1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

'67 Princeton tremolo shushing sound. Is it normal?

Discussion in 'Amp Tech Center' started by etype, Sep 29, 2020.

  1. etype

    etype Tele-Afflicted

    Posts:
    1,615
    Joined:
    Sep 23, 2014
    Location:
    Dallas
    I picked up my 1967 Princeton Reverb in 2017 as a 50th birthday present to myself. I was never much into tremolo, so other than making sure it worked when I got it, I have not used it.. until recently.

    When I turn up the intensity, there is a distinct "shushing" sound that rises and falls with the tremolo (even with no guitar plugged in). The rise and fall speeds up and slows with the speed setting (and it gets louder with volume). Is this normal or should I take it to my tech? I am planning on miking it up to record, but the sound it bad enough I'd rather use a tremolo pedal right now.
     
  2. King Fan

    King Fan Poster Extraordinaire Ad Free Member

    Posts:
    5,988
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Well, it *might* be normal -- the trem here comes from varying the bias, so it varies the amount of hiss and other noise you hear. But how much is too much? If the amp is 50+ years old, it seriously needs a once-over from a *good* tech -- the electrolytics and cap can, if nothing else. And several other areas could be adding more noise that the trem is 'varying'.
     
    etype and corliss1 like this.
  3. Dacious

    Dacious Poster Extraordinaire

    Posts:
    9,131
    Joined:
    Mar 16, 2003
    Location:
    Godzone
    It may be normal, as long as you only hear it as a background noise. If the amp's never been recapped its well past due. There's some 25uf/25v caps on the fibreboard that need to be changed out too.
     
    etype likes this.
  4. schmee

    schmee Doctor of Teleocity

    Posts:
    13,420
    Joined:
    Jun 2, 2003
    Location:
    northwest
    Probably a tube doing that. But could be a resistor or something related to the trem circuit.
    Only shushes with tremelo on right?
     
    etype likes this.
  5. ReverendRevolver

    ReverendRevolver Tele-Afflicted

    Posts:
    1,774
    Joined:
    Feb 2, 2019
    Location:
    Ohio (Nerk)
    If it hasn't had caps checked I'd take it to a tech anyway, but possibly re-seat or swap the tubes in the tremelo circuit. Then go from there. The fact that its only on trem certainly narrows it down.
     
    etype likes this.
  6. etype

    etype Tele-Afflicted

    Posts:
    1,615
    Joined:
    Sep 23, 2014
    Location:
    Dallas
    First off, it has been completely gone over by my tech, so it is all up to date. Second, good shout from a couple of you. There is always a hum/shhhh present but the tremolo makes it rise and fall. So the issue may be the underlying sound, not the tremolo, right?

    But this is making me wonder if the underlying hum has been getting worse over the last three years. It isn't bad, but it's there. Using the tremolo just makes it more noticeable and annoying!
     
    tubegeek likes this.
  7. jrblue

    jrblue Friend of Leo's

    Posts:
    2,399
    Joined:
    Nov 14, 2010
    Location:
    Santa Barbara
    Sounds like the tremolo is amplifying the sounbd as well as cutting it so I wouldn't rule out the trem. I don't own this amp so cannot say from my own experience, but I recall numerous posts and podcast discussions of this problem. I would think your tech would know about it, and not only through your amp. Sorry not to be more help. A small recording amp like this needs to be reasonably quiet and clearly yours has crossed a line.
     
    etype likes this.
  8. tubegeek

    tubegeek Friend of Leo's

    Age:
    60
    Posts:
    3,882
    Joined:
    Jan 31, 2020
    Location:
    Brooklyn, NY
    Hummmmm and shhhhh are two different problems.

    0. Which is it? Or both?

    1. Pull and re-seat every tube.
    Note any changes.

    2. Swap the trem tube for the input tube. Note any changes.

    3. Ask your tech if the amp has its original carbon comp plate resistors. These can be a source of shhhhh, even when they are still at their spec'ed values, which is what the tech may have checked.
     
    King Fan likes this.
  9. etype

    etype Tele-Afflicted

    Posts:
    1,615
    Joined:
    Sep 23, 2014
    Location:
    Dallas
    Good question! Tremolo off, I'd call it a higher pitched hum (def an ahhhhhhh and not a mmmmmmm), with an overtone of shhhh. But when I turn up the tremolo intensity, the shushing seems much more prominent... a shuh-shuh-shuh-shuh-shuh-shuh. I think it might be time for a trip to the tech. I'll ask him about the carbon comp plate resistors.
     
    tubegeek likes this.
  10. tubegeek

    tubegeek Friend of Leo's

    Age:
    60
    Posts:
    3,882
    Joined:
    Jan 31, 2020
    Location:
    Brooklyn, NY
    Beware that some players feel that there is mojo as well as noise in the carbon comps. They are capable of a small amount of signal distortion as well as the added noise.
     
  11. etype

    etype Tele-Afflicted

    Posts:
    1,615
    Joined:
    Sep 23, 2014
    Location:
    Dallas
    Just talked to my tech. His thinking is similar to the above -- including the hesitation about switching out the carbon comp plate resistors! I'm gonna take it in later today or tomorrow. Thanks!
     
    tubegeek likes this.
  12. King Fan

    King Fan Poster Extraordinaire Ad Free Member

    Posts:
    5,988
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    The place carbon comps make the loudest ssshhhh :) is in the input chain -- the 1M input resistor and 68K grid stoppers. Also, it might be good to make sure your bias is in the right range and kinda similar between your output tubes. And tubes can hiss, so maybe some judicious tube swaps with known good / quiet tubes. Truth told, a lot of things can hiss, but your tech will know this is maybe a newish problem.... Let us know what you find out!
     
