SE 845 circuit
John Weller
similar to Dinasaur from SP but without the mosfet and diodes. Any
suggestions?
Acrosound
Hi John: Just spoke to Dan "bottlehead" Schmalle and he told me that the next
issue of Valve should have two 845 circuits in it. One of the two circuits as
Bot relayed it to me will be a low power 845 version... somewhere in the four
to five watt range and near abouts the plate voltages you mention above. So
bookmark bottlehead's website and check back to see when the next issue of
Valve makes it online.
Buddy of mine Bruce "mono" Nielson built a four or so watt 845 and I heard this
amp on his system. Strong, powerful, robust, and full bodied... along with a
ton of air and delicacy. Had a very relaxed, on-vacation, stressfree, confident
sound quality. One of the better SE amps I've heard. I will check with Bruce
and see if the schematic for it is public domain available or not.
Tomorrow I will check through some of my schematics libraries and see if I have
something that falls into your description above...
and also try to find some of the small 71A and 417PP schematics that Bales,
Vintage and others asked about on a different thread.
In the meantime here is a set of operating points for a low powered 845 that
was published as a sonic fave by the senior staff members of Stereo Sound
magazine in Japan.
plate volts 430
plate current 62 madc
grid volts -51
primary impedance 5000 ohms
power output approx 4 watts
In my schematics folder I did find an eight watt 211 SE public domain design by
Gordon Rankin that is simple to build and somewhere in the 800 plate volts
range. If this would interest you or anyone else drop me a line.
wanting one (a lower powered 845 SE) for himself,
is
MSL
Thom Mackris
With all sincerity (I've been a bit facetious in a couple of threads,
lately) I have to wonder if an 845 is operating in it's sweet spot at
such a low plate dissapation. I don't know the answer to this myself.
A friend recently completed his 845 project. I can't rember how much
current he was running at the 800 "ish" plate voltage he started off
with, but when he bumped it up over 1KV, things really locked into
place for him. Keep in mind this was on a pair of Ariels so he might
have just been experiencing the benefits of more power.
(his site is at: http://reality.sgi.com/cbrady_denver/audio/ )
Perhaps the tube has a couple of sweet spots and 800 V was between the
two. Beats me. My question still remains.
If you're after only 4-5 watts from the 45, 2A3, 845 sonic family,
another option is the KR 2A3's .... deemed by Doc Bottlehead to be
45's on steroids. I'm drooling to try them, but don't want to hear
them until I have the spare change :-(
Just doing my part to add to the confusion :-)
P.S. Ron Welborne has them on sale at the moment:
http://www.welbornelabs.com/
P.S. to Mike - thanks for the research.
Cheers,
Thom
On 25 Jun 1999 06:35:10 GMT, acro...@aol.com (Acrosound) wrote:
>John weller wrote:
>
><< I'm looking for a circuit for an 845 SE amp running with B+ at 500vdc
>similar to Dinasaur from SP but without the mosfet and diodes. Any
>suggestions? >>
>
>Hi John: Just spoke to Dan "bottlehead" Schmalle and he told me that the next
>issue of Valve should have two 845 circuits in it. One of the two circuits as
>Bot relayed it to me will be a low power 845 version... somewhere in the four
>to five watt range and near abouts the plate voltages you mention above. So
>bookmark bottlehead's website and check back to see when the next issue of
>Valve makes it online.
>
>http://www.bottlehead.com
>
>Buddy of mine Bruce "mono" Nielson built a four or so watt 845 and I heard this
>amp on his system. Strong, powerful, robust, and full bodied... along with a
>ton of air and delicacy. Had a very relaxed, on-vacation, stressfree, confident
>sound quality. One of the better SE amps I've heard. I will check with Bruce
>and see if the schematic for it is public domain available or not.
>
>Tomorrow I will check through some of my schematics libraries and see if I have
>something that falls into your description above...
