Low power discrete designs?

[Dr.EM]

It seems the market for low power designs is catered for almost entirely by chipamps? I wondered what discrete amps in the 5-15W power output range were around?

I've searched, but am not turning up any relevant designs, generally either lo-fi fun projects or class-A amplifiers, a few old designs using discontinued parts mabye also. I am interested in a modern, true Hi-Fi discrete class-AB design, like a low power Symasym or similar. I suppose it'd use TO-220 output devices, perhaps even SOT-32.

I am thinking people may want such amplifiers for small, high quality desktop applications. If no applicable designs exist perhaps it'd be a fun design challenge!

[Glowbug]

Just curious, what's wrong with a Class-A design?

Certainly fits the bill for discrete parts & 5-15W

[Dr.EM]

Not strictly against it, if you know any good ones please post links! However, they have large heatsink requirements so won't make an ideal compact desktop amplifier. Something which can fit into a Hammond heatsink case would be great

[AndrewT]

try the JLH 10W and it's newer incarnation.
Look at the various Pass designs.

[Dr.EM]

Interesting designs, but feel that dissipation is too high, both in terms of heatsinking and supply power requirements.

If I were to build a discrete amplifier instead of using a chip, it'd have to run from 2x12VAC, 75VA, a power supply I've already built but quite a widely useable supply for most I think.

A modern low distortion design is what I think I want, I expect similar to the circuits inside the chips but sans all the protection systems.

[richie00boy]

I am working on a project that may be just what you are after. It's a compact top quality amp, but is rated about 80W. However, it will run from lower voltage rails just fine.

Let me know if you are interested.

[Dr.EM]

Sounds good! Ideally, it'd use scaled down output devices for low voltage operation or somehow be stripped back to just the drivers (if possible?) to save cost and space.

[Glowbug]

However, they have large heatsink requirements so won't make an ideal compact desktop amplifier.

Compact, bah

The Pass designs are where I'd look first.

[richie00boy]

It uses TO-247 Sanken darlingtons in the output, but you might get away with some decent TO-220 non-darlingtons at the power you want. The PCB wouldn't be any smaller though.



PS my hands are pretty small

[jaycee]

Very nice rich!
Is that a home etched PCB? looks pretty good if it is! Double sided too?

Looks like the sort of thing I want to put in a case I have spare. 160mm wide 50mm high 40mm deep heatsink in it. Got a transformer from a Technics SU-Z55 (which provides about 38V rails) i'd like to use too. Good enough for a small bedroom amp!