Sound diff's: "hard clip" v "soft clip"

[Chill]

What are the differences in sound between diodes in a "hard clip" arrangement between the output and ground (a la the D+, DS-1, and Rat) and diodes in a "soft clip" arrangement between the output and input (a la the tube screamer and big muff)?  If we could make a circuit that was as equal on other parameters but with the diff diode arrangements, how would the sound differ?

[Ansil]

hard clipping is more of a metal effect..  hard edges.. where soft clipping tends to round over the edges more.

[Mark Hammer]

The hard vs soft distinction is not a firm one, but more one of subjective taste.  For instance, a "hard-clip" device set for modest distortion and followed up with a bit of lowpass filtering to remove the fizz would be described by many as soft clipping.  Certainly anything that comes closer to yielding a square wave would be described by most as hard clipping, but anything less than a square wave would kikely result in differing opinions about its "softness", until you get down to barely audible distortion, at which point people start to talk about "colouration" rather than clipping.

Over the years, one often sees a resistor network used in tandem with a back-to-back diode pair described in construction articles as producing "soft clipping".  For instance, check out the "Pocket Rockit" headphone amp at my site and you'll see a simple 68R/68R resistive divider used to produce "soft-clipping" from the diodes.

Many of the arrangements used in Jack Orman's clever "warp controls" paper can be said to produce softer clipping, although in some instances, that is only soft clipping applied to one half cycle, so I'm not sure if that meets any strict definition of soft clipping.

Some folks describe the way a CA3080 transconductance amp distorts as soft-clipping, and the colouration it provides when doing so is a portion of what people like about the MXR Dynacomp (which uses one).  For instance, Craig Anderton uses one in his voltage-controlled sitortion module in DEVICE (issue 4 I think).

[aron]

This is just too difficult to answer generically... HOWEVER, I will say, try it. There is a definite difference between feedback loop clipping and diodes to ground clipping. It has different feel and it is significant enough for me to like one over the other.

It's a feel issue for me more than anything else as well as sound.

[WGTP]

I recently got a modified Muff Fuzz going that uses diodes in the feedback loop and it has a much smoother, processed/compressed sound than my Rat does which has diodes to ground, plus an AMZ Warp control.  I think in both cases the op amp contributes to the distortion when maxed, but the soft clip feedback loop design re-clips the sound in combination with the clean signal coming and mixes it all together and clips it again, etc. etc.  I think this accounts for the higher degree of SMOOSHINESS.  The hard clip design has the op amp distortion going past the diodes once for clipping and out into your amp.  I think the accounts for less SMOOSHINESS.  IMHO.  

I am currently enjoying smoothiness, experimenting with jfets and mosfet and leds as diodes and different op amps.

[Chill]

Thanks for the input, gang.  My own observation are that the soft clip arrangement is a bit more dynamic and responds better even if there is less clipping, while the hard clip arrangement clips a bunch and then the clipping dies out all at once--it's either 0% or 100% clipping.  This is based on using a fulldrive2, modded BMP, MXR D+, DS-1 stock and modded.

Which one clipping arrangement do you like better Aron?

[aron]

hehehehe! After all that... I like the diodes to ground!  

Take a look at the simple mods page. If you put series resistance in with the diodes to ground, you can adjust the clipping harmonics and if you use different types of clippers, there can be very touch sensitive things going on with diodes to ground.

The original Shaka Braddah uses feedback loop diodes.

I like feedback loop clipping for "Jazzy - smoother work" and in most cases, I like diodes to ground for most else.

Ultimately though, I like mostly no diode clipping and prefer clipping the JFET or MOSFET or IC or other type of transistor even more.

[Brian Marshall]

i like diodes in the loop better.  the lower gain settings seem more usable to me.  Diodes to ground sound good when the gain is maxed, but i dont find the lower gain settings to work well for me.  Of course i am basing this off of owning a distortion + when i was in highschool.  At one point i did build a copy of it on bread board, and it didnt sound bad after i added a tone control to it.