overdrive. Lot's of guys seem to
> like adding a choke in the 5E3 circuits.
I keep hearing different opinions on the choke issue. Doug Hoffman's
website recommends a choke, saying it "tightens up the sound", and
others say you really can't hear the difference. I'd love to hear from
someone who has actually tried it both ways. (Have you?)
> The 5E5-A circuit is workable without the feedback circuit. Disconnecting
> the feedback will increase the volume of the amp, and will definitely
> improve the "fidelity" of the amp, giving up much more harmonics, but it
> will be somewhat uncontrollable/raw.
I'm afraid that might make the amp somewhat less versatile.
[snip]
> Also, you don't even need a Presence pot to get Presence. If you want to add
> Presence to an amp that has negative feedback, but no Presence pot, locate
> the negative feedback resistor. That resistor will connect to another
> resistor that goes to ground. Place a 1uF/250V cap across/parallel to that
> resistor.
Do you mean 1uf or .1uf (point-one uf)? I'm just confused because the
Presence control in the 5E5-A and other tweeds has a 5k ohm pot with a
.1uf cap leading from it to ground.
So, you're saying that if that 5k pot and .1 uf cap weren't there to
begin with, the *next* resistor (1500 ohm in the 5E5-A, with one leg
attached to the cathode of the PI) is the one you bridge with the 1uf
cap. Right?
> That will act like a Presence pot that's turned all the way up. I
> didn't have a 1uF cap at the time, so I used a .68/250V cap on mine, so it's
> like a Presence pot that's a little more than halfway up. You can try
> different cap values to "season" your Presence to your personal taste.
Sounds reasonable. Or I could solder a miniture pot inside the
chassis so it would be more easily adjustable.
[snip]
> I'm currently doing a scratch build of a 5F6 59' Bassman. I picked up a 4x10
> custom Tweed Cab loaded with Jensen P10R's at a really good price on eBay.
> If you want to get the 59' Bassman tone in a smaller package, why don't you
> just consider building the 5F6 circuit, and get a smaller cab with either
> 2x10's or 2x12's? You can get a smaller PT and OT if you want lower power,
> but IMHO, it would be a much more cleaner build and much easier to go this
> route, than to try to combine various circuits from different amps to try to
> accomplish the same thing. There's much more probability of having problems
> and troubleshooting nightmares when you start messing around with combining
> this circuit and that circuit.
Yeah. This all started when I went out and bought a Tweed Deluxe
chassis before I knew at all what I was doing. But the 5E3-to-5E5 mod
is simple enough, and not radical at all, so that's probably what I'll
do.
> I would suggest that you start with the
> proven design of the 5F6, and just get a smaller cab and lower power PT and
> OT. I think you'll be much happier going this route in the long run.
Sounds like good advice.
By the way: I notice that there are only three differences between
the 5F6 and the 5F6-A:
1) A 25-25 cap added to the 820 resistor between the 12AX7 cathode and
ground.
2) 100 ohm screen-stopper resistors on the power tubes of the 5F6
versus 470
ohm resistors in the 5F6-A.
3) An "83" rectifier in the 5F6 versus the 5AR4/GZ34 in the 5F6-A.
I wonder how much of a difference those slight changes made. (Other
than the health issue: the 83 is a mercury-vapor rectifier, which
would be hazardous if it broke. Nothing like being an amp tech in the
1950's, with all that selenium and mercury!)
[snip]
> There's numerous differences between the 5E5-A and the 5F6 Bassman circuit.
> Just because a circuit is fixed biased, doesn't mean that it's going to
> sound like another circuit that's also fixed biased. The layout/design of
> the circuit, cap values, resistor values, type of PT, type of OT, type of
> rectifier, etc. all contribute to the final tone's of the amp, as well as
> the type/size of the cab and speakers used.
Ok. Good points.
I would love to see someone do a writeup, though, of a comparison of
all the Tweed-era amps, and what they sound like relative to each
other. That would be a really useful resource for future amp
hobbyists. The available amp books tend to leave out models like the
5E5-A Pro.