>> lots o' stuff snipped <<
Acrosound
>>With all sincerity (I've been a bit facetious in a couple of threads,
lately) I have to wonder if an 845 is operating in it's sweet spot at
such a low plate dissapation. I don't know the answer to this myself.<<
Not to be a smarty pants... but.. the answer depends on what and how you define
"sweet spot". The particular operating points that I put up for the 845
(either in this thread or another about low power amps) were derived from
reasonably seasoned ears with tons of actual building experience spanning a
timeframe of decades... it was from the senior staff members of Stereo Sound
magazine out of Japan.
I have heard an 845 at these "diminshed" operating points....
Bruce Nilsen built such a critter which borrowed upon the public domain circuit
of JC Morrison out of a Sound Practices article.
In my humblest of opinions (good for these ears anyway) the 845 and 211 at
higher (highish?) plate voltages sound a bit thin and mechanical. Bruce's amp
had tons more body and was smoother amongst it's other sonic virtues (again, to
these ears anyway).
One of the things that surprises me in the DIY and SE movements... is the
reliance on picking operating points that offer the promise (whether realized
or not is a different story) of low harmonic distortion. Just today I glanced
through a recent Glass Audio magazine and read snippets of some articles by
Lynn Olsen and Matt Kamma wherein they argue that THD numbers are not a very
good indicator of sound quality. So why folks would blindly build on this
*singular* basis stumps me. No one would purchase a cartridge based simply on
which had the lowest THD. And perhaps if THD is the holy grail we should all
be purchasing some good IC's instead of tubes anyway.
Also... even if one does consciously decide to pick an operating point based on
this characteristic (low THD)....
there are many operating points at low power levels, low plate currents, and
low primary impedances that offer the same low distortion levels as high plate
currents and high primary impedances. Check out the Western Electric data for
the 300B as just one example.
then also be cognizant of the fact that all of these tables were derived using
a resistor as the load. Throw in a bunch of real world variables like MUSIC
(not a steady sine wave at only one frequency), a varying speaker load, a
reactive primary (a transformer) instead of the pure resitive load used to
generate the data on graphs... and you can see that it may not be as simple as
picking out a primary impedance, along with voltage and current levels.
There are tons of variables that influence sound quality. Iron choice is
obviously one of these. Iron distortion can swamp (*read some of Cerrems posts
on rat on this topic) the distortion derived from the plate of the tube. Low
primary inductance creates tons of phase shift at the bottom end. Low OCL
(open circuit inductance) provides too little inductive reactance... so that
the nominal (just as an example) 5K primary at some low frequency behaves not
as a 5K load to the plate of the tube but something significantly lower than
this. And there goes all the beauty of your graph derived low distortion
operating point.
If great sound had only been related to low THD this would have been all
settled quite some time ago. But there are many subjective qualities to music
reproduction that folks seem to value that are not captured by these simple
quantitative measurements.
>>A friend recently completed his 845 project. I can't rember how much
current he was running at the 800 "ish" plate voltage he started off
with, but when he bumped it up over 1KV, things really locked into
place for him. Keep in mind this was on a pair of Ariels so he might
have just been experiencing the benefits of more power.<<
Or it may have been more in line with his subjective preferences... who
knows...
>>If you're after only 4-5 watts from the 45, 2A3, 845 sonic family,
another option is the KR 2A3's .... deemed by Doc Bottlehead to be
45's on steroids. I'm drooling to try them, but don't want to hear
them until I have the spare change :-(<<
One obvious factor to consider is the huge cost differential. Chinese 845's go
for about a twenty spot versus two whole c-notes for the KR 2A3's? To further
confuse issues of preferences.... recall that when bottlehead and smoothplate
were in philly for the NY NOISE show and after hours and hours of auditions of
many 2A3's... it was the Chinese critters that went to the show.
