Who Regulates Voltage

Discussion in 'Let's Talk Vintage' started by emitch.sr, Feb 1, 2018.

  1. emitch.sr

    emitch.sr Member

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    How many of you guys here use something to get your voltage down to the 110 territory for these old amps
    If so what is your preferred method
     
  2. Crunchifyable

    Crunchifyable Well-Known Member

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    I don't own one of these...but if I had vintage amps, and didn't have a "bench power" type set up (aka variac or buck / boost transformer) I'd have something like this



    Kind of expensive for what it is ($250)...but probably worth it on vintage gear.
     
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  3. Humbucking

    Humbucking New Member

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    I use a variac to feed my amps between 108-112v. I also put a digital meter inline with my variac so I always now what it is putting out.
     
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  4. ampmadscientist

    ampmadscientist Well-Known Member

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    Variac...
    The output of a SS regulator is not going to be a clean AC sine wave.
     
  5. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    What amplifier do you have that requires 110VAC?
     
  6. houseofrock

    houseofrock Well-Known Member

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    If the bias is set correctly, is it necessary to step down the voltage to 110 from 120/125ish?
    I believe my wall voltage is at 124 and my '79 2204 has been biased accordingly by my tech (64%).
     
  7. pleximaster

    pleximaster Well-Known Member

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    It is interesting two put an amp in front of a variac and listen to how the sound changes with a couple of voltage up or down. It is not super dramatic but their is a change in tone, nothing to worry about playing live on various pubs and clubs as in a band situation the drummer and bass kills your tone anyway!

    But since we here feel as if we can hear differences when changing the value of a single cap inside the amp only slightly
    A variac changes your tone more

    Plexi
     
  8. BowerR64

    BowerR64 Well-Known Member

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    Ide be worried my amp would blow up the whole time i was playing it.

    regulators.young_.guns_.jpg
     
  9. liontato

    liontato Well-Known Member

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    A variac at 110 (with bias) will have a different feel and sound. You’re running lower voltage throughout the entire amp. Considering the PT ramps up the voltage quite a bit it’s a significant difference. You can run 125 if biased properly. No question it’s a little more wear in the amp.
     
  10. emitch.sr

    emitch.sr Member

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    My 2203 from 1980 has a sticker on back that has model number and power ratings and such
    And a 110/240v~ Place on that sticker from factory.
    My 74 superbass does not have anything to indicate the voltage.
    This amp will be going to a tech soon so I will be finding out what voltage it wants.
    They both have stickers from techs that indicate mA.
    The 2203 says 27mA idle current.
    The super bass says 55mA cathode current.
     
  11. emitch.sr

    emitch.sr Member

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    What got me thinking about this in the 1st place is a video with jd simo running a variac to allow his amp to maintain proper voltage.
    So I’ve been doing research and finding different ideas about proper voltage.
    I like the brown box that crunchifyable posted a video of but I am in the dilemma of not enough cash to get one and get my superbass taken to a tech for new tubes and whatever else it will need.
    I am leaning towards variac $50-$60
    The voltage from my wall at my house has ranged from 117 to 124 at various times
    So that makes me wonder if I should also run a conditioner and a variac
     
  12. liontato

    liontato Well-Known Member

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    I like 110. Softer overall feel. More sag. Not as stiff. Less bass. More vintage sounding. Slightly lower in volume. I use a multi meter and get it exact when I use that option.
     
  13. danfrank

    danfrank Well-Known Member

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    The way to tell what voltage your amp wants (was made for) is to plug the amp into a variac and take the filament voltage reading (pins 2 & 7 on octal power tubes). Adjust variac to read 6.3 - 6.4 volts for the filaments. When I do this and then take a reading of the input voltage to the amp, it's always somewhere between 110 - 115 volts in.
     
  14. coldengray

    coldengray Active Member VIP Member

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    I've measured my amp (the method danfrank mentioned above) and it "wants" to see 108.9v so I set my variac to where it's jumping between 108 and 109. My variac was about $120 I believe...nothing fancy.

    Don't run a vintage amp at modern voltages!
     
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  15. danfrank

    danfrank Well-Known Member

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    By chance did you measure the B+ voltage of the amp while your variac was set to 108 volts?
    What amp is it?

    I have a friend that has a Sovtek MIG50 that has B+ voltages of 550-560 volts and filament voltages of 7.2 volts when the amp is plugged directly into the wall (USA 122 volts). The amp says "110 or 220 volts in". When I lowered the input voltage with a variac to 110 volts, the filament voltage was right at 6.4 volts and the B+ voltage was right at 495 volts, which are more reasonable numbers...
     
    Last edited: Feb 2, 2018
  16. emitch.sr

    emitch.sr Member

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    Checked the wall voltage today and it was 108-113 I had a quartz heater plugged in the same room
    When I unplugged the heater voltage went back up to around 120
    The amps did seem to be in a sweet spot with lower voltage
    I would have thought the heater would have added noise but it didn’t seem too add any
     
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  17. danfrank

    danfrank Well-Known Member

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    The heater is just a big resistor that gets red hot
     
  18. charveldan

    charveldan Well-Known Member

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    NO ...
     
  19. coldengray

    coldengray Active Member VIP Member

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    ‘65 JTM45

    B+ was 425 I believe.
     
  20. Crunchifyable

    Crunchifyable Well-Known Member

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    I was going to say..the same thing happened to me this year. Kid in the next room was using a space heater and the voltage dropped by about 8 volts. Enough to make modern amps sound better.

    But also enough to make me not want to use my "high tech" auto biasing amps under such changing voltages.

    It makes me want to make a simple buck converter to drop the wall voltage from 123 to ~115 to make everything sweeter.

    [​IMG]
     

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