EPI Valve Jr. Question

[Grip]

Picking up a like new Valve Jr. + Valve Jr 1X12 extention cab +
Digitecj rp 205 tomorrow lock, stock & barrell for 75 smackers. In the
event I don't just love it stock, what are some the mode you guys have
done and liked? The digitech will hit CL fast.

[Tony Done]

Here's a good link for Epi VJ mods:

http://duhvoodooman.com/VJr/VJr_mods.htm

Mine was a first series, and had mods done for noise reduction,
including a rectifier for the heater circuit, grounding, bigger caps
etc, plus a 12dB cut L-pad. I also included the bright mod shown in
the link, but with two different caps on a 3-way switch. I then added
another bright switch to bleed treble across the volume pot, also with
two different caps and bypass. All the mods were IMO well worth doing,
and the second bright switch acts as a drive/boost switch on the big
cap, very nice if you want a really bright acoustic-like sound with a
little grit.

I'm now contemplating installing a master volume, as suggested by RS.

Tony D

[Grip]

Sounds like I'll have to determine first which series it is, thanks
for the link.....there seem to be so many mod opps out there which is
why I decided tapping other players' hands reviews on was best :-)

[Lord Valve]

I get several people a week with sheaves of printouts gleaned from one
mod-freak site or another...

They read all this shit about how this or that mod
sounds, and they pick five or six of 'em and want
'em all done at the same time. I usually refuse.

I tell them the truth: if you have a whole slew of
mods done at the same time and the amp ends
up sounding like ass - and you'd be surprised at
how often that happens - you won't know which
mod(s) to undo to unfuck your tone. My advice
is always the same: pick one or two, and I'll do
it/both, and if you don't like it, I can undo one or
the other and we'll see how it sounds then. And
I also let them know that the FIRST thing to try
is a decent speaker, because all those cheap-ass
Chinese amps come with horrible speakers. Sometimes,
a good speaker is all it takes; sometimes, it takes
more. Good tubes don't hurt, either...current Chinese
12AX7s` are terrible, as are their EL84s. (They do
make some excellent 6L6s and KT-66s, though...)

Lord Valve
Expert (wankers please whine long and loudly...)

[Grip]

> Expert (wankers please whine long and loudly...)- Hide quoted text -
>
> - Show quoted text -

Makes sense to me! First thing I plan to do is run the head through
various speakers indeed. I think along the lines of "if it ain't
broke, don't fix it", but after putting it through it's paces, decide
where any possible weaknesses are(to my ears) and do as you
suggest.....one ata time.....thanks:-)

[RichL]

"Grip" <mbe...@comcast.net> wrote in message
news:037aff0f-6fa8-475a...@ge5g2000vbb.googlegroups.com...

I've got the second version VJ head. So far it's stock (partly due to my
own laziness) but the only mod I'd contemplate is a bright switch. The amp
as is sounds too muddy with humbuckers. Overall it's a one-trick pony but
it does that trick very well. It's not an all-purpose amp.

Mine's the head version, I usually run it through the Celestion greenbacks
on my AC30, so I can't really talk about the quality of the VJ extension
cab. But speakers DO matter, my VJ sounds like ass played through my 1960a
Marshall cab.

[gonjah]

On 2/8/2012 8:57 AM, Lord Valve wrote:
> Grip wrote:
>
>> On Feb 7, 10:15 pm, Tony Done<tonyd...@bigpond.com> wrote:
>>> On Feb 8, 12:57 pm, Grip<mbe...@comcast.net> wrote:
>>>
>>>> Picking up a like new Valve Jr. + Valve Jr 1X12 extention cab +

>>>> Digitecj rp 205 tomorrow lock, stock& barrell for 75 smackers. In the

Sound advice.

[Tony Done]

"Lord Valve" wrote in message news:4F328D3F...@ix.netcom.com...

