Yes ... of course ... 
I have a primary fuse in the IEC socket, closely rated (1.6 A or 2.0 A, don't remember and can' look at the moment, because the amp is running), so that I can easily change it if it should blow at switch-on every few months.
Then I have two secondary fuses, one for each transformer, not quite so closely rated (I think 1.0 A), because to change them, I have to take off the top panel of the amp ...
Regards, Claas
I have a primary fuse in the IEC socket, closely rated (1.6 A or 2.0 A, don't remember and can' look at the moment, because the amp is running), so that I can easily change it if it should blow at switch-on every few months.
Then I have two secondary fuses, one for each transformer, not quite so closely rated (I think 1.0 A), because to change them, I have to take off the top panel of the amp ...
Regards, Claas
Got the right channel converted to a solo monoblock chassis. Was hoping to eliminate the sight hum, but it's still there, albeit quieter than with everything in the single chassis. I have to have my ear literally right next to the woofer to detect it.
Having the RCA input plugged in or out doesn't affect it. Does that indicate that it's not a ground loop issue? I was going to say, I'm using a CL-60 between my PSU and earth, so it should be sufficient..?
I moved my IEC further away from the amp board to try and aid in keeping EMF away from the input.
Honestly, it's not loud enough to detect from the listening position, but there's that "you didn't do it right" voice in my head.
Having the RCA input plugged in or out doesn't affect it. Does that indicate that it's not a ground loop issue? I was going to say, I'm using a CL-60 between my PSU and earth, so it should be sufficient..?
I moved my IEC further away from the amp board to try and aid in keeping EMF away from the input.
Honestly, it's not loud enough to detect from the listening position, but there's that "you didn't do it right" voice in my head.
well, it's either Donut magnetic field coupling to input autoformer, or it is PSU unit
maybe it's worth trying coax cable from RCA to pcb
one more thing - I'm always tying all wires to chassis on one bolt, near mains IEC; I see that you have one in front, most likely static shield wire
one more thing ...... channel pcb - that one needs to go to other side heatsink ( you swapped them between cases, so to speak) so that output mosfet is on lower 1/3 of heatsink height, not as you mounted it - in upper 1/3
maybe it's worth trying coax cable from RCA to pcb
one more thing - I'm always tying all wires to chassis on one bolt, near mains IEC; I see that you have one in front, most likely static shield wire
one more thing ...... channel pcb - that one needs to go to other side heatsink ( you swapped them between cases, so to speak) so that output mosfet is on lower 1/3 of heatsink height, not as you mounted it - in upper 1/3
Some suggestions:
- rotate power transformer to find position of lowest noise
- move AC wires from middle of case to far left side against left wall of case, tightly twist wires
- twist PS ground wire with V+ and V- wires to amp board V+ and V- connection, then continue ground wire to ground connection
- tightly twist all wires
- rotate power transformer to find position of lowest noise
- move AC wires from middle of case to far left side against left wall of case, tightly twist wires
- twist PS ground wire with V+ and V- wires to amp board V+ and V- connection, then continue ground wire to ground connection
- tightly twist all wires
I re-used a 5u chassis from my old Aleph J. See post #720 of this thread. i specifically ran the power wires under the perforated base plate to the transformer, which is at the front of the chassis, and enclosed it on bottom, top, and 2 sides by the perforated steel plates,
I also use the “balanced” XLR plug. I know the negative lead is grounded, but I have no hum.
Most of us put mu metal shielding on M2x amp input transformers, but my SissySIT has not needed it.
I also use the “balanced” XLR plug. I know the negative lead is grounded, but I have no hum.
Most of us put mu metal shielding on M2x amp input transformers, but my SissySIT has not needed it.
Love how friendly and helpful this community is -- I appreciate the all the suggestions!
I think I'll give the adjustments in orientation a shot, as well as the mu metal. I have a feeling that the IEC inlet is the primary culprit, with the input and input xformer right there.
If the mu metal shielding works, are there any drawbacks (aside from being out some cash if it doesn't solve it)?
I'm hopeful I'll be able to solve it through the combination of everything mentioned above.
I think I'll give the adjustments in orientation a shot, as well as the mu metal. I have a feeling that the IEC inlet is the primary culprit, with the input and input xformer right there.
If the mu metal shielding works, are there any drawbacks (aside from being out some cash if it doesn't solve it)?
I'm hopeful I'll be able to solve it through the combination of everything mentioned above.
Hmm.
I've been playing around by placing the thick mu metal sheet in various spots just to see if I could even slightly lower the hum by doing so. But doing that, or moving wires closer or further from either source of EMI seem to make any real difference in the level of hum.
Makes me wonder if I have something going on with ground and a ground loop as opposed to an EMF issue. But then again, the hum stops immediately after I turn off the power switch -- but the caps still supply enough juice to keep the amp on for a second or so. Idk, sorry, I'm just thinking out loud lol
I've been playing around by placing the thick mu metal sheet in various spots just to see if I could even slightly lower the hum by doing so. But doing that, or moving wires closer or further from either source of EMI seem to make any real difference in the level of hum.
Makes me wonder if I have something going on with ground and a ground loop as opposed to an EMF issue. But then again, the hum stops immediately after I turn off the power switch -- but the caps still supply enough juice to keep the amp on for a second or so. Idk, sorry, I'm just thinking out loud lol
I had the same symptoms with my BA-3 PSU. No matter what I did, I could not completely remove the hum. It was like trying to wipe my behind by putting on an extra pair of trousers. Yes, the stench is reduced, but if you smell closely, it is still there. So I dismantled the PSU and swedish craptrannies, and built a new one from scratch. Took 6 months. Indicating how pissed off I was
old one, including trannies, are expecting being crushed by sledgehammer.
Mighty has the perfect PSU boards for your purpose
Crippled Sissy?.... Been messing with the system, in the form of some new digital source components... modern DAC (AKM 4499 variant), DDC (used as USB to I2S converter), Sonore opticalRendu streamer. Went ahead and disassembled the amps again to do some minor clean up work. Swapped out some stranded wire for solid, added some grommets where my speaker wire exits through the chassis, rewired the "power on" indicator, just OCD stuff. But mainly wanted to try these amps crippled, i.e."buffer delete". Super easy obviously, yank jumper and a 20 second rewire job. I would only try this with a linestage that can easily drive a difficult load and verified low DC offset on it's output. I have obvious expectation bias... and need some more time on them, but it's something worth trying I think.