> Instead of trying to take a
> circuit that's not a Bassman, and trying to make it a Bassman (like trying
> to put a round peg through a square hole), why don't you just build the
> Bassman circuit, put it in a 5F6 chassis, get lower powered PT and OT if you
> want, and a smaller cab with 2 speakers. THAT will probably be the closest
> that you're going to come to getting the tone's that you want.
As I mentioned earlier, I recently played through a Fender Custom Shop
"Bass Breaker", which is a reissue '59 Bassman with two 12" Celestion
Vintage 30 speakers. It sounded great--much better than the 4 x 10"
Bassman reissue, which sounded thin in comparison. So I'm thinking
that a 5F6-A chassis in a Tweed Twin cabinet is what I'm after.
> Without have
> the 4x10's, it won't sound exactly like the 59' version, but it will be as
> close as you probably can get. At least you'll be using the SAME circuit of
> the amp who's tone's you're trying to cop. My .02
>
> Mikey
Thanks for your brief note! Just kidding -- I appreciate the effort
you put into this response.
--E
Stephen Cowell
...
> By the way, do you know how the term "Long Tail" came about? What does
> it refer to? (I assume it has to do with the extra 12AX7 in the
> Bassman preamp stage.)
nope... it's the design of the PI. Read up on it at
Aiken's page, well worth the effort:
http://www.aikenamps.com/LongTailPairDesign.htm
Plenty of more stuff out there on the subject...
__
Steve
.
Recruiterman
> "Recruiterman" <recrui...@comcast.net> wrote in message
news:<yZadnS0VYLm...@comcast.com>...
> > Using the 2 - 100 ohm resistors is a smart move. Even if my PT's have a
CT,
> > I'll just tape it off and coil it out of the way and will still use the
2 -
> > 100 ohm resistors to create an artificial CT. I was checking some
voltages
> > on my power tubes, and was using the standard probes instead of my
insulated
> > alligator clips, as I was just going to do a few quick reads. I must
have
> > had too much coffee or something because my probe accidentally touched
an
> > adjacent pin, and a nice arc (fire) developed,
>
> Wow--good thing I don't drink coffee!
Coffee and I are very good friends! But, your hands can still shake a bit,
or you could still accidentally touch 2 pins of the power tube socket, and
whamo! Also, the tube itself can have a short. Regardless, the 2 - 100R
resistors are nice insurance.
> > But, to give
> > you an overall idea, cathode biased amps generally sound more
compressed,
> > they tend to give the smooth, singing type tones and overdrive. They're
less
> > efficient (about 30%) than fixed biased amps, so the volume will go
down.
> > You'll be cranking the volume to get the same volume level, which will
then
> > give you more overdrive. I personally like both cathode biased amps, as
well
> > as fixed biased, they both have their place and different tones. Fixed
> > biased amps are more efficient, usually offer more volume, and generally
> > offer more clean punch and/or headroom.
>
> That's as good and succinct a summary as I've read on the subject.
I've been doing a lot of mods and tweaks to my rebuilt DRRI. I used the
"unused" ground switch and made it into a cathode bias/fixed bias switch, so
that I could switch back and forth. With my particular AB763 circuit, this
was a pretty complex mod. My tremolo circuit pulsates the bias of the power
tubes, rather than using the optoisolator "roach". If my switch was wired up
the standard way, I would lose my tremolo, as it's tied into the fixed bias
circuit. I was fortunate to pick up a killer way to install this switch/do
the mod, and still keep my pulsating tremolo from Kevin O'Connor. THAT man,
KNOWS his shit!
> > If you build the 5E5-A circuit, you
> > can set the amp up to switch between the fixed bias and cathode bias.
>
> I was thinking about that, and it would require something like a
> 4-position dual-throw switch. The cathode-bias / fixed-bias switch
> would have to:
>
> 1) Remove the 250 ohm cathode bias resistor (and 25-25 cap) from the
> circuit.
> 2) Ground the cathodes of the power tubes.
> 3) Lift the junction of the two 220k ohm screen grid resistors
> from ground.
> 4) Connect the bias circuit to the junction of the two 220k ohm
> resistors.
> 5) Connect the bias ciruit to ground. (Or maybe it could just be left
> grounded even while in cathode-bias mode?)
