Well thanks for keeping us updated, and I'm sorry you haven't made more progress with it. It's a puzzle, I must say.
To recap, the noise is a pop followed by a 1s buzzing which is louder than the music. This happens at random intervals. (how often, by the way? you never said..) The effect is present on both boards independently, and is not altered by changing the shielding or voltage gain or any number of small alterations. It doesn't happen when no cartridge plugged into the input, but changing op amps changes the character of the noise. The DC operating points all seem to be correct. The boards seem nicely put together, clean and neat.
By elimination I guess that the problem originates in some interference on the earth of your building, injected into the signal by a ground loop on the input connections and/or the turntable earth/ground connection. Basically the way I designed the Phonoclone's ground layout is not playing nice with your system for some reason. That's not say say your system is a problem, or broken in anyway, just that the phonoclone's ground connections are not configured the way your system would need them to be. Outside of that, I'm pretty much out of ideas.
1) standing offer for a set of Emerald boards, I'll send them to you for free if you want to try the alternative, and more traditional, circuit topology.
2) what model TT\arm are you using and does the TT have a 3 wire power cord or a two wire cord? Anything unusual about the grounding/earthing in your system at all? That's about the only thing I can think of here, that the turntable has a second connection to earth somehow.
To recap, the noise is a pop followed by a 1s buzzing which is louder than the music. This happens at random intervals. (how often, by the way? you never said..) The effect is present on both boards independently, and is not altered by changing the shielding or voltage gain or any number of small alterations. It doesn't happen when no cartridge plugged into the input, but changing op amps changes the character of the noise. The DC operating points all seem to be correct. The boards seem nicely put together, clean and neat.
By elimination I guess that the problem originates in some interference on the earth of your building, injected into the signal by a ground loop on the input connections and/or the turntable earth/ground connection. Basically the way I designed the Phonoclone's ground layout is not playing nice with your system for some reason. That's not say say your system is a problem, or broken in anyway, just that the phonoclone's ground connections are not configured the way your system would need them to be. Outside of that, I'm pretty much out of ideas.
1) standing offer for a set of Emerald boards, I'll send them to you for free if you want to try the alternative, and more traditional, circuit topology.
2) what model TT\arm are you using and does the TT have a 3 wire power cord or a two wire cord? Anything unusual about the grounding/earthing in your system at all? That's about the only thing I can think of here, that the turntable has a second connection to earth somehow.
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I would agree this is a puzzle, a very interesting one.
I don't think there is a pattern in terms how often the noise happens. I have had it happen as frequent as every 1~2 minutes to as long as every ~20 minutes. Every time I though I have fixed the issue, it happens.
My TT is Rega P3 with RB300. Tonearm cable has been replaced with Cardas shielded tonearm cable to RCA sockets, then I use VDH Integration interconnect cable to connect to PC4. I have tested the continuity and tonearm is grounded.
Tonearm is currently grounded to the PSU chassis which is also directly connected to earth from AC socket. Tested COM on DBRB and no continuity between COM and chassis.
GND point on PC4 boards used to be where the tonearm was grounded, then I switched to the current configuration because I thought the noise was due to some kinds of interference.
Motor on P3 is not connected to RB300 and not grounded. Some people have had humming issues with P3 when the cartridge is moving closer to the spindle but I have never experience that. Also because I get the noise regardless the TT is ON or OFF so I never bother to troubleshoot that direction.
Please send me the PayPal request, it's not your fault that I'm having this issue so I don't think it's reasonable for you have to cover the cost of the Emerald boards. You know I was interested in Emerald boards originally anyway.
s.
I don't think there is a pattern in terms how often the noise happens. I have had it happen as frequent as every 1~2 minutes to as long as every ~20 minutes. Every time I though I have fixed the issue, it happens.
My TT is Rega P3 with RB300. Tonearm cable has been replaced with Cardas shielded tonearm cable to RCA sockets, then I use VDH Integration interconnect cable to connect to PC4. I have tested the continuity and tonearm is grounded.
Tonearm is currently grounded to the PSU chassis which is also directly connected to earth from AC socket. Tested COM on DBRB and no continuity between COM and chassis.
GND point on PC4 boards used to be where the tonearm was grounded, then I switched to the current configuration because I thought the noise was due to some kinds of interference.
Motor on P3 is not connected to RB300 and not grounded. Some people have had humming issues with P3 when the cartridge is moving closer to the spindle but I have never experience that. Also because I get the noise regardless the TT is ON or OFF so I never bother to troubleshoot that direction.
Please send me the PayPal request, it's not your fault that I'm having this issue so I don't think it's reasonable for you have to cover the cost of the Emerald boards. You know I was interested in Emerald boards originally anyway.
s.
No, radio interference has been ruled out because I have tested without any wireless devices (wifi/celluar/bluetooth) near by or off and issue persists.
S.
OK, despite your message above, I have to say that sounds (based on the link to your recording of it) a HECK of a lot like the noise I was getting from either WIFI or wireless interference (in fact, Kevinkr helped me figure it out). I know you have said you have removed all potential sources, but I feel pretty certain that's what it is. The trick will be to figure out the specific source.
