The noise is ok if you find a decent smps. I can recommend one if needed, dead quiet.
If the PCB layout is modified for v1.1 it would be great if the turn-on/off pop could be eliminated just like it was done in the F2 circuit. NP already mentioned this in the F2 manual so being both 5W why not implement it also on the ACA ?
With 5W output the ACA is mostly used with fragile full range driver, I know I do.
I had to add a switch before the speakers terminal.
It would be such an easy fix, any comment?
BR
Eric
If the PCB layout is modified for v1.1 it would be great if the turn-on/off pop could be eliminated just like it was done in the F2 circuit. NP already mentioned this in the F2 manual so being both 5W why not implement it also on the ACA ?
With 5W output the ACA is mostly used with fragile full range driver, I know I do.
I had to add a switch before the speakers terminal.
It would be such an easy fix, any comment?
BR
Eric
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Two blunders so far in my ACA build. Somehow forgot to order 100 ohm resistors and learned the hard way I understood nothing about heat sinks. I thought by ordering longer lengths I could mount them sideways. Yeah, stupid I know now. So I threw them on the miter saw and made 4 5x5's and intended to mount 1 mosfet per, and then wire them to the boards temporarily to get up and running. I drilled and tapped the sinks and a temp board for mounting everything till I got around to building the enclosure. But when I stuffed the boards I realized I forgot to order R5, R6 (100 Ohm 1/4W 1%).
So I'm taking the time to order the missing resistors, as well as the change to the feedback R12 (39.2 from 68.1) that Mr. Pass made for 1.1 (just watched his Burning Amp 2017 vid) and ordering 24V 5A power supplies from MPJ along with the 4 pin power jacks.
I figured I might as well deal with the sink issue too so I'm probably going to order these:
Width:203mm (8inch)
Fin Height: 76mm (3inch)- serrated
Base: 9.5mm (.375inch)
Height: 76mm (3inch)
C/W/3": approximately: 0.66
If anyone sees any issue with this sink choice please chime in and let me know. I guess I can make a sculpture or paper weights from the old ones.
Thanks.
Learning can be painful but it's worth it. Rinse and repeat.
So I'm taking the time to order the missing resistors, as well as the change to the feedback R12 (39.2 from 68.1) that Mr. Pass made for 1.1 (just watched his Burning Amp 2017 vid) and ordering 24V 5A power supplies from MPJ along with the 4 pin power jacks.
I figured I might as well deal with the sink issue too so I'm probably going to order these:
Width:203mm (8inch)
Fin Height: 76mm (3inch)- serrated
Base: 9.5mm (.375inch)
Height: 76mm (3inch)
C/W/3": approximately: 0.66
If anyone sees any issue with this sink choice please chime in and let me know. I guess I can make a sculpture or paper weights from the old ones.
Thanks.
Learning can be painful but it's worth it. Rinse and repeat.
This is a nice heatsink, pls provide a link.
My ACA runs at 24Vdc and draw 1.2A therefore roughly 30W dissipation / channel.
With your 0.66 C/W this would give a final heatsink temp of about 45C which is perfect.
Ex: 0.66 x 30W = 20C rise. So if your ambient is 25C your final temp will be 45C
BR
Eric
My ACA runs at 24Vdc and draw 1.2A therefore roughly 30W dissipation / channel.
With your 0.66 C/W this would give a final heatsink temp of about 45C which is perfect.
Ex: 0.66 x 30W = 20C rise. So if your ambient is 25C your final temp will be 45C
BR
Eric
Thanks!
8.000" Wide SERRATED FIN Extruded Aluminum Heatsink - HeatsinkUSA
Shipping is a bit high even in the US. Plus a handling charge (BS).
Each transistor dissipates about 10 watts, and the C/W of 0.66 is for a 3 inch length of heatsink. For a 5 inch length of the same heatsink, the C/W will drop a bit. But the C/W is for a 70 degree rise in temperature so for a lower rise, the C/W will increase. The temperature change factor is likely to be greater than the change due to the increased length. Assuming that the C/W will be 0.7, the temp rise will be about 10 x 0.7 ~ 7C, so the resulting temperature will be 32C if ambient is 25C.
I gave up on those guys. long ago.
Wayy too pricey for what is offered.
Try the DIYAudio shoppe ? Which now sells Sinks at reasonable prices
I didn't even see these or I would have bought from them originally. I only bought from Heatsinks USA because I thought it was my only option other than ebay. I thought the store was only selling those 4U and 5U versions, but now I see a bunch of options with lower C/W's than I saw on HUSA. Thanks.
Ok, now I'm thinking 300X80X40 with a C/W of .45. That should bring the temp within a tolerable range with even at 24V.
Their prices are much better than H USA especially when considering they are anodized and have 40mm serrated fins. These still need to be tapped and threaded but I'm fine with that part of the DIY process.
I wish I saw these before my first purchase. Thanks again, Bare.
Their prices are much better than H USA especially when considering they are anodized and have 40mm serrated fins. These still need to be tapped and threaded but I'm fine with that part of the DIY process.
I wish I saw these before my first purchase. Thanks again, Bare.
Question regarding R12 change from 68.1K to 39.2K. I couldn't tell from Nelson's Burning Amp presentation whether the change to R12 feedback was dependent upon using 24V power.
The final missing resistors are being delivered today so I'm hoping to be up and running this evening or tomorrow with the 19V power supplies and was wondering if I should swap R12 now or wait until I am using 24V.
The final missing resistors are being delivered today so I'm hoping to be up and running this evening or tomorrow with the 19V power supplies and was wondering if I should swap R12 now or wait until I am using 24V.
One of These UMS heatsinks would accommodate 2 of the current ACA boards
UMS 40mm Heatsinks – diyAudio Store
The new ACA 1.5 boards will be functionally the same but probably won’t work with them. Any ACA boards in the store now will work with thes heatsinks.
UMS 40mm Heatsinks – diyAudio Store
The new ACA 1.5 boards will be functionally the same but probably won’t work with them. Any ACA boards in the store now will work with thes heatsinks.
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