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68 custom twin reverb . Why so hissy ?

Discussion in 'Amp Central Station' started by fattboyzz, Nov 17, 2018.

  1. fattboyzz

    fattboyzz Tele-Meister

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    I've been eyeing one of these locally and have sat down with it a few times and had a chat .'Ive even had others sit down an play as I stood back and listened.

    She sounds good at all volumes . Reverb is killer !

    But that hiss is just irritating me to no end. :0(

    I've got the gas for a nice Fender twin tube amp ;0)

    Thanks in advance for your time and answers .
     
  2. trouserpress

    trouserpress Tele-Holic

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    Oh dear, there's probably no easy answer to that. If you are adventurous try to buy that amp cheap and take it to a good tech.
     
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  3. 8barlouie

    8barlouie Friend of Leo's Gold Supporter

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    A noisy preamp tube makes a sort of hissing sound. Sounds like radio static. It’s not usually a steady, single note hiss, but a muffled, warbley type of hiss.
     
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  4. RoscoeElegante

    RoscoeElegante Friend of Leo's

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    I'd try to find a good-condition vintage Silverface Twin Reverb--ideally one that's already running hiss-free--and have a good tech give it a tune-up.

    Then, to get that '68 Custom Twin's more easily overdriven sound, just run a decent overdrive pedal in front of the rehabbed vintage Silverface.

    This way you have a high-quality, quiet, famously reliable, readily repairable amp that gives you '68 Custom-style breakup at lower/variable volumes.

    Another good route, if you need less volume generally, is a Silverface Bandmaster Reverb, similarly rehabbed by a good tech. Match it with the speakers/cabinet of your choice(s). That's the route I've gone. It gives rich Fender cleans with the added benefit of being able to mix and match speakers and/or cabinets.
     
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  5. trouserpress

    trouserpress Tele-Holic

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    Oh I just realized that the amp in question is a RI and not vintage.

    The right thing to do would be to forget all about that hissy custom and follow Roscoes advice!
     
    Last edited: Nov 17, 2018
  6. brogh

    brogh Moderator Staff Member

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    i had a 68 deluxe, sold it for how much noisy it was, got me a sf twin, that's a whole another story, put an od pedal in front and i'm in heaven
     
  7. moosie

    moosie Doctor of Teleocity Silver Supporter

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    It may be a collection of things. Carbon comp resistors are going to be a lot noisier than their modern counterparts. Depending on the noise level, the first thing I'd try is swapping preamp tubes out, one at a time, ignoring the vibrato tube (it's not in the signal path).

    EDIT: just realized it's not a 1968 amp. Go get one of those, then follow my suggestions. :twisted:
     
  8. LOSTVENTURE

    LOSTVENTURE Tele-Afflicted

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    If it's more than a couple of years old, replace all of the tubes. Maybe have a tech check out the biasing.
     
  9. 1300 E Valencia

    1300 E Valencia Friend of Leo's

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    All of the '68 Custom models have less negative feedback. This results in the tiny, tiny bit of earlier breakup, and a slightly furry sound with softer high end.
    Reduced negative feedback also results in increased "hiss", or white noise, even at idle, with no input. Those of you who like to sit in front of the amp as close to the speaker as possible, or who record digitally and listen to playback on headphones, will probably dislike reduced negative feedback the most. If you're playing loud with a live band you likely won't notice at all.
     
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  10. dmagalhaes

    dmagalhaes TDPRI Member

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    A couple of good preamp tubes in V1 and 2 really help with the hiss -- at least it did on my Twin and Deluxe.
     
  11. schmee

    schmee Doctor of Teleocity Silver Supporter

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    vintage twins aren't that hard to find at a good price. I'd get one of those.
     
  12. Lef T

    Lef T Tele-Holic

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    I played a 65 TRRI and it was dead silent.
    Great amp,but at my age it was just too much to lug.
    As others have stated,get the real thing.
    If you're going to haul something that heavy,it should be the real thing.
     
  13. Lynxtrap

    Lynxtrap Tele-Holic

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    Maybe, but it's no excuse for a big brand to release a whole series of notoriously hissy amps in this day and age. Negative feedback might be an easy cure, but the hiss is more likely the result of bad design, cheap components and/or a combination thereof.
    IME those Vintage Modified such as the VM Deluxe amps suffer from the same problem.
     
  14. OldDude2

    OldDude2 Tele-Afflicted

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    I wouldn't flush the brand that quick.

    A gentlemen from Texas that just moved to the area schooled a small music store employee with "his" Anderson he brought in to test amps. He said his pickups didn't care for a particular head because of a hiss, but it had a irregular crackle that he identified to the kid to get fixed...it's likely still in the store.

    If you like it, take in your own guitar and try it. It might work?
     
  15. Wally

    Wally Telefied Ad Free Member

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    Anytime there is gain added, there will be an accompanying noise. Plug in that overdrive/boost/distortion pedal and switch it on....sit there and listen without playing....there will be added noise. The reduced NFB signal is simply a way of ‘adding gain’.....gain that is being cancelled by a stronger negative feedback signal in this vintage amps.
     
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  16. Lynxtrap

    Lynxtrap Tele-Holic

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    I don't mean to "flush the brand", but it is well known that the 68 Custom series suffer from hiss to the extent that some customers find it intolerable.
    I'm just saying that it is an unnecessary problem that could have been avoided through careful design of the circuit. It's not like these are high gain amps.
     
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  17. Wally

    Wally Telefied Ad Free Member

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    The ‘68 SF Custom amps that I have plugged into while being few in number have not been objectionably noisy. I also find that the mods to them do not go far enough for my tastes. I prefer to mod a vintage amp to take it even farther toward a hot, mid-range type of amp in that left channel....with an adjustment pot in NFB loop.one can hear the increase in the noise floor as one adjusts that pot....and one can hear the difference in the sonics while playing. The noise floor is not objectionable.......maybe since I don’t sit and fixate on a reasonable noise floor IF the resulting sonics while playing are what I want to hear.
     
    Last edited: Nov 19, 2018
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  18. JD0x0

    JD0x0 Poster Extraordinaire

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    *Zips up flame suit*

    Probably because they badly designed the reissues. Fender released the RI with poorly implemented mods, causing ground loops. Linked the reverb to both channels rather poorly which increased noise floor.

    1W resistors aren't just more reliable than 1/4W - they have less self-noise. Upgrading many resistors, particularly those over 47K in value, has a noticeable cumulative effect in the amp.

    Ceramic disc caps Fender uses in the power section fail all the time and can cause buzzing. They saved a penny by using underrated 1N4006 diodes for rectification..
     
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