Low power amplifier

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MarianB

MarianB

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Joined 2011
electronistul29.wix.com/electronicacudjmarik
#1
Greetings.

I'm in need of a simple low power amplifier, preferably with bipolar transistors ( complementary or not ), something between 30 and 50W on 4Ohm speaker, simple or duble power suply, it needs to be made with easy to find transistors, and not verry expensive, i need to built an amplifier like this for someone and i thougt here would be best to search, the net is full of things like that, yes, but not all of them are ok, and knowing here are many experts in the field i need youre advice in this matter, so any imput would be greatly appreciated.

Best wishes to all, Marian.
 
#7
The original DX, it was guaranteed by the designer.
Or try the latest DX or any of the twenty seven variations that came in between, all but one of which, were guaranteed by the designer.

25W into 4r0 requires 14Vpk and 3.5Apk.
50W into 4r0 requires 20Vpk and 5Apk.
These can be met by single pair output stage powered by a 18+18Vac or 25+25Vac 160VA transformer.

The most expensive parts will be the chassis, the next most expensive will be the transformer.
Replacing an amplifier because it blew up, or was a bad choice, is likely to add no more than 10% to your budget.
 
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#8
MarianB said:
Greetings.

I'm in need of a simple low power amplifier, preferably with bipolar transistors ( complementary or not ), something between 30 and 50W on 4Ohm speaker, simple or duble power suply, it needs to be made with easy to find transistors, and not verry expensive,
Click to expand...
The Circlophone fits the bill exactly:
http://www.diyaudio.com/forums/solid-state/189599-my-little-cheap-circlophone.html
Compared to other low-cost designs, it is adjustment-free, requires no thermal compensation, is thermally stable, and offers better quality and performances.
It is happy with any parts, requires no selection or pairing, and runs on identical output transistors rather than complementary: the OP devices can be 2N3055 or similarly cheap transistors.

The PCB designed by Wakibaki has been tried and validated by odysseybmx414.
 
#12
ingenieus said:
Methinks that one tries to be just a bit too simple. No differential pair? Less is not always more. In this case it seems like just a whole lot less. 🙄
Click to expand...

That amp is superb, me thinks you should research and understand a design before commenting. Did you know that a single cfp input stage is more linear than a LTP ???

Understand that design first, in some iterations that amp far exceeds the performans of so called blameless amps and it sounds excellent too,
Keep reading that site, Mike Renardson is a more than capable designer 😉
 
#15
Renardson's amp is a wonderful illustration of how good a huge amount of global Negative FeedBack with perfect mastering of frequency compensation can do. It totally disqualifies unsupported comments on NFB such as seen today here : http://www.diyaudio.com/forums/soli...dstage-imaging-transients-15.html#post2659513

I already built a MRJ stereo amp using two mono PCBs and currently assembling two MRJ stereo PCBs, all directly furnished by Mike Renardson.

So there is life outside the Blameless world. Hmmm.....

I built my Blameless in 1974, still working. My current interest with amps having a differential input stage now goes to the push-pull VAS structure suggested by Samuel Groner's in figure 56 of his comments on Self's Book.
 
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