List - $100.00

Specially selected from premium Groove Tubes preamp tubes which have been tested in their normal rigorous fashion to meet the GT standard. Groove Tube's Special Applications Group (SAG) provides further testing and grading for certain performance characteristics.

This three tube set is optimized for your Marshall, Bogner, Rivera, Mesa or British type amps which use (or will benefit from) the ECC83 (12AX7) preamp tubes. SAG-MHG includes two high output preamp tubes to be used in the V1 and V2 positions, and one MPI (matched phase inverter) tube for the V3 position. The matched phase inverter may be a 12AX7 or an ECC83, as it will be matched for it's response curves with the other two tubes. The phase inverter is not part of the tone generation stage, it is a current driver.

The V1 and V2 tubes will increase the front end output structure of your amplifier from about 10% to as much as 25% or more, over the typical stock tubes you may have now.

The V3, matched phase inverter tube will assure a balanced output section when used with matched power tubes (highly recommended) which will assure sustain across the entire range of your instrument.

The MPI (Matched Phase Inverter) is a SAG selected 12AX7 or ECC83, as this tube is not part of the tone generation stage, but part of the output section and is chosen for its current drive and rise time characteristics.

Use this MPI in any application where a phase inverter/driver of the ECC83/12AX7/7025 tube is specified. The phase inverter/driver position of a guitar or bass amp is a current driving position, and not part of the tone generation stage. These tubes are selected for specific characteristics, so may be a 12AX7R, 12AX7C, 12AX7M or another 12AX7 type that has been selected for specific curve traces as the objective. This tube cannot be specified as to type in the kit.

These kits also work particularly well in Fender Blackface and Silverface amps where the increased gain and current out of the first gain stage combined with a switch from the 12AT7 in the phase inverter to a 12AX7 will yield a much more agressive tone. These amps which are normally considered to be on the "clean" side will become more agressive with this kit.

These kits are very popular in the Fender Hot Rod series amps.

Each of the three kit tubes is marked as to it's specific rating. In the future if you wish to change your gain structure, it is a simple matter to request a higher or lower value as the actual characteristics of your amplifier's gain stage is now known.