Phase inversion? In TAFM and anything else

[Thylacine Dream]

I tried a search for this, but it didn't really work what with the ubiquity of the terms and all. I know what inverting the phase looks like, but what does it do tonally? Why is it a feature on the clean boost in the TAFM, and if you do it to a vintage pedal that requires it for clean blending how much will the tone change and why?

[Thylacine Dream]

PS thanks, people smarter than me

[coldbrightsunlight]

Tonally on the TAFM it's kinda weird and variable, and because the switch also turns on the input gain boosting the clean signal, it can be hard to tell what's doing what. Basically on most of the settings I normally use it turns the sound from heavy and the clean adding a nice attack to the fuzz sound with the switch in the 'normal' position, to superfuzz-y tones with the phase inverted. Lots of treble, very sensitive to pick attack and guitar volume, clean sound gets fuzzier and LOUD (if the input gain isn't on zero). There's sometimes a volume drop (from phase cancellation (?), which I think is the reason Brian added the switch in the first place?) which varies depending on what notes you play/whether you play chords or single notes. It's kinda unpredictable, very different to the 'standard' TAFM sound and really cool. I normally forget it even exists, then sometimesI'll flip the switch and love it.

I'm sure Brian and some other dudes have much better explanations. I think the phase cancellation stuff is the main reason it's there though, that does lead to volume issues. Probably something you would have to think about if you added a clean blend to something else.

Also, if you're thinking of using other stuff with clean blend, the upcoming ss/bs best friend looks awesome for that. It's the ss/bs subforum so I figure pimping is all good/totally expected.

[Thylacine Dream]

Ooh I am, shall look into that, thanks for a good start on an answer, dude, but anyone else feel free to stack on that

[Thylacine Dream]

The cancellation makes more and more sense to keep things notmud the more I think about it, nice hypothesis

[smallsnd/bigsnd]

excellent reply so far!

basically, phase cancellation can be a good thing or a bad thing... it just depends on the circumstances. in the case of the TAFM - i made the input gain stage inverting for 2 reasons... 1) i didn't have to change anything from the stage before it - i simply duplicated it. 2) it gives a radically different sound. when the volumes are set similarly, you'll hear the most amount of phase cancellation and the result is (as monkeydancer said) a very nasal, hollow sound that is very sensitive to dynamics, etc. it's certainly not a sound i would personally use all of the time, but it makes for some interesting textures.

re: other pedals (vintage and modern alike) and signal blending/phase inversion - you'll get a range of sounds similar to what i outlined. for fuzzes, etc. lots of unique decaying qualities, lack of a fundamental frequency, hollowness, thin sounds, etc.

keeping things from being really muddy when blending probably has more to do with eq than phase cancellation. eq'ing the clean signal to tighten up the bass will most likely go a lot further than using phase cancellation as a means to keep things clean as there are obviously some not-so-desirable (most of the time!) side effects.

http://en.wikipedia.org/wiki/Interferen ... agation%29
the section "mechanism" and in particular the bit about constructive vs destructive interference is particularly useful to read. the thing to remember about combining 2 similar signals, though with varying harmonics (due to the fuzz) is that they are constantly changing - it's obviously not so simple as the 2 pictures would have you think...

more good stuff to read here: http://www.recordingeq.com/EQ/req1001/mmi.htm
in particular, figure 3 re: comb filtering explains the "hollow" sounds.

hope this reply wasn't overkill. basically, phase cancellation should be avoided "most" of the time... though so should distortion apparently.

[Thylacine Dream]

Haha not overkill at all, I just wish I could read the links now but I'm supposed to be doing school stuff. Thank you so much for responding, I think it's so damn cool how active you are in here. I kinda wish the clean were overdrivable with or without the inversion, though I suppose that'd be achievable by just putting an OD before in the chain, but either way, if I weren't broke and in debt to myself through spending savings I assure you I'd be affectionately stroking a TAFM with gate mod this very moment, you make the lustliest pedals

[smallsnd/bigsnd]

yeah i thought about doing the drive with/without inversion, but then again i have a tendency to add more than i should. sometimes i need to restrain myself...

i love the image of someone stroking my pedals.

[Thylacine Dream]

I'm all for addiing it, sometimes you need to restrain yourself but sometimes you need to take the relationship between customer and product to the next level, heavy petting and beyond. Just don't have a little Tamagotchi in there that the player feeds with decibels or something and I'm sure not too many people will gum up the knobs and jacks

[Eric!]

yeah i thought about doing the drive with/without inversion, but then again i have a tendency to add more than i should. sometimes i need to restrain myself...

i love the image of someone stroking my pedals.

Oh, you! :blush: