Nope, McCormack DNA1 which seems to have a bit of a buzzy reputation. I'll likely live with the buzz for now and/or reach out to Steve and see what he has to say.
Add 1k resistor in series with the RCA output in the DCB1 that feeds the DNA1. Just to see if its an instability it falls in with low source impedance.
That DCB1 wiring has potential issues of course like many heavy AC cables close to your pot etc. But maybe not your main problem as for now from what you report.
That DCB1 wiring has potential issues of course like many heavy AC cables close to your pot etc. But maybe not your main problem as for now from what you report.
You're suggesting to raise the output impedance of the DCB1 to see how the noise reacts? The output impedance by default is 220ohms right?
I'm just trying to see if I have any other sources with a higher output impedance to try before I break out the soldering iron.
I'm just trying to see if I have any other sources with a higher output impedance to try before I break out the soldering iron.
Also as a general good practice make the metal neck part of your DCB1 pot to show continuity for signal ground through the chassis or otherwise.
I did check that, all signal grounds (pot, RCA ins/outs, and board) show continuity. Without being connected to anything else (equipment-wise I mean) the signal grounds and chassis ground do not show continuity in the DCB1. However when connected to the other components they do. This is what we discussed earlier with signal to chassis ground references. Seems to make no difference either way. I appreciate the input!
Reference the dcb1 signal ground to its chassis through a 10 Ohm resistor and 0.1 uF capacitor across it anyway.
post5586 shows the secondary wires twisted from transformer to DCB1 solder pads.
I think you have twisted that connection incorrectly.
What voltages are on the yellow, black and red red?
The mains wires are untwisted.
Because these wires are all close coupled, there may not be any improvement after twisting.
What are the measurements for Hum+Noise?
Can you post a detailed pic, in focus, of the input sockets and wiring?
Can you post a drawing of how you have wired the vol pot? and selector switch?
I think you have twisted that connection incorrectly.
What voltages are on the yellow, black and red red?
The mains wires are untwisted.
Because these wires are all close coupled, there may not be any improvement after twisting.
What are the measurements for Hum+Noise?
Can you post a detailed pic, in focus, of the input sockets and wiring?
Can you post a drawing of how you have wired the vol pot? and selector switch?
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Thanks for the input Andrew. I definitely agree things ought to be tidier in the DCB1. I am at work today (was home sick yesterday) so I can't immediately answer your questions. I will try and do so later this evening
Based on the fact that I plugged two other sources directly into the McCormack (a DAC and a phono stage) -- both unplugged from AC and from any other components -- and the noise remained, unchanged (to my ear) I'm beginning to believe that a ground loop is not actually the problem here. And, as you say, it's looking more and more like an issue with the McCormack.
Based on the fact that I plugged two other sources directly into the McCormack (a DAC and a phono stage) -- both unplugged from AC and from any other components -- and the noise remained, unchanged (to my ear) I'm beginning to believe that a ground loop is not actually the problem here. And, as you say, it's looking more and more like an issue with the McCormack.
I think it may be a loop in the input cables when connected at both source and receiver ends.
Have you read D.Joffe's paper on HBRR + HBRL?
Have you read D.Joffe's paper on HBRR + HBRL?
Definitely worth investigating. I have not read that paper. I'll try and track it down now.
Would a reasonable test be to try a cable with one of the channel's signal ground lifted?
Would a reasonable test be to try a cable with one of the channel's signal ground lifted?
except it's not signal ground.
A signal connection is two wires.
The Source sends a signal current and that current MUST return back to the Source.
This requires a signal Flow wire and a signal Return wire.
Both the Flow and Return MUST be connected, or the signal current cannot pass. The connection is broken if you deliberately, or accidentally, break either wire.
A signal connection is two wires.
The Source sends a signal current and that current MUST return back to the Source.
This requires a signal Flow wire and a signal Return wire.
Both the Flow and Return MUST be connected, or the signal current cannot pass. The connection is broken if you deliberately, or accidentally, break either wire.
Roger that; not a reasonable test. (in retrospect it was a silly question. Should've known better)
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To update, I just spent some more time trying combinations of power and components to try and induce a change in the buzz/hum, and I think I may have figured this out.
I noticed that when I pulled my rack away from the wall, the high frequency content of the noise was attenuated. I must be picking up some EMI from wiring in the wall. I live in a condo building so this is not unbelievable.
Also, when I plugged the McCormack and another component directly into the AC wall outlet, bypassing my cheap power bar that everything is plugged into, I was presented with no hum. Amazing!
So right now I'm willing to bet the issue is with grounding and the use of this cheap power bar, with a dash of EMI.
Sorry to derail the thread. My DCB1 continues to operate well 🙂
I noticed that when I pulled my rack away from the wall, the high frequency content of the noise was attenuated. I must be picking up some EMI from wiring in the wall. I live in a condo building so this is not unbelievable.
Also, when I plugged the McCormack and another component directly into the AC wall outlet, bypassing my cheap power bar that everything is plugged into, I was presented with no hum. Amazing!
So right now I'm willing to bet the issue is with grounding and the use of this cheap power bar, with a dash of EMI.
Sorry to derail the thread. My DCB1 continues to operate well 🙂
Pulling the rack away from the wall may have reduced the strength of the field impinging on the input circuit loop.
Moving the rack away from the wall may have changed the size of the input circuit loop.
Moving the two units onto a common mains socket outlet may have reduced the voltage difference between the Chassis Safety Earths.
Moving the rack can have a lot of unintended consequences, some of which could be good and others, bad.
Moving the rack away from the wall may have changed the size of the input circuit loop.
Moving the two units onto a common mains socket outlet may have reduced the voltage difference between the Chassis Safety Earths.
Moving the rack can have a lot of unintended consequences, some of which could be good and others, bad.
Hi, long time since this question was asked 😀
Just one more:
Will it be beneficial to "hotrod" the dcb1 any further (thinking of reducing the 10r resistors) if it will only be used as PSU for the dac?
Sincerely