Moskido - Hybrid Aikido/MOSFET amplifier

[beau2317]

Originally posted by Andypairo

BTW I also use a Hybrid with a Aikido frontend (E88CC - 6N6P) into a diamond buffer with OnSemi Thermaltrak devices.

Greetings

And how does it sound? And compared to what? Any chance of posting the schematic for that?

[Andypairo]

Hi,
to my ears it sounds pretty good, especially since I changed working point for the output tubes.

I still have to test it with different speakers tough.

The schematic comes from diyaudio's member Mtlin12 and was posted here : http://www.diyaudio.com/forums/showt...573#post816573

Cheers

Andrea

[Wavebourn]

Originally posted by beau2317
Yes but imho the Aikido is a better performer than the white CF, and the 6SN7 sounds better than any 9 pin tube. This is not idle speculation. I have built and compared both (ie white CF and all sorts of tubes). But I am sure that circuit would also sound good.

Yes, this one is better: it has the name.





My suggestion: turn heatsinks 90 degrees so they will be useful.

[beau2317]

They won't fit. Part of the difficulty in making this was finding heatsinks and a case that would fit. This was the best compromise I could come up with. Of course they would work better the other way round. Or maybe the amp needs to be turned thru 90 degrees

But they do work. Each side dissipates 130W and the heatsinks get to about 67C-70C, which is not hot enough to make toast.

[Wavebourn]

Originally posted by beau2317
They won't fit. Part of the difficulty in making this was finding heatsinks and a case that would fit. This was the best compromise I could come up with. Of course they would work better the other way round. Or maybe the amp needs to be turned thru 90 degrees

But they do work. Each side dissipates 130W and the heatsinks get to about 67C-70C, which is not hot enough to make toast.

Remove them and compare. You will be surprised.





Or better saw them vertically to make pin-type heatsinks from them (8 mm gaps between pins).

[beau2317]

If they were removed then they would not be bolted the the huge lump of the case, which also gets hot in the area where the heatsinks are bolted. Also the front and rear panels get nice and warm.

The sides that they are bolted to is quite a thick lump of aluminum, almost weighs as much as the heatsinks.

I agree that they would work much better with the fins the other way. I agonized over this when designing it. But in the end with the limited range of things easily available in lil ol New Zealand I decided to put them the wrong way round. I figured nobody would notice

But I think a calculation will suffice...

Each heatsink is dissipating about 32.5W And it's experiencing a rise over ambient of about say 50C. That makes it about 1.54C/W

The heatsinks are rated at 1.4C/W with fins vertical.

So yes they are not operating quite as well as if they were the right way round. But I can live with that. The MOSFETs are rated to much more than 70C

Sawing the fins would improve things I am sure, but to make it look nice I would need more than the simple manual hacksaw that I have access to. Also the fins would need repainting or coating to stop them looking a mess. Right now the amp looks pretty cool in real life.

But thanks for the suggestions!

[tinitus]

Nice to hear that Broskies hybrid design actually works well

[beau2317]

Yep he really knows his stuff. The aikido is so good I can't see why anyone would want to make any other voltage amp.

John would disagree as his mission is to make many different new topologies.

But the aikido is so beautiful, in concept and performance. Anyone who builds tube amps should make one. imho.

[tinitus]

How much preamp gain does the completed hybrid amp need - I guess you have a Aikido pre as well ..... or could it work as integrated amp

[beau2317]

I do have an aikido line preamp as well, for volume and switching. But I tried my squeezebox thru a DAC (as it has a digital volume control) directly into the amp, and it drove it to reasonable levels, but not full power as the preamp can. The DAC is putting out about 2V as most do.

It sounded pretty much the same direct and thru the preamp. I guess that's the aikido for you..