Amp Camp Amp - ACA

[Eric]

Random question - who has and uses the most ACA in their system (or total in the house)? Guessing someone has at least 6-8 running in mono for home theater use.

There are probably others who have/use more of these great amps, but I have 7 channels in the house: two daughters each have a stereo amp in their bedrooms and from time to time I use a 3-channel ACA for Center and surround duty for the family room system. If you count the office, I use a stereo pair there every day, so a total of 9 channels get used every day for various stretches at a time. These are fun little amps that just sound great!

 

[canonken]

Wow nice! And if your heat goes out, just switch them all on!

 

[Eric]

Ha- I did that a long time ago. Our upstairs furnace went out for a few days in the middle of winter. I put my a40 amp in my son's room to help keep it a little warmer overnight. It's a stereo chassis that kicks out 200w of heat.

My big Aleph-X amps can certainly keep the place warm - I have three mono amps that each idle at about 400w for a total of 1200w.

 

[sfwille]

I know to peal off and use the thicker, floppy Keratherm from its thin plastic backing, but is there a right and wrong side to the Keratherm? If so, which side should be against the heatsink?

Thanks in advance for entertaining this possibly inane question.

 

[TungstenAudio]

Rest easy. There is no right or wrong side to the insulator sheets.

 

[Mulburg]

Does anyone recognize this weird sound on startup? Nothing else seems wrong or strange and everything sounds fine. Right now it’s just hooked up to a couple 3 1/2” 8ohm speakers in a small ported box. It makes this sound with or without my iPhone attached to the amp via usb c to RCA.

ACA strange startup sound - YouTube

 

[RafaPolit]

Yes, it is described in several places with different names: “farting”, “spaceship”, you pick your description. Is the Caps charging.

 

[Mulburg]

Thank you very much. I’ll go with spaceship!

 

[TonyTecson]

Does anyone recognize this weird sound on startup? Nothing else seems wrong or strange and everything sounds fine. Right now it’s just hooked up to a couple 3 1/2” 8ohm speakers in a small ported box. It makes this sound with or without my iPhone attached to the amp via usb c to RCA.

ACA strange startup sound - YouTube

can't hear nothing...

 

[Pilk]

Does anyone recognize this weird sound on startup? Nothing else seems wrong or strange and everything sounds fine. Right now it’s just hooked up to a couple 3 1/2” 8ohm speakers in a small ported box. It makes this sound with or without my iPhone attached to the amp via usb c to RCA.

ACA strange startup sound - YouTube

LOL...I definitely want that sound when I finish my builds.

 

[myleftear]

I believe it depends on the speaker wether you hear it or not. In my workshop, I usually listen to a kef 101/2, no welcome-fart. Then I recently got a pair of Panasonic SB-PMX7, which I‘ll use as test-victims, et voila, fart was here [emoji3]

 

[mraudioguru]

I think it has to do with how it is hooked up? I remember reading on this thread that it didn't have that sound if used as balanced monos or parallel monos, etc. Not sure exactly what configuration cancels out that start up sound.

 

[tizman]

Does anyone recognize this weird sound on startup? Nothing else seems wrong or strange and everything sounds fine. Right now it’s just hooked up to a couple 3 1/2” 8ohm speakers in a small ported box. It makes this sound with or without my iPhone attached to the amp via usb c to RCA.

ACA strange startup sound - YouTube

My ACAs did that for years, and I thought it was normal, but when I changed to 24 Volt operation, it stopped. Recently, I switched back to 19 Volt operation and it came back. I think it is caused by the laptop bricks used. I call it the whale song.

 

[tripwr1964]

I think it has to do with how it is hooked up? I remember reading on this thread that it didn't have that sound if used as balanced monos or parallel monos, etc. Not sure exactly what configuration cancels out that start up sound.

yes i was experiencing that sound and then recently built a second unit and run in xlr mono. no startup sound now.

 

[ranshdow]

I wonder if the crossover configuration of one's speakers would effect this.

 

[mraudioguru]

I don't think it has anything to do with the speakers at all. It's how the ACA(s) are hooked up and used.

 

[tizman]

For me, the sound followed a particular computer SMPS on two different ACAs.

 

[TungstenAudio]

It is a feature of the SMPS. The big output caps cause the units to briefly hiccup until the caps are charged. When the two boards inside an ACA are bridged together, they tend to cancel. Linear power supplies don’t have this feature.

 

[mraudioguru]

Thank you for the explanation!

 

[sfwille]

When doing the DC Balance adjustments is it sufficient to just power the amp, or should there be speakers and/or source connected?