I figured it out. I was dumb and swapped the output +/- on the board. It took some sleep and a second time looking at it to realize the mistake. Swapped them to where they should be and it sounds great!
Hey guys, just a note that I'm going to be adding (chassis) ground terminals to my ACA 1.8's rear panel. I'm going to do some experiments in reducing ground-plane noise by connecting a Shunyata CGC cable from these chassis ground terminals to the GP-NR (ground-plane noise reduction) terminals of my Shunyata Everest power distributor. My hypothesis is the SMPS power bricks that power the ACAs put out a fair bit of ground-plane noise which could be reduced. Stay tuned...
The SMPS filter card sold for USD 10 at the diyAudio store, might be significantly cheaper. You could even think about connecting two of them in series, for additional filtration.
I'll check it out, thanks. I'd like to know what the filter actually does. My guess is it may attenuate high-source leakage impedance current, but it may not remove ground-plane noise. Thanks for the tip.
Apologies if this has been asked, or if this is being asked incorrectly. I've completed 2 ACAs, and am in the process of building 2 more. Was going to use as monoblocks for home theater, but wondering if possible to strap them (not sure what term is correct) as mono's, without bi-amping, ie running 2 amps for each channel (4 mono's total) to boost power to each channel. I believe this is accomplished easily if i bi-amp as mono's directly to my speakers that have 4 posts, but since i change amps often with speakers, was hoping to leave the speaker posts bridged as other amps won't be set up for bi-amping.
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in that case , strap them in classic series bridge
either fed them with XLR (balanced) or engage "self-bridging", switch on appropriate position and feed to just one RCA
more details somewhere in 6L6's Building Guide
either fed them with XLR (balanced) or engage "self-bridging", switch on appropriate position and feed to just one RCA
more details somewhere in 6L6's Building Guide
I was given parts for an ACA that its previous owner had given up on. I managed to piece together everything and get it all put together, or so I thought. When I powered it up and checked bias I found that one side was cold, though the LED was on. I measured just over 24v, which didn't change when I adjusted the trimmer. Any ideas for where I might start troubleshooting?
Thanks,
J
Thanks,
J
I would resolder all your joints. Some look suspicious. Also, make sure that you trim all the wires that goes THRU the circuit board, so they don't short out when you bolt the boards back onto the heatsinks.
Hello all,
I'm building a pair of ACAs at the moment and was just wondering - is the twisted pair of wires bringing power to the switch from the backplate a twisted pair simply to have gauge equal to the two wires that split off to the V+ on both boards? That is, if you had wire equivalent to double the gauge of the individual wires in the twisted pair, could you simply use one length of that from the power in to the switch? Say 16 or 17 awg for two 20 awg wires?
Cheers!
I'm building a pair of ACAs at the moment and was just wondering - is the twisted pair of wires bringing power to the switch from the backplate a twisted pair simply to have gauge equal to the two wires that split off to the V+ on both boards? That is, if you had wire equivalent to double the gauge of the individual wires in the twisted pair, could you simply use one length of that from the power in to the switch? Say 16 or 17 awg for two 20 awg wires?
Cheers!
Hello! I know this is working now but I thought I'd mention that in the third photo it doesn't look like the middle leg on the trimpot has been soldered - not sure if you fixed that one as part of your troubleshooting.
