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Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit

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Product 219129
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The Groove Tubes SAG-MHG Marshall High Gain Kitcontains 2 SAG ECC83S and 1 AX7-MPI tubes optimized for the preamp stage of Marshall-style amplifiers....Click To Read More About This Product

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Maximize your amp's tonal powers!

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.

  • Country of origin: Slovakia
  • Country of origin: Slovakia
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by PowerReviews
Groove TubesSAG-MHG Marshall High Gain Preamp Tube Changing Kit

(based on 5 reviews)

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Reviewed by 5 customers

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(1 of 1 customers found this review helpful)


th Best pre-amp tubes

Comments about Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit:

I have to give this tube kit props, thumbs up. I use them in my Marshall 1987X. I works perfectly for my rig. I use a Marshall Power Brake along with an Fulltone OCD it just smokes. I am able to achieve the ultimate tone I have desired. The amp gets pushed hard, the GT tube kit withstands the use I put them through. They react awesome when running an over-drive, distortion, or fuzz pedal through the amp. Great bass response, which I can loose with other pre-amp tubes while using an attenuator. Not an issue with these tubes, incredible bottom. It stays real tight. I can get smooth and creamy along with ripping highs. For my rig these tubes work the best out of any I have used. I never had a GT Gold High Gain pre- amp kit go sour or sizzle. A#1 quality. Groove Tubes has always been an awesome company to deal with

(1 of 1 customers found this review helpful)


High gain ECC83s in my Marshall

By kkatarn327

from Fresno, CA

See all my reviews

Comments about Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit:

I bought this tube set a few weeks ago for my JCM 800 2203 and it was great (btw i play a Les Paul). I was looking for something that would give me that slight push over the edge tonally but without compromising the 800 tone, so any distortion/boost pedals were out of the question. These definitely did the trick. Even straight into the amp they sounded great, and even better when burned in. Compared to my old tubes (JJ 12AX7s) these were obviously more dirty but still very defined. They compress your sound a bit but still offer great dynamics. All in all i guess it's a subtle difference (especially in a 2203) but believe me it's just enough. If you are debating about these tubes I suggest you get them, you won't be disappointed. I was actually surprised for the quality in these, being GTs. the only reason I gave quality a 4 is because I haven't had them nearly long enough to be an accurate judge of quality. Anyways, these tubes will give you tasteful gain that's just enough to push you over the edge, especially if you're like me and don't want to compromise your amp's tone.

(0 of 5 customers found this review helpful)


Groove tubes

By Tommy Skulltower

from NYC

About Me Experienced

See all my reviews

Comments about Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit:

I love Groove Tubes, I have four Marshall's
But why label your box made in USA and then plaster all over Slovakia?


Changed my whole amp!

By .Jamison

from Missouri

Comments about Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit:

These little tubes changed the overall sound of my amp completely! It went from a blah to a great Marshal Style Crunch. They do not have so much gain but with an Overdrive pedal it will push them into a really nice crunch style distortion! Overall the Price is a little steep, but you really get what you pay for.


Myles Rose SAG Kits

By Terence

from Douglasville, GA

Comments about Groove Tubes SAG-MHG Marshall High Gain Preamp Tube Changing Kit:

These kits were started by Myles Rose (i.e. Amplifier Blueprinting) when he worked at GT for industry "heavy hitters." Two (2) weeks before purchasing the kit my tech installed and biased a Slovakian 6L6GC matched duet from the tube manufacturer--impressive improvement. I purchased the Marshall High Gain (MHG) kit (my Fender's OEM PI is a 12AX7). The sonic results in my PROSONIC were AMAZING--the amp became quite "articulate/lively." I gave the GT screened tubes a value of 3.5 because I could have purchased three (3) Slovakian 12AX7's from JJ for about $30. However, the V1 & V2 Slovakian tubes (in this kit) have been selected for gain characteristics with respect to their "job" in the amps circuit. Likewise, the Chinese PI has been selected for gain AND rise-time "balance" between the triodes. The amp "feels" more "there" now.

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