Open303 - open source 303 emulation project - collaborators wanted

[mistertoast]

Yeah, I should have said that I welcome Q's and proposed tests. Goal would be to end up with a document and a set of files that support the conclusions.

[mistertoast]

Also trying to craft a question about the cutoff increasing with repeated accented notes.

[Music Engineer]

Also trying to craft a question about the cutoff increasing with repeated accented notes.

ahh - yes that is 'gimmick-circuit', right? and is it the same thing that Robin Whittle calls 'Accent Sweep circuit' in the devilfish docs?

[mistertoast]

Also trying to craft a question about the cutoff increasing with repeated accented notes.

ahh - yes that is 'gimmick-circuit', right? and is it the same thing that Robin Whittle calls 'Accent Sweep circuit' in the devilfish docs?

I actually don't think that one's gimmick (or rather, I don't know if it's an intentional part of the gimmick or just unintentional fallout).

The explanation I read is that a charge is added to the capacitor and doesn't have enough time to die down before the next note starts. So I'd expect that it is affected by bpm.

Read this note from Whittle (separate from the devilfish docs, I believe) and tell me what you think...

http://www.geuggis.com/tb-303/art06.htm

[antto]

yes, this is called "gimmick" circuit
others call it Accent-Sweep

it can be seen on accented notes, when the accent knob is high ;]
it is time dependant, but has nothing to do with BPM
so if you have two accented notes one after the other, the second one will go higher if you increase the BPM because it will be played sooner after the first one

probably the only thing in this document that is solid true ;]
the curve is not accurate or anything, but helps visualize the effect (better see it on a sonogram)

EDIT: it's like the envelope is added twice on accented notes
also, this is when resonance is high (MAX)
when resonance is decreased, the additional envelope (that goes thru the gimmick circuit) gets sharper and sharper
this is another reason why accented notes are so loud when resonance is 0
tricky stuff ;]

[antto]

Q. Do accented notes have the same filter resonance (Q) as unaccented notes? Background: Some references say that one of the characteristics of accented notes is that they have higher resonance than unaccented notes.

Proposed Test: Compare two sets of notes. One set is accented and one is unaccented. ACCENT and DECAY should be turned down completely (fully counter-clockwise).

Now, before anyone creates such a file with their TB-303, does anyone have any comments on the test?

Yes, accented notes have the same resonance level
but whoever has a TB-303 should ignore me, and record a test ;]

[antto]

Q: is the filter envelope added (by some amount) to the amplitude envelope?

proposed test:
-set Cutoff to 100%, Reso to 0%, EnvMod to 0%, Decay to 0%, Accent to 0%
-play some (long) unaccented notes and watch the amp-env
-set Decay to some higher value, play notes and watch if the amp-env has changed (longer initial decay)

repeat the same test with accent set to 100% and with accented notes (in order to spot whether accent influences this)

i have observed the described behavior in the ABL and autodafe's samples.

i think the cutoff envelope is added a little to the AMP only on accented notes, when accent knob is high

[mistertoast]

Q. Do accented notes have the same filter resonance (Q) as unaccented notes? Background: Some references say that one of the characteristics of accented notes is that they have higher resonance than unaccented notes.

Proposed Test: Compare two sets of notes. One set is accented and one is unaccented. ACCENT and DECAY should be turned down completely (fully counter-clockwise).

Now, before anyone creates such a file with their TB-303, does anyone have any comments on the test?

Yes, accented notes have the same resonance level
but whoever has a TB-303 should ignore me, and record a test ;]

I believe you, but you understand my desire to create a FAQ with evidence, right? The world has enough TB-303 assertions that lack evidence. I want a methodology that is something other than "I believe antto." No disrespect meant.

[antto]

i know, but this is easy to see if you got almost any good audio sample of a TB-303 playing accented notes with high resonance and Accent
you can see it in lots of the available samples on the net
just open it in a sound editor, look closely at the waveform
i still encourage someone who has a TB-303 to make that test
don't worry, i still hope someone here proves me i'm wrong ;]

[mistertoast]

i know, but this is easy to see if you got almost any good audio sample of a TB-303 playing accented notes with high resonance and Accent
you can see it in lots of the available samples on the net
just open it in a sound editor, look closely at the waveform
i still encourage someone who has a TB-303 to make that test
don't worry, i still hope someone here proves me i'm wrong ;]

But isn't it obvious that, despite a zillion 303 tracks out there and tons of tools, people still harbor misconceptions? I'm hoping we can put to rest some myths, because they are a distraction.

[brambos]

i know, but this is easy to see if you got almost any good audio sample of a TB-303 playing accented notes with high resonance and Accent
you can see it in lots of the available samples on the net
just open it in a sound editor, look closely at the waveform
i still encourage someone who has a TB-303 to make that test
don't worry, i still hope someone here proves me i'm wrong ;]

But isn't it obvious that, despite a zillion 303 tracks out there and tons of tools, people still harbor misconceptions? I'm hoping we can put to rest some myths, because they are a distraction.

Please don't fully demystify the 303. There's still room for mystery, legend and magical pixy dust in this modern world!

[mistertoast]

The wars shall never end.

[antto]

this question game.. i'm in
i asked the guy who recorded the previous audio, to record another one, this time, i'll be looking at the slide curve, and if it changes depending on the tempo, or is just scaled (as i think is)
waiting for reply ;]

EDIT: grr. i think i speak messy english
i want to know if the curve is something like:
1. "the pitch voltage going thru a lowpass filter with a fixed frequency, not tempo-dependant"
<or>
2. "something that is scaled depending on the BPM, so it looks the same at any tempo (might still be a damn lowpass filter)"

i am thinking it's case2 ;]

[mistertoast]

Call for TB-303 samples...

Q. Do accented notes have the same filter resonance (Q) as unaccented notes? Background: Some references say that one of the characteristics of accented notes is that they have higher resonance than unaccented notes.

Proposed Test: Compare two sets of notes. One set is accented and one is unaccented. ACCENT and DECAY should be turned down completely (fully counter-clockwise).

Anyone with hardware want to make some notes using these rules?

[antto]

i want to know if the curve is something like:
1. "the pitch voltage going thru a lowpass filter with a fixed frequency, not tempo-dependant"
<or>
2. "something that is scaled depending on the BPM, so it looks the same at any tempo (might still be a damn lowpass filter)"

i am thinking it's case2 ;]

got the sample, i was wrong!
it's case1
it looks exactly like the sequencer is outputing the pitch instantly, feeding it to a 1pole LP filter which is fixed, doesn't change (so it might not actually be a filter, but a RC circuit or whatever it was called)

now i have thinkered about this before, but wasn't sure, i didn't had good samples at low tempo to see the curves
and it still doesn't make much sense (again, false information on the net) since i've read here and there that the 303 has a fixed time portamento or something blah blah
ok, maybe i missed some word

so, i will investigate this tomorow, but it looks pretty much like a 1 pole LP at a fixed frequency (that doesn't care about what's the BPM)

it makes sence a little now, since the synth has the DYNSYNC thing, which is (i'm only guessing) like clock impulses
so it wouldn't know what the BPM is in this external sync mode

ok, gotta sleep now ;]