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cd-i 23rd August 2005 01:42 PM

some power amplifier recomendations

I want to build a power amplifier for using it at home and i need some recomendations on schematics.

I don't need something too powerful, i think something around 100 - 120 watts is enough for me. I also want the amplifier to have MOS-FET's on the output.

Browsing on the internet i found the A and T labs webpage and i think that their K9 project is ok.

If anyone know something about that amplifier because the schematic looks good at first sight. But i wanna know some ratigs about how it sounds, not only some specification and waveforms.

I should mention that i am not so experienced in audio designs (i built some amplifiers but nothing special).

Thanks in advance

funberry 23rd August 2005 04:29 PM

The K7 looks good.

What do you feed it?

I wish they had shown the bottom side of that PCB also, so we can duplicate it.

It seems like a pretty good desig, hard to beat that. There were a few MOSFET designs around the forum, look up postings by member "quasi", and they should come up.

creek amp

I'll try to dig up others.

Cum e vremea in Timisoara?


tlf9999 23rd August 2005 04:55 PM


Originally posted by funberry
creek amp

that particular design is quite different from the K7: it is closer to the JLH in terms of the use of a phase splitter, vs. a traditional VAS there both output devices work in phase.

funberry 23rd August 2005 05:10 PM

What can I say, I'm partial to quasi-complementary symmetry, at least with MOSFETS.

The supply chain for true-audio complementary MOSFET pairs is too strangled. Scarcity, high prices, few players, high counterfeit presence, I don't want to go near that market. I stick with N-channel, all the way.

Plus there are many authors who affirm there is no real compelling sonic advantage to a MOSFET amp vs bjt designs. And I can get complementary power bjts' at prices I find acceptable.
I know, this can start a long FET vs bjt argument.

Most emerging semiconductor technologies are plagued by the same inherent challenge in audio design: The initial lack of available complementary devices. That's where IGBT's are now.
( I wish I could find a quasi-comp design using IGBT's!, these things are so rugged)

Ok here's another:

citation amp


still4given 23rd August 2005 05:40 PM

My first amp was a "Project 101" from ESP Audio . It was very easy to build and sounds wonderful to my ears.

Blessings, Terry

cd-i 23rd August 2005 05:48 PM


Yes i like the design of the k7 amplifier too but unfortunately the layout presented on the web page, besides the fact that is incomplete, is also designed for their custom enclosure.
I have an enclosure from an old romanian amplifier and i can not use that layout. I know that a good layout is essential but i have to redesign it in order to fit my enclosure. The space is very tight in there because i intend to build 4 amplifiers in the same enclosure and power them up with the switching power supply they used in their k6 project.

Anyway this project is in a very early phase and i only have ideas of what i want to stick in that enclosure...

So if anyone can give me some tips and ideas please HIT ME !!!

p.s. hehe o surpiza placuta. La Timisoara vine toamna...

( nice suprise. The fall is coming in Timisoara...)


funberry 23rd August 2005 05:54 PM


My first amp was a "Project 101" from ESP Audio
That's a very nice amp.

The specs on it are outstanding, better than some commercial mosfet amps. It may well be the lowest distortion amp in the ESP portfolio.

Anyone wanting to build an amp owes it to themselves to consult the Elliot website, at least for some ideas.


cd-i 23rd August 2005 06:41 PM

yes i like the simplicity of that schematic but i have to check the availability of the power transistors in the local stores...

cd-i 23rd August 2005 06:41 PM

i also lihe the idea of building an N channel amplifier because i have some spare IRF640 mos-fets from an old project

thanks guys for helping me ;)

tlf9999 23rd August 2005 06:49 PM

you will not be able to use those irf devices with esp101 without modifications: you will have to replace the bias pot with a vbe/vgs multiplier.

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