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The Evil Twin ! What's the Myth ?

3/19/2006 8:31 AM
The Evil Twin ! What's the Myth ?
I have a lot of people come in and bring me these amps and everyone calls them the Evil Twin. It's the 94 Twin with the PCB board on the front and back. All the ones I've worked on have had the latest revisions or the two J111 fets inserted with the small 1/8 watt resistors added. Why are they called Evil Twins ? They are a pain in the ass and have freaky problems. IMO it has two much crap on it that makes for a higher failure rate. I have one that the reverb won't work and it's because the op-amp isn't switching from +16 to -16 when the switch is flipped but the switch is working properly and all the diodes and op-amps check good. I also noticed that the 820 ohm resistor that goes to the 27 vac gets extremely hot and the 7 watt 270 ohmers do also which causes the diodes to turn the board dark and the filter caps (1000uf 35 volters) to puff out. I see this alot of amps so I guess it's kinda common with these low voltage zener supplies. The other amp crackles sometimes and then it goes away and sounds awesome. All the preamp tubes were changed and it's something to do with the reverb as that's when it crackles but then at the spur of the moment clears up and sounds good. Just wondering why it's called the Evil Twin ?  
3/19/2006 9:19 AM

I think it's just a nickname. Compared to the '65 BF Twin (RI or original) it has a lot more gain. Not quite a firebreathing beast but more than a sedate country clean twanging machine.
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3/19/2006 2:22 PM
Tom Phillips

Re: Why are they called Evil Twins ? They are a pain in the ass and have freaky problems. IMO it has two much crap on it that makes for a higher failure rate.  
I think you answered your own question. (That would be my answer too)  
I will add thatthe ones I have worked on did not have the wires to the PCB passed through the strain relief holes so they break off after the board is folded back for service.  
3/20/2006 5:54 AM

That is a big problem Tom and I actually wire them to the top so I can see or to make sure that they don't break off. That way I can see it if they do.  
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