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previous: AMZ Re: Super Tube Screamer -- 8/19/1999 10:08 AM view thread

Re: Super Tube Screamer - Chip choices

8/19/1999 10:18 PM
Mark HammerRe: Super Tube Screamer - Chip choices
I see that the STS uses two dual op-amps. In the case of the TS808/9/etc, there is but a single dual op-amp. Since one wants the best sounding overdrive, you pick up one of the magic chips (JRC4558D, RC4558, etc.), and do your damndest with your soldering iron. Whether both op-amp stages require a magic chip or not, the other stage is along for the ride.  
In the case of the STS, it is not readily clear that all stages REQUIRE the services of one of these magic chips. Indeed, given the Son of Screamer design at DMZ, I'm not even sure the STS needs all 4 op-amp stages (i.e., the input buffer stage is superfluous with hard-wired bypass switching).  
(Given that an 8-pin package is as small as you're going to get, using a single op-amp for the distortion stage and additional transistors for tone shaping yields no advantage in terms of assembly/size, so I imagine Ibanez simply made frugal use of the space by using a dual op-amp for the original. The STS really only needs 3 op-amps, but once again, why use a single op-amp and transistor buffer if two op-amps fit in the same space as a single, and cost the same as a single?)  
So the question arises, where OTHER than the stage with the clipping diodes, does one receive benefit from a select op-amp? The related question is this: if this design only really needs 3 op-amps, can you stick in some single op-amp alternative to the dual JRC chip for the distortion stage, use any old dual op for the subsequent tone-shaping stages, and expect to get the same sound? If so, what would such an op-amp conceivably be from among those which are readily available commercially?  
Incidentally, am I correct in assuming this is ostensibly a regular TS9 with a variable frequency mid-boost stage before the tone control?

Daniel R. Haney Saw the schematic. I agree that t... -- 8/19/1999 11:14 PM
John Greene Personally, I think the only place ... -- 8/20/1999 9:55 PM