HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

I have listed two P2 heads in classified due to mods and Andy asked if they can be retro fitted and I said no.

So explanation. The inside of the case is being lined with a layer of self adhesive copper foil not connected to the earth side of the amp so acting as a Faraday Cage. This can never get rid of all RF or hum breakthrough but it helps especially with moving coil. I was concerned it would also stop internal field getting out so spoiling the music, but this is not the case as it seems to help stop RF and mobile phone signals especially not the frequencies of the music.

So as you can see to mod existing units the case would have to be stripped, so not an option and really not worth the hassle or expense. To begin with it was only going to be MC units that were done, but I have been thinking today that these units are often sent back for change from MM to MC so better to do all of them, and as sometimes P1 gets ordered for MC it means logically to do it for all P cases 1, 2, and 3, so there will be a P1 and a P3 listed in classifieds as well.

Out of interest, what foil are you using? I use a 15mm wide reel for wrapping round parts but it would be good to have a source to line casework if needed.

One thing to try on the subject of that foil, if you have a floating cap in the signal chain, its worth trying wrapping foil around it and grounding the foil. It came as a surprise a few years ago just how much the outer foil of a cap will act like an aerial. Only a worry if the cap is floating (neither ends connected to ground or power rails). Try on both film and electrolytic caps.

You end up with about a 100-200pf parasitic cap to ground via the foil.

I will PM you details.

Ta

Thanks for the clarification Doc.

I am in the throws of a strip down and reassemble at the moment and funnily enough I had been toying with the idea of copper foil as a wrap around the outside of the acrylic casework to act as a Faraday cage as I had noticed copper foil sheets were avaialble on ebay for not a lot of cash.

Been at Savvy's place today playing with turntables.

While driving back with plenty of time to ponder life and problems with my system, it occurred to me to ask whether Doc could provide an additional length of umbilical cable to extend the distance between the psu and the head unit of the Phono 2.

I am thinking each umbilical extender would be maybe 2.0 m long fitted with whatever plug (male and female) which would be inserted into the existing head unit /psu cable to allow them to be separated by a further 2.0m?

There may of course be a technical reason why this cannot be done.

Andy

Not really a problem, I don't know a price but under £50 for certain.

Thanks will come back and talk to you Doc once I have done some measuring and rearranging.

Andy

Cheers Doc after chatting with Savvy yesterday a bit of experimentation with his phone 2 and applying that logic to my set up has pretty much cleared the rfi problem I was struggling with without resorting to additional umbilicals although for anyone else struggling it may be a worth while thing to be offering.