ACA Redux

Official Court Jester
Joined 2003
Paid Member
try this on your own responsibility

:rofl:

use ZTX if you have them, instead of weakling EU types shown

it'll have same start-up behavior** as original ACA, if not even better

**farting affinity

ACA selfcentered.png
 
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As a fellow relative noob, I agree with A Jedi that the adjustment routine to achieve circuit balance, as it exists, would not be a deterrent to first-time builders like myself. The instructions given by Pass alert the builder to the need to adjust balance by successive approximation. From the descriptions given, the procedure does not sound any more challenging that setting bias on a conventional amp that has flaky pots.

Looking forward to the GB opportunity on this. Thanks again to Nelson Brock for continuing with this, and to the ideas contributed by Mark Johnson and Zen Mod.
 
The prospect of soldering 8-10 additional components is not an issue as far as I am concerned (after all, I'm already holding the iron in my hand...), but I remain very positive about the proven manual adjustment design.

That said, I suppose a potential advantage of an auto-adjust design might be that it would make needed adjustments not only during the warm up cycle, but in response any ambient T fluctuations that the amp might experience in a normal household setting? Might be a nice feature for those of us with drafty rooms.
 
Weighing in on setting the voltage on this project, vs auto-something...
Manually setting the voltage with DMM is required in my humble opinion—if my 11 year old can handle it—and she's totally interested in that part of the process to be sure (loved using the DMM and little clip leads to check resistors)—I see no reason to change it personally. If a new builder has to go out and buy an inexpensive DMM—some places practically give them away with an order—I see that as a good thing personally. Also, they didn't spend most of the $$ for the build on the chassis.... (I do love the OG ACA, and I have 2, so no dig there.)—BUT, this "hedgehog" project is special! (IMO) (Now if I could just get the kid to build the second one...LOL. It will happen—she's got a busy schedule.)
 
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Okay.... Finally got the kiddo to do that last 10 welds on the first monoblock... fired right up with no drama and she set the voltage. Definitely wanders pretty crazily until things get warm and then it all stabilizes. Then she built the second monoblock while we listened to the first (Taylor Swift)... took half the time! Start to finish maybe an hour and a quarter...I really didn't do much, she just got about measuring resistors and stuffing... She was pretty enthusiastic after hearing music from the first one—I'm pretty sure she wasn't 100% understanding what she was making until the tunes flowed, LOL. We did a little taste test from the iPod direct... then with ACP+ (her first project). What a difference! They sound fantastic. Good learning all around.

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Ha! Thanks. Weather is warming—paint is possible... should be able to finish these up—see pic—unexpected gift from a friend! way too long ago—My daughter (Poet) will do the soldering for the Xovers. She's building these next: OSMC.
(Just kidding—we already built those, well, I did...)
Actually her next project is also an MJ youth donation...NP ACA Mini... should be good learning there as I 'm pretty sure we need 2 DMMs to bias it...I'll post about it in that thread though...Lucky girl.
 

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