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Vintage threads from the first ten years

Re: The RAT and the EXpandora

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9/19/1999 6:08 PM
John Catto	Re: The RAT and the EXpandora Am I the only person (I think not!!!) who's noticed the massive similarities between the Bixonix Expandora and The RAT JC

10/4/1999 8:07 PM

You are not the only one. Expandora adds halfwave compression and a nice looking alloy case to the Rat look-alike circuit. The two I have also contain the famed JRC-4558 opamp. That's a lot of tone mojo for one pedal. You might guess that owning two indicates that I might like the pedal. After I bought the first one I turned right around and bought another in a panic before the company had a chance to change the design or go out of business. Still managed to change the value of the tone pot on me. Personally, I haven't found anything else that works quite as nice with a traditional tele or strat. R.G. has a schematic up on his site that agrees with mine.

10/4/1999 8:22 PM
Gus	Did you check your expandora against the schematic?

10/5/1999 12:03 AM

Gus as in Gustav? Yes. I took my first one apart because I'm a curious guy. As you know it isn't an easy circuit to reverse engineer, but I rather like a challenge from time to time. And it really sounded terrific, so I wanted to see what made it tick.

As far as I can tell you got it right. I wasn't absolutely certain of the polarity on the 2206. Now that I think on it, logically, I believe the way you captured it is right. I took the second one apart because it didn't sound like the first. My first one had a 90K tone pot and the second one had the 100K. Only component differences between the two. Adjusted the tone knob and they sounded the same. Duh-oh!

I ranted and raved to RG about this pedal design. The most interesting part to my mind is it gets sweeter, by that I mean less distorted and more sustaining, as the gig goes on. RG posited that the key to this is the 2206 (which I am assuming is a small signal high gain transistor, although I could never actually track it down, identify it). He suggested it was warming up over the course of the night and its gain was changing. Any opinions?

10/5/1999 2:43 PM
Gus	nek yes gus as in gustav. I did not get to play the petal it was a fast repair and trace. One thing I did not like was the battery snap construction it was one of the problems that needed to be fixed.

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