power amp comparison

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Hey all, I'm new to DIY audio, and I've been looking for a good comparison of popular DIY power amp designs, for instance the Zen, Leach, and Aleph amps and variations. Also, I've seen some stuff on 8ohm 400W and 550W MOSFET amps, but no info on what class they are. I'm interested in distortion, efficiency, max power, and cost figures, too.

Can anyone help me out?

You can see info on Zen and Aleph amps at www.passdiy.com.
400W and 550 W amps are class AB or B; a class A of this size would probably need liquid nitrogen or something for cooling.
You'll find that most of the members here feel that distortion is not the primary means of determining amplifier performance, and that efficiency is near the bottom of the list. You have to listen, which of course is difficult because you have to build the darn thing first.
So what you do is build two each of all the different topologies and listen. The first one is just a practice prototype for the real one.
Cost? Bwahahahaha!
Well, there are some that care about efficiency...

400W into 8ohm is either Class-AB or some fancy new Class-D or Class-T or what not.

Common paulb, cost matters to some people (me :))... But if you want to know the cost of the project, good luck. We don't know at what prices you can get a casing or the metal to build one, or heatsinks for that matter. As for the electronic parts, you can use expensive parts, cheap parts, or really expensive parts, it's up to you.
Actually, cost and efficiency are important. For instance, as you said, class A is so bad in that area, I'd need insane cooling. This is a bad idea. Since I'm new to this, I don't know what is a good idea and what is a bad idea. Cost means a lot too-- with no cost limit, nothing matters. I could make a 10kW class A and spend ten million dollars making it not fry. But that's ridiculous and hardly worth while... And I don't have tons of resources.

Some designs require more costly components, no?

I checked out the Nelson Pass's amps, but I'd like to get info about other types... I'm really looking for a quick comparison so I can figure out what sort of amps I'd like to screw around with. Too bad there isn't a nice article around.

Altaic: what I meant about cost was that you could use teflon caps, tantalum resistors, silver wire, custom built shielded torroidal transformers and a whole load of fancy expensive parts, or you could use bargain bin eletrolytic caps, with run of the mill carbon film resistors and an EI core transformer you ripped out of a piece of scrap, (or maybe something in between). But any design can be made expensive...
Sorry, I didn't mean to sound like I didn't agree. I'd like to spend a few hundred dollars max. I'm not concerned about pushing a design to it's max by using expensive components. For instance, one of my friends told me it's better to design an amp to be switching if it's to be scaleable to high powers.
Altaic, the cost is containing of three main things:

Power supply: Transformer, smoothing caps and rectifier

Case, can be expensive or virtually for free (if you make if of junk metal)

Power semiconductors: Can be expensive

The rest: PCB, res, caps, etc are usually cheap.

The three top items stands for 90% of the cost.

It's often a breakpoint if the amp shall work with voltages above +- 63V. Everything gets harder to get.
Now we're cooking.
Altaic, do you have any other requirements like power output, etc.? Cost, efficiency, and complexity are other tradeoffs. And finally, how much experience do you have building electronics stuff?
For example, one of the simplest amps to build is the Son of Zen, except it requires a beefy power supply. That and the heatsinks probably dominate the cost (as peranders said).
My Bwahahaha meant that it will always cost more than you think it will. You may want to start hunting up surplus shops in your area.
Hi Altaic,

The nice thing about DIY is that you can build something that you can't buy in a shop. Commercial stuff is allmost allways the cheaper option. But if you want something special, you gonna have to build it yourself: enter DIY audio.

For example: Class A commercial products are very expensive: Enter the JLH 10 Watt Class A amp, the Pass ZEN amp, the Elliots DOZ amp, The hiraga Monster amp, the MJ amp, Pass A40 amp etc.

Another example: 400 watt in 8 ohm... hmmm Aussieamps .. don't remember then name correctly, he sells PBC boards, the Leach amp.

make a list of these and select the one that fits your needs without being overly costly ..bwahahaha:D

I've got a fair amount of electronics experience. Recently, I had to solder some new capacitors (and a few other little things) on my overclocked Athalon motherboard. The old ones blew up. :D

It's amazing how resilient "delicate" computer components are.

I first found out about Elliot's 60-100W amp (project 3A), and I thought it might be fun. But since then I've been learning about new "fancy" amp technologies... I'm now thinking of looking for a switching design, or as JoeBob suggested a Class-D or Class-T. I've heard of Class-Js, too, but I'm not sure what their deal is.

Thanks a bunch for the help!

Altaic, can I just ask why you want such a high power amp? It's a common misconception that "more" is better in audio. Unless you are seriously going to raid junk markets, I think you will have a great deal of difficulty in producing a very good sounding 500W amp within that budget. Most people seriously overstate the amount of power they need, for all but the most absurdly inefficient speakers 100W is more than enough for a typical domestic situation. Of course everyone is different but to give you an example, I have a 100W amp and have never, and I do mean NEVER, got it anywhere near maximum power, indeed it would typically run at no more than a few watts (remember it's not a linear scale).

In terms of "bang for your buck" I believe that you would be far happier with the end result if you looked at amps up to the 100W mark. You should be able to produce a very good sounding amp within that budget.

Hope this helps.


Thanks for the advice. I don't specifically need a 400W or 500W amp, but they are more interesting to build than <100W ones. Also, I can use cheap parts if I only want to use, say, 150W of the design's spec. But I like flexibility, and I may actually need high power in the not-so-distant future (not for a home stereo system).

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