My initial posts are in the Wayne's BA 2018 thread starting on page 224 here: https://www.diyaudio.com/community/threads/waynes-ba-2018-linestage.329240/page-224
For the test table below, The VRDN units pictured will be named,Chuck, Alfred 1, 2 and 3 from the bottom up.
The bottom unit is closest to the front panel.
1 and 2 will power BA2018 channels right and left, respectively.
3 will power an Academy Audio ISS and MCU.
1 and 2 are set at +/-18V, 3 is set at +/-15V.
For now, the output transformers are disconnected.
For the test table below, The VRDN units pictured will be named,
The bottom unit is closest to the front panel.
1 and 2 will power BA2018 channels right and left, respectively.
3 will power an Academy Audio ISS and MCU.
1 and 2 are set at +/-18V, 3 is set at +/-15V.
For now, the output transformers are disconnected.
| Test | Results | Notes |
| Add jumper for VRDN Denoizer circuit | fail | noise did not change |
| Include ISS system / exclude ISS system | fail | noise did not change |
| Check that the screws attaching the PCBs to the chassis are not shorting the Ground on the PCB to chassis. | fail | no screws appear to be shorting to ground. |
| removing the 3rd set of power wires from the Antek (going to the 15 VDC board) then checking the two BA2018s (CraigI59) | fail | noise still apparent in both channels |
| disconnect the wires from the VRDN to chassis (andynor) link | fail | noise still apparent in both channels |
| short BA2018 inputs | pass | helped a lot for single channel test |
| run a short fat wire between those two grounds. From the center of that short fat wire, connect the rest of the ground wires from the loads.. "T" style. (william2001) | pass-ish | Tested a modified version of this by daisy-chaining ground connections to each other, then connecting the last VRDN to star ground. |
| gather those ground wires into one connection point, instead of leaving two inches between them as loop area. (andynor) | pass-ish | Tested connecting each VRDN to the next VRDN, then connecting VRDN 3 to star ground. Knocked the noise down a huge amount. Still there, but possibly getting some open loop noise from the two longer VRDN-to-Star-Ground wires which are hanging around. Will remove those and test again, but possibly on the right track. |
| Left channel run alone. Quiet or noisy? (benmah) | pass | quiet |
| Left channel with right channel power supply, run alone. Quiet or noisy? (benmah) | pass | quiet |
| Left channel with right channel power supply, run alone. Quiet or noisy? (benmah) | pass | quiet |
| add 0.1uF cap in parallel to 5 Ohm resistor (BH) | ||
| If lifting the chassis connections by and itself solves it, use a GLB. A simple resistor may not solve it. (andynor) | ||
| connect the two BA2018 halves’ ground sockets (andynor) |
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Please provide description of entire system. Need to know which parts are hum free and which have hum. Whole system please.
LOL. Awesome. Before I can even move data over. 
THIS PLACE ROCKS!
btw nothing was accomplished yesterday. Early winter yard work...brrr...
<edit> All tests mentioned in the BA2018 thread are now here for reference.
THIS PLACE ROCKS!btw nothing was accomplished yesterday. Early winter yard work...brrr...
<edit> All tests mentioned in the BA2018 thread are now here for reference.
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The test with "pass-ish" as a result above seems promising. Will dial this in on Friday to see what comes of it.
| Left channel run alone. Quiet or noisy? (benmah) | pass | quiet |
| Left channel with right channel power supply, run alone. Quiet or noisy? (benmah) | pass | quiet |
| Left channel with right channel power supply, run alone. Quiet or noisy? (benmah) | pass | quiet |
Channels running alone and with power supplies switched around were all quiet. That is a good thing.
But the channels were noisy when both were running at the same time. The issue may be with the preamp or it may be with the headphone amplifier used for testing.
The preamp is not quite dual mono as the power transformer is shared. For completeness, please show connection details from IEC input to power supply boards.
During tests, a headphone amplifier was used. Try a different amplifier (power amplifier) and test the preamp with both channels running. Short the preamp inputs for the test.
Ben, I appreciate your urging to try anything other than my headphone amplifiers, because I took the chassis down to the bonus room where the rest of the gear is. Currently for amplifiers I have a pair of modded ACA 1.8. The 3 VRDNs are daisy-chain connected to each other at their grounds, and the last one in line, #3, is connected to star ground. Result? Total silence. So a few changes from everyone's head and things are pretty darn good.
The next phase, then, is to connect the ISS board to the BA2018 inputs.
Thanks for all the help so far, everyone!
The next phase, then, is to connect the ISS board to the BA2018 inputs.
Thanks for all the help so far, everyone!
Good idea, RainfallSky, but I was careful to connect both to the same outlet.
The interaction between the two is still puzzling. This is my go to headphone amp, a CK2III designed by Ti Kan at AMB Laboratories and this is the first time it has given me problems when connecting to anything. 😳
Cheers!
The interaction between the two is still puzzling. This is my go to headphone amp, a CK2III designed by Ti Kan at AMB Laboratories and this is the first time it has given me problems when connecting to anything. 😳
Cheers!
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As for a ground loop breaker, should I install one anyway? I believe the parts are a rectifier bridge + capacitor but don't know what specs to search for or parts to source. Thanks!
Hello bhjazz,
I've built amps which were silent without a ground-loop-breaker. But most of my amps got one.
You can read about GLBs here:
https://www.diyaudio.com/community/threads/ground-breaker-isolation.384927/
Also Nelson Pass was answering.
Cheers
Dirk
I've built amps which were silent without a ground-loop-breaker. But most of my amps got one.
You can read about GLBs here:
https://www.diyaudio.com/community/threads/ground-breaker-isolation.384927/
Also Nelson Pass was answering.
Cheers
Dirk
If my build is quiet without a ground breaker, I leave it out. It is the safest.
And another excellent article from member bonsai / hifisonix (going more into the depth):
https://hifisonix.com/wp-content/uploads/2019/02/Ground-Loops.pdf
Cheers
Dirk
https://hifisonix.com/wp-content/uploads/2019/02/Ground-Loops.pdf
Cheers
Dirk
You guys are awesome. Thanks! I'll read up. 🙂
I would tend to agree with this. Although with my current system (using the passive pre section of a Mytek DAC) I ran into an issue with it and a phono pre just last year, long after I had begun to use it. Life is strange.