Turntable Balanced Upgrade (Part 2)

So the turntable itself is back in one piece and working well. Its easy to fall into the trap of thinking, hmm, I’ve spent time and money on this now so it must sound better. I’m sure there’s little if any difference so far, though it may be running a bit smoother, the cables don’t look like crap and the power button doesn’t stick any more.

On to the sound…

The pre-amp kit has arrived from the UK, but before I build that we need a power supply for it. Rather than get an off-the-shelf switched-mode supply I opted to build a linear supply. I needed +/- 15V for the pre-amp. No current draw to speak of, but it does need to be fairly well regulated.

The design is a 240-30VAC torroid with a bridge recitifier, a regulator for the positive and negative rail and a few smoothing capacitors. This gives a +/- 15V output. Fairly simple…

This all goes in a beautiful grey plastic box. Look at the awesome dremel work  yet again. And it even has a red neon lamp on the front that comes on! It does work though, with both rails running at pretty much bang on 15. The pre-amp design actually calls for, ideally, 17V to get the most headroom. 15 should be enough… though if not its going to mean swapping out the torroid and/or the regulators. I’m never, ever, going to attempt to take this thing on an aeroplane.

I'm sure the TSA would love seeing this in my hand baggage

The choice of the 4-pin XLR is rather strange, but what the PCB for the pre-amp uses so I stuck with it for the source end. Also the heat-sinks are currently missing from the regulators until I can pick up some thermal paste.

Now onto build the pre-amp itself…