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Old 1st August 2005, 06:19 AM   #1
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Smile Class A tube integrated circuit request

Hi Everybody,

Can anyone provide the circuit for my reference about the 300B / EL34 integrated circuit with 20-30W per channel Class A design, PP/SE type are also acceptable.

Does anyone know how to calculate the power of the output transformer require for above cases ?

Any brand of Output in a modest price can be chosen ?

Thanks for your kindly help.
CK
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Old 1st August 2005, 10:35 PM   #2
cerrem is offline cerrem  United States
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I will try to assist..But I am not really sure of your description..
EL34??300B?? integrated??
Could expalin in full detail what your requirements are..

Chris
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Old 2nd August 2005, 05:37 AM   #3
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Sorry to make you confusing.

I want to construct one all tube integrated AMP about 20-30W Class A output.

1) Front stage and middle stage can use any type of tube.

2) Speaker driving part either EL34 or 300B tube can be used.

3) Output can use push-pull or single-ended design.

4) Not sure which kind of design and matching at point 1-3 will turn out better responds.
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Old 3rd August 2005, 01:05 AM   #4
BHD is offline BHD  United States
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More detail, please...

Does the integrated you want to build need a phono stage? If not, you should be able to use a volume control and source selector at the input of the amp, and there are plenty of P-P 300B and EL34 amp schematics out there.

You should be able to get 20 watts class A operation out of two 300B's, although you'd be pushing them pretty hard. It's doubtful you'll be able to get the same out of a pair of EL34's in triode mode, assuming that's how you want to use them.

Good luck.
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Old 3rd August 2005, 01:41 AM   #5
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Hello BHD,

Nice to see your reply.

Sure that I only want to make a simple integrated AMP without phono , no selector (single RCA connection), no tone etc.

You mentioned single 300B must be boosted to get a higher output, can i use SE parallel mode (two 300B/channel) solve the less output power ?

You are right said that "many circuits can found out there" . However, most of it didn't draw a whole picture associated with PSU and a short description. For example, the internal wiring connection and the majority part in ground plane.

In practical, I am not sure anyone have ever made these successful so that such circuit may not been verified.

I would like to make it by hand-wired and some part will use PCB (prefer in PSU) , if in case the circuit values and drawing have any mistake, I must get a great trouble.

Which brand of output transformer suit for me ?

CK
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Old 3rd August 2005, 01:53 AM   #6
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Hi BHD, can you give me advice on the circuit ?

Do you know which circuit alreadly constructed with a positive result ?
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Old 3rd August 2005, 02:58 AM   #7
BHD is offline BHD  United States
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I'm not really a fan of paralleling tubes for single ended operation, but you could use 2-3 300B tubes (or more EL-34's) and get 20 watts (or more) power output.

Many of the amp schematics out there have a potentiometer at the input, allowing you to run a source straight in (usually a CD player). This isn't a bad way to go if you only have one source.

Examples:

Parallel single ended EL-34:

http://www.audiodesignguide.com/my/e...e/el34pse.html

Parallel single ended 6C33C (in German, use babelfish to translate):

http://www.jogis-roehrenbude.de/Lese.../Doppelamp.htm

Another parallel SE amp using One Electron transformers:

http://www.one-electron.com/Randall/Randall_Info.html

A parallel SE amp using three 2A3 output tubes from the same site:

http://www.one-electron.com/SEA1_Info.html

The last couple aren't 20 watts, but you get the idea.

Do some google searches under "parallel single ended" "triode push pull" and the like. There are also a lot of schematics on this site. I'd also suggest checking out the links listed in the "online tube learning for newbies" sticky thread at the beginning of the tube section of the site.

Hope I've been helpful.




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Old 3rd August 2005, 01:26 PM   #8
kmtang is offline kmtang  Canada
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Thumbs up schematics

Hi,

This is a great site for various of famous schematics:-

http://www.simpletube.com/databank/circuit_map.htm

It includes SE, PSE, & PP circuits for various tubes like 300B, 2A3, EL34, KT88 etc etc.


Johnny
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Old 4th August 2005, 05:14 AM   #9
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Sure that it is really a best site
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