240 volts - New internal transformer vs Step Down?

Hi there,

I have just bought a Road King (series 1) from the U.S.A, which is obviously wired for 110 volts. I live in Australia, where we have a 240 volt mains supply. I have a quote on installing a 240 volt internal transformer, and was about to do so, when somebody advised me that this can change the internal values of the amp, which impacts on tone.

This person advised that it is better to run a good quality external step-down transformer so the amp still runs on 110 volts.

The costs of the two are roughly equivalent, but cost isn't my concern - you don't buy a Road King to worry about stuff like that - it's all about tone.

I would appreciate the advice of some gurus please!

If you use the *correct* replacement transformer, none of the internal voltages change - the only thing different is the primary winding. There will be no impact on tone whatever.

However, using an external step-down transformer *can* affect the tone, if it's not large enough for the job - if you're going down this route, make sure you get one big enough. You need one with a capacity in Watts or VA (Volt-Amps, technically slightly different but effectively the same thing for this purpose) at least greater than the maximum power *draw* (not output) of the amp - and preferably a lot higher, I would go with a factor of at least two ideally. I can't remember the power draw of this amp but I expect it will be around 500W, so you really need a 1000VA transformer. Even this may be cheaper than replacing the transformer, but it's a big and heavy piece of kit to carry.

Before you do either of these things, check that the existing transformer can't be rewired - some Mesa export models have multi-tap transformers, although you can't tell from the outside of the amp.

Thanks very much for that,

I believe MESA recommend 1000 watts so you're spot-on there. I will chat to the tech who's going to do the work. He's a good bloke who will not rip me off.

As I said, cost isn't really the issue - I got the amp for $2000 USD, which worked out around $2300 AUD. When you consider that these amps retail for over $7000 AUD here, even the additional $450 -$500 AUD to install a transformer is well worth the money. If this amp does what my research indicates, it may well be the one amp that I own for the rest of my life!

Thanks again for your sage advice.

Kind regards,

John G

IMO, do the job right and have a Mesa branded export transformer installed.

Dom

domct203 said:

IMO, do the job right and have a Mesa branded export transformer installed.

Dom

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Thanks, I'll check it out. Much appreciated.

Hey.. Sorry I dont mean to hijack your thread but I just bought a Road King II from here in Western Australia and it is also a USA 110v... The guy I bought it from threw in the step down transformer he had been using with it... Its a PowerTech Class I Isolating Transformer and has

Primary Rating: 240v with 3a breaker
Seconday Rating: 120v 4.2a 500va Max

Is that transformer big enough... Who knows how long the amp has been used on this transformer from the previous owner... If it is to low power rating for it what damage could have been done by running it underpowered?

No damage, as long as the transformer is rated for at least the maximum power draw of the amp - if it's actually less, you may blow the transformer not the amp - but it might not sound good when the amp is cranked, if it's close to the limit. It will cause extra power supply sag and will make the amp sound mushy and may even cause noticeable (but not good-sounding) compression.

If you're not cranking the amp, it makes less difference - the maximum power draw is at least double the idle draw, so if you're only playing at fairly low volume the amp probably isn't using much more than half the transformer capacity anyway. If you're not driving it really hard and it sounds fine, I wouldn't worry too much about replacing it unless you really want to.

If you are going to replace it, you don't actually need an 'isolating' type by the way - they're larger, heavier and more expensive than the non-isolating or 'auto' type, and as long as they both have a through ground connection there is no particular extra risk (for running an amp) from an auto compared to an isolating one. Isolating ones are safer for things like power tools where there is a risk of cutting the cable and having an exposed wire.

I have a quote from the Mesa distributors of $875 AUD for genuine MESA export transformer, not including installation. I understand that MESA want to support their local distributors by not selling these items too cheaply.

Now the decision is whether to go with a local hand-wired non-MESA transformer for $500 AUD, or pay $1000 for the genuine article.

If I win the lottery then it's no longer an issue!

wow didn't think they'd be worth that much... I'm currently waiting for a quote from a certified mesa repairer here in Perth.. They only use genuine mesa parts so i don't have a choice

I mentioned in another thread that i ran my head without a load for about 5 mins accidentally... Now apparently that does damage to the transformer.. Being that i have to change the transformer to make it 240v i guess that makes any damage done irrelevant?

$875 for a power transformer is insane. Don't pay it.

The reason they need to "support" the local distributor by pricing it like that is because the amps are so grossly overpriced in places like Australia and the UK that there is a real "problem" with people importing amps from the US by the back door. If they stopped the overpricing they wouldn't need to rip you off for the parts either, because everyone would just buy the export amp in the first place. So it would then be the right price for anyone who needs the parts for an older amp too.

Just my opinion.


Running an amp with no load *may* damage the *output* transformer - the other one. But if the amp works normally now, it's unlikely you did any damage. It would most likely only occur if the amp was being played at high power with no load - although some Mesa amps are unstable with no load in some settings, so they will effectively act like they're being played at full volume. Be careful!

94Tremoverb said:

$875 for a power transformer is insane. Don't pay it.

