I am going to save you some money here, because I know you are all trying to get that Geddy tone.
I own an Ashly SC-40 preamp. This is the pre that Geddy Lee used for many years. It’s not Ashly’s bass-specific preamp (that was the BP-41), but a very good piece of kit that works quite well for many instruments. A lot of people also like the SC-40 for bass, and I am one of those people. It is a nice contrast to my expensive tube preamp that would totally impress you if I told you what it was, but I don’t want you rushing over here tearing at your clothes in a fit of mad lust, so I will not mention it any further.
I also use the SC-40 for my bouzouki, and whatever else might need preampin’ It’s got lots of handy features, a transformer-isolated direct out, and very reassuring-looking knobs.
This is a fairly old piece. It needed a good cleaning, and was kinda barky for bass when I bought it used. Great for snarly rawk tones, but with a definite hump in the high mids and a tendency to sound like it was working too hard.
I spent a whopping $22 and replaced the op-amps inside the thing (swapped the RC4558 chips for OPA2134). The new op-amps are cleaner, with more lows, highs, headroom and a broad, tanned, trustworthy forehead. It was a good move, and the thing sounds much, much better–for bass and everything else.
At some point, I should also replace all the capacitors. But that is like, actual work…
If you read boring bass blather sites on the Internets a lot, you will eventually come across the mystical secret to the Geddy tone–on the amp side, at least. This actually not much of a mystery–it was just a hookup mentioned in the SC-40 manual. Yep, I RTFM. You take a pair of 1N914 diodes, wire them in parallel but backwards to each other, and run them between the tip and sleeve of a 1/4″ plug, which you then put into the effects send jack. According to the manual, this will create “smooth distortion.”
Now, as anyone who subscribes to “Tiresome Pedal Nerd” magazine (or goes to their many sites online) can tell you, the 1N914 is the diode used in the clipping section of the original Tube Screamer. It’s used for clipping/overdrive in a lot of other pedals as well. When it comes to smooth clipping of guitar tones, this should be, as the kids said a while back, “the shizz.”
What you see in this picture is a phono jack with a pair of 1N914s wired in opposed parallel. I plugged one end of a cable into it, and the other end of the cable into the effects send on my great-sounding SC-40. And it appeared that nothing happened.
Then I realised that (of course!) I would only get clipping/overdrive/distortion if I turned that shizz up! So I whacked the gain way up, and the red light started to come on, and I have to tell you, I could not believe the difference in tone!
It sounded like total ass.
So what I am saying here is don’t bother doing this.
The question remains whether the change in the op-amps had any effect on this. See, as anyone who reads “I am Dragging This Out Too Long” (or watches me do that online) knows, the mighty Tube Screamer used JRC4558 op-amps in its original design. So is the smooth distortion effect a product of both components? Did I clean up the op-amps and ruin my chance at smooth distortion? Should I put the old op-amps in and test that?