Resistors and Capacitors:
The Critical
Components of Tone
RESISTORS:
Usually underestimated as to the contribution they make to tone, these
"passive" components make a real difference in sound when carefully
selected. Carbon composition resistors were used in most every amp made
until the late sixties when they were gradually replaced by carbon film
types, a inferior component choice in many ways. Metal film and metal oxide
resistors are the standard choice in high-end stereo equipment but do not
work as well in guitar amps. Remember that stereo equipment
reproduces music, While guitar amps
working with the guitar itself PRODUCE
sound . The warm coloration of carbon comp resistors, undesirable in
stereo equipment, is vital to the sound of a guitar amp.
Metal film and metal oxide resistors impart a slightly brittle tone and a
hard aural sheen, especially when a amp is just beginning to distort in the
preamp stages, before output stage loading can smooth these undesirable
overtones out.
In all audio stages we use carbon comp's in general repair and restoration
work. Metal oxide and wirewound resistors are only used in power supply
circuits.
CAPACITORS:
The effect on tone by capacitors
cannot be over emphasized. These so-called passive components are actually
highly reactive in guitar amp circuits and have a great effect on tone.
Our standard cap for guitar amps is the Mallory 150 film/foil wrap quite
similar to the ubiquitous Orange Drops, but having a softer response when
used in a overdriven preamp circuit. Orange Drops were the standard
replacement for almost any amp cap in the years before overdrive and
multi-gain stages. The Mallory's are a bit smoother when handling a
overdriven signal and have less harshness in sound compared to O'Drops when
played clean. We will also use Orange Drops at customer request. On Fender
amps we prefer Mallory 150 series caps as they are the closest match to the
old Astrons and Blue Mallory's used on most pre-cbs amps. Unless a more
"hi-fi" sound is desired this is our choice for classic Fender tone. We have
also had good results with SoZo Mustard caps in Marshall Vox, and Hiwatt
amps.
We do not use supposed "nos" or recycled old caps in any repair we do. It
is our opinion that old dried out caps are just that- old bad parts. The
caps we use are chosen to sound like the way original type caps sounded like
when new and will give best results after a break in period between 40-100
hours.
We do
not routinely change film (tone) caps unless by customer request, are
actually defective or have been replaced with improper parts in the past as
these are critical to the sound of a vintage amplifier.
In power supply areas we use high quality high reliability caps from
reputable manufactures, not cheapo imports from the far east.
