Be careful with LiPo batteries. If they are high capacity, they pack quite the wallop. I'm always very careful handling the ones used for my radio controlled flying machines, especially when charging them. If you have experience with them, then you know what I'm talking about. Otherwise, please do some research.
When the switch is off position , does the unit have any power draw in idle? Looking at the circuit diagram C3 would remain charged when switch is off, is that correct?
Asking because I plan to relocate the switch to my enclosure back panel. Alternately, could I just switch V+ 24V from the back panel and put a jumper here:
Asking because I plan to relocate the switch to my enclosure back panel. Alternately, could I just switch V+ 24V from the back panel and put a jumper here:
Yes, it keeps the filter caps charged at ‘off’ in order to help the PSU refrain from going into hiccup mode on initial power up.
I’m building a Mini using the power filter and FQP MOSFETs. The “chassis” is a 6x6x2 wood box from Container Store. The other change I made was to use 1k multiple turn pots.
I maxed the pots and got to half bias when the pots started clicking at max. Thankfully my parts box had some 2k pots, but they have straight line pins. A few minutes with needle nose pliers and the super duper hakko solder remover vacuum gun and I’m back in business biasing.
Suggestion to all of you trying FQP’s - get some 1k5 or 2k pots. Single turn or multi turn. If you go for multiturn, check the direction vs the single turn pots in the completion kit. I had to reverse directions for “clockwise” and “counterclockwise” with the pots I used.
I maxed the pots and got to half bias when the pots started clicking at max. Thankfully my parts box had some 2k pots, but they have straight line pins. A few minutes with needle nose pliers and the super duper hakko solder remover vacuum gun and I’m back in business biasing.
Suggestion to all of you trying FQP’s - get some 1k5 or 2k pots. Single turn or multi turn. If you go for multiturn, check the direction vs the single turn pots in the completion kit. I had to reverse directions for “clockwise” and “counterclockwise” with the pots I used.
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Got home yesterday afternoon and a package was waiting for me. Into the jig and it was together together very quickly. I let it cook all evening, slowly bring the bias up, listing with the brick supply in the shop I was impressed. I added TPs to VO and VB. Also, there always questions about flux residue and cleaning grade vinegar does an amazing job with a soft tooth brush.
This morning I got some lipos charged and put it into my main listening rig. The ACA mini powered by a lipo is unbelievable for the $$$ and I have a lot of amps to listen to: various Pass DIY and tube amps. It’s about 90% as good as any thing I’ve ever heard. I’m waiting for MJs SMPS filter board to get here so I can try the included brick.
If you use lipos make sure you do not let cell voltage drop below 3.7VDC. The lipo will hold 24+ VDC for a good 30% and I’ll be checking the bias as V drops. An inexpensive lipo monitor with alarm is what I use with audio gear. Once you hear audio driven by battery power it’s hard to go back to AC mains power.
I’m driving it with my TDA1541 tube dac directly or with various line stages.
For me, this is going to be great a summertime amp as my listening room is surrounded by courtyards and gets toasty with either tube or SS Class-A.
This morning I got some lipos charged and put it into my main listening rig. The ACA mini powered by a lipo is unbelievable for the $$$ and I have a lot of amps to listen to: various Pass DIY and tube amps. It’s about 90% as good as any thing I’ve ever heard. I’m waiting for MJs SMPS filter board to get here so I can try the included brick.
If you use lipos make sure you do not let cell voltage drop below 3.7VDC. The lipo will hold 24+ VDC for a good 30% and I’ll be checking the bias as V drops. An inexpensive lipo monitor with alarm is what I use with audio gear. Once you hear audio driven by battery power it’s hard to go back to AC mains power.
I’m driving it with my TDA1541 tube dac directly or with various line stages.
For me, this is going to be great a summertime amp as my listening room is surrounded by courtyards and gets toasty with either tube or SS Class-A.
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Looks very nice -- a couple questions -- where did you find the "TPs" you connected to VO and VB? Seems like that would make it much easier to keep my meter leads connected.
Also, I'd never heard of "cleaning grade vinegar" which I'm anxious to try. I've used flux remover wipes that just seemed to gum up the board and didn't work too well -- this looks much cleaner.
Apologies if this has been brought up before -- I read the whole thread a month ago, but it means much more now that I've got the Mini up and running.
Thanks!
Aha! TP = Test Point
100 of them here tomorrow -- and cleaning vinegar around the corner at Home Depot
Thanks again -- ggetzoff!
Yes, I should have mentioned that. I’ve been using them since around 04 and I agree.
That 3D printed base is from member @tom1066 back in post #1300 https://www.diyaudio.com/community/threads/diy-aca-mini.379037/post-7142197
In the time being reach out and ask for the file. I'll ask if the file can be made available to all builders.
In the time being reach out and ask for the file. I'll ask if the file can be made available to all builders.
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That’s interesting. I was able to bias mine using the 1K pot specified in the original BOM. Although the pot was near the end of it’s travel.
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At this price point, why not have two amps, one with IR devices the other Fairchild!
My actual build with FQP MOSFETs also reach only half bias. As I dont have 2k trim potis on my stock, can I add 1k resistors in series with the pots as shown here?
Both are nice. I’m hearing similar to your notes on differences in mids and highs between the two. The FQP’s are a little more prominent in the mids with a little less sparkle in the highs. I’m going to go a few more days with FQP jumpers out and then put jumpers in.