Williamsom amplifier with 829B?
WILLY KROGSTAD
coupled 807. They sound good to me, so I tried to change the 807's to
829B's - but that was not very successful.... the sound was THIN to say the
least.
Somehow I want this to work - I suppose the bias is wrong for 829B, just
substituted 807 for 829B, changed nothing else... (except filament circuitry
of course). There are two tubes inside the 829B, and I just parallelled
them.....
Another thing: The 807 amp runs off around 300 Volts DC, maybe the 829B's
require more voltage?
Willy
Chris Morriss
<wikr...@c2i.net> writes
get them to work well in psuedo-triode mode. I've often wanted to try a
couple of 829's P-P (both sections paralled), but I don't see many 829s
in the UK anymore. Not at giveaway prices anyway :-(.
I think you'll find the optimum a-a load will be a lot lower than for
two 807s or 6L6s.
--
Chris Morriss
DEMOSTENES A. Goksøyr
a common screengrid and that causes some problems. Data for 829B in
class AB1 is Va = 600V, Vg2 = 200V Vg1 = -18V, Raa = 13,75Kohm(!) and
Po = 44W. You can run the screengrid on 250V, but that is hard and
you'll probably reduce the life of the valve. The alternative is to
lower the anode voltage and put more valves in parallell push-pull.
How about single-ended? I have never seen any experiments with 829B in
this mode.
By the way, 3E29 is equivalent to 829B except that it is a for pulse
applications, but it has the same electrical data as 829B
Regards,
Arnold Goksøyr
On Sun, 11 Nov 2001 17:15:19 GMT, "WILLY KROGSTAD" <wikr...@c2i.net>
wrote:
DEMOSTENES - N6899 Balestrand, Norway
Tlf. +47 5769 1340 Fax +47 5769 1267
http://www.demostenes.no
Thousands of different valves in stock as well as
sockets,transformers,books,caps,resistors and
other components. Web site is updated every week.
You can order on-line.
Philip Lawrence
The original Williamson with 807's cathode bias had a power supply of
450 volts. 400 volts is the max for 807's Triode connected fixed bias but VTL
runs them at 560 volts I have used them at 500 volts with no problems. I have a
circuit for 829's Pentode connected [Williamson }if you like I can Scan it and
send, it uses 560 volts Anode 206 volts G2
Phil
Phil
RdM
>The 829B should be two 6L6 valves in a common envelope. They also have
>a common screengrid and that causes some problems. Data for 829B in
>class AB1 is Va = 600V, Vg2 = 200V Vg1 = -18V, Raa = 13,75Kohm(!) and
>Po = 44W.
You know, I have seen it asserted by several different people that an 829B
is similiar to, the same as, should be, two 6L6's or two 807's in one
bottle, but for the life of me I cannot see any basis for it. I'd like know!
The data in RCA TT5, as you have posted above, seems quite different from
AB1 data for two 807's at 600V, with say VG2 =300 as usually given
The inter electrode capacities are different, the Mu and transconductance
figures appear different (though measured at different conditions, so I
can't really compare them) and of course there's the low max screen voltage.
To me, this makes it appear quite an individual valve - maybe similiar to
the 5894, but not 2x 807.
Could someone please explain why it is considered like 2 x 807?
I mean, they are both beam tetrodes, but so are many other valves.
Why am I interested? Simply because I too have admired this valve, noted
the AB1 data, (very friendly drive voltage!) and long felt that, when I get
a round tuit, it might be worth experimenting, similiarly, with a P-PP pair,
ie both sections paralleled - which gets rid of the common G2 problem, and
halves that problematically high Ra-a figure.
Since I have a small stash of 829B's and 5894's, plenty of 6SN7's, and a
pair of Hammond 100W 1650R's (5k, not really enough but maybe suitable at
lower, say Va 500?), it's not a totally infeasible idea, especially if I do
it in a modular fashion so that I can revert to P-PP 807's or the like at
the prototype chassis / breadboard stage and compare them.
However, I freely admit it's only talk and thought at this stage !
The other thing I really like about 829B is their physical appearance.
Seems to me one could build a quite beautiful "antique" looking or
Victoriana* style amp with these bottles on display, four in stereo .
