Amp Camp Amp - ACA

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A 48V ACA should be about 30W at 8 Ohms, (double the Voltage, 4X the power) but it would need the biggest heat sink allowed by law :redhot:. Check local regulations, or your wife.
Theoretically, based on a formula yes, it will reach 30W.
In practice I very much doubt it.
All you have to do is look at Zen V4 which is a very close relative of ACA.
Runs at 42V, 2A and barely reaches 25W with 1% distortion.
So I'm very sceptical of claims that ACA will produce 30 W class A, single ended just because Vcc was doubled.
When I finish my ACA 48 sometime next month I will have a better answer.
 
Exactly.
ACA48 will have great difficulty reaching 15W at 1%, hence my point earlier.
Earlier experiments documented by me in this thread show that manipulating R1-R4 can reduce THD by almost an order of magnitude. I don't think it sounds as good. I listen to mine with the feedback disconnected but otherwise close to the original design. It's not difficult at all to reach 1%. Replace R1-R4 with one of those Dale adjustable 1 Ohm 10W resistors and adjust the slider for lowest THD. It will be close to Q2's Source. Adjust R15 to keep bias current appropriate for the intended load.

In the RCA input bridged mode THD reaches about 4% before clipping at around 20W @ 8 Ohms. Nobody wants to call it 6W and then blow up their really expensive speakers with 20W. See posts 7918 7038 and 7040 in this thread.
 
Earlier experiments documented by me in this thread show that manipulating R1-R4 can reduce THD by almost an order of magnitude. I don't think it sounds as good. I listen to mine with the feedback disconnected but otherwise close to the original design. It's not difficult at all to reach 1%. Replace R1-R4 with one of those Dale adjustable 1 Ohm 10W resistors and adjust the slider for lowest THD. It will be close to Q2's Source. Adjust R15 to keep bias current appropriate for the intended load.

In the RCA input bridged mode THD reaches about 4% before clipping at around 20W @ 8 Ohms. Nobody wants to call it 6W and then blow up their really expensive speakers with 20W. See posts 7918 7038 and 7040 in this thread.
Sorry, I don't think we speak the same language or have the same priorities and as such this discussion is of no great value to anyone else.
Happy new year!
 
Theoretically, based on a formula yes, it will reach 30W.
In practice I very much doubt it.
All you have to do is look at Zen V4 which is a very close relative of ACA.
Runs at 42V, 2A and barely reaches 25W with 1% distortion.
So I'm very sceptical of claims that ACA will produce 30 W class A, single ended just because Vcc was doubled.
When I finish my ACA 48 sometime next month I will have a better answer.
Do the math. 25W at 8 Ohms is 40V peak to peak. Pretty close to the rails with a 42V supply. 30W is slightly less than 44V peak to peak. The difference between 25W and 30W, about 0.8dB.
 
this is the power from the wall pulled by 4 channels of my 48 volt ACA amps, my tube OTL pulled even more at around 400 watts...
quick and dirty math, assuming 90% efficiency for the smps psu, that is 240 watts to the 4 channels or 60 watts each which seems about right.... i may do actual FTC testing to find out unclipped sine wave output.....
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Just finished up an amp camp project that I bought used last summer - I think it was a 1.1 or 1.2 version of the kit I bought used on AK. I ended up having my basement flood at the end of June (mass flooding here on the East Side area north of and including Detroit), and both kits were underwater. I had to replace the power supplies and sanitize everything else. I have to say, even after all that and some cheap replacement power supplies I am very impressed with the sound quality. I am running it with an Emotiva line stage into some Dayton bookshelf speakers - and the speakers were very disappointing, even with the folded ribbon tweeter for $60 new. I also paired them with a polk Audio sub.

The imaging on the setup is nothing short of amazing. Even from three feet away, the voices sound like they are coming from the air in between the two speakers. I can't wait to try this setup on better speakers! (Waiting for some Klipsch or Paradigm bookshelves to come up used.) They even do OK on volume for the 5 watts or so RMS into a speaker around 84 dB. Plenty for the basement workshop at least...

I am sold though, I can't wait to build another project! Maybe even double digit watts!

-Geoff

ACA3.jpg ACA1.jpg ACA2.jpg
 
After a long time I finally managed time to build a linear psu for my beloved AmpCamp.

No load dc voltage : 22vdc
On load dc voltage : 18.7v
Trafo used : 15-0-15 120va
PSU : C-R-C (24000uf - 0.33R - 24000uf)

Only one psu is driving both the channels as of now.

Here are the photos:

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Haven't done any critical listening so far. Will compare lpsu vs laptop brick psu performance next week.

Sent from a handheld device. Some typos may creep in
Hi pls help me! Share your Scematic
My toroidal 18-0-18 🙏
 
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edit: posted something thinking that I'm in Korg B1 thread :rofl:

@rubah - do some general reading; everything needed to connect xformer and full wave rectifier, to end with single rail supply - I already posted in my previous post

problem with reading and learning is - you need to be aware of facts and dangers working with mains voltage ........ and with that necessary level you'll be able to understand posted schematic

if you can't recognize what primary is , you're crawling in dark, waiting for disaster to happen - injury or even death

so, in short - if you're not able to deal with mains voltage based build - use switcher brick supply, as majority of ACA builders are doing
 
Last edited:
edit: posted something thinking that I'm in Korg B1 thread :rofl:

@rubah - do some general reading; everything needed to connect xformer and full wave rectifier, to end with single rail supply - I already posted in my previous post

problem with reading and learning is - you need to be aware of facts and dangers working with mains voltage ........ and with that necessary level you'll be able to understand posted schematic

if you can't recognize what primary is , you're crawling in dark, waiting for disaster to happen - injury or even death

so, in short - if you're not able to deal with mains voltage based build - use switcher brick supply, as majority of ACA builders are doing
i know and thanks ... is done ✔️
 

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