And throw in... sorry... the continuing filament problems with the KR's. Had
another KR arrive DOA on my doorstep. The chinese 845's have shown themselves
to be really robust at one tenth the price. And operating the 845 tube at
approx 27 watts dissapation out of an allowable 100 watts ought to enhance
longevity even moreso.
Earlier there had been some comments about the durability of the chinese 845 if
you do run it say at 1000 to 1250 volts on the plate. Allow me to relay a
quick story. I know a designer who has utilized the 845 at nearly 1400 volts
on the plate at 95 mils of plate current into a 4K primary... and these tubes
were in service.... hard service... long hours of music playing... for over two
years without any failures. Owner replaced them at two to two and a half years
cause he felt that he had gotten his forty bucks worth.... and wanted to
"treat" the amp to a new set of tubes. Another set of chinese critters went in
and play to this day. So I am not saying that there aren't infant mortalities
with the sino produced 845's... but... these guys do seem to hold up quite
well. and they are cheap, cheap, cheap.
>>Just doing my part to add to the confusion :-) <<
Likewise. No simple answers...heh?
>>P.S. to Mike - thanks for the research.<<
thanks tom for the interesting questions.
MSL
Andre Jute
> 845 and 211 at
> higher (highish?) plate voltages sound a bit thin and mechanical
Certainly true of the 211. I've been saying it for years. I'm glad to
hear you now agree with me, Mike.
Not true of the 845. This tube has lots of sweets spots, as Thom
surmises. Of those I know, 960V 90mA is one, 1040V 86mA is another. 900V
is about the lowest of the operating points I liked. 10K OPT primaries
are just about a minimum.
If you're going to build a 4-5W amp, a high current WE300B running into
5K or 5K6 is hard to beat, and very tunable with driver topology
changes. IMHO a low voltage, low current 845 is not a replacement for a
good 300B, except as symbolic penile extension.
Andre
--
Andre Jute an...@indigo.ie COMMUNICATION JUTE
--come with Andre's Jute's Classical Jukebox live to the
West Cork Chamber Music Festival
http://indigo.ie/~andre/WestCorkChamberMusicFest.html
Grover Gardner
> Not true of the 845. This tube has lots of sweets spots, as Thom
> surmises. Of those I know, 960V 90mA is one, 1040V 86mA is another. 900V
> is about the lowest of the operating points I liked. 10K OPT primaries
> are just about a minimum.
960vdc/90mA works well for me. Dropping the current to 80 mils softens the
attack too much for my tastes. 960vdc is derived from commonly-available
1400vct trannies with quality diodes. 1040vdc can be had from equally common
800vct trannies with a diode bridge.
>
> If you're going to build a 4-5W amp, a high current WE300B running into
> 5K or 5K6 is hard to beat, and very tunable with driver topology
> changes. IMHO a low voltage, low current 845 is not a replacement for a
> good 300B, except as symbolic penile extension.
Well, here I might disagree. Again, there's the cost issue, but also the 845
has a visceral potency, even at low voltages, which is hard to beat. I've
never heard a 300B reach THIS low :-)! At high voltages, you do risk a
sterile sound, and I've found that a VERY warm and sweet driver topology is
called for. Probably why so many folks like the choke-loaded 300B or
low-voltage 845 as a driver.
--
Grover Gardner
gro...@postoffice.att.net
Acrosound
>>Again, there's the cost issue, but also the 845
has a visceral potency, even at low voltages, which is hard to beat.<<
You've said it well Grove.... this was one of the impressions I was left with
after hearing such a low voltage operated 845. Bigness, impact, solidity,
confidence, richness... that elusive "I'm on vacation" stressfree sound.
Only other amp that delivered this given range of virtues was a 310 driven
300B. When Poppa Joe was still in the DC area he dropped off his replica WE
91 amp to me for several weeks. I am still haunted on some level by the huge
confidence level that this amp portrayed. It also had a very sensual quality.
I've heard amps with greater clarity and see through than this 300B rendition..
but none with markedly better visceral, hugeness, and confidence factors than
this amp.
