US to UK Transformer problems

[boola]

Hi,

I've had my MarkIV for about 4months. After fitting new power tubes it souded perfect but just recently it's sounded like the tubes were wearing, I've noticed a drop in sound quality.

I took it to a tech who said that one of the resistors on the power tube sockets had changed value and he's replaced that but everything else in the amp checks out OK. He said the resistor value hadn't changed enough to really be making a difference to tube life yet though...

I have a US MarkIV here in the UK and am using a transformer for it. The tech said that doing this is what is causing the degredation in sound quality.

He said that the Mark IV expects a low impedance power source (ie the mains) but a transformer has high impedance and is causing the MarkIV's power section to behave strangely, especially if the voltage is around 110V - it's normally between 115V and 110V.

He said the only way to fix the problem - so not to go through a set of power tubes every few months is to fit a proper UK transformer to the MarkIV which is going to cost $$$s!

Does anyone know enough about this to confirm what he's saying? It would be good to have a second opinion. This guy is an authorised Mesa tech.

 

[Restless Rocks]

Hmmm! I'm seeing a lot of the available tubes these days start to loose there mojo after 3 or 4 months especially if you play and transport the amp around a lot. I'm guessing that the transformer impedance issue he's referring to is the 60hertz U.S standard vs. the 50hertz Euro. Can't see why that would be an issue after the AC is rectified and filtered in the amp. Haven't heard of anyone having this problem before and a tranny swap would be a lot more expensive than trying another set of tubes including all the preamp tubes this time. I've played in lot's of places where variance in voltage effects the tone. Just my personnal experience but when the line voltage drops below 110 volts there is a noticable sag in sustain and responce. When my amps see between 115 and 120 volts my ears are happier.

 

[Harry the Horder]

You could always try using a variac to get your voltage.
Regarding Tone I to have had problems with differing voltages around UK so know use a Powerfactor pro to stabalize the voltage better.

 

[voodoo_child]

I've never had any problems using US-spec amps in Europe via step-down transformers. Including the MKIV.

Make sure you're using a high-quality (not a cheapo), grounded transformer thats powerful enough to handle the MKIV (500Watts or higher). They're the only precautions i ever suggest to people running a US amp with a step-down.

 

[boola]

Hmm food for thought. I do have a fairly decent (or so I thought) transformer:

http://www.tlc-direct.co.uk/Products/SC5476.html

Should I send an email to Mesa Boogie and ask if it can be having an effect on tube life? I've never heard of this before so I just don't know whether to believe what the tech is saying and it's not like he's pushing me to fix a new transformer.

 

[trem]

Rather OT, but this 110 vs 220 is really stupid and inefficient. Same goes for metric vs british/american customary unit. They cause nothing but extra unnecessary headache.

 

[Octavarius]

Rather OT, but this 110 vs 220 is really stupid and inefficient. Same goes for metric vs british/american customary unit. They cause nothing but extra unnecessary headache.

I couldn't agree more! Why can't we all just use one type of voltage and one type of plugs? I don't really mind the measuring unit differences, but the power thing is really unnecessary in my opinion. Everyone would be so much happier..

 

[Roadtripper]

So the session player rehearses at home in UK with his Mesa Boogie MKIII with the X101 Power tranny ( Export model ) 230 VOLTS 50 Hz nominal.
He then gets the nod to go record at some studio in USA ,flies over ,plugs into the mains outlet 117 volts give or take a volt 60 Hz and alters the amps rear switch to suit
Isn't that why Mesa offered such an extra a few years back now

:?
Uk voltage can fluctuate by 20 volts ac depending on grid demand etc

 

[boola]

Rather OT, but this 110 vs 220 is really stupid and inefficient. Same goes for metric vs british/american customary unit. They cause nothing but extra unnecessary headache.

I couldn't agree more! Why can't we all just use one type of voltage and one type of plugs? I don't really mind the measuring unit differences, but the power thing is really unnecessary in my opinion. Everyone would be so much happier..

The reason that you Americans are difficult and have different and often technically inferior systems (mobile phones are another example) from the rest of the world is that you normally invent these things first!

The Americans get the system up and running and the rest of the world tends to get a slightly better but different sytem sometime later.

Anyway getting back OT can anyone else give their experiences of using a mains transformer?

 

[tony777]

my best shot!
Replacement export transformer.

http://www.tubeampdoctor.com/product_info.php?cPath=27_46&products_id=98

 

[Tommy]

There is a risk of core saturation when mains frequency is below the design (50Hz vs. 60Hz), and the cheapo power tranny may run hot.

I'm sure that boogie trannys are designed with BIG margin and they can run at 50Hz with no problems.

I'm using a step down tranny for my Mk2b, it's working well and after long hours of playing boogie power transformer is warm.

 

[boola]

Well I've had the transformer changed to a proper mesa UK version and it has definitely made an improvement to the tone.

The main thing is the extra sustain, I always thought my amp was hard to play and that's how they were, seems it was mostly down to the transformer.

I don't think I'll buy another amp which doesn't have a 230v setting unless that $300 IIC+ I've been dreaming about appears on ebay

 

[trem]

Hey Boola, the new power transformer you had, is that the one sold by TAD? How's the quality?

 

[boola]

No, it's a MesaBoogie transformer

 

[trem]

How did you come across one? Direct from Mesa? How much? Thanks.

 

[boola]

The work was done by S-tech who are an official mesa repair shop so they ordered the parts from Mesa.

I only have the total repair bill I'm afraid including replacing the lead drive pot which had snapped off. The total was - take a deep breath - £484.

That's why I wont be using US amps in the UK again very soon!

 

[trem]

£484.

Are you sure the extra sustain didn't come from suggestion? JK. Enjoy your "new" sweet amp.

 

[boola]

Of course I wanted it to be better afer forking out that much but I do have a good ear and I have been able to hear the lack of sustain compared to mark iv clips I've heard. The proof is that now I need less gain dialed in, infact I don't even pull the gain control anymore, this thing sings now!

There's no noticible difference in tone, just sustain. The tech actually showed me a printout of the clean channel before and after through an osciliscope, before it wasn't a pure sine wave, there were fluctuations, now it's a pure sine wave.