a tube primer for guitar and bass players - Guitar Amplifier Blueprinting

One of the biggest benefits of SAG tubes, is that the end user KNOWS what is in the amp. They can replicate this later, or go “up or down”
in various parameters.
For very critical requirements, the rise time of the matched phase inverter is also optimized to the characteristics of the output tube set.
Most GT offered tubes can be processed through the SAG (Special Applications Group). It costs about $10.00 per tube to have one found,
and in some cases, some tubes may not be able to be accommodated in short order. Some tubes from some vendors, have such a high
reject rate, or extremely bad characteristics, that one would need to go through over 100 of them to find one example.
You may contact Myles Rose for specific requirements. Some of the more common SAG tubes are available off the GT website or may be
special ordered through any Groove Tubes dealer.
There is more on the SAG on the Groove Tubes website at http://www.groovetubes.com/product.cfm?Product_ID=1773 where one can
also add the SAG labor cost to any of the tubes in the GT product line.
Some of the more common SAG tubes generally in stock are:
SAG-AT7-MPI - matched phase inverter (on a tracer, not just statically matched) generally used in Fender Black Face, Silver Face, and
early Tolex era amps.
http://www.groovetubes.com/product.cfm?Product_ID=1722
SAG-AX7-MPI - matched phase inverter (on a tracer, not just statically matched). Used on most amplifiers
http://www.groovetubes.com/product.cfm?Product_ID=1723
SAG-FHG – Fender High Gain Kit for Black Face and Silver Face era amps, many of the newer amps also.
http://www.groovetubes.com/product.cfm?Product_ID=1766
SAG-FST – Fender Soft Touch Kit – same as above, also used for any 12AX7 front end based amp where a slower rise time is desired, a
quieter tube, more clean headroom, and a higher ratio of output tube distortion compared to stock V1 and V2 tubes in these amps. This
was the old “SRV” trick, where he would use 5751 tubes in the first gain stage. Unfortunately, there are not a lot of great new 5751 tubes
around today, so finding tubes with the same sort of characteristics was the goal here.
http://www.groovetubes.com/product.cfm?Product_ID=1767
SAG-MHG – Known as the “Marshall High Gain Kit”, this should really be called the high output kit. This kit is very popular in not only
Marshall amps, but in Mesa, Bogner, Fender amps that need a more aggressive nature, Diezel, Rivera, and many other high gain amps.
Most of these amps have very complex front end design. Having a tube that is down 30% or more on current drive ability will zap the life
out of the best of any of them. Many folks love these with the included AX7 phase inverter in Fender Blackface and Silverface
amps for an aggressive update on these amps.
http://www.groovetubes.com/product.cfm?Product_ID=1737
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