So, like all folks, you then wonder what *causes* this sound quality... what is
responsible for the tone and temporal qualities which are exhibited.
Just hunching... could it be the large voltage headroom of the 310 front end?
But, again, to take my own advice.... trying to reduce all of the intertwined
variables down to "ONE" probably only leads us down a path of mischief and
unsupported speculation.
>>I've
never heard a 300B reach THIS low :-)! At high voltages, you do risk a
sterile sound, and I've found that a VERY warm and sweet driver topology is
called for. <<
A balancing act? Fatten her up with the front end? Fair enough. Using the
pieces of the puzzle (different design choices) to achieve a given aesthetic
preference... that represents the art of this endeavour, heh?
>>Probably why so many folks like the choke-loaded 300B or
low-voltage 845 as a driver.<<
Hadn't thought of using a low volts 845 to drive the high volts 845.... perhaps
a good balance????
though... I tend for abstract aesthetic reasons to favor simple two stage
designs.... either direct coupled or cap coupled and have not had the need in
my system for the available power thusly obtained from a high volts 845.
All of this makes me think about Bruce Wenger's tricked out SE amps.. what
output tube whas that using Grove? From the aesthetics side the contrast say
btwn a replica WE 91 and Bruce's amps is marked... yet each was truly pleasing
and right in their own ways.....
good chatting with ya
MSL
Grover Gardner
> Hadn't thought of using a low volts 845 to drive the high volts 845.... perhaps
> a good balance????
Doesn't Sakuma do this? I think I've seen other designs like this, but it's
kind of a fun idea. The 845 at 500 vdc is so much warmer than at 1000vdc,
almost like two different tubes...
>
> though... I tend for abstract aesthetic reasons to favor simple two stage
> designs.... either direct coupled or cap coupled and have not had the need in
> my system for the available power thusly obtained from a high volts 845.
>
> All of this makes me think about Bruce Wenger's tricked out SE amps.. what
> output tube whas that using Grove? From the aesthetics side the contrast say
> btwn a replica WE 91 and Bruce's amps is marked... yet each was truly pleasing
> and right in their own ways.....
Interesting comments about Joe Robert's WE 91 replica. Bruce's little SE amps
use a 5998 regulator in a "patented" ;-) configuration. There's also a 6336
version--wish you could hear these--ultra sweet (much more so than the
"workhorse" 5998 you've sampled) and amazing bandwidth, transparency and
control, but it requires a very high load so some of the extra power is
sacrificed. Still, it drove my ProAcs very nicely.
One reason I keep coming back to the 845 is that there is no denying the
special authority of this tube, along with the amazing ability of DHTs to put
you right in the room with the performers.
--
Grover Gardner
gro...@postoffice.att.net
drumm...@my-deja.com
an...@indigo.ie (Andre Jute) wrote:
>
> Certainly true of the 211. I've been saying it for years. I'm glad to
> hear you now agree with me, Mike.
>
> are just about a minimum.
>
750 VDC plate volt 845 SE monoblocks. The curcuit I picked
up off Mattis's website Machmat.com.
Yes the 845 has a sweet spot at 750 vdc, and I don't think
I want to try to find out if my 300B Stereo amp can run at
that 750 vdc spot.
The cheap 845s gives us a chance to run a little higher
than the 450-500 vdc inexpensive 300b's run at. These 845's
also offer that crisp sound like 45's and 2A3's but like on
really really cheap steroids.
God I Love This Stuff !
Willie
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
Thom Mackris
This is a great thread. I'm having a blast listening to you all.
One comment about 2A3 brands. I've enjoyed my Billington (selected ?)
2A3's which came with my Moondogs. Then I plugged in (gift from a
close friend) a pair of old RCA's. I don't know how used they were,
but WOW !! Noise floor, extension at both ends of the frequency
extremes - music MUSIC *MUSIC* !! The difference took all of 4 - 8
bars for everyone to notice, switching from the warmed up Chinese
tubes to the cold RCA's.
