HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

I found some enthusiastic reports on a MoFo class A amplifier, so I downloaded and studied the details.

https://6moons.com/audioreviews2/mofo/mofo.pdf

I was impressed by reports of persons who had built them, so I've gone and built a pair.

I was helped by dismantling my Pass 50W mosfet amps, so did not need to buy much extra, and the (now voluminous) spare parts box contributed as well.

I was helped by a friend (yes, I have got at least one) who had a pair of the printed circuit board and two MOTs (microwave oven transformers) to use as the chokes.

End up, it's the best amplifier I've ever listened to in my house, so hugely well pleased.

Can it cook baked beans as well

These look fantastic, I'd love to build something like them.

I like the fact it looks like no other solid state amp I have ever seen

Thanks for the kind comments.

One day I'll put then into a box, well two boxes for each unit as they are a tad heavy for an old boy like me with a bad back..

valvesRus wrote: ↑Tue Jul 28, 2020 3:33 am Thanks for the kind comments.

One day I'll put then into a box, well two boxes for each unit as they are a tad heavy for an old boy like me with a bad back..

Pu them into a box each, move the heatsink to the front, the inputs and outputs to the back, give it a nice paint job and you have a pair of giant QUAD 303s.

Thanks Steve.

Yes, but ------------

Nice idea, but it would be too heavy, much the same as the lash up prototypes.

I was thinking of making one unit to contain the MOT ( microwave oven transformer ) a bean tin size capacitor and the heatsink, with the heatsink horizontal, a bit like the Musical Fidelity A1, or A100.

Mind you, nearly every amp i've ever made has never made it to the boxing up, being electrically safe and looking good stage.

When Morgan Jones signed my copy of his book at Owston a couple of years ago he wrote " to Phil, for perseverance in the face of safety and the use of MDF at high voltages"


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I see that this amp needs a decent output from the pre-amp to drive it. What are you using or is it a direct feed from a CD player?

Geoff.R.G wrote: ↑Tue Jul 28, 2020 11:21 am I see that this amp needs a decent output from the pre-amp to drive it. What are you using or is it a direct feed from a CD player?

I have two transformer coupled valve preamps. One is an Audionote copy built by Philip Ramsey of Bluebell Audio fame, and the other is a World Designs Pre3. Both work fine with MoFo.

My other two preamps are sadly lacking in drive on this amp. One is a passive and the other is a cheap as chips Chinese valve jobbie, and they both work well with my Chinese chip amp for lesser duties like powering my DIY computer monitors in the study.

ADDITION. A buffer like (for example) a Pass B1 would be something I would investigate if I had no suitable preamp. Knock off PCBs are on Ebay.

valvesRus wrote: ↑Tue Jul 28, 2020 11:36 am

Geoff.R.G wrote: ↑Tue Jul 28, 2020 11:21 am I see that this amp needs a decent output from the pre-amp to drive it. What are you using or is it a direct feed from a CD player?

I have two transformer coupled valve preamps. One is an Audionote copy built by Philip Ramsey of Bluebell Audio fame, and the other is a World Designs Pre3. Both work fine with MoFo.

My other two preamps are sadly lacking in drive on this amp. One is a passive and the other is a cheap as chips Chinese valve jobbie, and they both work well with my Chinese chip amp for lesser duties like powering my DIY computer monitors in the study.

ADDITION. A buffer like (for example) a Pass B1 would be something I would investigate if I had no suitable preamp. Knock off PCBs are on Ebay.

Thanks, I have a Quad 34 pre amp which might be suitable but obviously not the Moth passive.