Yamaha G100-115 II reverb tank

[Enzo]

I don't know that they were seconds, but they did use 20% resistors, which was the lowest grade.  Note right on many of the schematics that all readings were to be taken as +/-20%.  Cap tolerances were so poor in those days, you could almost ignore the value, or so it might seem.

Yes, when a store got in a shipment of Deluxe or whatever, one played through all of them to find the one that sounded best.  They were not remotely as uniform as they are today.

The 20% 100k plate resistor in an input stage could measure 80k to 120k and be within spec,  SO if it not hard to believe that all the accumulated parts variances added up to substabtially different sounding amps.  Even though made with the "same" parts.   Yeah, good luck chasing that sound down.

[J M Fahey]

One real world example, about "fabled tone" .
One Music Electronics Forum member, John Frondelli, runs a mythical New York Service Shop, where *all*and I mean *ALL* stars, nopt only Rock but everybody else (including Disney Studios, all NY Studios, Oscar organizers .... up to and including the Navy band and CIA  ) send their stuff to be repaired, every month a truck stops at their door and blocks the street with stuff from, say, Megadeath or Prince or whomever is going on World Tour and wants everything checked for safety, nobody wants to rush find a Tech 8000 miles away from home.

One day he said U2 had left their truckload of equipment, and everybody asked him about a fabled Fender Princeton which allegedly had been used to record all famous band Hits.
Intrigued he checked it, since in his eyes it was "just a normal Princeton, bought at a regular store and never modded" yet it was labelled with Sharpie on a piece of paper strip: "repair but do not modify".

He checked it part by part, schematic in hand, ticking one by one what he found "normal", all he could find was that it was exactly the same as all others (at least nominally) with the single exception that a .022 coupling cap had been replaced by a .01 one.

Not a Mod, it was there from Day 1 , put straight at the Factory.

Net effect was that it cut a little Bass, so when overdriven, distortion was slightly cleaner than all others; in any case a subtle effect, not day and night.

In another Tech Forum, a member used to be a Fender VP for some time, and was asked about it, "what were they experimenting or trying to achieve and why weren´t all other Princetons built the same way, given it "worked better"

  His answer? : "don´t read too much into it, probably that day they were out of .022 caps, they *had*  to ship out some of them, and all they had on hand was .01 caps" 
Since apparent effect was very small and still acceptable, so be it.

This matching what Enzo said about amp to amp variations, in this case because of an actual value change, not just tolerance spread.

Clearly The Edge tried a couple Princetons at some shop and bough the one he liked most

Just to check the *awesome*  customer list who relie on that particular shop:
http://www.dbmproaudio.com/customers.html

[semjmiyta]

Scoticus,
  I recently picked up a Yamaha G100 head awesome price and even better sound!
 I was wondering if you know or anybody on this forum would know how to go about making my own foot switches for this amp. Also have you found any literature on your amp if so where? Like an owners manual I believe mine is series 1 but I don't know for sure  how to tell.
  I was able to wire up one of my speakers from another little practice amp to tr out the head everything works I just don't have the foot switches or any info on the amp.
 Any info or help would be really appreciated.

thanks in advance

[J M Fahey]

*Most*  footswitches , specially old style such as those, work by grounding the tip and sometimes the ring connector in a plug, in this case one or both "ears"  to ground.
This picture I found shows a 3.5mm "headphone"  one but principle is the same with a 6.35mm guitar one which I bet your Yamaha uses.
So get a 1/4" (6.35mm) stereo guitar plug, pull thye plastic cover, insert it in thejack you are testing and alternatively short either lug to ground with a piece of wire, and check for yourself what happens.

Then add wire as needed and a footswth at the other end, so yo again ground active lugas at will, just with your foot.

Then you mount it on a suitable, pedal type enclosure, such as the cast aluminumHammond ones or anything you can build.

[Alesono]

Hello Scoticus, and you installed the 4ab2c1a reverb tank. Sound ok?.

Regards