*****************

In my case there were three obvious problems to be addressed, too noisy, not
bright enough and not quiet enough with OD. Had I found a lot of comments on
better speakers I might have included that, although it would have meant
significant cost, while what I did do didn't cost me anything except some
time.

The second round of mods included even brighter, and better tubes, though I
can't remember what I ended up with.

A different speaker could help, and the original mods also included an 8-ohm
speaker out, which I forgot to mention. However, I haven't felt any urge to
try it yet. My amp tech mate Terry borrowed it for a while and didn't
suggest any further changes to improve tone apart from giving me a handful
of tubes to try, as mentioned above. FWIW, he did comment that the speaker
mounting appeared to be good deal better than the felt padding used in the
little Fender and Gretsch amps.

Tony D

[Grip]

On Feb 8, 2:22 pm, "Tony Done" <tonyd...@bigpond.com> wrote:
> "Lord Valve"  wrote in messagenews:4F328D3F...@ix.netcom.com...

> Tony D- Hide quoted text -

>
> - Show quoted text -

After bringing it home this morning, close examination, and some
research it turns out to be in A+ condition, the head is the version 3
model (black board and 4,8,16 ohm speaker outs) ...the cab has the
"Eminence: Inside" badge and loaded with an Eminence Lucky Lady 12".
The speaker sounds really pretty good, also paired the cab up with my
30 watt Boogie which liked it fine. Also tried the JRhead thru my fave
open backed Celestion 2X12.....nice.....Marshall 1960A, with open back
( I open the backs on all my cabs ), nice again.....The EPI + cab
together are a sort of one trick pony as someone mentioned, but VERY
good tonewise about 1\3 to 1\2 open, super responsive to "leaning"
into your strings for for breakup. With my pedal board in line it was
more versatile of course. Works very well also with the guitars'
volume knob. Demoed with an older strat plus w\Duncan JB Junior in
bridge. I'm gonna mess with it for a month or so before deciding
whether or not to mod, but FIRST think I'm gonna do is get rid of the
sovtek tubes that are in it..... could maybe see a bright switch added
later. It also came with some Monster cables and a Digitech RP 200
with expression pedal.....pedal will most likely hit CL and pretty
much foot the tab for all the rest.....got everything mentioned for
$75. so worth the risk:-)

[jimmy]

...and trouble-shooting 101.

[Jim]

On 2/7/2012 6:57 PM, Grip wrote:
> Picking up a like new Valve Jr. + Valve Jr 1X12 extention cab +

> Digitecj rp 205 tomorrow lock, stock& barrell for 75 smackers. In the

> event I don't just love it stock, what are some the mode you guys have
> done and liked? The digitech will hit CL fast.

I've done a bunch to mine, including the simple input resistor change, a
bright switch, a tone stack (with a switch for two values of the mids,
real estate is lacking), a Hammond 125ESE output transformer, my own
output circuit that uses an L-pad to drop output level and that engages
a dummy load with no speaker attached, with a line out so that you can
use it as an overdrive in front of another amp...

Best for you to start a new thread after playing (into as many speaker
options as you have available), noting what you like and don't like
about it.

[Jim]

On 2/8/2012 3:57 PM, Grip wrote:
> On Feb 8, 2:22 pm, "Tony Done"<tonyd...@bigpond.com> wrote:
>> "Lord Valve" wrote in messagenews:4F328D3F...@ix.netcom.com...
>> Grip wrote:
>>> On Feb 7, 10:15 pm, Tony Done<tonyd...@bigpond.com> wrote:
>>>> On Feb 8, 12:57 pm, Grip<mbe...@comcast.net> wrote:
>>
>>>>> Picking up a like new Valve Jr. + Valve Jr 1X12 extention cab +

>>>>> Digitecj rp 205 tomorrow lock, stock& barrell for 75 smackers. In the

I should've read more of the thread before posting...

> I'm gonna mess with it for a month or so before deciding
> whether or not to mod, but FIRST think I'm gonna do is get rid of the
> sovtek tubes that are in it..... could maybe see a bright switch added
> later.

