running a 230v amp at 240v. Is it ok?

Cacofonix

Interested to know.

ICBM

Yes.

But if it has separate settings for 230 and 240V, use the 240.

ecc83

UK mains is allowed to wander by 10% from the nominal 230volts.

This means that equipment SHOULD be able to run continuously at 253volts input but not all manufacturers are that fussy about this I understand?

Dave.

ICBM

ecc83 said:

UK mains is allowed to wander by 10% from the nominal 230volts.

This means that equipment SHOULD be able to run continuously at 253volts input but not all manufacturers are that fussy about this I understand?

I think they must be to be passed for sale, but 'continuous' might be open to interpretation… how long is the test period? It's quite possible that something could pass even a fairly extended test (say 48hrs) but suffer premature failure somewhere further down the line, if it was very close to borderline.

The Fender amps that come wired for 230V from the factory - even though they also have a 240V tap - are a case in point, they do work reliably enough on 240V, but there is a higher long-term failure rate of the Deville model in particular because the voltages get a bit high when set like that.

I'm pretty sure that any amp that has only a 230V tap is definitely safe to use on 240V if it is sold as new in this country. The questionable ones are those like the Fenders with both taps (indicating the manufacturer thinks the voltage is quite critical) and European-market amps which are really intended for 220V but are marked for 230 to comply with European 'harmonisation'. I remember Thomann selling some like that from Germany to here which had problems.

Since the 'harmonisation' is on paper only, the voltages have not changed - just the way they're defined! A classic Euro fudge...

Cacofonix

Thank you for answering.  This forum is well-subscribed with talented and helpful people.  Awesome.

jpfamps

ecc83 said:

UK mains is allowed to wander by 10% from the nominal 230volts.

This means that equipment SHOULD be able to run continuously at 253volts input but not all manufacturers are that fussy about this I understand?

Dave.

All devices marked for 230 VAC operation should tested at 253 VAC.

However the regs set limits for surface temperature etc, ie the device should not become hazardous when run at higher voltages.

ANY device will be less reliable when run at higher voltages than designed for, so, as ICBM says, if you have the option to run at 240 V (as in Fender amps) use it.

I rewire all Fender amps that come into the workshop with this option to 240 VAC.

It's interesting to see how many Fender amps that have been through other repairers hands aren't rewired to UK voltage....

Phil_aka_Pip

My Harley-Benton GA5 ate EL84s for breakfast when the mains i/p was on the 230V tap. Moving it to the 240V tap solved the problem.

Cirrus

My AC30hw that says 230v on the back blew fuses/ tubes at 240v, because it was biasing tubes on the hot side of what is already a hot design - Had to mod it a little to bring it down into a sensible range and now run it with a little voltage reducing transformer which knocks 12v off the wall voltage. You can hear a slight sound difference, but the main effect was that it went from blowing fuses every month or so and eating valves for breakfast to being much more dependable.

I suspect that it was just a combination of component tolerances that led it to being ultra hard on the valves though - another amp and I might not have ever given it a thought.

jpfamps

Cirrus said:

My AC30hw that says 230v on the back blew fuses/ tubes at 240v, because it was biasing tubes on the hot side of what is already a hot design - Had to mod it a little to bring it down into a sensible range and now run it with a little voltage reducing transformer which knocks 12v off the wall voltage. You can hear a slight sound difference, but the main effect was that it went from blowing fuses every month or so and eating valves for breakfast to being much more dependable.

I suspect that it was just a combination of component tolerances that led it to being ultra hard on the valves though - another amp and I might not have ever given it a thought.

The original AC30s run their power valves over spec, around 14W static dissipation for a valve rated around 12W.

Most manufacturers seem to regard this as minimum, and of course any running of the amp over spec will stress the valves further.

SickSquid

Bought a Mesa head from a big retailer this year after a demo in store. Get it back and see it is a 230V model and was not impressed as the mains feed here is often 250+ on the meter. There is a 240V option on the shipping box, which indicates they are available. I called them about another issue with the amp (cosmetic) and asked about the voltage. Their head sales guy told me that it is Mesa policy to export 230V models to the UK as well as Europe. So I returned it for a new one from the distributor due the cosmetic flaw (floor model, but paid full price). The new one comes, and you guessed it, it is a 240V model. So, I was fed a line. For a 2k+ amp, and being a regular customer, I was less than impressed and haven't been back since. I didn't put it down to that until I read this thread and think it might well be the reason I've gone off that store. Interesting stuff about the Fender amps. I'll file that away.