can you hear saw up & down differences?

dorremifasol · Last edited by dorremifasol on Wed Mar 17, 2010 5:47 am; edited 1 time in total

This is something I noticed a while ago, but never so clearly. It must be an psychoacoustic thing.

To me, a simple saw up sounds different than a saw down. By default the G2 has saw up waveforms. When I turn the saw down it sounds like it has a bit more of low end. Of course when I look at the waveform it's just inverted, and there is no visual evidence of emphasized low frequencies, but I trust my ears. I can clearly and blindly hear the difference.

So, maybe is something related to the way my headphones work? or my audio interface? Maybe the ears can really notice the difference? what for?

In any case, I find that the saw down waveform to sound "fuller". Would a Moog synthesizer sound exactly the same if their waveforms were inverted? Curiously it has saw down waveforms.

Please let me know what you think.

I have attached a wave file and a simple patch. Just tweak the polarity knob.

polarity.wav

Description:

simple sound switching polarity

Filesize:

897.83 KB

Viewed:

2199 Time(s)

amicrazyorwhat.pch2

Description:

simple patch (with some analoguish tricks)

Download (listen)

Filename:

amicrazyorwhat.pch2

Filesize:

1.32 KB

Downloaded:

2471 Time(s)

iPassenger · Posted: Wed Mar 10, 2010 3:01 am Post subject:

I have also noticed this, more so once you start adding filters and such like but I have hunch that has something to do with the way the filter responds to the different waveforms, not sure at all though.

Roland Kuit · Posted: Wed Mar 10, 2010 3:12 am Post subject:

it is more a psycho-acoustic feel. it is like playing the violin. when playing the thing you touch the string with the bow descended and up. thats the reason for in an orchestra that the note lines are noted with the behavior of the bow. it would be a sonologic mess when the string players could decide for themselves to play up or down. hey, you are up early ross:)

dorremifasol · Posted: Wed Mar 10, 2010 4:11 am Post subject:

WOW! I didn't know that about the violin, great info Roland! Now I have something new and cool to tell to my neophyte friends Very Happy

iPassenger · Posted: Wed Mar 10, 2010 4:20 am Post subject:

Not especially early, i am usually in work for 8.30 - 9.00. Talking of which I should probably be doing some. Smile

Uncle Krunkus · Posted: Wed Mar 10, 2010 5:04 am Post subject:

Wouldn't the capacitance inherent in any routing behave differently between, a sudden positive excursion followed by a falling value, and a sudden negative excursion followed by a rising value?
I know, in theory, that capacitive reactance should present the same regardless of polarity. But what if there are polarised caps in the audio path?
Then again, I could be wrong. Just a thought.

Roland Kuit · Posted: Wed Mar 10, 2010 5:07 am Post subject:

a descending bowing gives a positive vibration, up-a negative. it is easy to make a pch and implement this.it will make things more realistic. i will have a look, but not now/have to do things. basically you are right uncle...and not. payed neg of pos after each other, in sound there is no difference in perspective. but played both at the same time it would.

Uncle Krunkus · Posted: Wed Mar 10, 2010 5:26 am Post subject:

I'm not really talking about the perception, more about how a saw wave and it's theoretically identical (and yet inverted) timbre may not make it out of the instrument, through the amp, speakers and into our heads with the same shape. There could be some anomaly in the hardware which modifies the timbre just because it's inverted.

Or not.

blue hell

dorremifasol · Posted: Wed Mar 10, 2010 11:14 am Post subject:

blue hell · Posted: Wed Mar 10, 2010 12:45 pm Post subject:

blue hell · Posted: Wed Mar 10, 2010 1:17 pm Post subject:

Ok, lill modification on the patch ...

Its not a saw of course we listened to , but some block was mixed in as well ... anyway, I've left that and most other things as is and I only changed the manual fade into an automatic one with an LFO ... and I removed the envelope to have it on continuously ... please up the main volume a bit after loading it.

I dont hear the effect anymore ...

amicrazyorwhat_bh.pch2

Description:

just a test, nothing interesting to download ;-)

Download (listen)

Filename:

amicrazyorwhat_bh.pch2

Filesize:

1.25 KB

Downloaded:

3258 Time(s)

dorremifasol · Posted: Wed Mar 10, 2010 1:38 pm Post subject:

You don't hear the difference because in that patch you are listening to many different voices, each one with its own LFO and phase.

The effect is only audible if there is only one voice, and one saw.

blue hell · Posted: Wed Mar 10, 2010 1:59 pm Post subject:

Oh, didnt look at the voice count, tried it in the demo ... so thats not an issue there.

xav · Posted: Sun Apr 25, 2010 10:36 am Post subject:

Incredible, what a nice discover! It's evident the filtered saw sound is different, especially in the first octave of a G2 (without noise and sub osc). I'll try to compare the NMG1 (that's in the other sense) or Minimoog paying attention to that point.