Odd problem with Pro Jet (Blacktop pickups) and Katana 50 amp

Discussion in 'Technical Side of Things' started by jasonek72, Jul 20, 2019.

  1. jasonek72

    jasonek72 Electromatic

    16
    Jul 13, 2019
    Wisconsin
    Hi all!

    First off, I'm a first time Gretsch owner and I'll be damned if this isn't the finest guitar I've ever owned. However, I have a bit of any issue that I can't wrap my head around and I'm usually pretty good at figuring out and fixing most problems with guitars and amps. I believe somehow that my problem is specific to my guitar and amp together.

    I bought the Pro Jet 3 weeks ago and played it through my Peavey Heritage VTX and various drive pedals with no problems at all. I decided to downsize this week and bought a Boss Katana 50. Well, it didn't take any time at all to notice that the guitar in general seemed to be noisier than with the Heritage by a good margin, almost as if it had single coils in it. Also, if I turned either the master volume or pickup volume down it would hum loudly until I turned the volume back to maximum.

    Here's what I've tried to sort it out:

    Checked the wiring. No problems there. This model does have the independent volume controls.

    Tried a different guitar cable and power cable for the amp. No change.

    Took the guitar to my brother's house and plugged into his Vox AC10 and also his H & K solid state amp. Hum and noise was much less even with higher gain and when I turned the volume down on the Pro Jet, everything went quiet just as it should.

    So I plugged both his G2622 (dependent volume controls, BTW) and cheap Ibanez into my Katana. Hum was much less than mine and the volume controls on those guitars did not produce increased hum after turning them down.

    So in the end, it seems there is something specifically about the combination of my Pro Jet and the Katana 50 that just doesn't seem to work together. My guitar is fine with other amps and the amp is fine with other guitars. The only thing I can think of is that there could be an issue with the independent controls on the guitar and the Katana amp. I'm going to switch the wires on the volume pots tomorrow to make them dependent and see if that fixes it. Other than that, I'm stumped for the first time in quite a while.
     
  2. Ricochet

    Ricochet I Bleed Orange

    Nov 13, 2009
    Monkey Island
    Intriguing... I don’t own a blacktop pro jet or a Katana so can’t help there. I do wonder about the shielding in the jet?
     
  3. jasonek72

    jasonek72 Electromatic

    16
    Jul 13, 2019
    Wisconsin
    None really to speak of, but the black top filtertrons are humbucking, so it shouldn't be much of an issue. Either way, obviously the G2622 isn't shielded and it doesn't have nearly as much noise with the Katana. My Pro Jet also isn't nearly as noisy plugged into other amps.

    It's just so dang frustrating. With the Heritage amp I played with some pretty stout gain all the way up to a Brian May-like lead tone. The result was never any noisier than one would expect with that level of gain. It also quieted down properly when turning the volume all the way down on the guitar.

    Let me describe a little more accurately what the volume on the Pro Jet is doing when used with the Katana. Let's say I have the switch in the bridge position. With both the master and pickup volumes full on, everything seems pretty normal. Very little background hum except when gain is up on the amp, as expected.

    As I begin to turn down either the master or pickup volume, hum starts to come into the signal. It doesn't seem to matter much where the guitar is positioned relative to the amp, so it really doesn't act much like typical electrical interference. As I continue to turn down the volume, the hum gets louder as the actual strumming of the guitar gets quieter. About 2/3 the way down the hum is loud enough to drown out any sound from the strings and when it is fully off, the hum is at its loudest.

    A couple things of significance: When touching the strings or anything metal, it does help to decrease the volume of humming but it does not make it go away. As to the character of the hum, it is exactly the kind of sound you get if you unplug the guitar and touch the tip of the cable while the amp is turned on. I would almost suspect the jack being wired backward, but if that was the case, touching the strings, bridge, knobs, etc would make it louder, not quieter.
     
    Last edited: Jul 22, 2019
    Ricochet likes this.
  4. jasonek72

    jasonek72 Electromatic

    16
    Jul 13, 2019
    Wisconsin
    Okay, I might have it figured out. I just watched David Collins' video on Independent vs Master volume wiring (basically Gretsch vs Gibson wiring) and toward the end he listed some disadvantages of independent wiring and one of them might be the key. He stated that with independent wiring, you are grounding out the coil instead of grounding out the amplifier when you kill the volume, which results in an increased noise floor almost as if the guitar cable was unplugged. That makes perfect sense given the sound I am hearing with the volume completely down. I will switch the wiring to the volume pots to Gibson style and report back with my results for anyone else who may find themselves with a similar issue. Here is a link to the video I referenced:



    EDIT: Looks like the wires on the master volume have to be switched too. I'll report back some time tonight with results. Still not sure why it (seemed?) to work differently on other amps.
     
    Last edited: Jul 21, 2019
    dswo and Ricochet like this.
  5. jasonek72

    jasonek72 Electromatic

    16
    Jul 13, 2019
    Wisconsin
    Okay, as promised I'm following up for any who may have a similar issue in the future. Switching the wires on all three volume pots took care of the problem. Now when I roll off the volume controls, everthing quiets down nicely no matter how much gain I'm using. As a slight benefit, the pickups behave as though they are slightly hotter somehow. It actually drives the amp slightly harder for whatever reason. The key was the video posted above.
     
    claypainter, dswo, Henry and 2 others like this.
  6. Ricochet

    Ricochet I Bleed Orange

    Nov 13, 2009
    Monkey Island
    That is great news, glad to hear you solved the mystery. I did have a look at the video, which is amazingly informative, and I'm sure he's right, but find his terminology confusing. I've never heard of master volume control in reference to Gibson guitar wiring. Does he mean Gibson '60s wiring, '50s wiring, modified '50s wiring, or something else?
     
  7. jasonek72

    jasonek72 Electromatic

    16
    Jul 13, 2019
    Wisconsin
    Yeah, I wasn't sure on that either. I guess he means wiring that causes either volume control to act as a master if completely turned down while in the middle position. I don't think he specifically mentions the Gretsch master volume in the video. I think dependent/independent or coupled/uncoupled would have been better terminology. Either way, my understanding of guitar electronics grew a great deal after watching all of his videos on the subject.
     
    Ricochet likes this.
  8. audept

    audept Senior Gretsch-Talker

    Age:
    71
    Dec 1, 2010
    Sydney, Australia
    Welcome to the forum. jasonek72! Glad to see that you got the problem sorted out.
    welcome mat 110.jpg
     
    Last edited: Jul 22, 2019
    jasonek72 likes this.
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