Posted by Lew on April 08, 2004 at 07:42:18:
In Reply to: Re: You are missing the point...Adding more points... posted by Austin fife on April 07, 2004 at 10:18:33:
I did not intend to dismiss your idea so peremptorily. After all, I freely admit we have no data to
support any hypothesis to explain why super-high wattage resistors in the hi-pass filter improve
dynamics, depth, holographic imaging, soundstage, etc. The fact is that 4 or 5 experienced
independent listeners have heard the effect. I am now one of those. I should have said that
others tried heat-sinking lower power resistors to determine whether the positive effects noted
above would result, and apparently that approach did not work. This is one of the reasons I
favor the notion that cross-sectional area of the resistive wire in the resistor is a determinant of
the phenomenon. I agree with you completely that resistors generate heat by their very nature.
The more energy they have to dissipate the more they will heat up. You state that resistors
increase in ohms as temperature rises. That property is quantified as the "thermal coefficient".
Really good resistors, e.g., Mills, have a very low thermal coefficient, so as I previously calculated,
R of a nominal 12-ohm Mills 12W resistor will increase by 0.12 ohms if heated 50 degrees C
above ambient temperature, i.e., much too hot to touch. That did not seem to be a significant
negative factor in explaining why much higher power-rated resistors work better in the SL hi-
pass filter. (You would never hear the tiny alteration of the cross-over frequency, for
example.) Finally, I don't know what you mean by "heat flash factor". As I understand it, the
resistor value will vary as its internal temperature varies up and down, centered around its
intended value and according to its temperature co-efficient.
By the way, I was thinking last night that perhaps even this very small drift in value in relation to
temperature (of lower power resistors) is enough to cause audible distortions which go away
when you get above 400 or 500W power rating where the resistor value may remain rock solid
stable during music reproduction. But if so, why doesn't heat sinking help, and what is the
nature of the disortion?