Whether performance would be worth the effort is an unknown as yet!
Regards,
Ross Matheson
*
Victoriana, Baroque, Rococo;- I don't know:- something ornate, anyway!
Patrick Turner
which has 600 volts B+, and +300 for G2 supply in beam tetrode.
That made 80 watts, mainly class B with 9% 3H thd.
For triode, the bias required gets rather high as you increase the B+.
VTL are renowned for running tubes with high B+ voltages.
Their Stingray with a quad of EL84 runs fine with 530 v B+, with
60% taps for UL.
But Musical Reference run 700 v B+, and +350 for G2 with
5% of CFB windings, and get 33 watts from 2 EL84 with RLa-a = 14 kOhms,
so supply volts have to be chosen with the load in mind.
If you have a 500 volt supply, and you have too low a load,
then when you drive up to half power, expect the tubes to
thermal out when sustained levels are used, so you gotta
keep the load line below the plate Pd max line, or not far above it
when designing and choosing loads.
Screen power dissipation must be watched during quiescent and
dynamic conditions, or else the tube fails, simple.
People tend to overload some of these PA high powered class B amps
by connecting too many speakers, and the current change x voltage
across the tube means they are likely to fail, often in this situation
it is the fragile screens that heat up, glow red hot, and collapse inside the tube,
and poof, there goes another one.
EL34 can take 900 B+, and +450 for G2, and make 100 watts,
but not continuously with a sine wave.
Load is about 11 kohms. This gives over a kV rms of signal swing
across the primary, so it needs good insulation.
How to work out power disipated in the tubes is in RDH4.
Just 2.83 volts worth of background info.....
Patrick Turner.
Ross Matheson
I seem to recall reading some years ago that VTL used Chinese tubes called
807 that may not have been identical spec to NOS 807, that could take 560V.
Not entirely sure about that though. I take it you mean 500/560 in triode?
I must say I'd be very interested in seeing an actual circuit for 829, it
sounds very like what I was hoping to do ... what is the Ra-a figure?
Is it using them with parallelled sections, ie in p-pp ?
Is it possible you could to email it to me as well?
I'd really appreciate it; thanks if you can!
Ross Matheson
(please replace the zz part with nz)
DEMOSTENES A. Goksøyr
I said in an earlier posting that 829B is two 6L6 valves in a common
envelope. Someone here pointed out that they are in fact quite
different in electrical characteristics. That is obviously correct. I
was only quoting Eric Barbour's excellent article in VTV No 4, Vol 1,
1996 - '6L6 forever'. On page 6 he says: 'The major VHF push-pull
tetrodes of Word War II, the 815 and 829, were based on the 6L6.'
Well, I may have said that 829B is identical to (two) 6L6 and that is
not the same as 'based on'. I am sorry for this.
Anyway, 829B is a very nice looking valve and I am also interesting in
circuit diagrams of amplifiers with this valve.
Regards,
Arnold Goksøyr
On Mon, 12 Nov 2001 19:19:41 +0800, Philip Lawrence
<hitr...@iinet.net.au> wrote:
>Hi Willy
> The original Williamson with 807's cathode bias had a power supply of
>450 volts. 400 volts is the max for 807's Triode connected fixed bias but VTL
>runs them at 560 volts I have used them at 500 volts with no problems. I have a
>circuit for 829's Pentode connected [Williamson }if you like I can Scan it and
>send, it uses 560 volts Anode 206 volts G2
>Phil
>
>Phil
DEMOSTENES - N6899 Balestrand, Norway
Pierre Buck
The 829B works very fine in the Williamson configuration. Use 2 Tubes.
Output transformer is a Millerioux XH36B 6K6 PP and the anode voltage
500V
Grid 2 is held at 200V DC. Grid 1 at -20V and cathode current 60ma for
each tube (2Tetrodes).Classic 5692 preamp. Output power 50 Watts. At
20W THD 0.09% IMD 0.07% and frequency response 20hz to 20 Khz at
+/-0.3db !
Sounds very good. If someone has ...anode caps for this tube .
