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ACA Mini "Almost Clone" Board - Outside U.S.A.

This thread is too quiet so I will make some noise...

I built my Mini last Sunday including a base made of Poplar, the popular was a fortuitous find since with my original base I managed to compound error after error until I surrendered it to the cutoff pile. That will teach me to complicate simple things.

I managed to bias the Left channel on Tuesday night and ended up with 299mV and 11.52V after ~ an hour so and the bias did not fluctuate so am confident the bias will hold. Will check it again in any case. I used Kevins Youtube video for guidance.

The Right channel hopefully I will get to tonight.

So, no music yet but no smoke either, thats still a good thing in my book.

I had to substitute a few parts due to shortages but nothing drastic, the 3% Power resistors I replaced with 1% (so its even better;)) and the super capacitor was a slightly more expensive model, the specified model was out of stock so I also "Upgraded" it, I think it was a whole 50 cents more.

I got everything from Digikey and the Diystore.

Maybe this weekend it will make music.

Oh, and BTW, even my wife thinks it cute. Thats high praise right there.

Anyone else making progress?

Thanks again to all who made this possible.
Picture please
Picture please 😀
Biased Right channel ~ an hour ago, the Left side creeped up slightly and I ended up at V0 11.50 Vb 305mV on Left side and Vo 11.51 Vb 303 on Right. Still no music but hopefully sometime Saturday it will sing. Heatsink temperatures were measured all four were close, between 137 - 139F.

Ambient temperature I would guess ~88F. Heatsinks are obviously hot but I can hold for a few seconds. Thats still quite a difference, almost 50F.

I biased in what is the warmest room in the house thinking it will be playing in a room at least 10F cooler with an overhead fan providing air movement so I should be good?

Comments / advice welcomed.
An initial review. My opinion.

It has been playing for about two and a half hours. For context, Source is Pi3 with Hifiberrry DAC, FLAC files with Moode player. Preamp is ESP P37 RevA. Speakers Mark Audio 10.3 in a design by Nandappe San named DDBH-B13-ML. I have many amps, speakers and preamps mostly self built or kits.

My reference is a clone of the Allen Wright FVP5 and either the Transcendent Sound SE-OTL (Class A)) or a Tripath 2020 (Class D) amp from Diyparadise named the Charlize. Listening was nearfield ~ 6 feet away. The room is about 16 x 40 feet and I was at the front.

Main reference recordings are Nova Bossa: Red Hot On Verve and Don Dorsey: Beethoven Or Bust but others included. (The Nova Bossa is an older recording, I think it may be from the 1950's or thereabouts and has some surface noise etc but has an openness and air about it that I really don't hear in newer recordings or any I have anyway EDIT, I have another CD by Ernic Ranglin : In search of the lost Riddims).

It is now in our "TV Room" ambient is ~78 and the overhead fans are on. Temperature on output heat sinks ~ 5mm above the mounting screw is 105 - 110F on one channel and 104 - 109F so much better.

Sound, well not what I am accustomed to. Jumpers were on for 99% of the time and I only removed them for about two minutes to see if I could hear a difference.

So my opinion this little amp is harmonically rich, much more so than I would expect from S.S. but not in any way excessively so. At the same time I find it very resolving and a detail freak but again at the same time not attracting attention to itself. I was thinking it would be more laid back but not at all, it kind of has that smooth tube sound but with detail and seems to be able to resolve everything and anything presented. I noticed in particular, things like reverberation and vibrato being so clearly defined but not at the cost of anything else, just there in its space along with everything else. Bass too is for lack of a better term "normal" I did not detect any weak, tubby, one note or orther aberrations.

What I did notice as well was the stereo image tended to stay mostly centered between the speakers and to the back and centre, no imaging beyond the sides or up front. I will see if that changes with setup bearing in mind imaging can also be an illusion but I do enjoy a magic trick.

Of course more efficient speakers would certainly help the sauce.

I really don't need another amp but I think I need to try something with more power, the Aleph J, maybe, just to know if there really is a difference.


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