I think your version already has the change in the input resistor values.

The most common complaint is "not bright enough." It was my immediate
impression the first time I played one. You can add a bright switch,
but if you think you'll always be using it, just add a cap to the volume
pot (between the two legs that don't go to ground). No drilling
necessary, and you can experiment with a few values to determine what
sounds best to you.

NOTE: Standard safety warning, don't open a tube amp chassis unless you
know what you're doing. Tube amps can store high voltages even when off
and unplugged.

[RS]

On Tue, 7 Feb 2012 19:15:28 -0800 (PST), Tony Done
<tony...@bigpond.com> wrote:

>On Feb 8, 12:57 pm, Grip <mbe...@comcast.net> wrote:
>> Picking up a like new Valve Jr. + Valve Jr 1X12 extention cab +
>> Digitecj rp 205 tomorrow lock, stock & barrell for 75 smackers. In the
>> event I don't just love it stock, what are some the mode you guys have
>> done and liked? The digitech will hit CL fast.
>
>Here's a good link for Epi VJ mods:
>
>http://duhvoodooman.com/VJr/VJr_mods.htm

A lot of those links seem to be dead, Tony.

>Mine was a first series, and had mods done for noise reduction,
>including a rectifier for the heater circuit, grounding, bigger caps
>etc, plus a 12dB cut L-pad. I also included the bright mod shown in
>the link, but with two different caps on a 3-way switch. I then added
>another bright switch to bleed treble across the volume pot, also with
>two different caps and bypass. All the mods were IMO well worth doing,
>and the second bright switch acts as a drive/boost switch on the big
>cap, very nice if you want a really bright acoustic-like sound with a
>little grit.

Lots of brightness mods! As I mentioned (about 50 times?), I'm not a
big fan of 'bright caps' in general, but I can see that if you keep
the amp cranked much of the time.

I know you know this Tony, but worth mentioning for others: Bypassing
the volume control with an extra 'bright cap' will do nothing if you
keep the control dimed. It's only going to have maximal effect when
the volume pot is in mid-position.

>I'm now contemplating installing a master volume, as suggested by RS.
>
>Tony D

Let me know if you're not clear on how to do that.

Also, I'd add a screen resistor! I don't remember seeing that on any
mod sites, but that could be important, given how often the amp is
driven hard.

[Tony Done]

On Feb 10, 11:36 am, RS <R...@nospam.com> wrote:
> On Tue, 7 Feb 2012 19:15:28 -0800 (PST), Tony Done
>

************

I haven't tried any of the ongoing links from the one I posted, but
the original one IIRC shows the key features.

I rarely go past 9 o'clock on the volume control so the treble bypass
is very effective. I can test the effect of the two brightness
swtiches fairly empirically from the volume and frquency RF noise I
get from the MV spotlights in the room with unshielded pickups, and
they certainly have a strong additive effect at the (almost clean)
volume setting I use.

I got got the idea of the volume control OK from the earlier thread,
thanks. As you said, drilling the hole in the front panel will be the
hardest bit.

Tony D

[RS]

On Wed, 08 Feb 2012 11:36:21 -0600, gonjah <gonjah.net> wrote:

Here's another take on that: It's true that many techs have no clue
about how a given mod is going to sound, even looking right at the
schematic. So in that case, best to stay conservative. But anyone with
decent engineering chops certainly should have good intuition about
how things will sound. Kinda like an experienced painter who should
know what's going to happen when you blend a couple different colors.
It's not all that complex if you study and work at it.

There are also a lot of mods that are simple no-brainers, like
increasing the input impedance of the VJ if it has the 68k to ground
(what were they thinking?) Or adding screen resistors. Or a slew of
other things. I wouldn't worry a bit about doing any of that a step at
a time, even if the client wasn't sure what they wanted.

So yes, some techs just mod things by rote, and will go into shock if
they see a schematic that doesn't have "Fender" or "Marshall" written
on it. Those are also the guys who won't see a possible problem when
it's staring at them. Best to find one who has a better feel for what
they're doing.

