Post good photos of wiring and board. Also, verify power supply voltages at voltage input, then at board power connections.
I had some noise coming out of my speakers (uneven hissing) and thought it was my preamp. After troubleshooting I re-did the power and input wiring inside the amp as my wiring was not clean the first time, and the noise is completely gone in one channel, and almost gone in the other. I did not think the wiring made this much of a difference, I thought it either made contact or it didn't.
I only have microphone cable, but even if it's not very thick it is higher quality than the one provided in the kit. I guess next step is to re-do the wiring for the speaker terminals as well, since now disconnecting my preamp does not reduce the noise in the remaining speaker.
Could the power switch wiring cause noise as well? It's now very minor but now that I''ve realized it is maybe possible to remove it...
Thanks, really enjoying the amp
I only have microphone cable, but even if it's not very thick it is higher quality than the one provided in the kit. I guess next step is to re-do the wiring for the speaker terminals as well, since now disconnecting my preamp does not reduce the noise in the remaining speaker.
Could the power switch wiring cause noise as well? It's now very minor but now that I''ve realized it is maybe possible to remove it...
Thanks, really enjoying the amp
Twisted all the wires much tighter, noise is now inaudible from listening distance on these sensitive speakers, and inaudible from basically any distance when using even slightly less sensitive speakers. Thanks everyone!
Just fot my understanding, what is the difference between ACA MinMax and an F5M apart of the single supply and cap coupled IN/OUT?
Those are the main differences. An F5m runs higher voltage and higher bias for more power compared to the MinMax.
The ACA Mini, maybe surprisingly, is not all that similar to the original ACA. Perhaps it could have been called an F5 mini (with caps) but I think the idea of an easy to build, beginner friendly project is what ties the names together.
The ACA Mini, maybe surprisingly, is not all that similar to the original ACA. Perhaps it could have been called an F5 mini (with caps) but I think the idea of an easy to build, beginner friendly project is what ties the names together.
yes ACA mini is a F5M mini and ACA MinMax is an F5M....
but then why build a MinMax? better a F5M with lower rails and no coupling cap?
but then why build a MinMax? better a F5M with lower rails and no coupling cap?
Many people have bought and built the ACA in the Modushop chassis, so the biggest value I see in the MinMax is that it repurposes that chassis and is IMO a better amp than the ACA. That gives an option to upgrade and build something new while not needing to start from scratch. DIYers tend to be frugal, or at least value conscious.
In a direct comparison I would agree that the F5m has the advantage, though it is physically larger and costs considerably more when building in a traditional chassis with linear power supply. My Redux version brings the size down and pricing closer, but still higher than a complete MinMax kit, and not everyone is into the "naked" amp aesthetic.
In a direct comparison I would agree that the F5m has the advantage, though it is physically larger and costs considerably more when building in a traditional chassis with linear power supply. My Redux version brings the size down and pricing closer, but still higher than a complete MinMax kit, and not everyone is into the "naked" amp aesthetic.
Yes it makes sense. after all this info I will build a F5M mini with smaller heatsinks and 2x 90w 19v psu GST90A19-P1M
Forgive me for asking, but why have you decided to use two switching supplies; and using the reduced voltage of 19VDC when F5m is speced for 24VDC?
Since F5m uses bipolar supply, you will have to wire the PS connections inside the amp chassis properly which may be an issue. Also I’m not sure 90 watts provides enough margin to run two channels at the recommended bias.
Since F5m uses bipolar supply, you will have to wire the PS connections inside the amp chassis properly which may be an issue. Also I’m not sure 90 watts provides enough margin to run two channels at the recommended bias.
because I need less power, at +- 19V 1A bias I can use smaller heat-sinks than regular F5
but still more powerfull than ACA mini and not cap coupled
90W psu should be ok for stereo
but still more powerfull than ACA mini and not cap coupled
90W psu should be ok for stereo
Don't ask me how I know but if you omit R12 and R13 but then forget to solder the pads together biasing is a real head scratcher!. like I said, don't ask me how I know 😡😡
New to amp building and electronics. I just finished the Camp Amp and starting the ACA Mini Max amp kit. I am familiarizing myself with the wiring and parts. I notice in the pictures of the completed circuit boards that the large transistors Q3 and Q4 are missing but are included in the kit. Should these be deleted? If not, the circuit board printing does not show the orientation. Are these soldered from the bottom with the single hole face oriented to the heat sink?More progress this evening. I've got nearly everything assembled and it's time for first power on and biasing
The front power switch I ordered is 22mm diameter, so it doesn't fit in the 20mm hole provided. A substitute DPDT will do for now. Gotta read those datasheets carefully!
I flipped the rear plate around and drilled new holes for the XLR jack.
Wiring is a bit tight in this chassis, so I'd suggest something smaller than the 14 gauge that I used for the power and speaker connections. I'm on the lookout for a DC jack with larger solder terminals as well.
New to amp building and electronics. I just finished the Camp Amp and starting the ACA Mini Max amp kit. I am familiarizing myself with the wiring and parts. I notice in the pictures of the completed circuit boards that the large transistors Q3 and Q4 are missing but are included in the kit. Should these be deleted? If not, the circuit board printing does not show the orientation. Are these soldered from the bottom with the single hole face oriented to the heat sink?More progress this evening. I've got nearly everything assembled and it's time for first power on and biasing
The front power switch I ordered is 22mm diameter, so it doesn't fit in the 20mm hole provided. A substitute DPDT will do for now. Gotta read those datasheets carefully!
I flipped the rear plate around and drilled new holes for the XLR jack.
Wiring is a bit tight in this chassis, so I'd suggest something smaller than the 14 gauge that I used for the power and speaker connections. I'm on the lookout for a DC jack with larger solder terminals as well.
Q3 and Q4 need to have the leads bent (just like Amp Camp Amp) and are mounted to the heatsink with insulators at the same time as the boards. The metal side of the transistor goes against the insulator. They are then soldered to the PCB from the top side. Some example pics before and after solder:
N Brock used my picture! I'm somebody! 😁
Finally getting to the final wiring on these. Hoping to bias them up this week. Maybe by New Year's Day.
Finally getting to the final wiring on these. Hoping to bias them up this week. Maybe by New Year's Day.
@6sX7: now that I’m focused on your photo of the soldered FETs, can you identify what that special washer/nut that you are using to attach the FET to the HS, the size, and the source for the washer/nut? It looks like it is a thumbscrew with no way to use a tool to tighten the washer/nut. Am I totally off base here?
Looks like a Belleville washer on top of the fender washer and a hex socket head cap bolt to me.
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Each picture is of a different build.
The first picture is mine. Unsure who's build is the 2nd picture.
For securing the output fets I use:
M3x10mm SS screw: https://www.mcmaster.com/92855A310/
M3 SS split washer: https://www.mcmaster.com/92148A150/
and a big ol' SS fender washer for an even clamp: https://www.mcmaster.com/90313A101/
The first picture is mine. Unsure who's build is the 2nd picture.
For securing the output fets I use:
M3x10mm SS screw: https://www.mcmaster.com/92855A310/
M3 SS split washer: https://www.mcmaster.com/92148A150/
and a big ol' SS fender washer for an even clamp: https://www.mcmaster.com/90313A101/