If you have a balanced out on your preamp you could drive input to ACA from (-) pin and ground. In this case two wrongs do make a right! I used this technique to drive mine and it sounds great on headphones. I put a 100 ohm resistor between the true output of the ACA and the headphone jack. This is an old trick I learned from 1960 vintage amp designs. Because the signal is inverted twice it comes out correct absolute phase from the ACA.
Ofcourse you can swap leads with headphones too, but with lots of headphones it does mean dissasemble them and make your headphone own cable. There are much better amplifiers for headphones then ACA.
Noise from fan
Hi,
oI have ACA with small heatsink, so I used fan to cool it down. I am using LM317 regulator to lower voltage for fan and also to make the fan voltage adjustable. Problem is I can hear electrical noise from speakers when fan is running. I made two seperate ground points - one for ACA and one for fan PSU. The noise is now little less, but still audible.
Hi,
oI have ACA with small heatsink, so I used fan to cool it down. I am using LM317 regulator to lower voltage for fan and also to make the fan voltage adjustable. Problem is I can hear electrical noise from speakers when fan is running. I made two seperate ground points - one for ACA and one for fan PSU. The noise is now little less, but still audible.
Zen Mod
Would a film cap across the fan in a addition to the 4700 mF help?
Also might try separate power fan power supply.
I don't agree with "MUCH" in your statement. Better possibly yes but not MUCH better.
Is it possible to buy the ACA chassis separately with switch, rcas, powersupply jack, keratherm pads and mounting hardware. They are the perfect size for headphone amps and I have a ton of designs I would like to build using this chassis.The new version that is now available for sale should have this fixed
PS. I also love the big washers to spread the load on the mosfet. I'd buy a stack of them if you sold them separately.
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Not at the moment but in about 2 weeks when we re-launch the store, we'll have ACA and all kinds of Hifi2000 chassis available.
Very nice.
More kits are always a welcome addition (especially if they originate from Pass Labs subforum
)
I've built them all. It's not about building the best, it's about building everything.
Judging an amp from one example you built doesn't seem a perfect test. Maybe you made a mistake. Others seem to enjoy it a lot, I do. Of course I like the F-5 very much also, but their sounds are from different camps.- single-ended and low power vs. complementary. The ACA is pretty sensitive to what speakers it's used with, full-range seem to work best. Mark Fenlon of MarkAudio raved about it, but of course he makes full range drivers.
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