Was just typing but see Ben has just posted...
Yes that needs checking and those power FET's look wrong with the metal tabs facing away from the heatsinks.
I'll look in again tomorrow 🙂
Yes that needs checking and those power FET's look wrong with the metal tabs facing away from the heatsinks.
I'll look in again tomorrow 🙂
Q1 and Q2 in both channels are facing the same way. All four wrong?
And the 3 power FETs need to be facing correctly to work?
And the 3 power FETs need to be facing correctly to work?
The power mosfets need to have their metal tabs facing in and coupled to the heatsinks.
Q1 and Q2: the silkscreen on the pcb shows rounded corners on one side. The round side of the JFET needs to be matched to the silkscreen. Looking at your picture the right channel Q1 and Q2 are incorrectly placed.
if in doubt - there are myriad of pics around, of successful builds
The Jfets in the kit were all tested and matched with Idss greater than 5 ma, which mates with Mosfets in the low 4 volt range. I haven't encountered any that didn’t bias up, although they all have pots operating mostly clockwise - deliberately.
Good Morning ACA_mini- builders,
last night I finished my build of the ACA_mini. I was listening to it and was very impressed. Nice little amp.
It is running in my active-setup driving Air -Motion - Transformers.
Frontend 2022-preamp / 6-24-AXO /ACA_mini for AMT / BA-3 driving bass/mid.
PSU is build with toroid (2 x 9V AC sec. / 100 W typical DIY-overkill), CRC-filter,...
I measured an V-output unloaded of 27.4 V DC. Thought could be a little high. Sagged to 25.4 V loaded and biased up.
I biased the amp higher. At the moment 0.200 V (VB).
I added an aluminumplate with the switches (higher / lower 2nd - harmonic) and labsockets for easier measurements.
Thanks, Nelson Pass!
Cheers
Dirk 🙂
last night I finished my build of the ACA_mini. I was listening to it and was very impressed. Nice little amp.
It is running in my active-setup driving Air -Motion - Transformers.
Frontend 2022-preamp / 6-24-AXO /ACA_mini for AMT / BA-3 driving bass/mid.
PSU is build with toroid (2 x 9V AC sec. / 100 W typical DIY-overkill), CRC-filter,...
I measured an V-output unloaded of 27.4 V DC. Thought could be a little high. Sagged to 25.4 V loaded and biased up.
I biased the amp higher. At the moment 0.200 V (VB).
I added an aluminumplate with the switches (higher / lower 2nd - harmonic) and labsockets for easier measurements.
Thanks, Nelson Pass!
Cheers
Dirk 🙂
Attachments
Thanks a lot for the kind words!
Another good exercise. I thought, if I really need a 5W-amp? Now I would say: Yes!
Cheers
Dirk
Another good exercise. I thought, if I really need a 5W-amp? Now I would say: Yes!
Cheers
Dirk
Nice design! I like the port hole.
Every amp is different, so you can't have too many.
Every amp is different, so you can't have too many.
It bumps pretty hard for a 5W amp though. For someone with a pair of efficient speakers, it is a pretty good deal.