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As others have said, that's all suspiciously like wifi/cell tower/RF interference. Given your efforts, we can conclude it's not local to your residence at least, and that it nothing to do with shielding or RFI-proofing the phonoclone circuit itself. It gets into the signal by some other vector, somewhere between the cartridge and the phonoclone input IC1. I suspect coupling between the IN- and earth.
While you are being really helpful to supply all the needed info and I appreciate that there are several times I feel you could be more precise in your description. To say the tonearm is grounded is imprecise since I don't know with respect to what, or under what test circumstances, or how exactly that connection is routed.
I do wonder a little bit if the shielded tonearm and the modifications there could be causing trouble somehow.
With the turntable/arm/outputs disconnected from the rest of the system, the tonearm should be isolated from the RCA grounds of the TT. The tonearm connects to the ground lug of the phonoclone by external wire.
COM should be electrically isolated from the PSU chassis, in terms of the phonoclone build. When connected to the system however, the connection would be made regardless through the shared earth buss bar of the power strip. PSU chassis goes to earth, the amplifier chassis goes to earth, and the amplifier circuit common goes to earth, and the amplifier circuit common is connected to the phonoclone circuit common through OUT-. All common 0V circuit reference potentials will connect to each other, and the idea is there is just one connection to earth made in the audio system signal chain.
You should get more interference with the tonearm connected to earth of the PSU chassis than the phonoclone chassis/GND. The tonearm needs to be kept at the same potential as IN- to avoid interference, and the PSU earth is further away from that in terms of noise than phonoclone GND which is connected to IN- directly within the Phonoclone boards.
Let me ask one more thing: how is the noise apart from the 1s bursts, is it otherwise quiet and hum free? Does turning on the Rega motor made a noise in the speakers for example? Does disconnecting the tonearm ground wire made a big increase in noise?
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Still struggling with my VSPS - there's a noticeable hiss/high pitched whine audible.
Is this a grounding issue? If so, how would the grounding scheme for a single enclosure (transformer and PCB in a single aluminium case) look like?
Or is there some other issue at play here?
Note that the noise is present even without a turntable connected and that removing the ground wire to the turntable adds the regular faulty ground-noise to the distortion...
Thanks in advance!
Is this a grounding issue? If so, how would the grounding scheme for a single enclosure (transformer and PCB in a single aluminium case) look like?
Or is there some other issue at play here?
Note that the noise is present even without a turntable connected and that removing the ground wire to the turntable adds the regular faulty ground-noise to the distortion...
Thanks in advance!
@alpuy
I am limited to 80x100 board size. A stereo emerald is of course possible, with the usual compromises of using dual op amps but it would be a tight squeeze. Perhaps someone would take the stab at modding the Eagle files?
@Lohengrimas
A hiss sound with no TT connected means the circuit gain is set too high, typically. What you describe as a "whine" on the other hand could be one of several things, depending on the actual frequency and shape. One suspects interference between the power supply or diodes and the VSPS input wires. Please post a photo.
I am limited to 80x100 board size. A stereo emerald is of course possible, with the usual compromises of using dual op amps but it would be a tight squeeze. Perhaps someone would take the stab at modding the Eagle files?
@Lohengrimas
A hiss sound with no TT connected means the circuit gain is set too high, typically. What you describe as a "whine" on the other hand could be one of several things, depending on the actual frequency and shape. One suspects interference between the power supply or diodes and the VSPS input wires. Please post a photo.
That's about as clean as can be expected and as reasonable a layout as can be hoped for given the space constraints you are working with here.
Perhaps try changing op amps, or adding the 0.1 uF ceramic caps. I'd also consider changing the coupling caps as those large cans could be picking up noise. Try disconnecting the indicator LED. Try disconnecting the safety earth (temporarily).
I worry however that it's none of the above and the power transformer is simply too close. You could try powering the circuit from an external supply to confirm that, and, if so, consider using a shielded transformer (Triad VPM) for example, if you have to have a single-chassis unit.
Even with a photo, "noticeable hiss/high pitched whine" isn't enough information to be able to make a diagnosis.
We know it's independent of the TT connection and ground connection, we know that the build is clean and appears correct, we know, from WntrMute2 and others, that the VSPS runs reasonably quietly even when placed in close proximity to the power supply.
Best option, if you are up for it:
Record the VSPS output noise with a soundcard (or digital recorder, anything with a line in jack - a cheapo USB audio adapter and a smartphone if need be), upload the wav file and let me access it or ... analyze it yourself, just run it through RMAA or Audacity. That, together with the DC voltage measurements at the V++/-- and V+/-, should give us a good idea of the problem we are dealing with.
We know it's independent of the TT connection and ground connection, we know that the build is clean and appears correct, we know, from WntrMute2 and others, that the VSPS runs reasonably quietly even when placed in close proximity to the power supply.
Best option, if you are up for it:
Record the VSPS output noise with a soundcard (or digital recorder, anything with a line in jack - a cheapo USB audio adapter and a smartphone if need be), upload the wav file and let me access it or ... analyze it yourself, just run it through RMAA or Audacity. That, together with the DC voltage measurements at the V++/-- and V+/-, should give us a good idea of the problem we are dealing with.