    Last edited: Sep 30, 2020
    etype and tubegeek like this.
  13. Wally

    Wally Telefied Ad Free Member

    Posts:
    37,913
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    I am not trying to poke sticks at a wolverine in a cage(;^) but rather need clarification. Often people say that “it has been completely gone over by my tech”, but that means nothing to me. What one wonders is whether or not this amp has been recapped? I do not spend much time worrying about this noise type of problem or other minor problems until an amp of this age has fresh electrolytics.
    if the amp has been recapped and properly serviced, the. I would first suspect that V2 triode, it’s contacts or circuit components or the power tubes. Is there any noise of this type that perhaps you have not noticed when the trem is not in circuit? If so, suspect the power tubes or their associated components...like their plate resistors. If there is no noise of this type with the trem out of the circuit, then one would look to that trem circuit.....even the contact for the pedal??
    Good luck with the search...looking forward to what the tech finds.
     
    BobbyZ, etype and King Fan like this.
  14. schmee

    schmee Doctor of Teleocity

    Posts:
    13,420
    Joined:
    Jun 2, 2003
    Location:
    northwest
    If the amp has been “completely gone over by my tech”, what does HE say about the whoosing sound?
    Often going through a working amp is replacing cathode and filter caps, setting bias and cleaning pots/jacks. But that doesn't necessarily make all things right.
    Also, are you using a switch to stop the tremelo or just turning it down? Does it still make the noise using the switch?
     
    etype likes this.
  15. King Fan

    King Fan Poster Extraordinaire Ad Free Member

    Posts:
    5,988
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    If I'm reading right, it's at the tech right now. That switch v. intensity thing is a clue, though, isn't it?
     
    Last edited: Sep 30, 2020
    etype and schmee like this.
  16. loopfinding

    loopfinding Tele-Afflicted

    Posts:
    1,317
    Joined:
    Jun 19, 2011
    Location:
    europe endless
    a high pitched buzz can be that center tap for the heaters isn't truly balanced. you can eliminate this completely with a humdinger pot.

    barring bad grounding, a slight hum could be that your output tubes aren't completely matched. this could either be the tubes themselves, or tolerances in resistors that reference the bias voltage.

    a hiss is always going to be present, especially with carbon comp resistors. like mentioned earlier, you're probably noticing it because the tremolo by acting on the bias is not making it constant anymore. if you don't want to mess with the resistors in the amp too much, you can attenuate some hiss by selecting lowest noise tubes and possibly lowering the input resistor and adding a very small cap to ground.
     
    etype likes this.
  17. etype

    etype Tele-Afflicted

    Posts:
    1,615
    Joined:
    Sep 23, 2014
    Location:
    Dallas
    I now feel like this is going to be a complete letdown of an answer. I took it over to the tech and we fired it up. It was his opinion that this is actually one of the quieter mid-60s Fenders he has worked on and that this is just the noise floor the amp has. The amp did sound quieter at his place, but my music room is extremely quiet and his shop has plenty of single pane windows and there was just more ambient noise there. I think it was just that I was for the first time really using the tremolo that made this so noticeable.
     
  18. EsquireBoy

    EsquireBoy Tele-Afflicted

    Age:
    40
    Posts:
    1,889
    Joined:
    Jun 21, 2019
    Location:
    Paris, France
    IME tremolo always makes the amp's floor noise much more noticeable, to the point where you can sometimes start wondering if it's normal. It's a bit like turning off a fan and suddenly realising it was on and actually making noise.
     
    etype likes this.
  19. Don Rich Rules

    Don Rich Rules Tele-Meister

    Age:
    57
    Posts:
    155
    Joined:
    Sep 29, 2020
    Location:
    Long Island, New York

    I took my 75 Princeton out of moth balls and I turned it on the tremolo made a bizarre swooshing and pulse like sound that varied with the speed knob. So I took out every tube including the rectifier and sprayed the tube pins and sockets with QD Electronic cleaner.
    I waited 15 minutes so all the contact cleaner dried. Then I put the tubes back in and the amp sounded and worked perfectly. I also sprayed the pots, inputs and speaker outputs.
     
    etype likes this.
  20. loopfinding

    loopfinding Tele-Afflicted

    Posts:
    1,317
    Joined:
    Jun 19, 2011
    Location:
    europe endless
    I
    I have a 66 bassman that I just can’t squeeze the last however many millivolts of hum and hiss out of short of redoing the thing with a totally different grounding scheme and modern components. Which I’m not about to do. It sounds good, but It only gets used for rock gigs as a result.

    Vintage amps used to be affordable ways to good tone in most scenarios, despite the noise. But nowadays I’d rather stick to a modern clone with a turret board, metal film resistors, shielded cable, new transformers and caps that aren’t going to crap the bed. I can’t even tell my 5e3 clone is actually on half the time.
     
    Last edited: Sep 30, 2020
    Don Rich Rules and etype like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.