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Tough spot to be in with a new Matchless

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  • Tough spot to be in with a new Matchless

    A Matchless sponsored player brings me a new C-30 that was built for him. It is an AC-30 inspired build. His complaint is that it lacks treble, and sounds like there is a blanket over it on the drive channel. The drive channel is built around a EF86 tube, my first experience with one. He complained to the guy who now runs Matchless, and it was suggested he bring it to me to work with him, rather than ship it back to get it checked out. (it's a 210 combo).

    Customer bring it to me, and shows me what the problem is, except it sounds darn good to me, but he says, no it needs maybe 70% more brightness. OK, I tell him, but I have never seen one of these before, and I am not sure if I will even know what to compare it to. I work for a week off and on with the builder Phil, I send him detailed photos, and solder, check and measure whatever he asks me to. Finally, he says everything looks good on his end, and that it was working just fine when it left the factory, because he "played the hell out it". The last thing he suggests is changing out the EF86 tube, and to stay away from the JJ one because for some reason it's different and should not ever be used in this amp. I do know the owner tried a JJ EF86/EF806 in it at one point, I don't know if this is part of the problem.

    He suggested EH, Amperex, or better yet for a brighter tone, a NOS Dario miniwatt which is new to me. The latter will run $50 - 100 if you can find one.

    So now I find myself in a situation where the builder is seeming to suggest there is nothing wrong except maybe a tube, the customer insists the amp isn't right, and I have hours into this with it clogging up my small shop in a road case. With the head of Matchless saying he sees nothing wrong, I stand no chance of solving this myself with no schematic. The customer is going to be unhappy, and after all, what do I charge him for a week of trying to solve a problem that might possibly be his expectations? He's a high level experienced player, so I need to be careful about that.

    I think I am going to call him tomorrow and tell him I did my best, but he needs to come get his amp and decide which brand tube to get to decide with his ears if it does the trick. I will cut my losses and only ask my minimum bench fee, and after that it's between him and the builder.

    I repaired a '64 Gibson Scout combo today that was buzzing like a nest of angry bees, and the reverb and tremolo didn't work. All 4 filter caps were bad, I changed them out, and now it's very quiet and everything works as advertised. I so much prefer that type of challenge where it is pretty black and white vs. "this amp does not sound like I think it should" kind of jobs.
    It's weird, because it WAS working fine.....

  • #2
    Amp sounds good, is good. Now make it sound how the owner wants, and document your changes. Small cathode bypass caps, treble peaker, bright caps, etc. You can tack these components in quickly, and get it road worthy later once client is pleased.
    --
    I build and repair guitar amps
    http://amps.monkeymatic.com

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    • #3
      A simple solution might be to just add a bright cap across the volume control of the drive channel. It's easily reversible.
      "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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      • #4
        Having worked on several, I feel bad for you.

        Their construction is a Tech's nightmare.

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        • #5
          Yes they are beautiful, but very much a difficult situation to deconstruct. And There is NO WAY I am at all interested in re-engineering an amp that was just built for a guy, and is currently being dealt with by the builder. Especially with no schematic. Totally unrealistic from my perspective.
          It's weird, because it WAS working fine.....

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          • #6
            I gave up on EF86s. I had tried them in 2 of my builds. The first one, the owner hasn't called about it yet. The 2nd one, I had 2 JJ, an old Mullard, & 2 Seimens go belly up on me. Ring, hum, random other noises. Tried every trick I could find. The damn things just are not useful in tune amps, IMHO. They sound great until they break, & getting a good nee or old one is a crapshoot.

            I've got a small stash of other pentodes I'm willing to try, but I'm skeptical. Part of me just says, work to make the best out of what's available rather than try to chase some golden-age ideal. And look for cheap alternatives, so that when your pentode preamp blows up, at least you're only paying $3/tube instead of $100.

            Justin
            "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
            "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
            "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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            • #7
              The main feature of the EF86 Miniwatt Dario, Valvo, TFK and other European Philips models is the treble dimension and its articulation capacity. It can be interpreted as brighter than a Svetlana or JJ but this is not able to redirect that masking effect (according to the guitarist).

              In your case I would see if the cut control works well * (I imagine it has one), if the lead circuit has any bypass capacitor included in anode resistors or filters somewhere else and what type of bypass capacitor has the gain control. In the latter case and depending on the setting used (to measure its effect) a pushpull could be installed raising its value. Sometimes in two-position miniswitchs I have installed one of three for the same purpose. In some cases to offer an intermediate adjustment if the activated effect is extreme.
              It can also happen that if the amp has some use and the bias setting is very high (relatively common) the power tubes have degraded, that the amp uses some dark preamp tube (a Sovtek 12AX7WB, for example), etc. Finding elements that obscure the sound is not extremely complicated.

              (*) Once I found an AC15 with a defective cut control. It kept the filter closed in any setting.

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