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Yet another 230V/120V thread

Dgl44

Dgl44

Oct 30, 2014
114
96
Slovenia
#1
Hi!
So I just recieved the long awaited GK 200RCB head just to find out that it's not going to be such a piece of cake to get this thing powered up here in Europe. (Facepalm for not researching that earlier)
But now that I've got the pretty little head here, I'd like to get it working. I can't seem to find a suitable power transformer for a reasonable price (they're all too weak). Also I don't believe the amp can be simply rewired, since it has only three wires inside, two blue and one black. It's an older model from 89' and uses a 3A 125V fuse. It's wired for 120V - 60Hz - 3A which comes out to 360VA or 360W that the step down transformer needs to handle.
What are my options?
(and yes, I searched through a whole lot of TalkBass threads before posting)
 
#7
Dgl44 said:
...360W...
What are my options?
Click to expand...
How technically competent are you about performing modifications that will void any warranty ?
Transformer is definitely the easy way, although it won't do anything about converting 50Hz to 60Hz, if that's a factor...

The following is SPECULATIVE ONLY and not a recommendation.
I don't know what kinds of industrial parts are available to you.

But I'd guess that AC doesn't stay AC inside that box very long - I'd guess it heads immediately to a rectifier power supply and everything important actually runs off 12 or 5 VDC. So "all you gotta do" (these are frequently words that strike terror into anyone who's had an over-simplified solution suggested, so be advised...) is find out what DC voltages you actually require and source your own power supply module, bypassing the factory part.

This may well be more expensive and/or troublesome than simply finding a 220VAC amp you like...
 
#10
Bypassing the original power transformer sound like an interesting idea, but probably a bit out of my range of DIY electrical knowledge.
I got a reply from GK tech support (the [email protected] address) saying that I can not modify it in a simple way (as B-string already stated earlier), and that they do not carry 220v transformers anymore which would be in their opinion the only simple way of modifying it internally. Apparently though, not only do they not have 220v transformers in stock, they don't have any specs on them anymore either. That cracked me up when I read it, realising how vintage this thing is, even if 89' sounds quite recent. :D
But since then I have managed to find a step down transformer on german ebay for an affordable price that I'll most likely be buying.
Considering that the amp requires 360W, would a 500W transformer suffice? I read somewhere that with musical gear, at least 2x the power supply is recommended to avoid distorting, which to me makes no sense, since the fuses are usually rated 50% higher than minimum already.
 
#12
From looking at a few graphs, I'm assuming that the peak saturation swings are not defined by the amp or the power output of the transformer but by the quality of the build of the transformer. But in general, I understand your point.
 

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