help with 1959SLP issue

Discussion in 'The Workbench' started by raybert, Oct 21, 2020.

  1. raybert

    raybert New Member

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    Hi,

    I'm having an issue with my 1959SLP and I'm hoping someone here may have some insight.
    After not gigging for a while (thanks pandemic) I did a couple outdoor gigs recently and noticed an issue that I couldn't figure out. It was fine in July (last rehearsal) and I first noticed this issue in early Sep and again in early Oct.

    The issue is hard to describe but it seems the high-end is much "edgier" than normal and it seems overall more gainy/distorted (fizzy even). I used to be able to get near-clean tones when rolling the channel volumes down to around 11 o'clock (I normally run them at 1:00 (treble) and 12:00 (normal)) but it was now breaking up at lower volumes. Also, the amp sounded so much brighter than normal I had to crank up the mids & bass at the gig (again, not normal for this amp). When bending the first string the tone is a bit gnarly, over-bright and distorted (fizzy). I also noticed that when I turn the treble up to 10 the sound gets thin and gnarly/fizzy and most of the bass seems to drop out (this is normal to some extent, of course, but it now seems more extreme).

    For some background, this is a relatively recent RI (with FX loop). I have a PPIMV installed and I normally use a Tumnus Deluxe OD with some FX in the loop and a 4x12 with V30's and the channels jumpered. I also normally use a Weber MASS 200 with the level around 85/95 (depending on the room) and I bypass it with a FS for a solo boost. When testing it back at home I used only an Archer IKON in front, nothing in the loop (and the loop bypassed), no attenuator and a 2x12 w/ V30's -- but the issue remained. I tested with the Archer both on and off; the issue is much more noticeable when it's on.

    I have a fairly new set of TAD tubes in it. I tried swapping all of the pre-amp tubes (individually and then the whole set) but it didn't cure the problem. I haven't tried swapping the power tubes yet. I'm also starting to wonder if this isn't something to do with the OT, but I have no experience with OT problems or replacements.

    Additional background: I had a similar problem a little over a year ago. I took it to my amp tech and he found some bad solder joints. He reflowed them and that seemed to fix the problem (although I'm starting to doubt my own memory, ears, and sanity right now.... :( So, idk... maybe more solder joints went bad?

    I will likely take it back to my amp tech soon but I thought I'd ask here first in case this is a common issue (although I haven't found any evidence of that in my searches). TBH, I'm not sure the tech knows these amps very well. He's very qualified (well known in this area) but he was telling how he was enjoying mixing the two (jumpered) channels like he had never seen that before... (huh?) :)

    Thanks in advance for your insights! :)

    ~ray
     
  2. william vogel

    william vogel Well-Known Member

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    Do you keep track of the voltage you feed the amp? Voltage variation can cause the tone changes.
     
  3. South Park

    South Park Well-Known Member

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    It sounds like you have a unstable tube back off the gain
     
  4. raybert

    raybert New Member

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    I have actually been monitoring voltage. I started doing this about a year ago when I first had this problem (or a very similar one). Thus far I have not seen any voltages that are out of range; they've all been within a few volts of 120, including at my home (122).
     
    Last edited: Oct 22, 2020
  5. raybert

    raybert New Member

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    Do you mean the channel volumes? (There is no "gain" on this amp). Assuming so, backing them off is what I've had to do (also the gain on my OD). Although that improves the gaininess, it still isn't right (fizziness, etc).

    When I had this problem (or a very similar one) a year ago I changed all the tubes and that did not fix the issue. It still had the original Marshall tubes in it at that point and I replaced them with a new set of TAD tubes. Also, as I mentioned, I did swap all the preamp tubes recently while troubleshooting. Given that I reproduced the problem at home at low volumes, I'm not sure this is likely to be a power tube problem?
     
  6. thetragichero

    thetragichero Well-Known Member

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    could it just be the fact that you're outdoors and the low frequencies are going everywhere because there's no solid mass (ie walls) to reflect off of?
    similar to how a combo amp can sound fuller when it's back against the wall?
     
  7. raybert

    raybert New Member

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    IDK... I did think of that but (1) I reproduced it in my basement, and (2) IME it usually goes the other way around: more air to push outdoors requires more wattage/gain, which results in more power tube & speaker distortion, which is mostly low freqs (and sometimes gets too muddy). I seem to have the opposite problem here.

    TBH, I also haven't eliminated my ears (and aging memory!) as the problem -- thanks to the pandemic they're out of practice... ;(
     
    Last edited: Oct 22, 2020
  8. thetragichero

    thetragichero Well-Known Member

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    that's another thing: maybe they've recovered a bit from previous hearing damage
     
  9. raybert

    raybert New Member

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    Sad but true.... ;)
     
  10. raybert

    raybert New Member

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    So no one has any other ideas about this?

    What about an OT issue? As I mentioned, I don't have any experience with OTs going bad. What does it sound like when one goes bad (or is just poor quality)?

    Thanks!
     
  11. thetragichero

    thetragichero Well-Known Member

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    maybe you're looking for a problem to fit a solution?
    just play you guitar man
     
  12. raybert

    raybert New Member

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    very sage advice... I'll make a note of it while I wait for someone to offer something actually helpful...
     
  13. neikeel

    neikeel Well-Known Member

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    We cannot hear what you are hearing so it is absolutely impossible to say from your description, particularly when we did not hear it before. Your descriptions are very subjective tonal opinions - not specific fault descriptions

    Post some decent clips and we will be all ears!
     
  14. raybert

    raybert New Member

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    Okay, fair enough...

    I was hoping my description might match someone's experience with some issue or another but I also knew it might not. I don't think it's normal for an amp's gain and/or treble response to suddenly increase beyond what it was before and thought it might be related to a known problem that someone might recognize.

    I can try to capture it in a recording but I'm not sure that will, by itself, tell you anything, since you still won't know what it sounded like before. I'll work on it and see if I can come up with something...
     

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