Speaker hiss in overdrive channel

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Brian, Feb 17, 2009.


  1. Brian

    Brian Member

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    Hi there !
    I need some advice on why a small 5 watt valve jr,rebuild,has this
    really bad hissing sound ? the amp works fine on the normal channel
    but once the overdrive channel is turned on it gets this awful hiss, I,ve
    tried different tubes,cables, speakers,ect,ect, any expert advice?
    thanksfor any help!:hide
     
  2. FrankieSixxxgun

    FrankieSixxxgun Member

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    Sounds like one of the mods may be culprit then, sir.
     
  3. Blue Strat

    Blue Strat Member

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    Absolutely. May be nothing more than normal tube hiss amplified by the higher gain or a cheesy or incorrectly done mod.
     
  4. FrankieSixxxgun

    FrankieSixxxgun Member

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    My Valve Jr. is voiced with decent gain and it's dead quiet even cranked. What kind of mods were done?
     
  5. Brian

    Brian Member

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    umm its a Phaze 5 sold by a guy from Canada ,sells different amps on
    ebay all his own design,hand wired uses 1 6V6, two 12ax7, seems O.K.
    except when the throttle,(boost) switch is turned on..........
     
  6. donnyjaguar

    donnyjaguar Member

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    I'd have to see the roadmap to have an opinion on this. My Concert II is modded with 4x 12AX7 stages before it hits the power amp and there's no hiss so it is possible.
     
  7. FrankieSixxxgun

    FrankieSixxxgun Member

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    So it's not a Valve Jr. at all anymore then, 'cause stock they're 1x12AX7, 1xEL84. I'd be on the horn with the guy who built it like, "What's up with this?"
     
  8. phsyconoodler

    phsyconoodler Member

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    Or maybe you have it cranked to the pin and are plugging in a single coil guitar?Or playing next to your computer monitor?
    Or maybe the builder has too much gain too soon in the circuit.
     
  9. Brian

    Brian Member

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    Hi again, well I traced down the problem I think that the mini toggle switch
    that changes the gain stage in the pre amp section to (Hi-gain) is suspect,
    I,m going to replace it and the short wires, amp sounds fine without this
    feature but hay what the heck!!
     
  10. Blue Strat

    Blue Strat Member

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    Is it really the switch or the fact that the switch turns on the mod? :D
     
  11. Brian

    Brian Member

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    Yes ! altho this amp is a simple point to point re-do using a valve jr
    chas... the main idea I had was a small 5 watt (high gain) cheap build
    that would sound cranked at low vol, without any effects help
    Well It must have been banged around in shipping or had a bad connection
    I went to the local Radio Shack bought a new mini toggle switch,and
    some extra wire,came back home got out a iron and in a few (30) minutes
    or so got it back up..............Yes!!! it now sounds really,really, awful!
    but hay what the heck if you were tone deaf and blind you,d think its
    great .:drool
     
  12. FrankieSixxxgun

    FrankieSixxxgun Member

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    Hah! My Valve Jr. with a few tweaks sounds like ******** Tony Iommi through a Laney when cranked, I dunno why you'd wanna put some other amp that sounds like crap in that chassis.
     
  13. Brian

    Brian Member

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    Just kidding, no really its sounds awfully awfully like an overdriven
    small amp on acid AC/DC crunch man its just so cool!!!!!!!!:dude
     

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