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-   -   20 Watt SE. I had found it. (http://www.diyaudio.com/forums/tubes-valves/77326-20-watt-se-i-had-found.html)

Hojvaelde 7th April 2006 09:26 PM

20 Watt SE. I had found it.
 
Hello

As You all know am I looking for a 25 Watts SE amplifier.

After help from You here at the forum, I had decided to build 4 pcs clones of Goliath from Triode Dick. 2 to my friend and 2 to me.

I can also see the new Hammond 1638SEA OPT fit to the 211 tube.

Does any had build a Goliath clone? Sound?

I have a few problems and the first is where can I buy D3a tubes? :confused:

Regards

Benny

tinitus 7th April 2006 09:38 PM

http://www.ahrens-audio.de/tubes.htm

tinitus 8th April 2006 05:33 AM

Hi, I forgot this one

http://www.acoustic-dimension.com/

audiomanics 8th April 2006 02:06 PM

Find some on eBay, frequently....good replacements: 6922, 7788 (even very nice Amperex PQ's) for just a few bucks..

Miniwatt 8th April 2006 04:18 PM

Hey, that's great!! I'm going to build them too -once my turntable and pre-amplifier are ready:rolleyes: )

Do you understand Dutch? If not, there's a firm in Holland that quite closely cooperates with Triode Dick, they have complete transformer sets for this amp: www.ae-europe.com. They also have silver output transformers for this project (). Without them, power xformers and chokes are about 300 I recall..

I'm not so worried about finding those d3A's, I'm more concerned with those EY500A rectifiers..

Keep us posted about your project, I'm very curious about your experiences!

Good luck!

P.S. 211's are great!!:cool:

Hojvaelde 8th April 2006 05:27 PM

Hello

No I can't dutch.

If I can't find the EY500A's I have some 4 kV diodes I can use. Not optinal but better than nothing.

I will first try the Hammon OPT and after that change to better.

Benny

tinitus 8th April 2006 06:41 PM

Try and translate with this - most of it gets understandable

http://world.altavista.com/

schiller 9th April 2006 06:13 PM

I don't want to discourage you, but this amp cannot produce more than 12 watt (with 1000v at the plate). The only way to get such power from a 211 at plate voltages around this, is driving the grid in the positive region, supplying grid current.

The circuit you pointed uses a coupling capacitor, which will rectify your signal and create horrible distortion. You need a direct coupled cathode follower or an interstage transormer to provide the needed current.

By the way: One 5687 cathode follower with 8mA cannot drive the 211 in the positive region, despite the "ongaku" shematics that you can find in the net.
You need at least 15mA anode current for the driver (e.g 2 sections 5687 in parallel). I don't believe that the original ongaku has such a big mistake, this simpy cdoesn't work.

Greetings
Konstantinos

Hojvaelde 9th April 2006 08:49 PM

2 Attachment(s)
Hello Konstantinos

Maby correct but now I had made some surfing about "Ongaku".

It seems that they using a 211 to drive the output tube (also 211).

I had attached Audionote diagram.

continue....

Hojvaelde 9th April 2006 09:06 PM

Continued

I also found a schematic where they using a smaller driver tube.

http://www.diyparadiso.com/proj/uesugi.htm

I think i will rise to 1200 volt and I will use tube rectifiers ( EY500A ). I have some on stock.

I change to 10k OPT an 70 mA current.

Comments wanted

Benny


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