Von Ah, what are you using to terminate your speaker wires that are going into the output terminal blocks on the pc? Thanks
They’re called ‘bootlace ferrules.’ They crimp on to the wire. They’re a joy to use. Some adjustment of the crimper will likely be needed, but that’s part of the fun. Here’s what I got from Amazon:
https://www.amazon.com/gp/product/B07MZXWTVQ/
https://www.amazon.com/gp/product/B07MZXWTVQ/
Getting my 'clone' biassed up. Struggled initially until I realised my pots are maybe the wrong way round. I had FULL bias and VO! Got warm pretty fast! Not powered for long though until I sussed it out so all good. One channel now settling at 11.43VO and 298mVB. Sinks are warming up nicely and so I will see how much farther it settles until I do the other channel . Once I'm happy and given it a test on some speakers I shall put the spare boards up for grabs.
One week later, no change! Hey, @Jason : Whats going on? When can I order another ACA Mini Essential Kit, please?It takes the fulfillment house a week or so. I expect sometime next week.
In the immortal words of Robert Parr,
https://tenor.com/view/mr-incredible-the-incredibles-well-get-there-gif-16300647
https://tenor.com/view/mr-incredible-the-incredibles-well-get-there-gif-16300647
You mean the input resistor? It's there to prevent parasitics, and at that low value might not.
The active input impedance of those Jfets is so high that there is no practical difference between
1 ohm and 1K.
The active input impedance of those Jfets is so high that there is no practical difference between
1 ohm and 1K.
My ACA Mini in progress inside a small cabinet having its own heat sinks. Now I see that the mounting holes of the ACA are shorted to the ground I am using the Nylon spacers to isolate from the chassis. I have a quick question on the mosfets as the ground pins are shorted to the metal portion of mosfet, so I am using the TO220 plastic bushes to mount them on the heat sink. I still see that the mosfet metal portion is shorting to the sink. I hope that is fine to mount them this way or do I need to somehow isolate the mosfets from the sinks completely?
That's no good. The metal back on the Mosfets must be isolated from the heatsink (and more so, when the same heatsink is used for both, as in your case). Else you will have a short circuit between the different voltage potentials of N and P channel.
Since you already have thermal pads and bushings, perhaps you have overtightened the screws? - causing contact through the pads.
Connecting the ground plane of the ACA pcb to the chassis ground shouldn't be a problem, but I don't know if it's actually "recommended" (or intended) for the ACA Mini...?
Here - https://www.aliexpress.us/item/3256...irect=y&gatewayAdapt=glo2usa&_randl_shipto=US
I plan to add a Alps 10k pot and make it as an integrated amp for a small bedroom system.
This case is perfect but now I need to figure out how to isolate the mosfets from the sinks as using TO220 bushes and not tightening much still shows me shorted to the sinks 🙁
Thanks
Yes I did try to reduced the tension of the screen but still the shorting is present. I am using the silicon thermal pads so let me try some Mica sheets if it helps as I think the screw is isolated with the TO220 plastic bush. The only issue is the pad I am guessing let me check.
Thanks
Nelson Pass explained how to isolate the mosfets from the sinks here (Post #1156): https://www.diyaudio.com/community/threads/diy-aca-mini.379037/page-58#post-7109835
Hi manniraj, I can see now, that what I wrote this morning was not quite right: I was thinking of a more "regular amp" with +/- power supply. Sorry about that..
You do need to isolate the Mosfets in some way, but not for the reasons I wrote - rather because you else will be summing the output of R and L channel through contact with the aluminium case you are using. Signal OUT from the Mosfets is coming from the Drain pins, which are tied together on the PCB.
The PCB is designed to have seperate heatsinks for R and L ch, so whan you are using a metal case, where everything becomes connected, things change... 🙃
See the link from Chris Jones above, and also the manual:
You do need to isolate the Mosfets in some way, but not for the reasons I wrote - rather because you else will be summing the output of R and L channel through contact with the aluminium case you are using. Signal OUT from the Mosfets is coming from the Drain pins, which are tied together on the PCB.
The PCB is designed to have seperate heatsinks for R and L ch, so whan you are using a metal case, where everything becomes connected, things change... 🙃
See the link from Chris Jones above, and also the manual: