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Old 12th September 2013, 02:27 PM   #1321
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Quote:
Originally Posted by 51frankie View Post
So those of you who have built and use the ACA, what speakers work well and how to you do a volume control?
Something like Lowther PM6A + 15" bass or an Audio Nirvana 15" Full Range driver are extremely good speakers for this amp. Either of these drivers in an open baffle setup, and if you have a small room don't be concerned about that, just keep the baffles moderately sized.
Open baffle all the way.
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Old 12th September 2013, 04:35 PM   #1322
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@all212

Your readings (as corrected):
C1 + = 10
C1 - = 0
Q1s = 0
Q1d = 10.1
Q1g = 4.5
Q2s = 10.7
Q2d = 19
Q2g = 15.3
C4+ = 19
C4- = 0
Q4d = 19
Q4g= 4
Q4s= 4.5
C3+ =4
C3-=0
Q3e=10.1
Q3b=10.7
Q3c=15.3

Those voltages all look correct to me. It seems to me that there is some kind of fault in the ground. Check all ground points with an ohm meter (power off, inputs disconnected) and check for any voltage difference between ground points (power on).
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Old 12th September 2013, 04:38 PM   #1323
12B4A is offline 12B4A  United States
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On each of the ACAs I built, I had to rub some of the anodization off at the corners where the heat sink mounts in order to get the entire chassis grounded.
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Old 12th September 2013, 05:55 PM   #1324
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Quote:
Originally Posted by 2 picoDumbs View Post
It's very easy to learn how to drill and tap holes. I understand you may not want to go down that road though
While that's true, I don't have a drill, and wasn't planning to purchase one to put this kit together. Still waiting for the diyAudio folks to reply.
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Old 12th September 2013, 10:19 PM   #1325
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Have you sent Variac, Jason, or The Store a message?
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Old 12th September 2013, 10:32 PM   #1326
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by JP14 View Post

.... Because heat rises, that means that every other part on the board gets the heat from the mosfets.

My thinking is that if I put the mosfets at the top, the capacitors would get the cool air coming underneath and therefore operate at a lower temperature.
no, it is classA and everything gets hot

but you still lower efficiency of your heatsink that way
you should not mount your out devices at top of heatsink
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Old 12th September 2013, 10:33 PM   #1327
Jason is offline Jason  Australia
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Quote:
Originally Posted by JP14 View Post
DIY Audio - I'm working on the ACA kit that I recently received and just noticed that the screw holes on one of my heat sinks are off.
Yes, definitely looks like the heatsink was offset incorrectly during drilling. Please contact diyAudio store support and they'll arrange a replacement for you.

Quote:
Originally Posted by JP14 View Post
Still waiting for the diyAudio folks to reply.
Please direct all private requests for diyAudio store support here: Contact Us or public requests here: The diyAudio Store - diyAudio - store support doesn't watch the threads in the main forums - sorry!
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Old 13th September 2013, 12:20 AM   #1328
all212 is offline all212  United States
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@LoudThud and 12B4A

Thanks for help!

I used a slightly better grade input RCA that I had laying around and it has two plastic washers on the inside of the chassis - I managed to get the grounding lug for the RCA in between these and perfectly centered and it was making no contact with the RCA body.

Put the grounding lug on the outside of the washers next to the nut and watdayano - no more humming.

Gratuitous pictures...

With Bottlehead Quickie Pre:
Click the image to open in full size.

They are not powering the DQ's! Look for the small mini's resting on the inside of the DQ's. Dq's will get some of this but they are horribly power hungry.
Click the image to open in full size.

Very nice sound!
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Old 13th September 2013, 01:03 AM   #1329
billyk is offline billyk  United States
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Quote:
Originally Posted by all212 View Post
@LoudThud and 12B4A

Thanks for help!

I used a slightly better grade input RCA that I had laying around and it has two plastic washers on the inside of the chassis - I managed to get the grounding lug for the RCA in between these and perfectly centered and it was making no contact with the RCA body.

Put the grounding lug on the outside of the washers next to the nut and watdayano - no more humming.

Gratuitous pictures...

With Bottlehead Quickie Pre:
Click the image to open in full size.

They are not powering the DQ's! Look for the small mini's resting on the inside of the DQ's. Dq's will get some of this but they are horribly power hungry.
Click the image to open in full size.

Very nice sound!
Dang, sure looks sweet! Don't ya just love this stuff!!!
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Old 13th September 2013, 09:27 AM   #1330
Jason is offline Jason  Australia
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Quote:
Originally Posted by WalterW View Post
Hi, does anybody know what the Digikey partnumber is for the red rockerswitches for the ACA chassis?
Or the manufacturer and model?
My chassis arrived in Holland, I can pick them up tomorrow
There were some photos with red rocker switches. Andrea and I just bought them from a local electronics shop. I think they looked really great with the red chassis personally, but we'd already bought the parts for the kits and the power switches come with the kits not the chassis.

I think changing the switch is a nice way to personalize the design a bit and it would be great to build a list of possible switch alternatives people can order to trick up their chassis.

The power switch that comes with the kit is Digikey 401-1303-ND (Invalid Request). I imagine at a guess anything the same dimension should work, including the colorful 401-1307-ND (Invalid Request), but don't quote me on that
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