The reason they need to "support" the local distributor by pricing it like that is because the amps are so grossly overpriced in places like Australia and the UK that there is a real "problem" with people importing amps from the US by the back door. If they stopped the overpricing they wouldn't need to rip you off for the parts either, because everyone would just buy the export amp in the first place. So it would then be the right price for anyone who needs the parts for an older amp too.

Just my opinion.

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Well said Sir,

my thoughts exactly. I believe I'll go with Dale Sherlock's transformer - he made a 4 channel amp for my mate with his own transformer and it's excellent.

Thanks for contributing

Oh ok... Yeah well it should be ok.. I haven't had a real good thrash on it cos i been to worried about cranking it on my 500w rated step down because its apparently running underpowered.

I also just got my quote... $840 + $110 labour.... Well i guess i can only try source one cheaper myself.. Will be hard with the rip off aus prices though... I'd prefer to have a genuine mesa transfores... When i get them to do it i'll ask em to run over it and make sure the output transformer and anything else isn't damaged from my stupidity.

Schulzy said:

Oh ok... Yeah well it should be ok.. I haven't had a real good thrash on it cos i been to worried about cranking it on my 500w rated step down because its apparently running underpowered.

I also just got my quote... $840 + $110 labour.... Well i guess i can only try source one cheaper myself.. Will be hard with the rip off aus prices though... I'd prefer to have a genuine mesa transfores... When i get them to do it i'll ask em to run over it and make sure the output transformer and anything else isn't damaged from my stupidity.

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Good luck with that brother Road King

To be perfectly honest, at those prices I would just save all the hassle and just buy a nice big 1000VA stepdown transformer - it's going to be far cheaper than any replacement internal one. Yes, I know it's a big and heavy piece of kit to carry about.

If you do that, the most important thing to remember about running a US-voltage amp in a 220-240V country is to make sure the US-plug power cord can't become detached or lost (on amps with an IEC/'kettle' plug at the amp end) - if it does, it's all to easy for someone to accidentally use a normal straight power cord instead and fry the amp... I've seen that happen a couple of times. If you're lucky the fuse will blow before any other damage occurs, but you aren't always lucky. I would use a P-clip or strong zip tie to secure the US cable to the amp just to make sure.

Schulzy said:

Oh ok... Yeah well it should be ok.. I haven't had a real good thrash on it cos i been to worried about cranking it on my 500w rated step down because its apparently running underpowered.

I also just got my quote... $840 + $110 labour.... Well i guess i can only try source one cheaper myself.. Will be hard with the rip off aus prices though... I'd prefer to have a genuine mesa transfores... When i get them to do it i'll ask em to run over it and make sure the output transformer and anything else isn't damaged from my stupidity.

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Yuck.

I (an American) might be getting a job offer in Canberra next year, and if so, I might take it, but one of my first thoughts when I heard about this possible offer was about how it would affect my gear. It would sure stink if I have to pay this much for the change. Hopefully it's cheaper to do the installation here in the States.

eudaimonia02912 said:

Yuck.

I (an American) might be getting a job offer in Canberra next year, and if so, I might take it, but one of my first thoughts when I heard about this possible offer was about how it would affect my gear. It would sure stink if I have to pay this much for the change. Hopefully it's cheaper to do the installation here in the States.

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I just bought a 1000 VA step-down transformer from Dick Smith Electronics for $275. I see them on e-bay for even cheaper, but I got a 12 month warranty on this one. My thinking is that if I don't like using the step-down, I can always get a tranny fitted later, but if I get a tranny fitted, I can't go back.

Just waiting for my amp to clear customs, and I'll hopefully be jamming with it on Saturday.

I'll report back on how things work out.

Good luck with Canberra - not exactly the excitement capital of Australia, but Australia is a great place to live (except if you wanna buy Mesa gear!)

You could install a number of third party aftermarket transformers, and the amp will work fine. However, something tells me you'll devalue the amp quite substantially if you were to resell the amp. Just a thought...

As for not getting the transformer replaced with a genuine 240V one, well, I bet it still works out cheaper than a brand new one here... :lol:

KH Guitar Freak said:

You could install a number of third party aftermarket transformers, and the amp will work fine. However, something tells me you'll devalue the amp quite substantially if you were to resell the amp. Just a thought...

As for not getting the transformer replaced with a genuine 240V one, well, I bet it still works out cheaper than a brand new one here... :lol:

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Yes, but then being an old geezer I hopefully won't want to sell it again anyway. I'll see how the step-down works out, and when I get $500 together I might for the Sherlock transformer.

Got my amp, tried out the 1000 VA step=down tranny. It works perfectly and this amp kicks serious arse!

Thanks to everyone's assistance - it's much appreciated.

I've been using the step-down transformer for a while now, with no problems at all. Changed the power amp valves and the pre-amp valves (SP12Ax7's), got my new Eventide Modfactor to complement the Timefactor, and I now have everything I need.

Unfortunately, I'll have to sell my Dual Recto Solo Head to pay for the Road King