symmetrical vs. asymmetric clipping - which gives the best sound?

[Tubaholic]

I would be interested to hear anyone's thoughts on what type of clipping gives the 'best' overdriven sound.

If a valve is biased very warm (close to the point of grid current) then it will clip on the up-going (at grid) peaks while the down-going peak will be undistorted, that is, asymmetric clipping will happen.

A very cold biased valve will also clip asymmetrically, as it is driven into cutoff on the down-going peaks.

When a valve which is biased at its mid-point is overdriven, both peaks will clip (i.e. symmetrical clipping).

In theory, symmetrical clipping should produce mainly odd harmonics, while asymmetric clipping should produce mainly even harmonics.

Any ideas out there on this?

[NippleWrestler]

If you take the cold clipper out of an amp circuit it sounds a lot less interesting.

I have a pedal where you can dial in as much asymmetry as you like until one side is totally cut off. It's cool.

But there is no best. There's only what you like the most.

[MikeC]

I did a cold clipping experiment on the Sixty-One SRT because I read that some later Marshall amps use a CC stage. I couldn't hear an advantage but it doesn't mean someone else wouldn't.

[NippleWrestler]

I did a cold clipping experiment on the Sixty-One SRT because I read that some later Marshall amps use a CC stage. I couldn't hear an advantage but it doesn't mean someone else wouldn't.

Amp topology has a lot to do with it, up and down stream. It's a marked difference on higher gain amps. Interestingly (to me anyway) the Dual Rec on vintage mode uses a 39k cold clipper, but removes it in modern mode... Which might be why I don't use modern mode.

Rob Robinette has a 3 way cold clipper which is a fun and easy addition to amps but if it's already high gain it tends to oscillate.

[FuzzMonkey]

Best is highly subjective.

[calling card]

What kind of clip does a old Fender 5E3 have?

[Optical]

Interestingly (to me anyway) the Dual Rec on vintage mode uses a 39k cold clipper, but removes it in modern mode... Which might be why I don't use modern mode.

The dual rec always has the CC in the circuit on channels 2 and 3, the vintage vs modern modes change the presence frequency and power amp negative fb

[Tubaholic]

The amp I am building will have the overdriven valve's bias resistor switchable with 3 positions: warm, mid and cold. I plan to measure the harmonics patterns and listen to the tones, and compare the settings. Hopefully some insights may follow.....

[Tubaholic]

What kind of clip does a old Fender 5E3 have?

Just looking at the 5E3 schematic, the 12AX7 and the 6V6s are pretty much mid-point biased so I would expect fairly symmetrical clipping.

[RectifiedAmps]

Just to complicate things, you can also have a warm-biased stage feeding a cold-biased one, or vice versa.

Most vintage amps are roughly centre-biased, but although that produces clipping on both ends of the waveform, it’s not usually symmetric until you reach brutal square-wave levels of clipping.

[Tubaholic]

What a coincidence that you mention this - in my last amp I had a warm-biased stage feeding a cold-biased one. As gain is increased it first produces a lot of 2nd harmonic and then flips to predominantly odd harmonics. It sounds great!

[Slowy]

My only contribution is based on the the 3 position clip switch on the Timmy.

Up position is asymetrical and to my ears has a Marshall flavour.
Middle is symmetrical with high headroom and low compression. It makes for a good tone when you want people to wave their phone screens in the air.
Down is symmetrical with low headroom and more compression and sounds like a small Tweed amp.

As an aside, Timmy and Princeton are the best of friends.