Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups darrenriley.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

Tested - Garnet Revolution II / III

Discussion in 'Amp Central Station' started by mgreene, Aug 6, 2018.

  1. mgreene

    mgreene Tele-Holic

    704
    Jan 27, 2010
    south carolina
    Ok, so I finally got around to trying the Garnet amp I got recently off Craigslist. It is a so called stencil amp – badged Pro II but has 6L6s so it is kind of like a Rev III.

    I was pleased that it actually worked and only has low-moderate AC hum on the clean channel. I see on the web that they are supposed to be loud but it is not very powerful – nowhere near the 50 watts stated on the schematics available on the web. I haven’t tested the tubes and they could be weak – but it sounds like 20-25 watts at this point. The pre tubes look like originals (Canadian mullards). The original speaker was replaced with a generic celestion.

    It reminds me of a Standel amp I had once – kind of jazzy w/ all the tone controls set to zero. That said, the tone stack is weird in that “all off” sounds pretty normal; bass just keeps adding low bass and treble makes things brighter in the upper highs – but the mid control swamps the other two - when they are up – and makes the high mids Very dominant. With the bass and treble on zero the mid control is much less active. Very non-Fender like.

    Any suggestions on the tone settings would be helpful. As would any insight on how the pull switches work.
     
    uriah1 likes this.

  2. codamedia

    codamedia Friend of Leo's

    Apr 4, 2009
    Western Canada
    This amp will be at least 35 - 40 years old... it needs some service, the sooner the better.

    The AC hum you mention is likely the filter caps screaming in pain... and Gar's amps were LOUD, so if it is under performing there is something amiss. I doubt it's anything serious... just general maintenance required. I don't know much about the Stencil amps and/or the quality Gar put into those, but I have a hard time believing he would have cut many corners.

    There are a couple of amp techs on these forums from the land of Garnet, hopefully they will notice the thread and jump in with some suggestions about the tone circuit.
     
    Wally likes this.

  3. mgreene

    mgreene Tele-Holic

    704
    Jan 27, 2010
    south carolina
    Thanks for the confirmation that they are loud.

    I mentioned the hummmm - which is pretty minimal - meaning to indicate that it needs work, which I can handle myself :p I am pretty happy that it works as well as it does.

    This was literally the first time I heard a Garnet amp. Very interested to hear any opinion re the tone stack - the online schematics are not very detailed.

    Oh yes, I also meant to mention that I am considering putting this amp back to 6V6s - JJs because they can supposedly handle the voltage.
     

  4. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    codamedia likes this.

  5. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    The 6L6’s could be pulling the voltages down unless the PT has the ability to deal with the current draw. I would be servicing that amp before running....ommv.
     

  6. mgreene

    mgreene Tele-Holic

    704
    Jan 27, 2010
    south carolina
    I was thinking the same thing. I read elsewhere that the Revolution was originally sold with 6V6s but they were unreliable and Garnet switched to 6L6. One schema shows the same power xformer for both versions.

    The tone stack is so different than a fender that I could see people back in the day being flummoxed by them.
     

  7. codamedia

    codamedia Friend of Leo's

    Apr 4, 2009
    Western Canada
    The Revolution I (g45tr) & II (g90tr) used 6V6 tubes, but the Revolution III (g100tr) used 6L6. The big question is... "what amp was this one suppose to be"? That schematic shows the same pre-amp for all versions, but the power amp looks to be tagged as the G90TR.

    For comparison to the one above, here is the schematic for the power supply for the Revolution III (g100tr) with 6L6 tubes. You are right, the PT looks to be the same.

    garnet_g100tr_lb100tr_power_supply_schematic.pdf_1.png
     
    Last edited: Aug 7, 2018
    mgreene and Wally like this.

  8. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    Canada
    Basically a Baxandall tone control, same as on almost every stereo, I could see why people had a problem.
     
    Wally likes this.

  9. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    I missed the PT numbers there. They don’t give a number for the OT, but the schematic for the g90tr shows two taps at 4 or 8 ohms while the g100tr indicates a single tap. That might be a clue as to what your amp started out as, Mr. Greene. That is the only difference I see.
     

