My take on the PASS ACAs

hatrack71

distracted by everything
I picked up some heat sinks, angled aluminum and some populated PASS ACA boards. I owned these amps in stock kit form once but never really got to listen to them before a man from Oregon made me an offer I couldn't refuse. Well, I got these together in the last 3 days to see what I missed. I am impressed with these little guys on the right speakers. Nice tight, extended bass and really nice wide and deep imaging.

I used a piece of 6061 aluminum for the face plates and cocobola wood for the side pieces. I used brass wood inserts and lightly threaded and epoxied them in as cocobola is hard as heck and terrible for threads...... and tiny drill bits. :sigh: Anyway, I couldn't even finish sanding the aluminum and cocobola because I wanted to hear them so badly. Did I mention you can fry an egg on these after about an hour of listening. I'm glad I used really hard wood so as it won't combust.:smoke: These are pics of them still in the rough stage cosmetically. I am going to polish the outside of the aluminum heatsinks too. 2500 grit wet and then Brasso. I'm happy with the small form factor. Now I am trying to find a cool preamp design to go with these that is also small form factor. I already built the chassis. I'm looking at Hypnotoad's pre that he came up with. Any ideas welcome that I could cram into a 4.5" x 5" x 2" box. No, I didn't mean to have different colored LEDs. It's all I had. I will match them when I can find one or the other. Got to admit, I like the amber.
 

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WOW!!! I liked it:thmbsp: unique design,very very professional looking mono blocks.I have recently completed my second ACA.It is superb sounding even with my 86db GR Research speakers.Here is my build http://audiokarma.org/forums/showthread.php?p=7942073#post7942073
You can use Hypnotoad's SSP for preamp.It will provide just enough gain to drive your speakers.
I am planning to make Le Monstre 8W Class amp now with our own PCBs.

Regards,
Sachin
 
Very snazzy! Did you do bone-stock or did you run the resistor mod to get these to 6W class A?
 
I would suggest little ventilation for your amp.Its Class A and everything inside gets very hot.We have purposely designed our cab with ventilation on top and bottom.I am also using footers for proper air circulations.

Regards,
Sachin
 
I would suggest little ventilation for your amp.Its Class A and everything inside gets very hot.We have purposely designed our cab with ventilation on top and bottom.I am also using footers for proper air circulations.

Regards,
Sachin

Yep, I'm paying attention to that. It is hot but it gets to a certain point and gets no hotter. I may set them on laptop cooler fans.
 
I can say one thing. These things keep sounding better and better. I think these have displaced the Radii monos. Unreal! And nothing has melted yet.:tresbon:
 
Where do you get the boards from? this looks like a good time :)

I think Nelson Pass said something like they were easy enough to build P2P, but he knew not many people would build it unless there was a PCB available. I've been contemplating a P2P F5 build, maybe I'll try my hand at one of these first!
 
I think Nelson Pass said something like they were easy enough to build P2P, but he knew not many people would build it unless there was a PCB available. I've been contemplating a P2P F5 build, maybe I'll try my hand at one of these first!

I agree it does appear easy enough to P2P build but I'm not all that confident in my layout abilities.
 
I agree it does appear easy enough to P2P build but I'm not all that confident in my layout abilities.

Take your time and plan out a nice enclosure. The heatsink and aluminum you will mount your outputs on is critical. Definitely keep in mind what Sachin said about heat. I'm gonna raise mine a little and definitely try to find matching power supplies. Right now I'm using mismatched laptop chargers. Still sounds amazing and for anyone contemplating this build- it is NOT a waste of time. These sound as good as amps in the $1K mark. I for one am shocked. I might try to pick up a bunch more boards. These can be built for under $200 if you are thrifty. I always find stuff made out of nice hardwood (tables, chairs, headboards, etc.), cut it up and reuse it on audio stuff. And I go to the recycler and pick through the 6061 aluminum bin. Yesterday I saw some heatsinks but they were way too big. I will be keeping my eyes open for more little ones like these. Angle aluminum 90 degree chunks too.
 
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I actually have an enclosure with sinks in it that should be adequate for the task already. Well maybe anyway :)
 
I just had a brainstorm. I may try to find two PC fans and build these same aluminum/ cocbola looking enclosures to house them. Cutout in the rear for the power connector. The amps would stack on them- same dimensions except height. They would be shorter. Are most of those fans 12V?

I like the idea of a fan cooled ACA. But quiet. A laptop fan actually might be ideal.
 
Put a pair of 12VDC fans in series for a 24VDC fan? Run it with 19VDC and it should work fine.
 
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