I suggest that you use a higher voltage cap than the 25/25 that you mention,
like a 50 or 100 volt cap. I've found, with most brands of electrolytics,
that there's usually no price difference between a 25/50 and a 25/25.
> > Hopefully, you'll be using a 3-prong grounded AC cord, so you won't need
the
> > "ground" switch in the chassis. You can use that location to wire in a
> > cathode-bias/fixed-bias switch instead. Then, you'll be able to switch
> > between both modes and hear the differences for yourself.
> I'm using that position for a standby switch (which I will need if
> using a 5AR4 rectifier). So I'd have to put the switch on the bottom
> of the chassis by the power tubes.
Check out this link: http://www.westlabs.com/Switches.HTML West has a
Double Pole Triple Throw Progressive switch that you can use for power
on/off and also for standby. You'll be able to get all 3 functions with 1
switch, 1 hole. Now, you can use the ground switch for the cathode/fixed
bias switch.
>> > The 5E5 and the 5E3 are basically the same circuit, there's a few minor
> > resistor values that are different, and there's an extra 16uF
electrolytic
> > in parallel with another on the 5E5 to create 32uF of B+ filtration for
the
> > first stage. The 5E5 rectifier is a 5U4, the tubes are 6L6's and the PT
> > would be larger as well, so the extra first stage filtration is needed.
But
> > otherwise, the circuits themselves are almost the same.
>
> Yes--I noticed that very quickly. So, if using the 5E3 preamp stage
> and the 5E5 power stage, do you have to change the 22k resistor to the
> 5E5 value (10k), or do you leave it as is because you still only have
> one preamp tube.
My initial thought would be to stick with the 22K, but I didn't see any
voltages listed on the 5E3 layout or schematic, so I'm not totally sure at
this point. Those power resistors are dropping the voltage that leads to the
preamp stages. The plate resistors are further dropping the voltage to the
preamp tube. Maybe one of the other guys have done a build similar to this
and can chime in.
> By the way: Would a 22uf cap as in the *preamp* power filter position
> change the way the amp sounds (versus the schematic's 16uf cap)? I
> notice that Bruce Collins' "Tweedy Deluxe" keeps this cap at 15uf
> while using higher values in the other filter positions. (I already
> have some 22uf 450V caps.)
Not anything noticable, if at all. Those values are pretty close together.
You may find that you get a bit more solid low end. I used 20uF/500V Atoms
in my 5E3 circuit. Now, if you went from a 16uF to a 40 or 50uF, then that's
another story, but in your case, no biggie.
> > You may also want to consider removing the 5K power resistor connecting
the
> > first and second power cap stage, and inserting a choke in it's place. A
> > choke, IMHO, gives smoother tones, smoother overdrive. Lot's of guys
seem to
> > like adding a choke in the 5E3 circuits.
>
> I keep hearing different opinions on the choke issue. Doug Hoffman's
> website recommends a choke, saying it "tightens up the sound", and
> others say you really can't hear the difference. I'd love to hear from
> someone who has actually tried it both ways. (Have you?)
I've been down both of those roads and I prefer using a choke. It's a
personal preference. Either way will work, but it's just like some guys
prefer fixed bias and some like cathode biased amps, that kinda thing. I do
agree with Doug in that it does seem to "tighten up the sound", but I
noticed a bigger difference in the "feel" of the amp. I don't think anyone
in the audience is going to be able to tell whether you used a choke or a
5K, but you probably will. LOL. I view the amp as an instrument unto
itself. It's 1/2 of the tonal equation, IMHO. Personally, when I play, I
notice not only the tones that I'm getting from the amp, but also the "feel"
that I'm getting. Just like your guitar sounds a certain way, but, it also
"feels" a certain way as well. There's a variety of things going on here,
not just the tones. The "feel" (response) of an amp is just as important to
me as the tones, just like the feel of my guitar is just as important as the
guitar tones.
> > The 5E5-A circuit is workable without the feedback circuit.
Disconnecting
> > the feedback will increase the volume of the amp, and will definitely
> > improve the "fidelity" of the amp, giving up much more harmonics, but it
> > will be somewhat uncontrollable/raw.
