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829 or GU-29 audio amplifier schematics?

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I'm looking for audio amplifier schematics using 829 or GU-29 tubes. After searching this forum, no schematics of my "taste" could be found for these tubes... The following interesting schematic was found for the little brother of the 829, the 832:

http://www.audiohobbyist.com/projects/832.htm

Does anyone have a comparable schematic for an amplifier with the 829 or GU-29 tube (more output than 832)? SE schematics are also welcome!

Kr,

Martin
 
Saw this thread on friday and thought for myself, this I must try

I built a prototype today and I find it quite interresting I must say, the first thing I notised was that the amp is completely noiseless.

When I started the first channel to test it I thought it didnt work, there was no hum or fiss in my speaker. Then I turned the sinusgenerator on and sure, there was sound :)

I havent meassured dist and outputpower yet but there is potensial in this tube, I will build one in a real chassi, thats for sure :)

Got a bad pic from the prototype, I got no real camera so no closeups :(

tubeamp
 
Hi Adalin,

The results from your prototype sound very promising!

Did you use the 829/GU-29 or the 832/GU-32 tube for this setup? What schematic and operating voltage are you using?

Please keep us informed on your project and findings, I like the concept of using unusual tubes for audio applications :)

Kind regards,

Martin
 
I have a small stock of 832-A philips and some qqe06/40 I can try both in the amp just have to change the bias a little, I got no 829 Im afraid.

distortion, hmmm worse than I expected. with the 832 @ 7W outputpower I have 2,5% and the 1% mark is at 4W measured with my ferrograph

but if one compare it with disortion
its allmost spot on.


Its not a high power unit :) one can probably squeese out a few extra watts with qqe 04/60 I guess but i have not tried yet
 
Adalin,

From what I have found on 832 audio amplifiers on the Internet, the output power in PP does not exceed 10W (7W is OK). Do you apply feedback with your setup? If yes, what resistor value are you using in the feedback link?

Both GU-29 and GU-32 tubes are frequently found on Ebay for a reasonable price (between $3 and $5 each). For those who happen to have a pile of output transformers on the shelve, a nice (and cheap!) way to get some experience with the less common (but still interesting) tubes available :)

Kind regards,

Martin
 
I have found a nice 829B schematic, using the 6N9P for preamp and phase shift:
 

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  • k_6n9p_829b.jpg
    k_6n9p_829b.jpg
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I had planned to glue a 829SE together but I sort of came to a conclusion that the transformers intended for the job were too small so I am going to use a 807 instead.
The original idea was something like this:
http://www.pastisch.se/faktiskt/6sj7_829b.jpg
I have a pushpull design design similar to some 832PP-amps.
http://www.pastisch.se/faktiskt/k_6N9P_829B.pdf

The 6N9P is confusing. I can find a (Russian tube) 6N9C = 6SL7 in my lists and a 6N6P = 12BH7A but not a 6N9P...
 
Ooops the 829PP was already posted.

Both GU-29 and GU-32 tubes are frequently found on Ebay for a reasonable price (between $3 and $5 each). For those who happen to have a pile of output transformers on the shelve, a nice (and cheap!) way to get some experience with the less common (but still interesting) tubes available :)
I find no information what so ever about the Pout from 829 and 832 in PP and SE respectively.
A 832PP is scheduled - got a pair of nice (blue) X-formers from Edcoreusa: 10W, 8Kohm Raa, 8ohm O/P.
 
The 6SL7 is known in China as the 6N9P:

US 6SL7
Chinese 6N9P
Russian 6N9S

Since the last schematic I have posted is from China (there are some Chinese characters visible in this schematic), the 6N9P is used. I have ordered some 6N9S tubes for the preamp and phase shift section of this amplifier.

I plan to use PP transformers from a local company (www.klare.nl) for this setup, they sell 30W PP transformers (8K primary) at a reasonable price.

The Chinese schematic promises 20W (@ 10% distortion without NFB...) using the 829 as power tube. Most 832 setups report about 7W in PP.
 
Thanks for the answers!

I belong to a Swedish HiFi-forum where there has been a discussion on so called UFO-tubes (UFO-tube spotting ) The duo 829/832 are tubes that look queer and pose a challange to be put into amplifying audio signals. And the idea of using ONE tube for a PP-amp is thrilling.

However I follow up with yet another question. How to you (who use these tubes) arrange for a connection to the "anode horns"?
 
I haven't found a ceramic anode connector dedicated for this tube. Looking at the audio projects on Internet with these tubes, several improvised solutions can be found:

Wire-wrapping: looks like a very reliable connection, often found in mil-spec equipment. Only solid copper wire can be used for this type of connection.

Soldring: with a risk of damaging the tube, solder the wire directly on the anode pins. I'm not sure if the solder connection is reliable when heated by the vacuum tube.

PC connector: some brave people have trashed a powerconnector of a PC powersupply and removed the pins of one of the plugs. These connectorpins seem to have the right size for a good clamp on the anode pin. Advantage with this setup is that you can use flexible silicone wire soldered to the connector pin, without risk of damaging the tube.
 
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