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TStrong_06 10th January 2003 12:25 AM

Some trouble reading schematics
Hey guys (and girls),
I am trying my darndest to become an "expert" at reading a schematic, but I am having some issues. Particularly, when I see the actual amplifier section of the design, I am constantly wondering where the power supply is (and sometimes, how its wired to the output transformer)...Can anyone point me to a tube-amp specific site where I can see a complete schematic showing power supply, amplifier section and output?

But, thanks to all of the brilliance here, I am at least ready to define my project.

I would like to build an amp to meet the following characteristics:

Type: 2 channel stereo Tube Amp
Output: 10W per channel
Speakers: (relatively inefficient) Wharfedale Diamond 8.2 (86 dB/1W/1m)
preamp: Harman Kardon Citation 21 preamp
Sources: CD player

After all the reading (The DIY handbook, thanks to Ryder especially, and the posts put up on the board), I think that I am nearly ready to get started.

fdegrove 10th January 2003 12:48 AM



Type: 2 channel stereo Tube Amp
Output: 10W per channel
Speakers: (relatively inefficient) Wharfedale Diamond 8.2 (86 dB/1W/1m)
Unless you're living in a tiny room 10W is too few for comfort.

I ran a PP EL84 amp (15W) on my 92db/W speakers in a smallish living room and easily ran out of steam...

It's your call though and I can easily refer to a couple of 10 to 15 W circuits on the web.

Do you have a budget in mind?


TStrong_06 10th January 2003 01:01 AM

Hi Frank,
Oops...yes, about 15W would be necessary, since I figure the loudest I intend to drive the system is about 90-95dB (or about 8-16W by my calculations).

I am really intrigued by the possibility of SE but it looks like PP might be my choice. My budget is moderate...Less than say $200 for all the parts. Based on the catalog at Antique Electronic Supply and a visit to Triode Electronics, I <i>think</i> this might be possible.

Any help with reading the schemas as well? Its like I look and I see these arrows or dots where i <i>think</i> a power supply should be...


SHiFTY 10th January 2003 01:05 AM

10W will be enough to start with. With more power, you need bigger transformers, complex circuits and tubes which cost lots more... to paraphrase Bill Gates, 10W should be enough for anyone!

You could look at a simple EL34 or KT66 or 6L6 Single ended amp, or maybe a 2A3 single ended (Sovtek 2A3 can be run at 30 Watts dissipation ~= 10W audio) if you wanted a triode amp.

For transformers you could use the 125ESE (cheap and choice)

Here is a good site for schematics of all kinds. I have made a couple of these.

Good luck! :D

fdegrove 10th January 2003 01:09 AM


In that case a kit would be the best way to keep a handle on the budget.

Somehow I get the feeling I said it before...a PP of EL84 or even more compact a pair of ECL86s come to mind.

I'll check what I can find if the idea appeals to you.


dhaen 10th January 2003 07:35 PM

Yes, SE can become very expensive. I'm a "victim".:D
Really, if the budget is limited, PP should be the first consideration.

TStrong_06 10th January 2003 07:51 PM

Whichever is better sounding...
Thanks for the input. I would rather have SE, but if PP is going to provide nice sound, and be less expensive, then I will try that...

As it stands, though, I still need some help with the schematics, and some design advice, but I think that I know enough to at least start moving forward.

Shifty -- thanks for the link!


dhaen 13th January 2003 03:45 PM


Whichever is better sounding...
Well, beauty is in the eye of the beholder.;)
Perhaps you should go and listen to some examples before shelling out:$:


TStrong_06 13th January 2003 03:58 PM

For my first project, I just expect the thing to work :) and not blow up on me. I would like it to sound good, but it appears that from what everyone is saying, I can always deconstruct the project and replace pieces with better sounding (read more expensive) components. So I will start there...

Now as to the schematics, do you have any tips for me? I understand enough to get started but any other advice would be cool...


dhaen 13th January 2003 04:12 PM

Hi Tony,

Now as to the schematics, do you have any tips for me?
How about this:

************************************************** *


The voltages used in valve (tube) equipment makes DIY potentially very dangerous. Electric shocks are life threatening.

Do not work with this kind of equipment unless you are fully conversant with the safety proceedures associated with high voltages.

Even though you may be conversant, users and other people in the vicinity may not be. These people are your responsibility.

Consider your construction carefully, and be sure to comply with safety regulations active in your country.

Especially important are earthing, exposed parts, creepage distances, and flammabiliy. This list is by no means exhaustive.

************************************************** *

Sorry to be a bore! But it is important.

Now, the possibilities out there are (almost) infinite.
But your budget (whoever you are) isn't.
You are lucky to be living in the land of "budget iron", and easy mail order access to parts.

Let's start here:
Have you decided how many watts you need yet?

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