I never disliked the Chinese tubes and can still recommend them, but
when my friend Chris Brady heard the difference, he started to wonder
aloud if there's as much of a difference between NOS 845's and their
Chinese descendants.
So many variables, so little time.
... Thom
Andre Jute
I've heard NOS 845 next to Chinese several times now, and once in amps
side by side that were only marginally different and that I knew
intimately (I'd built both). For myself, I wouldn't spend the money on
the NOS... but some people with good ears claim it makes an appreciable
difference.
I suspect this whole NOS business is overheated (I don't say "overrated"
because I work so much with in-production tubes, I don't have a lot of
NOS power tube experience--in Ireland my opportunities are less than you
lucky guys in the States).
Andre
--
Andre Jute an...@indigo.ie COMMUNICATION JUTE
--come with Andre's Jute's Classical Jukebox live to the
West Cork Chamber Music Festival
http://indigo.ie/~andre/WestCorkChamberMusicFest.html
Thom Mackris <tmac...@earthlink.net> wrote:
Jac
> I'm looking for a circuit for an 845 SE amp running with B+ at 500vdc
> similar to Dinasaur from SP but without the mosfet and diodes. Any
> suggestions?
Hello John,
A Mosfet can be very low Impedance. Many types will work at even at
or 50Volts SE too.
The 845 is a high impedance tube per design. The problem is, you only
get the
power out, at the voltage it is designed for, and that is a four number
digit at least.
If you go below 800Volts. (or so) you get to do with problems, that you
can see
best on an oscilloscope, when driving the tube. You get posititive grid
voltage,
and you can't drive the tube properly any more.
Here you'll find a 800Volt and a 1200Volt circuit, designed by me.
http://www.machmat.com/tubes/schese.htm
I found, if you go below 800V, the achievable output power drops
suddenly
very rapidly, and the tube starts to produce lots of 3rd harmonics,
which is very
untypical for this tube. There is no way to solve this. It simply
doesn't work,
using a high impedance tube in a low impedance mode. It's too difficult
to
show here, but on an oscilloscope, it quite easy to see the problem.
If you want to try someting less dangerous, you can try to make a real
nice
circuit to operate a 2A3 at 175 Volts. Not so dangerous, cheap
capacitors
etc. Why is nobody doing that? You'll run into design problems. Low
output
power at very high distortion is what you get. In the end you'll
increase the voltage. This is really a nice experiment. Don't talk
about it ... do it. ( I really mean it!)
Same thing with an 845. It needs 800V or more.
- Jac
Paul Gustafson
Just an aside about the 845,
I was talking to an old timer (ham guy, tube audio nut) about the 845
because this thread got me thinking about making one (for a really
whacked out guitar amp!). I have an 800 vct transformer that puts out
like an amp of b+ and fourteen amps of filament current to play with, so
I asked him if he had one (an 845) or something similar hanging around
that he could part with. He told me that NOS 845's are notorious for bad
filaments. He said they need to be stored upright or the filaments could
sag and break due to mechanical shock or the brittleness of the filament
itself. He said they bake as much thorium into the filament as possible
to get good emission, the trade off is fragility.
What do you guys think about that? I told him that I thought there were
current production 845s and he told me to use them if there were, and
that they like to run at around a kilovolt. I trust this guy's knowledge
and he confirmed what you all have been saying about the magic of an
845 single ended.
He also mentioned the sv572 and the 211 as being good candidates also.
Anyone have opinions on those babies?
Paul G.
Thom Mackris wrote:
>
> Mike, Andre, Grover ...
>
> This is a great thread. I'm having a blast listening to you all.
>
> One comment about 2A3 brands. I've enjoyed my Billington (selected ?)