[RS]

On Thu, 09 Feb 2012 15:25:20 -0800, Jim <ask@first> wrote:

>I think your version already has the change in the input resistor values.
>
>The most common complaint is "not bright enough."

The lower value 68k to ground on some models will indeed roll off
treble. I'm referring to R1, NOT to the 68k inline between the input
and the grid (R2).

BTW, I've seen mods that recommend changing R2 from 68k to 22k or
whatever. I wouldn't bother with that.

> It was my immediate
>impression the first time I played one. You can add a bright switch,
>but if you think you'll always be using it, just add a cap to the volume
>pot (between the two legs that don't go to ground). No drilling
>necessary, and you can experiment with a few values to determine what
>sounds best to you.

Bypassing R6 (1Meg) with a small value cap can provide almost 10db
treble boost without having to bypass the volume control. I'd
recommend starting with the R6 bypass, since the boost would not be
dependant on the volume control setting.

In fact, I'd think that the treble boost would generally be more
useful when the amp was cranked.

[Jim]

I kind of like it the other way around. I like to let the harmonics
take over as the preamp treble gets rolled off by the volume. But it's
all a matter of taste.

And I should mention that I added a tone stack as well, so have the
treble knob to fiddle with.

Here's a picture, but it was before I added a "mids boost" switch, which
actually gives two preset values in the Fender style tone stack:

http://i40.tinypic.com/244whox.jpg
http://i40.tinypic.com/2rzqmx4.jpg

BTW, I'll be getting back to that reel to reel conversion soon. I just
bought and fixed a broken B.K. Butler Tube Driver this week. Had a
loose connection from the AC line to the primary of the transformer.
AND a broken footswitch. I'm picturing the previous owner scratching
his head when the power went of, then STOMPING on the switch to see if
that would fix it...

[RS]

The page shows a change of the input -series- resistor (not the one
going to ground) from 68k to 22k. That's unnecessary. The other change
of the resistor to ground from 68k to 1M is absolutely necessary. I
wonder how that 68k got past final engineering checkpoints.

>I rarely go past 9 o'clock on the volume control so the treble bypass
>is very effective.

Yeah, I knew you already had a handle on that. Just mentioned in case
others are doing that mod.

>I can test the effect of the two brightness
>swtiches fairly empirically from the volume and frquency RF noise I
>get from the MV spotlights in the room with unshielded pickups, and
>they certainly have a strong additive effect at the (almost clean)
>volume setting I use.

That's a -lot- of treble boost when combined with the bright switch.
But if that sounds good with your rig, then it's all good. It may not
work well with a bright speaker though.

>I got got the idea of the volume control OK from the earlier thread,
>thanks. As you said, drilling the hole in the front panel will be the
>hardest bit.
>
>Tony D

Very good then. Let me know how it goes.

[RS]

Very true. I do know people who like the more airy acoustic sound as
volume is rolled back, but I personally find it too shrill and hard to
control. Different strokes and all. We talked about that in a recent
thread about bypass caps on guitar volume pots.

>And I should mention that I added a tone stack as well, so have the
>treble knob to fiddle with.

Good idea. Did you substitute that for the 2X 1M resistor attenuator
after V1?

>Here's a picture, but it was before I added a "mids boost" switch, which
>actually gives two preset values in the Fender style tone stack:
>
>http://i40.tinypic.com/244whox.jpg
>http://i40.tinypic.com/2rzqmx4.jpg

Nice work, Jim. You silkscreened the panel?!

>BTW, I'll be getting back to that reel to reel conversion soon.

I was wondering where that went.

>I just
>bought and fixed a broken B.K. Butler Tube Driver this week. Had a
>loose connection from the AC line to the primary of the transformer.
>AND a broken footswitch. I'm picturing the previous owner scratching
>his head when the power went of, then STOMPING on the switch to see if
>that would fix it...

