Max AC voltage for old US (110V) gear

Hi, what is the max voltage for 110V gear? I have many step down transformers in my (European) studio. Some of these were made when we had 220V in our outlets, now it is around 235-237 V in my studio and some of the transformers give up to 125V now. Will I damage anything?

The imported equipment is: DBX 160 & 162, Gates SA39, RCA BA25A, Neve 33609, PCM60, Dynamite...

Thanks.

I'm willing to bet that the DBXs, Neve, Lexicon and Dynamite will be fine. I'm not familiar with the other units, though...

Peace,
Al.

Thanks for the reply, Al.

The RCA and Gates are very old tube limiters.

I read somewhere that more than 220V could be bad for the old German tube stuff (V72, V76, U73b etc) so I wondered if the same thing applied to the old US tube equipment.

A 10% variation from nominal is usually fine. More than that may cause problems with certain equipment; others won't care. It's not possible to generalize.

Having a Variac around is very handy for this reason!

Thanks Dave,

Have you heard the "exactly 220V for certain German equipment" rumour?

I have owned a pair of V77 amps for many, many years. They work fine and sound beautiful with ca 235V.

The story is that the voltage coming into a building is supposed to be 120v, but equipment is supposed to be able to run reliably as low as 110v to compensate for line loss. Hence the constant confusion of 120 vs. 110 or 240 vs. 220.

I started a thread here before asking about stepup/stepdown transformers it seems most up or down are 110(115) to 220(230). I the USA we need 110,115,120,125 to 220 for some gear.

Yes you can hurt some heaters in some tube stuff in the USA using a 1:2 transfomer for some overseas gear. You need to check if it is reg or passive RC if a DC supply. I have measured in the mid 7,s on some heaters. My wall runs about 122 most of the time sometimes higher so I get about 244, 24 volts higher with a 1:2 2:1 transformer

It is about 10% higher so for the heater 1.1 X 6.3 =6.93

US line voltage started at 100V but was soon pushed to 110V and 120V. Most older electronic gear would have been intended for 115 or 117V nominal, but HAD to tolerate wide variation because there are a lot of small-area (and some large-area) utility companies that just won't control their voltage.

In tube gear, measure the heater voltage under load. If it is within 10% of 6.3V (5.7V to 6.9V), it is working as designed.

A bigger concern: US/Can-market gear was NOT expected to be fed 50Hz power. The transformer will run warmer; maybe OK, maybe smoke. But changing the Hz is hard work.

[quote author="Scodiddly"]The story is that the voltage coming into a building is supposed to be 120v, but equipment is supposed to be able to run reliably as low as 110v to compensate for line loss. Hence the constant confusion of 120 vs. 110 or 240 vs. 220.[/quote]


actually ther is no confusion.


in the world there are countries whose target voltage is 100, 110, 120, 240, 220, or 230. in the UK we were originally targeting 240. but now its 230.... to conform with the rest of the EU. Japan is 100. North america is 120, but gets somewhere between 110 and 120. some say 117.5 in some parts, and now and then i have heard 115....

overall north american electronics should work from 105 through 127 (as a general rule... as that is what the US grid can vary between.. even in one day.. i know becuase i have seen it on both sides of the country.

check out

this page tells every country and its voltage, frequency and plug type

Thanks for the informative replies guys! This forum rocks!

In most transistor gear where the line voltage is stepped down to 15/24/etc. rails, differences in line voltage are reduced- but of course in tube gear where line voltage is frequently stepped up, differences are magnified- I run all my older tube gear variaced down to 110.

In the USA the line volts are 108-132VAC
I have never seen it above 128VAC
But I live near the utility substation and mine is usually
always 124VAC unless it is very hot summertime with the AC units on and the power somtimes sags towards 109VAC.

Just like PRR said if it is tube gear measure the filament directly
at the tube socket with the gear operating and tubes in the sockets.