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Author Topic: 120V Power  (Read 2125 times)

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Offline cheshirecat

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120V Power
« on: June 21, 2005, 11:47:50 AM »
Since the topic of power has come up a few times, I'll throw this one out there.  In NYC I get about 128 or 129V according to my DMM, that being said my tube amp was designed to run at 117V.  I built a transformer to drop the voltage to about 122V which is much better, but still runs a bit hot.  Anyone else addressing this in anyway?  I assume its the same for SS amps as well where all voltage coming off the power transformer will be a little hot, unless it was designed to run at 125V or up.
« Last Edit: June 21, 2005, 12:10:58 PM by cheshirecat »
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BobW

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Re: 120V Power
« Reply #1 on: June 29, 2005, 10:23:46 PM »
Since the topic of power has come up a few times, I'll throw this one out there.  In NYC I get about 128 or 129V according to my DMM, that being said my tube amp was designed to run at 117V.  I built a transformer to drop the voltage to about 122V which is much better, but still runs a bit hot.  Anyone else addressing this in anyway?  I assume its the same for SS amps as well where all voltage coming off the power transformer will be a little hot, unless it was designed to run at 125V or up.

117 +/- 20 %  is typical.  (ergo 140 to 90 VAC should work)
If the manufacturer's tolerances are a tight 10% then you're looking at 129 to 105 with the low end usually the trouble spot.
No one would expect less than 10 % tolerence from power lines. 

Are you using a Fluke 40 to read the voltage ?  Did you check the Power Factor, cos(Phi) ?

Swing transformers are used in critical designs to stabilize voltages.
Regulators should be covering your DC voltages after power supply.

Tube amps get very hot. You may want to check your PA bias, just to be sure.

Otherwise, don't sweat the small stuff.

 

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