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Old 24th September 2012, 09:09 AM   #2071
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by dimkasta View Post
.....................An alternative might be to use something like Pass`s rectifier-thermistor trick to earth the case to the socket`s earth. I have seen others using a cap to do this.
This will require a non-metal IEC socket though, so that you can feed the case`s earth through the separating components, and then to the earth terminal of the IEC.
Dim,
I think you have got this wrong.
The metal Chassis must be connected direct to the third wire (PE) in the mains cable. No other components or wires in between. NONE !!!!

Connect the external conductive parts to the chassis. It is here that you can use a Disconnecting Network (DN). But, very importantly, that DN must be able to pass Mains Fault Current from Main Audio Ground to PE.
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Old 24th September 2012, 11:36 AM   #2072
rjm is offline rjm  Japan
Richard Murdey
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I'm with Andrew. If you are using the power line earth, it has to connect directly and securely to the metal chassis. It's the circuit common-to-chassis connection you can play around with.
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Old 28th September 2012, 10:15 PM   #2073
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Allright, I finally cracked it. So my vsps is in two separate housings. One is toroid+bridges+caps & regs; the other is purely the vsps. So the cable between the two housings is running DC. It was filtered adequately (and the opamps decoupled with 100nf to gnd; parallel with 1uf tantal). So I had a ferrite core lying around, figured I'd take a look what would happen with that. Snapped it on as close to the preamp as possible, on the cable running DC power: 50hz hum gone. So was the occasional faint radio hum when my amp was at full volume. So this brings me to the following: was this purely due to the fact that I have a long DC-cable feeding the vsps instead of AC and regs on the vsps board?
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Old 29th September 2012, 12:31 PM   #2074
bucurb is offline bucurb  Romania
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Default Cables

@ Wirehead.be

What kind of cable did you use, please?

Thank you!

Warm regards,
Ion
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Old 1st October 2012, 05:44 AM   #2075
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Hello Bucurb -

I've use unshielded twisted pair cable. Could it be that I need thicker cable?
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Old 1st October 2012, 07:02 AM   #2076
bucurb is offline bucurb  Romania
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Hello Wirehead.be,

Twisted pair it's very fine. Thicker cable... I don't know. I never tried in such situation. Ferrite core it's the best solution, as you did experiment.

Warm regards,
Ion
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Old 8th October 2012, 12:56 PM   #2077
rjm is offline rjm  Japan
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@wirehead

I do get the occasional reports of RFI pickup. Usually the Phonoclone, though. I don't recall anyone having a problem with the VSPS, but your configuration is non-standard in that you have the regulators in the power supply rather than in the VSPS chassis.

If the ferrite works, I'd be inclined to give thanks and call it a day.

Various other options include moving the regs to the main chassis, or using shielded power cable. The thickness (gauge) or the cable won't have any significant effect on anything here.
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Old 8th October 2012, 05:42 PM   #2078
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Quote:
Originally Posted by rjm View Post
@wirehead
If the ferrite works, I'd be inclined to give thanks and call it a day.

Various other options include moving the regs to the main chassis, or using shielded power cable. The thickness (gauge) or the cable won't have any significant effect on anything here.
Indeed, very happy now that the last bit of noise is gone now. I took another critical view at the wiring to get it even lower and twisted every conductor of 220V inside the PSU casing. Also made sure the umbilical cable feeding the VSPS (the twisted pair..) actually carries V- and V+ over a twisted pair, to make sure nothing gets picked up.
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Old 10th October 2012, 06:19 PM   #2079
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@RJM

Took the time to do some measurements, shows what the VSPS is possible of:
-First; the 1kHz reference signal. When I maxed out the signal, to the input of my Edirol FA-101 interface; there's still an offset of -9dB (the ripple of the signal was a "clicking" noise when taking a screenshot..):
Click the image to open in full size.

-Now, if we take note of this -9dB offset, this is what the VSPS is possible of:
Click the image to open in full size.

Pretty silent now Still well in -90dB range taking note of the offset. So as said, measured with the reference signal @ 1kHz and with 1K resistors on the input.
Very happy
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Old 18th October 2012, 02:04 PM   #2080
Hikari1 is offline Hikari1  United States
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RJM,

i have a Denon 110 HOMC cartridge. Output is speced at 1.6mv, 160 ohm impedence. I have successfully used MC phono stages in the past, loading them at 8K. I need the extra gain as I am running a passive preamp (attenuator in font of a tripath amp).

Is your recommendation to avoid the phonoclone and go for the VSPS for HOMC cartridges due to the gain factor of the phonoclone (overloading) or the zero impedence nature of the phonoclone? I could use the phonoclones extra gain, not sure if the zero impedence design will play well with the relatively high impedence of a Denon 110.

Also, any experience/thoughts on using switch mode (brick-type) power supplies with either the phonoclone or VSPS?
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