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Amp Camp Amp - ACA
Amp Camp Amp - ACA
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Old 14th February 2020, 03:36 PM   #8531
TungstenAudio is online now TungstenAudio  United States
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The little ACAs are great amps to experiment with the different options for monoblocks. They are compact and lightweight. I tried both bridged and parallel modes with my first set, and found that the parallel mode worked better with my speakers.

Then I went on to build other First Watt clones, but not before making a pair of larger ACAs using higher voltage linear PSUs and the old Hafler DH-220 chassis. I never tried connecting those as monoblocks, because one has a different set of Mosfets – the IRFP140. Check out ACA amp with premium parts. The development went on from there.
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Old 14th February 2020, 03:59 PM   #8532
TungstenAudio is online now TungstenAudio  United States
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The ACA had been a wonderful gateway, as it was intended. I went on to build an M2x, Aleph J and F6. They all sound great in their own way. After building the M2x with a shared PSU, the others were built with dual-mono supplies. The F6 is the most heavily modified of the trio; the Aleph J was just given a really good set of PSUs.

Now I'm working on an enhanced version of the original "Penultimate" Zen V4, the amp which I regard as parental lineage for the ACA. See where the old Hafler transformers are going to be put to good use.
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Old 14th February 2020, 04:09 PM   #8533
mraudioguru is offline mraudioguru  United States
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Quote:
Originally Posted by thomasnadeau View Post
In stereo mode, listening to anything "complex" like rock/etc... sounds like a mess in stereo mode
I don't find/hear that at all? I'm sure the speakers play a large part. I only built one and have always used it in stereo. I'm positive two in mono would be better, but one has been great for me...
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Old 14th February 2020, 06:18 PM   #8534
planet10 is offline planet10  Canada
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Quote:
Sound is different because theres a lot more power available to a single channel than in stereo mode
A lot more power is a bit of a stretch. MonoBloks are 3dB more powerful.

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Old 14th February 2020, 06:20 PM   #8535
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I'm sure the speakers play a large part.
With the ACA's highish output impedance the speaker plays a very significant role. Balanced/bridged more so than stereo or parallel.


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Old 15th February 2020, 01:58 AM   #8536
TonyTecson is offline TonyTecson  Philippines
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Quote:
Originally Posted by TungstenAudio View Post
R16 (in the ACA16 mods schematic) drops the voltage into the drain of the input Jfet. It allows use of higher voltage on the power supply and provides some supply filtering to the input as well. I have been using a value of 499 Ohms more recently with a linear CRCRC supply of 28.5V.
r16 is a gate leak resistor, it biases the input jfet so that the gate of the output mosfet has a voltage at around 4 volts and so that the drain of the output mosfet is biased to 1/2 the B+....r16 plays a big role in the ACA. while its value is not critical 100k to 1 meg will work fine..
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Old 15th February 2020, 03:27 AM   #8537
TungstenAudio is online now TungstenAudio  United States
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The gate leak resistor is R10.
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Old 15th February 2020, 09:33 AM   #8538
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Is it possible to change power supply to 30v and DC offset to 15v

Then roughly we have 11watt per channel?
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Old 15th February 2020, 09:53 AM   #8539
Zen Mod is online now Zen Mod  Serbia
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covered in thread with changes in schematic , at least twice

edit : last time few pages back
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Old 15th February 2020, 12:25 PM   #8540
TonyTecson is offline TonyTecson  Philippines
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Originally Posted by TungstenAudio View Post
The gate leak resistor is R10.
my bad, r10 is it...
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