Comparing Auto Clean to Breakup Threshold Playing

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Comparing Auto Clean to Breakup Threshold Playing

Post by rbc »

One of the defining characteristics, and perhaps a contentious feature of the Rockman products is the use of compression. I think it may turn off some guitar players that like to keep their amp or distortion pedals at the edge of breakup and use pick dynamics to push into distortion from the guitar.

I was curious if anyone has really gone deep to compare the auto-clean circuit to use of playing the threshold of break-up from their guitar? Are the two approaches similar? Do they wind up being really different from the player perspective? How do you see the advantages/disadvantages of using the auto-clean circuit?
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Re: Comparing Auto Clean to Breakup Threshold Playing

Post by RockmanCentralBob »

I don't really think of the auto clean that way.... I see it more for its intended purpose, going from distortion to clean and back again. Even then, I find that I have to get the volume on my guitar almost completely off before it cleans up the way I would normally expect clean to be. Even then, I have be very careful how I pick in order to keep it clean. Some strings take a lighter touch than others. The Rev 20 definitely works better in this regard, and I think the XPR actually works very well too.... it seems to clean up nicely, even without the auto clean circuit.

I did some experimenting some time ago with the idea that you are talking about. What I found was that it's more a characteristic of the way output tube distortion works rather than preamp distortion. The basic idea is that you want the preamp stage to be very clean and the output stage very loud, but again, still pretty clean when you have the volume on your guitar turned down about half way.... maybe a little more. From here, what we are looking for is "presence"... ie- the clean signal of your guitar more or less bypassing your preamp stage and going directly to the output stage. This needs to be focused on the higher frequencies (your lower, thinner strings) and they need to be boosted quite a bit compared to your lower strings. Now, when you turn your guitar volume up, or pick/strum hard on those thin strings, they push the output stage into clipping, but not so much on the lower strings unless you really hit them hard too. A lighter touch on the thin strings (not to mention the thicker strings) or lowering the volume on your guitar and they don't clip the output stage and it sounds very clean, but still loud and clear. So it's a very strat and fender amp-ish sound.

If you think about it, this is how the early non-master volume amps worked. When they were designed, they weren't intended to distort. The amp was always running wide open at the output tubes, and you used the preamp gain as your "volume". Since most people wouldn't be playing with the preamp gain turned up very loud, the amp stayed clean since you never hit the output stage that hard. Again, that was by design. Of course, then the rockers figured out that if you did turn the preamp up, you still had a clean signal, since there wasn't really much preamp distortion going on, but if you hit the strings hard, that clean signal would pass through the preamp stage and hit the output stage hard enough to drive them into clipping. So now, you have a really nice clean sound if you pick or strum softly, but hit them hard, and it's crunch time! This is where overdrive pedals came in... they boosted your signal from your guitar before it even hit the preamp stage with the added volume (but still not into preamp distortion.... you want to let the output tubes do that).

Tom took this idea, and finessed it with a wah or the 6 band EQ to tailor how, and what frequencies, get distorted and when. Lower the low frequencies since they just produce mud, move the low point to the mid range around 800 to 500 hz with a big boost, drop out the mids to reduce the overall signal level and then boost the highs again for strong presence. Run that into a Plexi cranked full up to get that output tube distortion (which really wasn't THAT distorted by todays standards) and control the overall volume with the Power Soak. Compress and EQ it some more afterwards, and then layer up tracks to get a combined effect of all those relatively clean, but still crunchy, rhythms.

Tom talked about this in an interview I have somewhere.... describing it as a very complicated thing in how the signal is compressed, eq'd, clipped at certain frequencies, compressed and eq'd again to be clipped at different frequencies, then compressed and eq'd some more. The way I read it is that the compression stages are to simulate how tubes compress the signal, evening out the frequencies so that you can accurately and consistently filter them with the EQ. That allows you to control what get's distorted at each stage.

The late, great EVH basically did the same thing, except instead of using a Power Soak to lower the overall volume, he used a variac to lower the voltage (ie- the "brown" sound) and thus the volume, while still allowing the output tubes to "crunch" while still having a lot of clean presence.