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240v PT in Fender Concert II Rivera

Jumpinjeff

Member
Messages
4
I have a really nice 2-10 Concert II sitting at my mother's in LA which I will soon bring back with me to France, so I will need to put in a 240v PT. I have only found one direct replacement in Germany but it is very expensive (€160 with the shipping and they don't even include the bell!) and I am not 100% confident of the source. The new Hammond 290YEX (fender 75) looks perfect as far as the voltages are concerned, but it is physically wider and won't go in without some cutting and drilling, and it is pretty pricy as well for some reason.
It looks like the tried and true Hammond 290CEX (vibrolux) would be a perfect fit (and a lot cheaper), but in order to get it to work, I would have to remove the 4 diode bridge rectifier and replace it with the classic blackface style full wave diode setup, and make some adjustments to get the bias off the 50v tap. Looking at the C2 schematic, it looks also like the footswitch is getting juice from the 50v, but unless there is some trap I don't see, that it shouldn't be a problem to get everthing working with the tradtional style PT. The B+ with the stock PT is 475V, I expect to get around 430v-450v with the vibrolux version. I think that if the sounds changes it would be subtle; if anything it may even improve it, softening up this amp's so-called brittleness that seems to bother so many tinkerers when totally stock.

I personally think that out of the box these amps are some of the best sounding Fender ever built although I do know what people are talking about- particularly when compared to a good blackface. I do appreciate the extraordinary headroom (I play a lot of jazz with an archtop) but figure that 20-30 less volts on the B+ will leave me plenty and just may sweeten things up a bit. I do intend to cut out the caps on the preamp tubes as soon as it is on the bench, and may tinker with a component here and there, but intend to keep it pretty close to what Rivera intended except for the adjustments needed to get the vibrolux PT working if I go that route. I've seen lots of stuff all over the net on modding this amp, but I've never once seen anybody change the PT to lower the B+ voltages into blackface territory. Of course that is the most expensive mod possible so this doesn't surprise me. But I have to change mine anyway. Any opinions?

It looks like a lot of guys on this forum know this amp inside and out; I would be interested if anybody has any opinions on which way to go before I get into the job. Also if anybody is aware of any dangers I'm not seeing that may get me into trouble (powering the footswitch; this wierd business of the center-tap going in between the two big caps at the beginning of the power supply, the second wire of the stock 50v coil going to ground, etc) I would certainly be grateful. Also if by any chance someone knows a good source for the PT I need please let me know. Any opinions on whether or not it's worth the extra $20 for the upgrade Hammond PT's with the M6 laminations? Thanks, Jumpinjeff
 
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