Vinyl Asylum: Re: phono preamp design question by Victor Khomenko

***This gives me the option of connecting the pickup balanced, the gnd lead to the neg.input of the pre instead to ground.

This also gives you more noise (6dB more given the same resouces) - and I don't know if that is a consideration for you. Choice of the first tube is paramount.

***In this case I use 23.5kohms at each input to give 47kohms total loading for the pickup. I'm hoping this will eliminate possible hum from gnd-loops wich at times may be amplified extremely well in phonopres.

Not really. It would if your gain stage had some pretty high common mode rejection - but yours will not, most likely. So don't really count on it.

In a phono preamp, perhaps the most difficult task will be in reducing ITS OWN hum and power supply buzz to levels well BELOW the front tube thermal noise. Only few circuits manage to do so. That is going to be your criteria for success. If all you can hear is clean hiss, then you are OK. But that is far from trivial. Controlling the rectification pulses from spreading all around can drive you nuts.

Contrary to some beliefs, the signiture of a good cricuit is NOT no noise, but it is GOOD noise.

***Am I on the right track or waisting my time? Inputs would be greatly appreciated since time is something I just dont have a lot of...

Well, you have not told us much yet. How much gain and noise you are trying to achieve, with how many stages, etc. In your case you also definitely want a differential RIAA, and that is a small research in itself. With tubes given their less than ideal nature, they ARE part of the RIAA circuit and should be treated as such. But given right approach you can easily and quickly get into tat under-.1dB range. If it comes to that point and you are having difficulties, I may be able to help you calculating your network.

Good luck