Variac for voltage regulation

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dynosoar1, Jan 30, 2008.

  1. dynosoar1

    dynosoar1 Member

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    My line voltage in my house is around 124v. Is a variac a good way to run my vintage amps to hold the voltage to around 110-115v on my vintage amps..or is a line leveler (voltage regulator) better??

    Any advice appreciated....
     
  2. phsyconoodler

    phsyconoodler Member

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    If you have any vintage amps worth a lot of money,use a voltage regulator.A variac is not for lowering line voltages while playing an amp.Dangerous practice to be sure.
     
  3. TubeAmpNut

    TubeAmpNut Member

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    Uh, not really. A variac will be fine. An AC voltage regulator (at least one you could use in your house) is nothing but a transformer with preset taps that are automatically switched by logic to adjust the output voltage based on input voltage. A variac is a constantly variable tranformer whose output voltage is adjusted by the user turning a knob. Most AC regulators regulate 120V +/- 3V which does you no good getting to 'old world' voltage of 110-115V.

    I wouldn't get a 'vintage' variac, however. Also make sure you convert your plug to a 3-lead safety ground type.

    BK
     
  4. 67super

    67super Member

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  5. TD_Madden

    TD_Madden Gold Supporting Member

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    I use a Weber "Browner" to drop my 125v wall-voltage to 115.5 for my '66 AC50. I did it mainly to keep the tube heaters at 6.3v
     
  6. dynosoar1

    dynosoar1 Member

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    Why is it dangerous as long as you keep it set at the desired 115V???
     
  7. Steve Dallas

    Steve Dallas Supporting Member

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    A Variac is perfectly safe as long as it is properly grounded and large enough to handle the load. My wall voltage is a whopping 128V. I use my Variac all the time to keep voltages under control.
     
  8. dynosoar1

    dynosoar1 Member

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    So running my vintage gear on the variac while playing is ok as long as I keep it set at 115V??
     
  9. Structo

    Structo Member

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    Are most variac's regulated?
     
  10. TubeAmpNut

    TubeAmpNut Member

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    Only if your hand can automatically dial the variac to compensate for a fluctuating source voltage!

    BK
     
  11. rog951

    rog951 Member

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    FYI, Weber sells what appears to be that same Variac for a little less $$$. Not sure about the shipping charge differences between the two places though. Here's a link:

    https://amptechtools.powweb.com/variac.htm

    I've been waiting for the Tenma 72-110 variac to go on sale at MCM Electronics but they sure are taking their sweet time. :bkw Regular price is around $140 but it seems like they put it on sale for ~$80 pretty regularly.
     
  12. Tripower455

    Tripower455 Member

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    I use a Staco 7 amp Variac to run my vintage amps at exactly 115V. They sound better and it's easier on the tubes running the heaters at 6.3 ish instead of the 7.5 I get with wall voltage!

    I've never had an issue and my amps/ears thank me!
     
  13. Steve Dallas

    Steve Dallas Supporting Member

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    Absolutely.
     
  14. AdmiralB

    AdmiralB Silver Supporting Member

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    If you're really concerned about regulation, get a Tripp-Lite or Furman regulator, and run the variac between it and your amp.
     
  15. Steve Dallas

    Steve Dallas Supporting Member

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    A good power conditioner with a true regulator costs around $500. A Variac set to 115-120V is a decent cheap alternative.
     
  16. AdmiralB

    AdmiralB Silver Supporting Member

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    Not if you watch eBay, in the computer sections. I bought a NIB Tripp-Lite 2400W rack regulator for $175 a few years back. Stuff that says "Musical Instrument" on it seems to cost a lot more than plain ole data center stuff.
     
  17. Structo

    Structo Member

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    OK, so that answers my question.
    Say if you set your variac to 110v on an older amp and your house current fluctuates by a few volts either way then it really isn't doing you any good to be dialing down the voltage.
    Too bad they don't sell power strips that have regulated 110v output.
    I know about conditioners such as Furman but they are spendy.
    So I just gave away an $64,000 idea!

    The Vintage Voltage Power Strip!
     
  18. Steve Dallas

    Steve Dallas Supporting Member

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    If you say so. I haven't seen anything audio grade for that price. But my Variac was $40 new from Harbor Freight.
     
  19. donnyjaguar

    donnyjaguar Member

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    Call the power company and complain the voltage is too high. They can drop it down. I don't know about where you live, but where I do the power company (Hydro) is responsible for damage caused by faults. Overvoltage is a fault of theirs.
     
  20. Bonenut

    Bonenut Member

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    I was able to get the Tenma 72-110 at MCM on sale for $69 a couple of years ago. The regular price went up 10 or 15 bucks since then.
     

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