  10. mgreene

    mgreene Tele-Holic

    704
    Jan 27, 2010
    south carolina
    I would agree but I find it weird that the tone is very normal with all controls at zero.

    They add in their frequency bands from there - as opposed to a stereo where there would typically be a null point at 12:00 - and the controls cut or add from 12:00.
     

  11. mgreene

    mgreene Tele-Holic

    704
    Jan 27, 2010
    south carolina
    Yes - noted, good eye. I am curious - will report when I get it apart.

    Like I said in another thread, I always wanted to hear a Garnet but never really wanted to own one. I threatened to trade a pedal for this amp and changed my mind but the seller decided he had to have the pedal - so here I am with yet another amp on the pile to fix :rolleyes:

    Meant to mention: in peripherally related irony, the guy I got this amp from (in Augusta GA) previously lived in the same small neighborhood I once lived in on LI NY - Wading River. What are the odds?
     
    Last edited: Aug 7, 2018
    Wally likes this.

  12. mgreene

    mgreene Tele-Holic

    704
    Jan 27, 2010
    south carolina
    Dont want to beat the horse - but the passage below describes what is NOT happening. Given that the full range guitar signal isnt all that wide - with B and T set at zero the signal sounds reasonably full range - not the dull mush you might figure.

    R1 and VR2 at Minimum

    With the bass and treble controls both set to maximum cut (Fig. 4.2.4), the full bandwidth signal passes through R1 but with the slider of VR1 at the bottom end of its resistance track, C1/R2 now form a high pass filter having a corner frequency of around 7 to 7.5kHz so only frequencies appreciably higher than this are allowed to pass un-attenuated. The mid and higher frequencies are therefore fed to R3 and C4, which now form a low pass filter to progressively attenuate frequencies above about 70 Hz, the mid-band frequencies (about 600Hz) are reduced by approximately −20dB, and at 20kHz by as much as −43dB, as can be seen from the response curve in Fig 4.2.5.
     

  13. Crobbins

    Crobbins Friend of Leo's Ad Free Member

    Jul 10, 2014
    Meiners Oaks CA.
    Congrats, and good luck with that amp.
     
    mgreene likes this.

  14. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    I found it interesting that the article noted that with the bass and treble controls set at the center point onthe sweep there was a 20db cut. A 20 dB cut might affect the output and using the controls below that point might have a larger effect of restricting output???? Just wondering....this may be why you say the amp doesn’t seem to be making the 50watts that you were expecting to hear? Curious, I am because I don’t hVe much experience with this type of control....at least conscious experience. I am sure that if and when I have played through a Bacandall tone controlled circuit I have avoided any cut by pushing th controlS on up the dial.
     
    mgreene likes this.

  15. dead mike

    dead mike Tele-Meister

    Best sounding live band I’ve seen (the Sadie’s) use a Garbet Revolution, check them out. Been looking for one of these for a while...and a Herzog. Anyway nice find
     
    mgreene likes this.

  16. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Dead Mike, I did not know that surf music was a big thing in Canada. Very ‘60’s pop when they go vocal...but the surf thing is still there. I was a big Ventures fan back in those days....still understand what an effect surf guitar has had on all guitar playing. Check this out...you may like it, too.

     

  17. stormin1155

    stormin1155 Tele-Meister

    308
    Sep 26, 2010
    Iowa
    I have a Revolution II. It's loud, but not OMG THAT'S LOUD! About what you would expect from a 20 watt amp into a single 12". I put an Eminence Swamp Thang in it, which opened it up a bit and give it a bit more clean headroom. I run all the tone controls at about 1:00 o'clock. I seldom use it myself.... it sits in my shop, and my customers use it to test guitars. A lot of them comment how good it sounds. I have one customer in particular that brings his Les Paul over and plays on it for hours.
     
    mgreene likes this.

  18. dead mike

    dead mike Tele-Meister

    I can get into that!
    Canada the home of Shadowy Men ( hero’s of Man... or Astroman), Atomic 7, Heuvos Rancheros, Johnny and the Cowabungas etc.
    I’ve got a couple of strays, Jazzmaster and a Sweptwing through a pro reverb drip face for my surf sound
     
    Wally likes this.

IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.