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Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

Protecting Vintage Tube Amps From Wall Amps

Discussion in 'Glowing Bottle Tube Amp Forum' started by keithb7, Jun 18, 2017.

  1. charlie chitlin

    charlie chitlin Doctor of Teleocity Ad Free Member

    Age:
    55
    Mar 17, 2003
    Spring City, Pa
    I use a bucking transformer with my tweed amps.
    It knocks 120 back to about 109.
    I think it's a good idea, but I still haven't found anybody who thinks the difference in tone is anything more than 'very subtle'.
    YMMV
     

  2. peteb

    peteb Tele-Afflicted

    Apr 25, 2003
    Cascadia
    I have half size fuses in all of my vintage amps, been that way for many years. It's the exact opposite of using an over sized fuse.

    Also, I see no reason why a light bulb current limiter couldn't be used regularly, and it seems like it would help keep the current down in the case of a short, like it's meant to do at initial start up.
     

  3. E5RSY

    E5RSY Poster Extraordinaire

    Age:
    50
    Mar 5, 2009
    Georgetown, TX
    I'm not an electronics guy, so my first reaction would be a regular run-of-the-mill power strip/surge protector. Would that not give the desired result/protection?

    p.s. Never mind. I didn't read the original post correctly. :confused:
     
    Last edited: Jun 19, 2017

  4. robrob

    robrob Poster Extraordinaire Ad Free Member

    Dec 29, 2012
    United States
    A light bulb limiter will make the amp sound funky. A larger wattage bulb might help that though.
     
    codamedia likes this.

  5. moosie

    moosie Poster Extraordinaire Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    Tell your friend that his amps are an impossibility. He can either never turn them on, in which they're useless IMO - might as well be rocks. Or he can gently upgrade, and play them. Or, he can let them undergo catastrophic unrecoverable damage. And then he will neither have a collectible or a player.

    Your friend should sell those amps while he has the chance.
     

  6. BobbyZ

    BobbyZ Doctor of Teleocity

    Jan 12, 2011
    Snellman MN
    Cut the cords off them so he can't plug them in.
     

  7. moosie

    moosie Poster Extraordinaire Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    If I understand the electronics, a variac will reduce the primary and secondary voltag s, bringing them down to gentler levels. But this in no way will protect if an ecap shorts. Still goes boom.
     

  8. David Barnett

    David Barnett Poster Extraordinaire

    The main concern with plugging old amps into modern AC supply is the voltage. An amp made for 110/115V AC plugged into the wall in most places in the USA will run the 6.3V AC heaters at nearly 7V. And the DC bits will be similarly high, compared to their design center. Knocking down the AC voltage will return the amp to what it was designed to do, and will help tubes last longer.

    Some amps were already on the ragged edge of reliability when they were designed, such as the Vox AC50 and AC100, which were biased very hot. Plug one of those into a 125V wall socket and it's likely to be red plate city, unless you've got a really robust set of EL34s in there. Keep a fire extinguisher handy. Or be smart and use a bucker or variac.
     
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  9. moosie

    moosie Poster Extraordinaire Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    All this is good and true, but if the e-caps are dried out, none of this matters, I think.
     

  10. RLee77

    RLee77 Friend of Leo's

    May 15, 2016
    Silicon Valley
    I think the core issue is that a person has to decide if they want a museum piece (perfectly reasonable thing to want) or an amp that can be used. Trying to have both only works for a period of time, then you have neither...
    I don't see an issue with replacing the e-caps, that are inside and no one sees, and putting the originals away for safekeeping. Aged solder joints are easy to recreate. But then I'm not a collector, and I would understand if this is not acceptable to a collector.
     
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  11. alnicopu

    alnicopu Friend of Leo's

    Oct 3, 2009
    georgia
    Personally, as an electronics guy, I don't think an extra 5 or 10vac is gonna stress the primary, it's the innards you need to worry about. I had an old Airline I rebuilt once and played with some resistor values to get the filament and rail voltages in spec. Made sure to use NOS carbon comp resistors. IIRC, the filaments didn't even get much, if any, above 6.4. Worked and sounded great up until I sold it a couple years later. That being said, replacing old components is just normal service. I did a full cap job on it. I gently took the old ones out of the paper covers and stuffed the news ones in. Look totally stock when I finished.
     

  12. David Barnett

    David Barnett Poster Extraordinaire

    But that's a service issue, not a use issue. Obviously an amp in need of service should be repaired first.
     

  13. Cjl77

    Cjl77 Tele-Meister

    416
    Nov 12, 2013
    lake charles ,La
    To each there own, of course.
    But the thing is with these old amps that have all original caps, resistors, etc. they don't sound as good as they could. I don't understand why people want to play them when there not in there best operating condition. Any amp from the 50's or 60's that I have recapped, it made a huge sonic difference. Even if the caps looked great. On my 57 LP twin the phase inverter resistors had drifted so bad it was swinging half the voltage it should have been. I own 6 original tweed amps and all have had caps and some resistors replaced. All had never been touched when I got them. They all sound great now. Huge difference
     
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  14. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    It's foolish to play those amps at all. No matter *what* condition they are in, filter caps have a limited service life, and he's playing with fire using amplifiers that old with original filter caps.

    If one blows and takes out a transformer he can kiss several thousand dollars in collectors' value goodbye even though a transformer costs just a few hundred.

    NOTHING can protect electrolytic caps, and they can fail with no warning and the amp sounding great.

    He needs to make a decision - either those are 1) collectors' items and store them on display only, or 2) if plans to play them *at all* they need to be serviced. Period.
     
    codamedia likes this.

  15. Wicked-T

    Wicked-T Tele-Meister

    Age:
    47
    266
    Apr 1, 2017
    USA
    I use a bucking transformer with my vintage Hi Fi stuff maybe I should start
    using it with my guitar stuff as well.
     

  16. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    Why? What purpose do you feel it will serve?
     

  17. telemnemonics

    telemnemonics Poster Extraordinaire

    Age:
    57
    Mar 2, 2010
    Maine
    We do see vintage amps with multi section cap cans left on the chassis while new caps get mounted elsewhere to make the amp function.

    I wouldn't choose to fix a Champ that way, but it would be possible to leave the old caps in place and piggyback or otherwise add new caps.
    I've never seen this done, but?

    The whole "never been changed/ fixed/ altered- all original" thing is a thing that can't be denied.
    It's an irrational idea in terms of function, so maybe an irrational solution is in order?
     
    RLee77 likes this.

  18. moosie

    moosie Poster Extraordinaire Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    But that's the point of this OP. The owner wants to play them, but refuses to service them, because they won't be original anymore. That's what we've been talking about here.
     
    robrob likes this.

  19. moosie

    moosie Poster Extraordinaire Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    Sometimes the cans are stuffed with the new guts, I hear. But that seems to be overly concerned about 'fake' looks, to me. It's been serviced, be happy!
     

  20. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Horse, water, drink. :)

    The analogy I've heard, and somewhat successfully used, is no one in their right mind would drive a 57 Chevy with all original tires, oil, and filter.
     
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