Waiting until the ACA has settled down after some hours of use?
In my experience a ‚linear psu‘ sounds different somehow. I‘ve in use an electronic psu from Studer-Revox (made in Taiwan), which could have a similar effect soundwise like the meanwell and a psu from Studer Revox with transformer, rectifier and three large capacitors (Made in Germany for their old mixing desk).
With the older psu the sound has little bit less articulated details and more, very enjoyable smooth sound. Hope this helps.
In my experience a ‚linear psu‘ sounds different somehow. I‘ve in use an electronic psu from Studer-Revox (made in Taiwan), which could have a similar effect soundwise like the meanwell and a psu from Studer Revox with transformer, rectifier and three large capacitors (Made in Germany for their old mixing desk).
With the older psu the sound has little bit less articulated details and more, very enjoyable smooth sound. Hope this helps.
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Hi 100ohms,
What is your question?
ACA is a Class Amplifier and to work exactly like it should you have to wait about 30-45 minutes for "extra perfect" class A sound.
the operational point are then settled. after this, you can do your set up for the DC point. this should be measured between GND and the point before the big cap C1 is (on the pcb is the point where every big resistor R1,R2, R3, R4 are connected together- this is the operational point for single supply = 24V --> about 12,3-12,5Volt.
kr
chris
What is your question?
ACA is a Class Amplifier and to work exactly like it should you have to wait about 30-45 minutes for "extra perfect" class A sound.
the operational point are then settled. after this, you can do your set up for the DC point. this should be measured between GND and the point before the big cap C1 is (on the pcb is the point where every big resistor R1,R2, R3, R4 are connected together- this is the operational point for single supply = 24V --> about 12,3-12,5Volt.
kr
chris
Thanks! Which one is the old one? So I hear that you like both and they are different, one with more details and one smoother?
Hi ChrisHi 100ohms,
What is your question?
ACA is a Class Amplifier and to work exactly like it should you have to wait about 30-45 minutes for "extra perfect" class A sound.
the operational point are then settled. after this, you can do your set up for the DC point. this should be measured between GND and the point before the big cap C1 is (on the pcb is the point where every big resistor R1,R2, R3, R4 are connected together- this is the operational point for single supply = 24V --> about 12,3-12,5Volt.
kr
chris
Thank you for the information. I‘ve biased mine a little less than 12V. The capacitors need probably a time to settle down.
@peterpan
The psu with transformer, rectifier and caps is the old one and it is rated for 250 VA and it sounds smoother.
Eric
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First I’ve listened with the old psu and I liked the sound very much. Before the ACA there was a PP dht triode amp (audio innovations first) in that setup installed. I was impressed by the ‚soul of sound‘ with this tube amp. The ACA shows more details, controls better the bass and ‚has a kicking forward attitude‘ (a Forum member has mentioned that). Than I invited a friend for a listening session and he preferred the electronic (switching) psu because of better details. After having listenend both and tried out also different caps at the input, the newer psu is now in use and I‘ve added a B1K preamp, which adds a little bit of ‚soul‘ to the sound.
All that took me about two months of listening and learning and having fun.
I hope you‘ll have a happy time with that amp too and your mac house is second to none
Cheers
Eric
All that took me about two months of listening and learning and having fun.
I hope you‘ll have a happy time with that amp too and your mac house is second to none
Cheers
Eric
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Thanks for your impressions! Sounds like you had quite a journey too. So much to try out and learn aye?! At the moment I am not even listening to the "MACA" but rather chermann's Premium ACA, it sounds more liquid and smooth to me. When I compare it to the MACA, the latter seems a bit harsh. Not sure why this is though as power supplies differ from one another. Combined with a Wayne Preamp it's a match made in heaven! I am amazed by the attack, dynamics, soundstage and accuracy of this combination. No matter what music I feed them, it never seems to fail. And it's both fun and relaxing, I guess this is what people call synergy in a system. Using quite oldie but goldie ALR Number 2 speakers, designed by another another legend, Karl Heinz Fink.
And did that filmcap help with the harshness?
And what did you mean with power resistors? I didn't understand that part. My boards are surely burnt in well I used them for over a year now.
Yes, filmcaps will help or make a change in my experience. There are other things, that can be changed too upon personal taste (thread: ACA with premium parts).
Power resistors (intuitive translation of ‚Lastwiderstand‘) can be used instead of loudspeakers at output terminals for testing purposes.
Power resistors (intuitive translation of ‚Lastwiderstand‘) can be used instead of loudspeakers at output terminals for testing purposes.
Hi both,
yes some film caps parallel to the big output cap 10mF fine gold could help.
but please don´t forget, that MACA and my ACA are different.
mine is a premium version with the Polymer elcos and the other changes. the MOSFESTS are different too - in this version IRF140 at Q1,Q2.
@peterpaan89
should i tell you that i have a second p_ACA?
heheheee....
it is exactly the same but with other MOSFETS ---> IRFP044N Vishay.....sounds different
yes some film caps parallel to the big output cap 10mF fine gold could help.
but please don´t forget, that MACA and my ACA are different.
mine is a premium version with the Polymer elcos and the other changes. the MOSFESTS are different too - in this version IRF140 at Q1,Q2.
@peterpaan89
should i tell you that i have a second p_ACA?
heheheee....
it is exactly the same but with other MOSFETS ---> IRFP044N Vishay.....sounds different
@chermann : Different how? I know you have and I am aware that it's very different to the MACA as I have seen the PCBs. Maybe I need to hear the other one too. I wonder which parts of your premium version make the most difference in sound quality and whether it's easily doable to tame that harshness with little effort because this is my main criticism on the original version.
| Component | Original Value | TungstenAudio | Mouser P/N | Comments |
| Q2 | IRFP240 | IRFP140 | 942-IRFP140NPBF | |
| R3b, R4b | 2 Ohm | 667-ERX-3SJ2R0V | Parrallel with R3 and R4 | |
| R11 | 10K Ohm, 1/4W | 20k Ohm | 71-RN65C-F-20K | |
| R12 | 68.1K, 1/4W | 90.9K, 1/2W + 10pF | 71-RN60C90R9F | Feedback resistor. Parrallel with C5 10pF |
| C1 | 3300 uF, 35V | 4700uF, 35V | 647-LKG1V472MESBBK | |
| C2 | 1000 uF, 16V | 1000 uF, 16V | 647-RNL1C102MDS1KX | Nichicon RNL series |
| C3 | 10 uF, 25V | 10uF Elna Silmic II | 555-RFS35V100ME3#5 | Input cap |
| C4 | 10 uF, 25V | 100uF, 35V | 647-RL81V101MDN1 | |
| C5 | 10 pF | 598-CD5CC100JO3F | Parrallel with R12 |
I ordered and received my ACA kit. I had assembled a couple Dynaco and Hafler kits and was happy with the outcome. I was excited about this kit, 59 steps and classified as an"Easy" build. Rather humbling when trying it for the 1st time to get-Nothing-, only a small thump from the speakers when turning the amp off. On closer examination I saw that I had not differentiated the difference in the small transistors. I had installed like pairs on each channel. Repairing that mistake having the proper transistors in their correct place I was rewarded with sound, but only on the right channel. Did I ruin something?