Can anyone hear the difference between symmetrical and asymmetrical clipping?

[skiraly017]

I've just spent the last two hours messing around with diode and LED combinations in my TS clone. Personally, I cannot hear a difference between sym and asym clipping. Am I missing something? Is it only noticeable at loud volumes? The only difference I heard was when I switched to a diode that was oriented the same way both on the switch and the board. There was a large volume jump with less gain overall. Any opinions?

[petemoore]

  Definitly more perceptible at louder volume IME.
 

[Jaicen_solo]

You might hear it whilst your playing as a subtle difference in harmonics, but I personally don't buy into it, especially if you're already pushing a cooking valve amp. All the subtlety will be lost then anyyway. Where you might hear it is when you hit a chord and let it ring. As the notes decay, there's a definite difference, but i'd be hard pushed to define it. Put it this way, at full gain, a Fuzz Face is heavily asymmetric, it becomes more symmetric as the gain decreases. This is one instance where you definitely do hear the difference. In a TS, where it's more subtle, i'm not convinced. I think it actually increases the available gain before clipping, allowing more push to the front end of a valve amp. Maybe that's where the mojo comes from, who can say

[Tim Escobedo]

Depends how asymmetrical the distortion is and how much overall gain. A sine wave asymmetrically clipped, could be amplified to essentially a square wave.

[TheBigMan]

Yeah, 1 vs 2 1N914s isn't hugely audible but is noticeable to some people.  Different diodes types is more noticeable IMO, e.g. 1N914 and 1N4001 or adding LEDs or Ges.

[amz-fx]

I find it to be noticeable but subtle...  definitely not as much difference as LEDs vs. silicon.

regards, Jack

[Mark Hammer]

The thing about the symmetrical/asymmetrical difference is that asymmetrical clipping is *meant* to be relative, but diodes are absolute.

Huh?

The goal of attempts to produce asymmetrical clipping is to make some harmonics always more noticeable than some others, but a certain degree.  Unfortunately, we tend to do it by means of diodes.  The diodes themselves have absolute voltage drops, which translate into fixed clipping thresholds.  If one was using a synth-generated, or other fixed amplitude, signal source then the intended impact of a 2+1 diode complement would occur if the signal level it got was well-suited.  But that rarely happens in the world of guitars.  If the diode arrangement was two 1N914s in one direction and 4 in the other, then the clipping threshold would be twice as high for one half-wave as for the other, but if the amplified signal hitting the diodes rarely had any peaks above 300mv p-p, there would be no clipping or harmonic emphasis of any kind - asymmetrical intentions, but symmetrical outcome.

I installed a pot in series with one of the clipping diodes in a Tube Screamer clone (it replaced one of the diodes in the El-Griton) so that the effect of one of the diodes could be lessened.  The impact of increasing the series resistance with one of the diodes is evident and audible, AND describable, but not always there.  At max gain, you hear it mostly as generally louder volume, since there is clipping on both half cycles.  At lesser gains, what you hear is not so much a tonal difference as a dynamic difference.  If you dig into a note, it jumps out more.  If you don't, it pretty much sounds the same.  Consequently, it would seem that the dynamic differences introduced by symmetrical-vs-asymmetrical clipping strategies completely overshadow any tonal differences.  At least that has been my experience.

[spudulike]

No.

But I always tell people I can.

[amz-fx]

Someone posted at Musictoyz that there will soon be a new Rat pedal that has asymmetrical clipping... "Rat Solo" was the name, as I recall.

-Jack

[sovtek50]

I built me a "Green Machine", a TS clone with switchable TS-9 / TS-808 parts, which you don't hear,  and switchable symm. / asymm. clipping, which you hear quite well. I didn't notice the difference when I changed the diodes by hand, while building it, though.

[Steben]

I have to agree with Mark here. Assymetrical clipping gives you more dynamics, since in the half-clipping stage you have distortion AND headroom at the same instant. Assymetry on your Tube screamer gives it even more tube feeling, but indeed not much more tone certainly at full drive. Let us not forget that EVERY od or dist sound a bit the same at the extreme ends...
Real "Sweet" tone comes from soft-clipping, not assymetry. Think of a plexi or bassman: pure symetric yet soft-clipping.

But assymetry is not "rubish". A FF is actually IMHO very hard distortion, but gets mellowed by its dynamic range. It is this that makes a FF so good. Without assymetry, a FF would be less musical and "spongy", much more standard solid state device. It also gives a bit more character to possible feedback when letting the chord ring, when the signal is coming back to "half-gain zone".

Or think about the Samba Pa Ti sound: veeeery rough clipping if you ask me but oh so dynamic (in fact it works as smiple as an harmonic enhancer, which involves in most cases an assymetric clipper). At low attack you simply get only the clean sound. At full attack it is as fuzzy as my chain saw.

Only if you start exagerating (for example: LED vs. Ge diode) the thing, it is more audible and tends to be an octave sound.

[dosmun]

Someone posted at Musictoyz that there will soon be a new Rat pedal that has asymmetrical clipping... "Rat Solo" was the name, as I recall.

That was me.  I got to try the Prototype.  I didn't compare it next to a Standard Rat so I can't tell you the difference.  It is going to have a New Tone Stack which I think will make most of the difference.  It will have both bass and Treble controls that are interactive so you can get a scooped tone as well.

Here is a pic of the Prototype

[Swain]

    Hey Dosmun, I found this site while on Musictoyz and saw your name. I've never built any pedals, but thought it looked like fun. Anyway, just stopped by to say hi.

[WGTP]

I hear it as a more warm mid-range, more body, thickness, etc.  I agree other changes are more noticable.

I put the AMZ Warp control on my RAT, so it is already asymmetrical.   

[aron]

It depends on how much the clipping levels are different. Put an LED on one side and a 1N4148 on the other and you will be able to hear and feel the difference (I believe).

You can get cool octave/harmonic effects with this along with changes in a transistor bias.

[brett]

Hi.
Yes and no.
Through a "clean" type tube amp with a solid-state front end (Musicman) I find that assymetrical clipping makes all the difference in tone(in TS9 and Bluesbreaker circuits).   
Into my Marshall 18W, there's virtually no difference, presumably because the pre-amp valves re-clip any signal (assymetrically).
cheers

[JimRayden]

Into my Marshall 18W, there's virtually no difference, presumably because the pre-amp valves re-clip any signal (assymetrically).
cheers

The 18W does not, in most cases, have a distorting preamp.

---------
Jimbo

[Steben]

Quote from: brett on Today at 10:13:44 AM

Into my Marshall 18W, there's virtually no difference, presumably because the pre-amp valves re-clip any signal (assymetrically).
cheers

The 18W does not, in most cases, have a distorting preamp.

I think brett was referring to a TS -> 18W situation, where every preamp could be distorting...
It is mostly the case that a driven push-pull power amp gives symmetric clipping to the bone. It is, even more so, also the case that (like in a FF) when you let the note and chrods ring, the power amp comes back from clipping and you hear more the preamp harmonics (mostly going from odd to even order).