Does anyone know how to change the MM/MC gain on a Tresham Audio DR-1?

[Primalsea]

Just realised that my Tresham DR1 has selectable gain and loading for MM and MC. I can see where you have to solder in resistors and capacitors for loading but it is not so obvious how you change gain. I suspect it involves the changing of some feedback resistors somewhere.

[Primalsea]

Okay now, I worked it out. There are 3 places where components can be soldered in for each channel. These are marked RG, RZ and RC / LG, LZ & LC Obviously right/left Gain, Impedance & Capacitance. Gain was set using 14 ohm resistors, whiched seem a low value to use, Loading was set at 470 ohms which was obviously for a MC cartridge.

[Firebottle]

The 14 ohm is almost certainly at the bottom of a potential divider setting the gain, so makes sense. Also having low values is good for low noise circuit operation.

[Primalsea]

Cheers, Alan. I had read somewhere that low values can cause issues, if used for gain setting. Having thought about it a bit I realised it was used for noise reasons, as you say.

I should remember not to get too caught up on everything I read, especially if it’s from the internet.

[DSJR]

Not sure if Tannoy can help now either. They took on full sole responsibility and all the documentation for Tresham designs I believe, but not sure if these docs are gone or buried in a paper store somewhere...

[Primalsea]

Years ago Tannoy did promtly send me the schematics when I requested them, but I subsequently lost them. I asked Tannoy a few months back and got some guff about not being able to release their IP.

They have become a corporate entity now, so I imagine that their customer facing people have all been laid off, as is the way.