Resistors types in original early Marshalls
Posted: Thu Oct 03, 2019 12:16 am
Hello Marshall experts and historians
I'm wondering if anyone out there knows why Marshall used a combination of carbon film and carbon composite resistors in their early amplifiers?
I have been pouring over gut shots of as many 65 - 67 era amps as I could get my hands on. Based on what I what I've seen, it looks like the positions that carbon comp resistors show up in vary somewhat, however, there does seem to be some sort of underlying "theme" as to where they were used (ie some positions always seem to be CC). Also, that "theme" seems to change slightly from year to year. That suggests to me that there was at least some kind of conscious reasoning behind the placement of CC resistors by Marshall.
Nowadays, there is school of thought that carbon film resistors in certain positions will help give the amplifier's tone more of a "brown" sound. Could that have been what Marshall were trying to do in the 60s? Personally, I would consider that to be unlikely. Marshall were a relatively small and expanding business at that point and I would be surprised if they had the time and resources to invest in that kind of research and experimentation (particularly given that the end result does not achieve a massive difference in tone).
One known factor of the early Marshall days was an inconsistent supply of parts. It has often been discussed that Marshall frequently subbed out parts for whatever components they had available at the time. This certainly could account for some of the differences - but not all of them. I have seen a number of examples where the same value resistor shows up in both CC form and CF form within the same amp. That to me rules out parts shortages as the sole cause and implies a more deliberate reasoning.
Was unwanted noise a consideration? Are carbon film resistors noisy in some positions but not others?
If anyone can offer any insights into this it would be greatly appreciated.
I'm wondering if anyone out there knows why Marshall used a combination of carbon film and carbon composite resistors in their early amplifiers?
I have been pouring over gut shots of as many 65 - 67 era amps as I could get my hands on. Based on what I what I've seen, it looks like the positions that carbon comp resistors show up in vary somewhat, however, there does seem to be some sort of underlying "theme" as to where they were used (ie some positions always seem to be CC). Also, that "theme" seems to change slightly from year to year. That suggests to me that there was at least some kind of conscious reasoning behind the placement of CC resistors by Marshall.
Nowadays, there is school of thought that carbon film resistors in certain positions will help give the amplifier's tone more of a "brown" sound. Could that have been what Marshall were trying to do in the 60s? Personally, I would consider that to be unlikely. Marshall were a relatively small and expanding business at that point and I would be surprised if they had the time and resources to invest in that kind of research and experimentation (particularly given that the end result does not achieve a massive difference in tone).
One known factor of the early Marshall days was an inconsistent supply of parts. It has often been discussed that Marshall frequently subbed out parts for whatever components they had available at the time. This certainly could account for some of the differences - but not all of them. I have seen a number of examples where the same value resistor shows up in both CC form and CF form within the same amp. That to me rules out parts shortages as the sole cause and implies a more deliberate reasoning.
Was unwanted noise a consideration? Are carbon film resistors noisy in some positions but not others?
If anyone can offer any insights into this it would be greatly appreciated.