I like those old Butler boxes. I had a couple (Blue Tube and Tube
Driver) and sold them to clear rack space. I probably should have kept
them. They take a bad rap for running the 12ax7's at low plate
voltage, but it's not really fair comparing with a high voltage tube
amp (or to the HK boxes for that matter). They're more like good
sounding overdrive boxes implemented with tubes. A useful sound.

You do have to take care with the type of 12ax7's that you use. Many
will not work at all. Sovteks sound absolutely wretched at that plate
voltage (even more than they usually do) if they work at all. Many
otherwise-good-sounding 12ax7's won't work. The originals used EI's,
which sounded great when they were hand-selected. You probably won't
ever need to swap that tube, but be warned.

[RS]

On Wed, 8 Feb 2012 11:55:59 -0500, "RichL" <rple...@yahoo.com>
wrote:

>I've got the second version VJ head. So far it's stock (partly due to my
>own laziness) but the only mod I'd contemplate is a bright switch. The amp
>as is sounds too muddy with humbuckers.

I think V2 had the 1M input resistor (R1), but if it has 68k there (to
ground), you'd lose a lot of high end there due to loading. I'm sure
you're already aware, given your experience with modeling guitar
circuits.

The other obvious place where treble can be lost is in the R6/R7 (both
1M) voltage divider. Not sure why they used values that high. They
didn't need to. Triodes exhibit "Miller Capacitance" which effectively
multiplies residual grid capacitance by the amplification factor of
the tube. That can add up, resulting in an R-C filter when series
resistance is high enough. As it is, you have a 1 M volume control, so
the additional 1M resistor in series will start to roll off audibly.

Hey, you could break out the Excel spreadsheet and work out values for
compensation caps. :-) It really wouldn't be any tougher than your
guitar circuit calculator.

[Tony Done]

That's a -lot- of treble boost when combined with the bright switch.
But if that sounds good with your rig, then it's all good. It may not
work well with a bright speaker though.

**************************

That set up suits me well, because I'm primarily an acoustic guitarist and
it adds a lot of 'acousticness' to the tone. This good at the the low
volumes at which I play, and it still only puts it in the same tonal range
as my H&K Statesman, and shielded pickups still sound a bit dull to me. It
also adds some OD 'grit' to the high notes, which takes the scream out of
them; altogether it makes it into a different kind of amp. It's true that it
might be too much of a good thing with a brighter speaker.

Tony D

[Tony Done]

"Tony Done" wrote in message news:jh2f7c$6kc$1...@dont-email.me...

That's a -lot- of treble boost when combined with the bright switch.
But if that sounds good with your rig, then it's all good. It may not
work well with a bright speaker though.

**************************

and shielded pickups still sound a bit dull to me.

Tony D

***************

Just a quick follow-up on this. I shielded the pickups on my 2*vintage P90s
with kitchen foil when installed them. I just removed the shielding and
there is a very striking increase in brightness through the VJ. Also a
proportional increase in RF noise, alas.

Tony D

[RS]

On Fri, 10 Feb 2012 16:58:44 +1000, "Tony Done" <tony...@bigpond.com>
wrote:

Tony, It sounds like you're looking for more presence in 'air zone'
(5KHz and above). Unfortunately, electric guitars and amps evolved
around -eliminating- those frequencies; it's part of the sound we're
accustomed to.

Right off the bat, you're feeding an inductive pickup into a
capacitive cable. Major potential for rolloff. After possible
additional filtering in the amp circuitry, the signal hits the
speaker, which will have very little response about 5K or so.

Not sure that you'd want to add tweeters to address the speaker side
of things, as that can get complicated. But you may want to check
into internal preamps in your guitars. They can drive the cable
efficiently and provide a lot of shimmer on the top end. Maybe give
you some of the extreme highs that you're looking for.

And yes, even non-magnetic shielding can affect the tone of a pickup.

