I recently bought a Fisher 400 in Ebay. It´s in working condition, but I want to restore it. I have read some articles about this operation: remove the selenium rectifier, recap, set the FM de-enphasis to today's value... And then I thought: would not design a stabilized supply for this receiver? It will improve the Fisher? The tube warmer's don´t will work better in DC? (It will remove a supply of hum, isn't?) I have in mind a Ic regulators for the lower tensions, and a discrete transistorized supply for the +B tension. What you think about?:confused:

but I'd suggest that the cost and effort would be more rewarded with doing what you'd propose to do to return the 400 to original but with updated components. You're dealing with a lot of different voltages you would have to design for plus the high voltage rails would require some special attention. That, coupled with a small space to work with under the chassis, would certainly make such a power supply design a challenge to work through. Better to leave it as designed.

BTW, some of the Fisher receivers - I haven't worked on one in 30 years so forgive the memory loss - did run the low-signal tube filaments on DC by design. I seem to recall it may have been the 800 series, though.

Cheers,

David

I think in the Fisher 400 the phono preamp tube filaments run off of the dc bias supply...with new diodes and caps it should work very well, I don't think you would see much improvement in a voltage regulated supply as the load is fairly constant.

I suspect it would alter the sound and not for the better. You could try it and see. Sort of like a wife getting an husband who is everything she ever wanted in a man and then setting about changing him in every way. (sorry if this is sexist but I've never heard a similar phrase in the other direction - usually the man marries his mother personality type).

IIRC, the adage goes like this: A man marries a woman, hoping she will never change. A woman marries a man, hoping to change him. Often, both are disappointed.