Salvation!
Yesterday, we got my old LP12 working properly.
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Note Linn jig in background.
Not using my old ring-mains for anything hi-fi anymore, plus careful Superline positioning and cable-dressing equals no hum (unless the volume knob is past noon). If anything, it is now quieter than it was before we started all the faff.
I have also had a demonstration that cable-dressing may have less obvious and immediate impact with Witch Hat cables than with Naim cables, but I can’t ignore it if I want proper sound: I was just lucky with how it sounded last month.
We started today with Ekos attached to T-Kable but not in Stiletto – no hum.
We tried the same with the Lyra arm cable – still no hum.
We put the Ekos and T-Kable into the Stiletto – the hum was back, as loud as ever. However, touching the metal plinth clearly reduced it a bit, which told us where to go next.
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There is an earth cable from the Keel. We removed it. The loud hum was still there.
We already knew that removing the earth connection from arm cable to Superline had no effect by itself, but now we tried removing both the earth lead from Keel inside the Stiletto AND removing the earth lead from arm cable to Superline.
The hum dropped dramatically!
Emboldened, we went back to the piece of wire used for earth-testing. With both of the above earth connections removed, we (again) ran a wire from Keel directly to the earth connection on the LP input on my 52 preamp. Despite it having its phono boards removed long ago, having that wire in place while not also having the other earth leads connected solved the hum problem completely!
Next, with no hum, we tried the BNC adaptors – they give a small hum all by themselves as well as deadening sound.
The T-Kable is also longer than the Lyra cable by a useful amount. The T-Kable is staying and Infidelity can sell the Phonopipe to someone else, which will pay for the new T-Kable.
We still don’t know why this was such a problem in my house, yet the standard earth connections caused no hum for the previous owner or at the shop. However, I don’t care. So far, every LP I have tried (and there will be quite a few more played this evening) sounds as good as I have ever heard it in my house – or better than I have ever heard it sound in my house. I don’t even care that the extra earth wire looks silly.
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I should extend huge thanks to Infidelity, who devoted huge amounts of time to getting this fixed and succeeded. Also to Grahams for their suggestions, and to all those here who made suggestions.
This Stiletto (with Keel, Radikal, Ekos, Kleos, T-Kable and Collaro mat) is now very possibly my perfect LP12 and a great turntable by any measure – just like it was in the shop. Hurrah!
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