[RS]

On Fri, 10 Feb 2012 01:17:17 -0500, RS <R...@nospam.com> wrote:

>On Wed, 8 Feb 2012 11:55:59 -0500, "RichL" <rple...@yahoo.com>
>wrote:
>
>>I've got the second version VJ head. So far it's stock (partly due to my
>>own laziness) but the only mod I'd contemplate is a bright switch. The amp
>>as is sounds too muddy with humbuckers.
>
>I think V2 had the 1M input resistor (R1), but if it has 68k there (to
>ground), you'd lose a lot of high end there due to loading. I'm sure
>you're already aware, given your experience with modeling guitar
>circuits.

Typo. Make that "V1" above. The input tube.

[RichL]

"RS" <R...@nospam.com> wrote in message
news:09dbj75hvdpqgtrvc...@4ax.com...

Heh, I though you meant V2 = version 2. It makes sense if you take it that
way, except "version 2" has the 68k input resistor.

[RS]

On Fri, 10 Feb 2012 19:50:28 -0500, "RichL" <rple...@yahoo.com>
wrote:

Hah! Maybe I did mean version--I should have written it out. It was
late.

Anyway, the first revs evidently had 68k inline with the signal (like
Fender), and 68k to ground (bad mistake). As you know, the latter will
roll off a lot of highs and make for relatively weak sound.

[Jim]

Yup, and I like a .001uF across the volume on passive guitars. I'll
have to try Rich L's method, some day.

>
>> And I should mention that I added a tone stack as well, so have the
>> treble knob to fiddle with.
>
> Good idea. Did you substitute that for the 2X 1M resistor attenuator
> after V1?

I believe so. It's been a long time. I have a schematic, somewhere.

>
>> Here's a picture, but it was before I added a "mids boost" switch, which
>> actually gives two preset values in the Fender style tone stack:
>>
>> http://i40.tinypic.com/244whox.jpg
>> http://i40.tinypic.com/2rzqmx4.jpg
>
> Nice work, Jim. You silkscreened the panel?!

No, laser printer slide decals.

>
>> BTW, I'll be getting back to that reel to reel conversion soon.
>
> I was wondering where that went.
>
>> I just
>> bought and fixed a broken B.K. Butler Tube Driver this week. Had a
>> loose connection from the AC line to the primary of the transformer.
>> AND a broken footswitch. I'm picturing the previous owner scratching
>> his head when the power went of, then STOMPING on the switch to see if
>> that would fix it...
>
> I like those old Butler boxes. I had a couple (Blue Tube and Tube
> Driver) and sold them to clear rack space. I probably should have kept
> them. They take a bad rap for running the 12ax7's at low plate
> voltage, but it's not really fair comparing with a high voltage tube
> amp (or to the HK boxes for that matter). They're more like good
> sounding overdrive boxes implemented with tubes. A useful sound.

I agree. I need to A/B, but I can tell you this: My "TubeWorks" ear
pedal has way more gain than my Chandler rackmount. Not a good thing,
because I'm running the drive well below 25%. Here's the schematic that
I consulted when fix it:
http://www.freeinfosociety.com/electronics/schematics/audio/pictures/tubedriver.gif
I suppose I could try a resistor across the R8 pot to increase the
negative feedback, or play with R6/R7 and/or R9/R10. What would you do?

>
> You do have to take care with the type of 12ax7's that you use. Many
> will not work at all. Sovteks sound absolutely wretched at that plate
> voltage (even more than they usually do) if they work at all. Many
> otherwise-good-sounding 12ax7's won't work. The originals used EI's,
> which sounded great when they were hand-selected. You probably won't
> ever need to swap that tube, but be warned.

I have a couple of Chandler marked Yugo EI's, one came out of the
rackmount. I went through MANY tubes to see what I liked best. Ended
up with what appears to be a Mullard, but it's missing the top seam on
the envelope. I've heard that not all of them had that seam, but who
knows. Whatever it is, it sounds good.

This one came with a unlabeled Chinese tube.

