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Date: Wed, 29 Mar 1995 14:14:48 -0800 (PST)
From: Mike Curtis
Subject: Re: 'Feedback' on Pickle Plug

Mine is a little more complicated than this, but I designed it for a specific application (the effects loop of my Music Man 112RD)

There is a lot to be said for "dry master/wet slave", especially if you drive the master (a smaller amp in my case) into distortion. When I use a slapback echo, it becomes more intense as I drive the master more into distortion. For example, if I set slapback level to 20%, but clip the signal at the 40% level, the slapback is now at a whopping 50%. By using the slapback on the (clean) slave, the level is fixed, and the echo is much more "natural" sounding.

Many other effects sound better post-distortion, such as chorus, reverb, gated delay, etc.

Others sound better pre-distortion, such as octave dividers, envelope followers (volume actuated wah-wah effect, popular with funk bass players; Mutron, EH Dr. Q, etc.), and probably pitch shifters and harmonizers.

Using a "direct box" (which is what the Pickle would in fact be) is better for minimizing feedback than micing (and given the price of an SM57, cable, desk stand, and possibly a transformer, cheaper, too - my box cost under $10 for all new parts), but it bypasses the sound of your speaker(s), something many consider to be of great importance, especially in vintage amps.

-o-

A comment on tubes vs transistors: When you run these "clean", with _no_ peaks in the nonlinear region, a solid state amp will be able to compete favorably with tubes. Many feel that tubes running linearly have an edge in warmth, but I personally have not found this to be significant. When any peaks as seen on an oscilloscope hit the nonlinear region of the amp, tubes _do_ in fact start sounding noticeably better.

However, when you distort them, there is no comparison. Unprocessed transistor distortion sounds terrible. Remember the "fuzz tone" of the 1970's (boy, was it 25 years ago? Time sure flies - I still have a Jordan Boss-Tone and original EH Big Muff!), and how it sounded like 7 inch fingernails on the biggest blackboard ever made? Tube distortion is infinitely easier to listen to. It sounds better and is much less
fatiguing to listen to.

This has been shown scientifically. (Summary: Transistors create more high order harmonics and odd order harmonics e.g. 3rd, 5th, etc., and lack the lower order harmonics necessary to make these palatable. Tubes create more low order harmonics, and even harmonics, e.g. 2nd, 4th, etc., and are much more pleasant to the human ear.)

Simple explanation: Transistors "clip" abruptly, creating a more shrill distortion. Tubes "clip" much more softly and gradually, creating a distortion with a "fuller" and "fatter" sound. Perhaps the easiest way to visualize this is to drop your sons marbles onto the floor (or better yet, get him to do it, and clean 'em up when he's done :-) If it's carpeted, the sound is a dull "thump". If the floor is marble, granite, or other hard flooring material, it makes a very shrill and harsh "crack!"

(And be nice to the poor kid; no jokes about "you lost your marbles :-)

Of course, there are other factors involved, and some solid state amps (in particular, VFETs) sound better than others. But tube amps are definitely the way the smart money bets.

Many of us use solid state equipment, and it will work, even if overdriven. There are steps we can take to make the sound more listenable, such as facing the speakers so the highs don't hit the audience directly (speakers are directional at higher frequencies), cutting the tone controls so that more low frequency sound is fed to the
speakers, etc., so please don't construe this as "You can't use solid state amps", because the obvious fact is, many do in fact use them. If you have a good harmonica tone, you're going to sound great through whatever you use, be that a vintage Bassman and vintage JT-30 or a Pignose and $5 replacement mic. (Of course, you'll sound great-ER- through the Bassman :-)

-- mike