Regards
Pierre
RdM
>I said in an earlier posting that 829B is two 6L6 valves in a common
>envelope. Someone here pointed out that they are in fact quite
>different in electrical characteristics. That is obviously correct. I
>was only quoting Eric Barbour's excellent article in VTV No 4, Vol 1,
>1996 - '6L6 forever'. On page 6 he says: 'The major VHF push-pull
>tetrodes of Word War II, the 815 and 829, were based on the 6L6.'
>Well, I may have said that 829B is identical to (two) 6L6 and that is
>not the same as 'based on'. I am sorry for this.
Thanks, Arnold, I see it was a language problem, and not only yours.
"Based on" , meaning, say, 'as a starting point', makes it all clear.
>Anyway, 829B is a very nice looking valve and I am also interesting in
>circuit diagrams of amplifiers with this valve.
I agree with with you there. It is very nice looking indeed.
Let us keep the interest up!
7 pin Septar bases would be nice to obtain.
I am not so worried about plate pin connectors, yet.
I think it may be possible to adapt some other connector.
RdM
nz not zz
Mr D
> The 829 screen grid supply maximum isn't very high so I doubt if you'll
> get them to work well in psuedo-triode mode. I've often wanted to try a
> couple of 829's P-P (both sections paralled), but I don't see many 829s
> in the UK anymore. Not at giveaway prices anyway :-(.
>
You could put a zener between the plate and the screen grid. That
will drop some volts but still put the full signal on the screen grid.
I know zeners have a reputation for being noisy but that doesn't
matter in this application. I think Bruce Rosenbilt does something
like this for exactly this reason in his Single Ended With Slam triode
strapped 6550 amp.
WILLY KROGSTAD
I'll have to try Mr. B. Rozenblit's screen regulator using a 6BM8 one of
these days.
For instance: What exactly IS the Williamson configuration? Eh - what is the
Williamson part of it?
Or is it harmful in any way to let the tubes glow for hours with no B+? (The
803 is my real winner! - shines like some kind of yellow wine..)
WiKro
RdM
>How about single-ended? I have never seen any experiments with 829B in
>this mode.
>By the way, 3E29 is equivalent to 829B except that it is a for pulse
>applications, but it has the same electrical data as 829B
Have a look at this:
http://www.sparkaudio.com/E929d.htm
It's a bit confusing though;- it says these are mono block amplifiers of
single-ended, class AB1 (!)
I think they must really mean there's just one output valve (in p-p).
Still, these are the first commercial examples I've ever seen (or heard of).
Also see the large 4x monoblocks at
http://www.sparkaudio.com/E800.htm
Very nicely made amplifiers.
RdM.
RdM
(American 829 B, European QQV07-40, Russian FU-29/GU-29)
http://www.audio-arts.ch/facts500.html
(and another pic at)
http://www.cayin.de/amps_de/vollverstarker/500/500mk.htm
(also)
http://www.cayin.de/amps_de/vollverstarker/500/500_neu.htm
http://www.cayin.de/amps_de/endverstarker/800/800.htm
http://www.cayin.de/amps_de/endverstarker/800mk/800mk.htm
http://www.cayin.de/amps_de/endverstarker/929D/929D.htm
(and same pic at)
http://www.audio-arts.ch/facts929d.html
(confirms my previous suspicion that it is a p-p amp in AB1!)
Those links are in German;- English speaking folks can get a rough
translation by copying & pasting
http://translate.google.com/translate_c?hl=en&u=
in front of the links, with no space between the two.
The pictures (and specs) need no translations though. (Tube Lust :-)
[NB:- Some of these links are frames, "opened in a separate window".]
[Might get an error message to click OK to. Go to the root URL later ...]
You can see a nice close-up of a single valve (equivalent) at
http://ly1dq.hypermart.net/gu-29.htm
if you've never seen one before ... (or even if you have;-).
Yes, the search engines have been working overtime a bit tonight!
And these valves aren't *that* expensive, if you look around a bit.
Regards,
Ross Matheson
reply to nz not zz
Doug Schultz
a lot of otherwise good sites usable to a linguistically challenged
individual like myself.
"RdM" <ste...@ihug.co.zz> wrote in message
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