[RS]

On Fri, 10 Feb 2012 18:45:19 -0800, Jim <inse@ttle> wrote:

>On 2/9/2012 10:04 PM, RS wrote:

>>> Jim wrote:
>>> I just
>>> bought and fixed a broken B.K. Butler Tube Driver this week. Had a
>>> loose connection from the AC line to the primary of the transformer.
>>> AND a broken footswitch. I'm picturing the previous owner scratching
>>> his head when the power went of, then STOMPING on the switch to see if
>>> that would fix it...
>>
>> I like those old Butler boxes. I had a couple (Blue Tube and Tube
>> Driver) and sold them to clear rack space. I probably should have kept
>> them. They take a bad rap for running the 12ax7's at low plate
>> voltage, but it's not really fair comparing with a high voltage tube
>> amp (or to the HK boxes for that matter). They're more like good
>> sounding overdrive boxes implemented with tubes. A useful sound.
>
>I agree. I need to A/B, but I can tell you this: My "TubeWorks" ear
>pedal has way more gain than my Chandler rackmount. Not a good thing,
>because I'm running the drive well below 25%. Here's the schematic that
>I consulted when fix it:
>http://www.freeinfosociety.com/electronics/schematics/audio/pictures/tubedriver.gif
> I suppose I could try a resistor across the R8 pot to increase the
>negative feedback, or play with R6/R7 and/or R9/R10. What would you do?

Hi Jim,

R8 on the schematic above is a plate resistor. Maybe you're referring
to R5? If so, see below.

R6/R7 would work, but check the previous stage: The ratio of R5 to R4
determines the gain of the opamp stage. That's 500k : 1.5K, a huge
gain range, and liable to be squarewaving. You can knock the gain down
easily by increasing the value of R4. Or maybe mount a small internal
trim-pot in series with R4. Not sure what gain range you're looking
for, but I'd start with maybe 100k as the trim-pot value. Changing R4
or using the series trimmer would allow you to keep the usable range
in R5.

If you have a scope, it would be easy to set the trimmer. If not, you
could try attenuating the output (see the Blue Tube) and bridge the
attenuated signal directly to an amp, skipping the tube stages. Set R5
to max. Then adjust the trimmer til you hear clipping. That will be
the most headroom you can get without squarewaving the solid state
section.

That was also a good guess re R9/R10. That's the next place to look
for decreasing gain. In fact, the Blue Tube was a near-identical unit
but lower gain. You'll see by the schematic that those resistors are
different:

http://i731.photobucket.com/albums/ww317/MillsApparatus/903.jpg

(You may want to capture that schematic. Not sure how long it will
stay there).

The Blue Tube also uses 500k : 1.5k for R5 : R4, so the same caveats
apply. I'd try decreasing the gain of that opamp stage first. Then if
it needs more gain reduction, go for R9/R10.

>> You do have to take care with the type of 12ax7's that you use. Many
>> will not work at all. Sovteks sound absolutely wretched at that plate
>> voltage (even more than they usually do) if they work at all. Many
>> otherwise-good-sounding 12ax7's won't work. The originals used EI's,
>> which sounded great when they were hand-selected. You probably won't
>> ever need to swap that tube, but be warned.
>
>I have a couple of Chandler marked Yugo EI's, one came out of the
>rackmount. I went through MANY tubes to see what I liked best. Ended
>up with what appears to be a Mullard, but it's missing the top seam on
>the envelope. I've heard that not all of them had that seam, but who
>knows. Whatever it is, it sounds good.
>
>This one came with a unlabeled Chinese tube.

Mullard--I'm surprised. I had tried lots of great tubes in that
circuit -- diamond-bottom Telefunkens, Amperex Bugle-Boys, etc. None
of them sounded as good as the EI's. I don't remember if I tried
Mullards though.

I once worked in R&D for an amp manufacturer who had -tons- of Mullard
tubes in stock, including 12ax7's and EL34's. I could have bought
those tubes for cheap, but I never thought to do that at the time.
(Doh!) It just seemed like they'd be around.