> 2A3's which came with my Moondogs. Then I plugged in (gift from a
> close friend) a pair of old RCA's. I don't know how used they were,
> but WOW !! Noise floor, extension at both ends of the frequency
> extremes - music MUSIC *MUSIC* !! The difference took all of 4 - 8
> bars for everyone to notice, switching from the warmed up Chinese
> tubes to the cold RCA's.
>
> I never disliked the Chinese tubes and can still recommend them, but
> when my friend Chris Brady heard the difference, he started to wonder
> aloud if there's as much of a difference between NOS 845's and their
> Chinese descendants.
>
> So many variables, so little time.
>
> ... Thom
>
> On 26 Jun 1999 07:37:02 GMT, acro...@aol.com (Acrosound) wrote:
>
Acrosound
<<
The 845 is a high impedance tube per design. The problem is, you only
get the
power out, at the voltage it is designed for, and that is a four number
digit at least.<<
But what was this tube designed for? Old RCA literature, for example, clearly
shows examples of this tube operating at 750 volts on the plate for example.
One of the past issues of Sound Practices featured the 845 in it's Meet the
Tube article... with reprints of classic literature regarding the 845 tube.
Obviously, you will only get maximum power out if you run at or near the max
plate dissapation of the tube. But... if your not seeking just plain ole
horsepower than there may be other considerations (both technical and sonic)
that would make the lower operating points *potentially* attractive.
>>If you go below 800Volts. (or so) you get to do with problems, that you
can see
best on an oscilloscope, when driving the tube. You get posititive grid
voltage,
and you can't drive the tube properly any more.<<
RCA shows a set of operating points at 750 volts on the plate.... with,
presumably, the same approximate THD as examples also given at 1,000 and 1250
volts.
Any (or should I say most) triodes can be driven grid positive.. and, IIRC,
this is called class A2 operation. But one need not design or operate the tube
in Class A2. Class A1 operation is an alternative... wherein the tube does not
draw grid current.
This is simply a design choice isn't it? The reason folks drive some tubes A2
is to get a few extra watts of power... but, generally, A1 is considered to be
a more linear manner in which to bias the tubes.
>>I found, if you go below 800V, the achievable output power drops
suddenly
very rapidly, and the tube starts to produce lots of 3rd harmonics,
which is very
untypical for this tube. There is no way to solve this.<<
Is this behaviour your noting the product of a "complete circuit"? Where is
the genesis of the distortion within the circuit? Is it coming from the front
end (the voltage amp) or the output transformer? On what basis are you
isolating the output tube as the basis or cause of this distortion?
Again, on static measurements the 845 can be run (accdg to RCA published
information) at least as low as 750 volts with no severe penalties in THD
vis-a-vis other published operating points.
>>It simply
doesn't work,
using a high impedance tube in a low impedance mode. .<<
By the same token then a 45 tube, if I understand your argument correctly,
should not work except at high plate volts. Note that the 45 tube and the 845
have roughly the same internal plate resistance. yet the 45 thrives at, what
(?), 250 volts on the plate? And actually cannot absorb much more than that.
>>Don't talk
about it ... do it. ( I really mean it!)<<
Been there... have done that.... at least on a listening basis....
again... my sense is that circuits are very complex with many, many variables
as to front end design, coupling methods, power supply design, output stage
design, transformer selection, other parts selection... experienced designers
have achieved success with these tubes at conditions you claim not possible.
Check out back issues of MJ magazine and Stereo Sound for some examples.
>>Same thing with an 845. It needs 800V or more.<<
Disagree... based on actual listening experience with this tube.
MSL
Grover Gardner
You're also lucky to have such a transformer!
Paul Gustafson wrote:
>
> Hi everyone,
> Just an aside about the 845,
> I was talking to an old timer (ham guy, tube audio nut) about the 845
> because this thread got me thinking about making one (for a really
> whacked out guitar amp!). I have an 800 vct transformer that puts out
> like an amp of b+ and fourteen amps of filament current to play with, so
> I asked him if he had one (an 845) or something similar hanging around
> that he could part with. He told me that NOS 845's are notorious for bad
> filaments. He said they need to be stored upright or the filaments could
> sag and break due to mechanical shock or the brittleness of the filament
> itself. He said they bake as much thorium into the filament as possible
> to get good emission, the trade off is fragility.
