Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit
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The Groove Tubes SAG-MHG Marshall High Gain Kit
contains 2 SAG ECC83S and 1 AX7-MPI tubes optimized for the preamp stage of Marshall-style amplifiers.
Specially selected from premium Groove Tubes preamp tubes that have been tested to meet the GT standard. Special Applications Group (SAG) provides further testing and grading of vacuum tubes for certain performance characteristics.
This 3-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 its response curves with the other two tubes. The phase inverter is not part of the tine generation stage, it is a current driver.
The V1 and V2 tubes will increase the front end output structure of amplifiers from about 10% to as much as 25% or more over typical stock tubes.
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.
Country of origin: Slovakia
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 aggressive tone. These amps which are normally considered to be on the "clean" side will become more aggressive with this kit.
SAG-MHG Marshall High Gain Preamp Tube Changing Kit Specifications:
- Country of origin: Slovakia
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Comments about Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit:
The GT SAG-MHG Marshall high gain preamp tube set is the godfather of high gain. They have a gorgeous midrange snarl, with more than enough mongrel to satisfy any well 'ard metal head. The difference they made to my JCM 800 was off the wall. The amp had 3 12AX7s in valve position 1,2,3. Very bland, little saturation. The SAG (special applications group) brought my amp to life. A very worthy investment indeed. If you're after beautiful, creamy midrange distortion, these are the go. The hard part is to work out how to tame them down, but you don't buy a Marshall to play any thing but unadulterated rock now do you?