Gromit's music centre...

[Will]

Yes I think its a Arm grounding problem
I use 5ft of unscreened wire from the cartridge to sut inside the phono amp.
No hum and there are 4 anode 2 grid chokes and a bridging transfomer in the phono.
Connection of the sut output wire has to be about 1 inch any more and there is hum high imp. hum, low imp no hum pickup.

[Marco]

Hi Will,

Thanks for that - interesting. There is no issue with the cable I'm using for the output of the SUT to the preamp. I can 'jiggle' that about the place and nothing happens. It's the input lead on the SUT (from the tonearm) that's the problem when used with my A23 SUT.

Marco.

[Will]

Check the tonearm grounding by attaching a wire to a gound point and then to the arm.
Its not the cable, if the cable is conducting hum from a ungrounded arm the hum will change with its position to other kit. This was what I found with a Hadcock or Haddock more like.

[Marco]

Cool. Where's the best place to attach the wire to the arm (it needs to be somewhere I can get easy access to without dismantling anything) and what's the best "ground point" for the other end?

Marco.

[scoobs]

Marco did you try wrapping the bare end of the A23 earth lead around the end of your Jelco earth lead? This is how I solved my hum problem, having tried everything else in the book. It is now dead silent.

Incidentally, when I used a P10 with a highphonic sut, I had hum problems, which were cured only when I swapped out the 2 pairs of NVA super soundpipes for cheapo 'in box' interconnects, given that Richard (Gromit) now uses those very same cables I would recommend he tries the same if he encounters the same problem in the future, I'm not sure NVA pipes are the best type of cables to use with sut's and MM stages.

[Marco]

Marco did you try wrapping the bare end of the A23 earth lead around the end of your Jelco earth lead?

Hi Nick,

I tried that and unfortunately it didn't cure the hum. I think the grounding idea of Will's is a good one, but doing the wire thingy he suggested needs to mean that I don't have to mess with dismantling the T/T or arm to attach it. If that's not the case then I'll leave it for Dave to sort out.

Marco.

[Will]

Marco
Just hold the ground wire against the arm tube, no need to dismantle at this stage.

[Marco]

Thanks for that, Will. I'll give it a go later

Marco.

[Prince of Darkness]

The Phono2 doesn't have an MM input as it's MC only.

To be more accurate, it is MC or MM only. For MM, use 47k input load resistors. For MC use step up transformers and select input load resistors according to cartridge.

Of course, I am assuming that the Phono2 in question is the WAD design.

[Gromit]

Of course, I am assuming that the Phono2 in question is the WAD design.

It isn't