I have read about bypassing a big cap with a smaller cap that has better high frequency performance and all the for and against (also a YouTube video that shows that there are no difference if the input is a sinus signal). What I did yesterday was to contact the Jensen Capacitor factory and ask if they have something "good". I got a positive reply and I have just ordered some 3300 uF / 63 V Jensen audio grade capacitors. I will pick them up next week from the factory. I live close to the factory ("Jensen" is a very old capacitor factory in Denmark). The size is 35 mm X 80 mm ......so a large one and also a "bit" more expensive than a normal 3300 / 63 cap. I assume the large size is to get low ESR etc. Will be interesting to make some measurement on it.....and hear how it sounds. When building the Amp I will need to mount the cap close to the PCB and then use short wires to the cap. It should be possible I think. Think I will get the kit when it is available and start from there. Then later build a new external PSUs for the monoblocks. I could also just get the PCB and the Mosfets.....and then get large cabinet(s) where there is space for PSUs etc. Don't know what will be the best solution.
I found a little bit of info at Jensen Cap homepage about Audio Grade Capacitors:
White Paper - A/S Tobias Jensen Production
.....but there are no real deep technical information on how such a cap is made....
The caps I have ordered it not to be found at the homepage yet.......
I found a little bit of info at Jensen Cap homepage about Audio Grade Capacitors:
White Paper - A/S Tobias Jensen Production
.....but there are no real deep technical information on how such a cap is made....
The caps I have ordered it not to be found at the homepage yet.......
After what I have read the amp (one monoblock) draw about 1A from the 19V supply. So from the 230 VAC mains it will be about 100 mA and from a 115 VAC main 200 mA......in rough numbers.
19 VDC or 24 VDC will not make a big difference at the main outlet current.
IRFP240 out of production and out of stock for ACA
this is my first Pass amp build I ordered the PCB from dyiaudio but now can not source IRFP240. Digi-key cross reference shows this as a replacement (IRFP240PBF-ND)
this is the link to the Digi page.
IRFP240PBF Vishay Siliconix | Discrete Semiconductor Products | DigiKey
I asked this qusetion on another thread i thought was for ACA but may be the wrong or old one not to active.
this is my first Pass amp build I ordered the PCB from dyiaudio but now can not source IRFP240. Digi-key cross reference shows this as a replacement (IRFP240PBF-ND)
this is the link to the Digi page.
IRFP240PBF Vishay Siliconix | Discrete Semiconductor Products | DigiKey
I asked this qusetion on another thread i thought was for ACA but may be the wrong or old one not to active.
Hello,
This is my attempt at an ACA.
I have used it to try and gain more knowledge since my other builds.
Started with the basic ACA, then added and removed R15, R12, 24volt and heatsinks and other bits.
Well the figurers below have all gone funny when I added them so I hope they make sense.
Measurements are Average not RMS,(something else I have to get my head around)
Input 8ohm load clipping
Volts, amps, Volts, Amps, watts, amps, volts, amps, watts
242, 0.079, 19.6, 0.979, 19.19, 0.778, 6.34, 0.807, 5.12
242, 0.140, 24.0, 1.404, 33.69, 1.275, 7.07, 0.899, 6.36
Have ended up going back to the basic 19v ACA with the home made heatsinks.
Also added the B1 pre.(this was in my junk bin as I did not like it compared to the B1.2 or the BA3 pre I had built but it sounds great with the aca)
It all runs of a single computer power supply.
Now I need to put it in a box.
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How will you describe the sound quality of the amp in absolut terms and not as a relative term compared to its price?
Assuming that you have >93 dB speakers that does not need more power than the amp can deliver. I am also assuming smaller living rooms so you are approx. 3-4 m from the speakers.
Assuming that you have >93 dB speakers that does not need more power than the amp can deliver. I am also assuming smaller living rooms so you are approx. 3-4 m from the speakers.
Its a great little amp to me it sounds very much like a flee power SET amp. I have a 2W one with Mundorf supreme silver in oil output capacitors stepped attenuators etc etc and the ACA is close. My SETS sounds a little sweeter the ACA has a little better grip on the bass frequencies.
The Elna Silmic caps are decent sounding caps.
I paired my ACA up with a Bottlehead Quickie which is an inexpensive battery powered DHT tube pre amp with CCS (constant current source $99 + $35 extra for the PJCSS) The sonics of this combination is very engaging. It easily drove my Fostex FX120 Fonken speakers
The Elna Silmic caps are decent sounding caps.
I paired my ACA up with a Bottlehead Quickie which is an inexpensive battery powered DHT tube pre amp with CCS (constant current source $99 + $35 extra for the PJCSS) The sonics of this combination is very engaging. It easily drove my Fostex FX120 Fonken speakers
you can , but I wouldn't advise more than twofold , or you'll loose highs
R11 to 22K , R12 to 150K
Thanks for that.
Do you think the heatsinks on this case would be big enough?
AMP case 210*90*257mm Q2 All aluminum amplifier chassis / Pre amplifier / Class A amplifier case/ AMP Enclosure / case / DIY box-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
Once again thanks for your help and support of this thread.
Appreciate the fact that we have someone available 24/7 to answer our many questions.
Dave