>
> I'm afraid that might make the amp somewhat less versatile.
Being able to switch between having feedback/not having feedback gives you
two options, which is 1 more option that you had before. It's more
versatile, not less. Put a pot in, instead of the switch, and then you'll be
able to adjust the negative feedback, which is way versatile.
> > Also, you don't even need a Presence pot to get Presence. If you want to
add
> > Presence to an amp that has negative feedback, but no Presence pot,
locate
> > the negative feedback resistor. That resistor will connect to another
> > resistor that goes to ground. Place a 1uF/250V cap across/parallel to
that
> > resistor.
>
> Do you mean 1uf or .1uf (point-one uf)? I'm just confused because the
> Presence control in the 5E5-A and other tweeds has a 5k ohm pot with a
> .1uf cap leading from it to ground.
1uF. I was confused myself at first, as the layout does show a .1uF
connected to the pot. I've checked with several different sources of mods
and they all suggest 1uF. I have a .68uF in mine, as I didn't have a 1uF at
the time.
> So, you're saying that if that 5k pot and .1 uf cap weren't there to
> begin with, the *next* resistor (1500 ohm in the 5E5-A, with one leg
> attached to the cathode of the PI) is the one you bridge with the 1uf
> cap. Right?
That would be the one. One leg of the cap at the intersection of the 1.5K
and 100K, the other leg to ground with the 1.5K.
> > That will act like a Presence pot that's turned all the way up. I
> > didn't have a 1uF cap at the time, so I used a .68/250V cap on mine, so
it's
> > like a Presence pot that's a little more than halfway up. You can try
> > different cap values to "season" your Presence to your personal taste.
>
> Sounds reasonable. Or I could solder a miniture pot inside the
> chassis so it would be more easily adjustable.
You could do that.
> > I would suggest that you start with the
> > proven design of the 5F6, and just get a smaller cab and lower power PT
and
> > OT. I think you'll be much happier going this route in the long run.
>
> Sounds like good advice.
I've spent a good portion of my time on this planet doing things the hard
way. I've learned that sometimes, actually many times, that simpler/easier
can be better. Simple is good.
> By the way: I notice that there are only three differences between
> the 5F6 and the 5F6-A:
>
> 1) A 25-25 cap added to the 820 resistor between the 12AX7 cathode and
> ground.
> 2) 100 ohm screen-stopper resistors on the power tubes of the 5F6
> versus 470
> ohm resistors in the 5F6-A.
> 3) An "83" rectifier in the 5F6 versus the 5AR4/GZ34 in the 5F6-A.
>
> I wonder how much of a difference those slight changes made. (Other
> than the health issue: the 83 is a mercury-vapor rectifier, which
> would be hazardous if it broke. Nothing like being an amp tech in the
> 1950's, with all that selenium and mercury!)
Just some tweaks, updates, just like software comes out with improvements
and updates. It's not necessarily a new design, but it just may be some
things that they found would work better or offer more protection (such as
using the 470R resistors instead of the 100R).
> I would love to see someone do a writeup, though, of a comparison of
> all the Tweed-era amps, and what they sound like relative to each
> other. That would be a really useful resource for future amp
> hobbyists. The available amp books tend to leave out models like the
> 5E5-A Pro.
The book, "Fender Amps, the First Fifty Years", by John Teagle and John
Sprung. Check out page 55, talks about the 5E5 and 5E5-A.
> As I mentioned earlier, I recently played through a Fender Custom Shop
> "Bass Breaker", which is a reissue '59 Bassman with two 12" Celestion
> Vintage 30 speakers. It sounded great--much better than the 4 x 10"
> Bassman reissue, which sounded thin in comparison. So I'm thinking
> that a 5F6-A chassis in a Tweed Twin cabinet is what I'm after.
That sounds like a winning combination. I've thought of doing that one
myself on numerous occasions. I just might have to add that one to my
project list!
> Thanks for your brief note! Just kidding -- I appreciate the effort
> you put into this response.
>
> --E
No problem. I hope I was able to help in some way.
Mikey