> What do you guys think about that? I told him that I thought there were
> current production 845s and he told me to use them if there were, and
> that they like to run at around a kilovolt. I trust this guy's knowledge
> and he confirmed what you all have been saying about the magic of an
> 845 single ended.
> He also mentioned the sv572 and the 211 as being good candidates also.
> Anyone have opinions on those babies?
--
Grover Gardner
gro...@postoffice.att.net
Phil Frakes
<gus...@res.raytheon.com> wrote:
>Hi everyone,
>Just an aside about the 845,
>I was talking to an old timer (ham guy, tube audio nut) about the 845
>because this thread got me thinking about making one (for a really
>whacked out guitar amp!). I have an 800 vct transformer that puts out
>like an amp of b+ and fourteen amps of filament current to play with, so
>I asked him if he had one (an 845) or something similar hanging around
>that he could part with. He told me that NOS 845's are notorious for bad
>filaments. He said they need to be stored upright or the filaments could
>sag and break due to mechanical shock or the brittleness of the filament
>itself. He said they bake as much thorium into the filament as possible
>to get good emission, the trade off is fragility.
I don't have enough experience with NOS 845's to say for sure that
your old timer friend is right, but I do have a NOS RCA 845 that I'll
sell you cheap. Its filament is rolling around on the inside of the
glass in many pieces...
-Phil
Jac
Many of todays (cheap...) Power tubes were ment for militiary Radio
Transmitters
during a (possible) nuclear war in the 1970's. All semiconductors within 100 km
of a nucleair explosions are dead. No matter how strong the shielding.
The Chinese 845 served that purpose. They are not manufactured
any more since many years.
It is fully impossible to build these things for the price we are buying them for.
Also in China. This NOS. All tubes we get are from that same
old militiary stock, and sold now through commercial channels, under
various brands.
The factory specs are a too optimistic. Off the factory you can
select 10% away, because they are not an 845. Good tubes,
but just no 845. However ....the 90% that are left, are of
magnificent quality, and impossible to destroy almost.
I had no loss of emsssion, with any of them yet. (Whis IS the
a weakness of any tungsten tube) Very good is, they don't
drift ( in my PSE application.)
I did a test with on/off at 100Watt / 2Hz. They accept that kind of
mis-use without any complaint. In fact, I still use that set in my 845 amplifier,
because there's nothing wrong with it.
The only weakness of this tube is: Don't tap on it when under full power,
with a screwdriver or something, to hear if it's mircrophonic.
Under high temeprature conditions the anode contact is more
shock-sensitive than you would expect. This contact is temperature-shrinked,
and the only part of the tube I managed to damage.
For the rest, these are strong as dinosaures. You can actually soft-drop
them on the floor. (like on a carpet) This confirms they're made for
High-G applications. (Militairy requirement)
I don't think you have to be carefull with these at all. They take full power,
and perform best at 1200Volt.
Please be EXTREMELY carefull with experiments....
-Jac van de Walle
gkau...@the-planet.org
like to play with a few.
- Gary
Jac <j...@gmx.net> wrote in message news:3779FD50...@gmx.net...
> here is some additinal information about the 845, I think you should
know.
Fred Whitlock
while but maybe you can tell me if I'm out of the ballpark.
Just go to tubes and then Chinese tubes from the home page.
Good listening.
Fred
AudioNow!
http://www.audionow.com
gkau...@the-planet.org wrote in message ...
Tubesonic
Tubesonic is selling at US$38.00 for 1-10 and 35.00 for 11-20
John
gkau...@the-planet.org 撰寫於文章 ...