• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Tube amps from eBay (China)

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#21
It's a crapshoot.

I heard a nice sounding tubeamp from China that was $200 landed cost at the 2006 diyCascadia. Was it great? Heck no. Was it worth $200? Absolutely! 😀

Then I've heard $1,500 Shanling's magazines rave about.

...

I'd offer $20 for it :dead:

Then use its parts for something else.

Caveat Emptor!
 
#27
Re: Slightly OT

poynton said:
What is a FU29 ?

It looks like my avatar.

Andy
Click to expand...


It is an Asian clone of the popular 829B, a common VHF transmitting tube from the war. It was also used as a radar modulator known as a 3E29 in selected batches that could handle the high peak pulse voltages. Two 6L6`s basically in one hard glass envelope but sharing a common screen grid connection.
 
#30
Before you buy this - get the schematic and how to bias the amp. There are two pots for each channel. There's a 6N1 and 6N2 in each channel as drivers. and tell them youwant to see the schematic before you buy else NO DEAL.
The FU29 is the Chinese label for the Russian equivalent GU29. Here we call it the 829B or the 3E29.
Oh - make sure you get them to wire it for US voltage - the power transformer is dual voltage.
Bob
 
#33
The Music Angel example may or may not apply to this amp. I'd like to see the schematic for this 829B amp. It could be paralleled SE or push-pull depending on the circuit and the transformer. I suspect PP since the output is higher than expected with SE.

I would really like to see a schematic.

I have sent emails to the ebay sellers asking for a schematic - may be if others here on this forum were to also ask for a schematic - then they would get the message: their amps won't sell without a schematic and biasing instructions.

Bob
 
#34
Re: Dynavox VR70

Bierbauch2000 said:
Hi,

pleas have a look on my websites

I have tuned an Dynavox so that he has a better curve linearity

ther are not much things to

here is a link to ma homepage (sorry it's only in german)

the modifications are in blue in the cuircuit.

http://www.retro-optonica.de/Dynavox/DynavoxSchaltplan.htm

http://www.retro-optonica.de/Dynavox/Dynavox.htm

i hope you can understand what i have done.

Kind regards from Odenthal / Germany

Bierbauch2000


🙂
Click to expand...

Viel Dankesehr ! 😀

Very Good Schematics, in 1940 they not have a large capactor (or it was not cheap)
for anode supply then they used a pi-greek filter with big inducitor.

Today it is very better to use a big capacitors (IMHO)

...I have redraw some schematics 🙂

(only redraw - not tested - not build :att'n: )



 
#37
can you just tell me the type of pilot lamp and phase shifter lamp ?
I ask you this because your amp looks like a lot of old amp, it is possible that the scheme is the same as several amp sold for years under different brand.
of the kind
Cochet AL2
43540522a.jpg
 
#40
napovo said:
Hi, did you ever get the schematic for the CST-80 tube amp? I am in need of a schematic. I have an OR.M CST-80 and one channel is weaker than the other. Thanks
Click to expand...

Napovo-
Instead of 'bringing back to life' this old discussion (from 11 years ago), you might get more up-to-date info by starting a new discussion thread: "Schematic for Chinese CST-80?" or something like that.

But you did get some answers here, so perhaps you will be OK. 🙂
 
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