Robben Ford Discussion

[frank0936]

Question - Is it feasible to convert a Marshall G30RCD from 220 volts to 110? (I'm betting Aeolian knows the answer to this). It is not a tube amp and has no external voltage switch. This was a question from another forum and, while I think it's probably possible, I would think it would be cheaper to get another amp, since this is a practice amp. Thanks,
Frank

[Aeolian]

Actually, I have no idea If there is no voltage switch on the back, odds are good that the transformer doesn't have the multiple input voltage taps either. Such transformers are more expensive. If you could find a busted 110 US version and swap the transformers, it wouldn't be that bad, but I don't know what else is upstream of the PT in those amps.

I would recommend going to the GearPage and posting this question, or PM'ing John Phillps there. He is an amp tech in the UK and knows a great deal about various Marshalls. I've never owned one in my life.
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There are no such things as wrong notes, there's only the look on your face.
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[frank0936]

Steve, I am amazed! I'm so used to you having the answer to my electronic questions. I think it would be cheaper to get a new US version that to fix this one. Thanks for the help.
Frank

[diatonicdude]

Hi Frank,

in short the answer is almost always yes!

Not knowing this amp personally, and therefore, not knowing exactly what type of circuit is used I would opt for the following based on my electrical engineering knowledge.

Use a step up (110V to 220V) safety isolating transformer independent from the amp (a 150VA transformer should suffice but it is worth verifying).

This may not be as neat as modifying the internal power transformer, etc, but it will mean that the original amp stays unaltered. A neat job could be made of the step up transformer, and enclosure and power outlet (for a standard mains socket outlet). Remember to protect (fuse) the primary of the transformer for short circuit and overload protection, and the secondary for overload protection. Seek further advice if necessary from a local amp tech or electrical engineer.

This should be a relatively inexspenive project.

I hope this puts you in the right direction. Good luck!
All the best,

DD
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Music is the universal language; speak it with emotion, listen with a passion.

[frank0936]

Thanks DD, that does help.
Frank

[Aeolian]

You could try mounting the step up transformer inside the cab somewhere for a neater grab and go practice rig. Out here, Fry's Electronics sells tons of step up transformers for folks who bring appliances from overseas. They do have a website that they sell some stuff though.

DD, since you're an EE (there's a mouthfull) do you think that having two transformers in series like that will raise the source impedance to the power supply and make the amp noticeably saggier? At least all that series inductance should low pass things a bit and make it less susseptible to noise.
_________________
There are no such things as wrong notes, there's only the look on your face.
My Stuff: www.stevekirbymusic.com

[diatonicdude]

Aeolian,

you are quite right with respect to the change in the inductance and impedance characteristics. However, if an isolation transformers is used, the associated galvonic isolation should not give rise to the "sagginess" you refer to, in paricular as we are speaking about discrete components (solid state rectification). The phenomenon you are refering is more likely to be noticeable in the output transformer stage of an all valve amp.

Good luck Frank, and happy playing and listening to all.

P.S I like your music clips on your web sight Aeolian. Keep up the great music, and contribution to the board.

Cheers,

DD
_________________
Music is the universal language; speak it with emotion, listen with a passion.