Resistor Design
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Circuits
Resistor Design
From Mark Amundson Thu Sep 19 14:32:36 CDT 1996
Article: 23028 of alt.guitar.amps
From: Mark Amundson
Newsgroups: alt.guitar.amps
Subject: Re: Carbon comp vs carbon film resistors?
Date: 19 Sep 1996 06:19:23 -0700
Organization: mamunds--(at)--tk.com
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>>>(William Allan Whittaker, Jr.) writes:
>>>Hell with NOS carbon comp, and carbon film, too. Go metal film for
>>>plate load resistors. No tone difference...just a LOT less hiss. Use
>>>1-watters. Metal-oxide works just as well, too. Don't listen to the
>>>vintage wankers, trust me on this one.
>>(TimTube) writes:
>>It's hard to argue with a self proclaimed "GOD", but good ears can hear
>>the difference. Trust me on this (but then again I'm not God). The
>>metal-oxide resistors will add an abrasive edginess that disappears
>>with a carbon comp, especially for coupling resisistors. Try it out, test
>>your ear. The above testimonial attests to the fact that not everyone can
>>hear a difference.
>(William Allan Whittaker, Jr.) writes:
>AWWW...Gee, Tim...some folks imagine that they can hear the difference
>between 6 inches of 10-gauge Monster Cable and 6 inches of brass
>coathanger, too... Fat Willie Denver's...uh...VACUUM DEITY?
To the mortal (Tim) and the immortal (William), you both are right to an
extent. The differences in resistor audiability are slight to the golden
eared audiaphile and are un-noticable to most musicians and audiences. A
carbon composition resistor is just a convient way of repackaging a
charcoal bricket in a leaded package. The resistance is adjusted by the
carbon pellets physical shape. Also, the effective resistance may vary
slightly under higher voltage drop conditions due to the grainularity of
the pellet. This gives the Carbon Comps their characteristic sound.
Metal Film resistors are different in that a non-conductive pellet is
coated with film of metal. The thickness of the film and the selective
removal of the film determines its resistance. Inductance is added if the
mechanical or laser trimming of the resistor leaves a spiral pattern of
metal film. Some manufacturers use zig-zag patterns to eliminate most of the
inductance. Again, the resistive value determines the films physical
layout on the pellet body. Low resistances tend to be tubular paths with
minimal trimouts and higher values have alot of film removal. Soundwise,
the film resistors are purer in performance. Metal oxide and carbon film
resistors perform similarly but the carbon film may have some grainular
artifacts depending the carbon slurry used.
Mark Amundson,
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