[RS]

On Fri, 10 Feb 2012 18:45:19 -0800, Jim <inse@ttle> wrote:

> My "TubeWorks" ear
>pedal has way more gain than my Chandler rackmount. Not a good thing,
>because I'm running the drive well below 25%. Here's the schematic that
>I consulted when fix it:
>http://www.freeinfosociety.com/electronics/schematics/audio/pictures/tubedriver.gif

PS: That schematic shows the tube cathodes going directly to ground.
The Blue Tube schematic shows a cathode resistor and bypass cap. I
suspect that's in the TD also, right?

[Tony Done]

"RS" wrote in message news:js8bj7lfkfpl862f6...@4ax.com...

****************

I've sometimes wondered about using a more hi-fi type of amp. Keyboard or
pedal steel maybe, if I ever want to do it loud enough for performance? Good
comment about cables, it isn't something I had given much consideration to;
I might try with a very short cable and see if I can hear the difference.
Preamps and EQs can be well another look, I loved the Pandora PX4 for its
brightness until it packed up - it made my LP Special sound like an acoustic
straight into the PC, but I don't know if it would have the same effect with
an amp, because of the overall roll-off effect you mention.

Tony D

[RS]

On Sun, 12 Feb 2012 05:31:07 +1000, "Tony Done" <tony...@bigpond.com>
wrote:

>>That set up suits me well, because I'm primarily an acoustic guitarist and
>>it adds a lot of 'acousticness' to the tone. This good at the the low
>>volumes at which I play, and it still only puts it in the same tonal range
>>as my H&K Statesman, and shielded pickups still sound a bit dull to me. It
>>also adds some OD 'grit' to the high notes, which takes the scream out of
>>them; altogether it makes it into a different kind of amp. It's true that
>>it
>>might be too much of a good thing with a brighter speaker.
>>
>>Tony D
>
>Tony, It sounds like you're looking for more presence in 'air zone'
>(5KHz and above). Unfortunately, electric guitars and amps evolved
>around -eliminating- those frequencies; it's part of the sound we're
>accustomed to.
>
>Right off the bat, you're feeding an inductive pickup into a
>capacitive cable. Major potential for rolloff. After possible
>additional filtering in the amp circuitry, the signal hits the
>speaker, which will have very little response about 5K or so.
>
>Not sure that you'd want to add tweeters to address the speaker side
>of things, as that can get complicated. But you may want to check
>into internal preamps in your guitars. They can drive the cable
>efficiently and provide a lot of shimmer on the top end. Maybe give
>you some of the extreme highs that you're looking for.

>****************
>
>I've sometimes wondered about using a more hi-fi type of amp. Keyboard or
>pedal steel maybe, if I ever want to do it loud enough for performance? Good
>comment about cables, it isn't something I had given much consideration to;
>I might try with a very short cable and see if I can hear the difference.

Try George L cables or maybe the new Elixir line, if they have demo
cables at your local store (they're expensive). But you won't have to
worry about cables if you have a preamp close to the guitar. Someone
used to make a small booster box that plugged directly into the
guitar's output jack, but I forget who that was...ElectroHarmonix
maybe?

>Preamps and EQs can be well another look, I loved the Pandora PX4 for its
>brightness until it packed up - it made my LP Special sound like an acoustic
>straight into the PC, but I don't know if it would have the same effect with
>an amp, because of the overall roll-off effect you mention.

It won't. I use Pandoras for practicing (w headphones), and I try to
design patches with lots of rolloff at the extreme top. I don't like
digital overdrive sims in any boxes I've heard so far, but I do look
for more classic electric sound. Obviously our tastes are about polar
opposites in that respect, but I do understand what you're after.

I think a hifi/PA/keyboard rig (w speakers) may do it for you. You'll
need to make sure you have high input impedance (at least 250k+) for
guitar, but aside from that, an amp with flat frequency response will
add those very high overtones. Don't expect great tone when you step
on an overdrive pedal though.