Dynamics in clipping devices

[Plectrum]

Hi,

A question:
What are the most dynamic clipping circuits you've futzed around with?
By dynamic, I mean that when one backs-off the guitar volume pot, or picks gently, or a note sustains out, there is a smooth and wide transition between the cleaner and clipped ranges.

The rangemaster (even with larger input caps) and fuzzface seem to be very dynamic, their "clean range" seems to retain a very present (maybe it's the "asymetrical" aspect as well) quality - whilst some units clean up in this context, but sound a little woolier.
Is there a dynamics advantage from multiple gain stage devices (3 and up)?

It's led me to believe that carefully set-up transistor saturation stages are inherently more dynamic than say - most opamp clippers, and their threshold seems more abrupt.  (even taking in to account different diode types) (!?).

Grant.

[jrc4558]

I would say that BSIAB II is the most dynamic one.

[Plectrum]

I would say that BSIAB II is the most dynamic one.

Ah! Thats the one I've been looking at recently... with a view to build.

[Steben]

Hi,

It's led me to believe that carefully set-up transistor saturation stages are inherently more dynamic than say - most opamp clippers, and their threshold seems more abrupt.  (even taking in to account different diode types) (!?).

Grant.

Well, it's something that has my full attention. But I believe there are even more dynamic solutions when using (germanium) transistors. I'm going to test some emitter- follower buffers driven into stauration this week.

[bwanasonic]

The Nobels ODR1 is very *dynamic* and responsive. I've studied the schematic (available at the Nobels site), trying to figure out what gives it these traits, but my grasp on it is still rudimentary. I use an AMZ Mosfet boost after my OD, and this seems to open up the response and helps with using the guitar voulme knob for control. I love germanium Rangemasters and Fuzz Faces, but they are just not consistent enough, and gave me a lot of headaches in live settings with *thermal* issues.

Kerry M

[DDD]

Generally: devices that vary duty cycle accordingly to the level of the signal seem to be most "dynamic". Duty cycle variations provides very "dynamic" impression.
The above mentioned Ge vintage circuits as well as the "mu-stages" like BSIAB etc. are good examples.

[Mark Hammer]

I'll put a plug in for multiple gain/clipping stages, with the proviso that the amount of gain in each stage and the clipping threshold, need to be carefully selected.

Keep in mind that gain is multiplicative, so a x10 gain stage followed by a x10 gain stage, followed by another of the same gives you a cumulative gain of x1000.  If one is relying on diodes for clipping, keep in mind they have fixed threshold but that the threshold and softness of clipping can be altered by using different numbers or types of diodes in series or by sticking resistors in series with the diodes.

Reducing the level of the input signal (i.e., turning down the guitar volume) can produce a signal which, when the gain of the pedal is applied, may result in some clipping in stage X, but much less in stage Y and Z.  Increasing the signal level via picking or increasing the volume control can now result in clipping being introduced in more than one stage.

By carefully juggling the amount of gain in the stages, and the degree of clipping likely to be produced in stage X, Y, or Z, you should, in theory, be able to get a sound which produces a graded degree of clipping, depending on picking and volume setting.

[Plectrum]

I'll put a plug in for multiple gain/clipping stages, with the proviso that the amount of gain in each stage and the clipping threshold, need to be carefully selected.

Keep in mind that gain is multiplicative, so a x10 gain stage followed by a x10 gain stage, followed by another of the same gives you a cumulative gain of x1000.  If one is relying on diodes for clipping, keep in mind they have fixed threshold but that the threshold and softness of clipping can be altered by using different numbers or types of diodes in series or by sticking resistors in series with the diodes.

Reducing the level of the input signal (i.e., turning down the guitar volume) can produce a signal which, when the gain of the pedal is applied, may result in some clipping in stage X, but much less in stage Y and Z.  Increasing the signal level via picking or increasing the volume control can now result in clipping being introduced in more than one stage.

By carefully juggling the amount of gain in the stages, and the degree of clipping likely to be produced in stage X, Y, or Z, you should, in theory, be able to get a sound which produces a graded degree of clipping, depending on picking and volume setting.

Right, this was what got my interest going in the BSIAB, could be very intersting - to cherry pick the transistors and tailor the thresholds...
Could you use "gain clipping" only, 'till the last stage - attenuating the signal back down to an appropriate level prior to some clipping diodes?

I suppose one could theoreticaly use a 4049UBE in this application too... Dynamic "Tube sound fuzz" - in a neat package too... mmmm.

Grant.

[stm]

For a long time now I've had this "dynamic" idea in my mind:

Imagine you put a 1st order phase shifter (half of a Phase 45) and vary the FET control voltage with an envelope detector of the input. Then the output of this circuit is fed to you favourite OD or Dirt box.  The result will be that the fundamental and harmonic frequencies in the signal will be moved around in a... well, dynamic way which keeps the same amplitude as the original, but indeed changes the zero crossings, thus adding dynamics to the distortion.

Here we don't mix the phased signal with the original, so we're not producing a notch in the response, thus the signal is not coloured, just "moved" around.

[Processaurus]

Generally: devices that vary duty cycle accordingly to the level of the signal seem to be most "dynamic". Duty cycle variations provides very "dynamic" impression.
The above mentioned Ge vintage circuits as well as the "mu-stages" like BSIAB etc. are good examples.

Great point, varying duty cycle is a great way to have some kind of touch sensitive variation in a signal when its been squared off by clipping.The "Great Cheddar" at Geofex (a Big Cheese clone) does that.  Noticed that when I had it hooked up to the scope.  Its very nice sounding fuzz, perhaps because of this? 
Somewhere here on the forum theres some interesting discussion, from a couple years ago when RG was putting the Great Cheddar together, about how it works, its different than a regular silicon FF...

A version of Tim Escobedo's PWM hooked up with envelope control changing the pulse width would probably be great for the Blue Box/Atari  crowd.

[A.S.P.]

I reckon stm is more after "tubelike dutycycling" than "8bit derivates"...