Easiest to build class-A?

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Doug Kim

Doug Kim

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Joined 2008
#1
Hi all

I have been building tube amps quite some time, but I want to build a nice class-A solid state amp.
I searched the forum and there are (as always) many different opinions on which design sounds best.

Since sound quality can be quite personal, let me ask this question (which might have been asked already) differently.

Q: Which class-A solid state power amplifier design is easiest (but with decent sound quality accepted by many) to build?

By easiest I mean, easy to obtain parts, fewer parts and adjustment, stable after adjustment, etc.

Power about 10W or up will be fine, and the total cost will be nice if it's 3-digit range.

Link to the schematic and tips will be great also.

Thanks in advance.

Doug
 
#4
Doug Kim said:



Thank you for the reply, ZM.

The JLH design is quite old, I wonder all the parts are readily available. I will look up Mouser or DigiKey.

Doug
Click to expand...


you'll find plenty of information here and on A class site , regarding parts subs with more modern ones ;

you can also build any of Pass amps ( most recent ones F5 or F4 or any other Aleph ) - easy to construct , even with PtP ....

being a toob man - you'll not be scared with some temperature ...... 😉

anyway - considering that yoou want A class - you'll need substantial heatsinking ..... ya know - what is it - big Al gunk , which preserve these poor xsistors from poofing white smoke ........ :clown:
 
#5
Zen Mod said:



you'll find plenty of information here and on A class site , regarding parts subs with more modern ones ;

you can also build any of Pass amps ( most recent ones F5 or F4 or any other Aleph ) - easy to construct , even with PtP ....

being a toob man - you'll not be scared with some temperature ...... 😉

anyway - considering that yoou want A class - you'll need substantial heatsinking ..... ya know - what is it - big Al gunk , which preserve these poor xsistors from poofing white smoke ........ :clown:
Click to expand...

Yeah, those big heat sinks... those make all the nice class-A amps (like the legendary Mark Levinson 20.5) look beautiful, but also made me stick to tube amp. I don't have proper tools to deal with metal pieces.
I'm thinking of using water-cooling computer CPU heatsinks... haha

Thanks again.

Doug
 
#6
Doug Kim said:


Yeah, those big heat sinks... those make all the nice class-A amps (like the legendary Mark Levinson 20.5) look beautiful, but also made me stick to tube amp. I don't have proper tools to deal with metal pieces.
I'm thinking of using water-cooling computer CPU heatsinks... haha

Thanks again.

Doug
Click to expand...


naah ....... you'll go nutz because of noise ....... if you wanna go that route - you need substantial radiator and slow & big fan(s) .......

sometimes is really easier with passive cooling , especially if you spend some time on junkyards , looking for them ....

try also at www.apexjr.com ; Steve often have some cheap elkos (for PSU) , and some heatsinks ;
 
#7
Doug,

For 10W, you should consider the Mini-A Aleph. Easy to source, build, and almost no adjustments of any kind.

Search the Pass Labs forum for the Mini-A schematic. There are versions that are both balanced and single ended.

Heat sinking is rather modest, and Choky said the apexjr website has perfect heatsinks for this type of project. Stay away from computer heatsinks or water cooling for something like this. It's more trouble than it's worth.

-David
 
#10
and there's the option of really minimizing parts count with gainclone/chipamps, just parallel 2 amps (in one dual package) with output sharing Rs and DC bias them to get a Class A output

Class output bias principle, needs modification for pwr chipamps which have min stable gians of >20:

ClassApp.png


a single LM4780 package should easily go over 30W in one channel with a push-pull Class A bias, more with really good heatsinking
 
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