JCM800 1960A vs. Mojo/Germino 4x12": sound and quality

Discussion in 'Amps and Cabs' started by Roe, Oct 7, 2005.


  1. Roe

    Roe Member

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    Does a mojotone or germino 4x12 cab sound better than a marshall cab from 1985? [Mojo made the germino cabs earlier.]
    Does the marshall cab have a particle board back plate?

    I'm thinking about selling my old cab.
     
  2. Rusty G.

    Rusty G. Member

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    Are you saying that Germino cabs are built by Mojotone?
     
  3. Roe

    Roe Member

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    yes I am. Unless greg g. has found someone else during the last few weeks, it's still mojo. greg even used to work for them earlier. on the mojo web site [under one of the marshall style cabs], they say they make the germino cabs.
     
  4. Rusty G.

    Rusty G. Member

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    That's cool! I always thought that Greg's stuff was great.
     
  5. RichSZ

    RichSZ Member

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  6. Roe

    Roe Member

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  7. Lerxst2112

    Lerxst2112 Member

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    Didn't Greg work for Mojotone?
     
  8. Lerxst2112

    Lerxst2112 Member

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    Ahem... when can we expect the new Germino stuff up there?

    Also, ever thought about posting an update on the site? I mean, the Rockgrinders and Masonettes aren't even produced anymore... maybe put something about the new 6V6 versions and estimate their output?

    I dunno, I'm just always searching like crazy for info on amps... and your site has a ton of great info, but some is outdated...

    ...which makes me an angry panda.
     
  9. KLB

    KLB Member

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    Lerxst2112,
    New 6V6 Germino? Tell us more.
     
  10. Lerxst2112

    Lerxst2112 Member

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    There isn't one. He discontinued the Masonette because, as I understand, most (if not all of his amps) he can create to run on 6V6 at lower wattages anyway.
     
  11. Lerxst2112

    Lerxst2112 Member

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    I meant your site. :)

    And yeah, I wanted a Masonette for a good while. Ended up going with an Invader, which I'm absolutely in love with...

    But I think he should also put up more info on his site...
     
  12. KLB

    KLB Member

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    Oh I see. By "new 6V6 versions" in your earlier post to Steelbender, you meant using 6V6 in the LV55, Club 40, Classic 45?


    I currently own a Club 40 and have had a Masonette and LV55. IMO, the Club 40 sounds better with 6V6 than the Masonette did. The Masonette has a bit too much sag/compression for my tastes, from about 4 on up. The filtering on the Club 40 is larger, so it has more punch than the Masonette. The Club 40 and C45 preamps are voiced for flatter mids and less gain than the Masonette, which also helps, especially with pedals. The LV55 is OK with 6V6, but I think the other two amps are better suited.

    If you want to use 6V6 all the time in a Club 40, change the Phase Inverter 10K/470 resistors to 47K/820 to reduce its output and let you keep using a 12AX7. Else, at least sub a 5751 or 12AT7 for the 12AT7. 6V6 input grids don't require as much signal as an EL34 before saturation. This mod will let you crank the preamp more before overloading the 6V6.

    You can use a 5U4GB or old stock (RCA!) 5Y3GT rectifiers, instead of the 5AR4, to drop the plate voltage to 400v or less. Using a 5Y3GT rectifier, I've had a Club 40 biased at 32ma and 365 volts with 6V6. That was a fat tone reminiscent of an old Brownface Fencer Deluxe!

    Another trick to make those 6V6 sing is to put a 1K 5W resistor in series after the choke, before the 2nd filter stage that goes to the screens. This will drop the screen voltage a good 8-10 volts compared to the plates. This will improve the touch response, and to my ears, make the amp breakup even better.

    I have to mention, and Greg Germino and Mr. Hanky will agree, the Celestion Heritage G12M20 is a beautiful sounding speaker! You will probably want to run a pair, even with 6V6, because the 20 watt rating will be exceeded by a stout pair of 6V6 in any of these amps, including the Masonette.
     
  13. KLB

    KLB Member

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    Jason,
    I guess we are somewhat off topic here, but I'm having fun talking about Greg's fine amps, so "what the hay!"

    Thanks for posting that. A few more points I'd like to share based on my experience:

    For 6V6 in the C45, switch to a 5U4GB, which will drop the plate volts at least 30. The JJ's can handle this. No problem, but don't bias too hot. 450v at 17ma is a good point. Greg told me recently that he no longer biases tubes beyond 50-55% of their dissipation, feeling it is not necessary to get the tone, and the tube life and reliability is extended.

    Yes, using half the impedence into the speaker load is important for 6V6. By the way, the Masonette output transformer primary impedence was ideal for EL84 (9K), and put a slightly higher than optimum load on the 6V6 (6.6K), making it somewhat darker and more compressed in the process. It sounded very good anyway!

    Another reason the C40 and LV55 have more headroom with 6V6 than the Masonette is there is substantially more power supply filtration. I have to say the Masonette, because of the lower filtration, has a seductive FEEL for med/high volume playing. It doesn't always work on the bandstand unless mic'd, but it is fun to play.

    I have to praise Greg for having probably the best support of any builder I've ever worked with. I'm a an amp tinkerer/hack, and he has been more than accomodating at sharing info and helping me understand how the TONE is made in these type amps.
     
  14. Roe

    Roe Member

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    I've found out that my marshall cab has a particle board back plate (the rest is birch plywood).

    This might give it a little bit more (deep) bass and more weight, but less resonanse than a all ply cab like a Germino or a Mojo cab.
    Also the particel board might get worse (looser) when it ages so that the cab will not be very tight sounding.

    The thinner grillcloth on my marshall will give a brighter, harsher sound. The thick grillcloth on a germino cab will give a more hollow and woody sound. It will also increase the power handling of the speakers slightly.
     
  15. Roe

    Roe Member

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    Thanks for correcting me jason!
     

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