Tweakers' Asylum

Posted by hukkfinn (A) on February 09, 2010 at 09:20:17

In Reply to: RE: I'm still concerned that the circuit topology may have been changed. posted by Al Sekela on February 08, 2010 at 15:17:45

This question refers to a tubed phono stage with no volume control. I replaced the internal wiring and 3 resistors that appeared to be cheapies with vishays, 1/3 watt, not any particular brand or model of vishay. Just metal film.

The previous question was about a tubed preamp that had a volume control. I still have to track down what exactly the modder did to that unit. He replaced the volume controls with the same kind of vishay resistor but did not touch internal wiring.

In the volume knob mod, the vishay resistor carries the signal. In the more recent tubed phono stage mod, the vishay resistors are all just shunts to ground. Strangely, both units share the same undesirable qualities (strident, way too much upper midrange, loss of depth and loss of bass).

I am very intrigued by the suggestion above that shunts to ground are even more crucial to sound quality than resistors that carry signal. Wow. Would never expect to hear that.

Hukk