KVR Audio

antto · Post by **antto** » Sun Oct 04, 2009 12:47 pm

neotec: well, the whole point in the square shaper is that it makes a "pseudo" out of the sawtooth, with variable PW (what you call duty cycle)
this wierdness is because of the HighPass filter before the tanh() shaper

the other thing is that the shaper doesn't make a "sharp" enough edge where the sawtooth crosses zero, and there the filter doesn't get excited at high cutoffs+resonance

Kriminal: will you tell us some facts or show us these "drawings" or anything else helpful?

i get the impression that you just look around and when someone is about to make something nice - you come in and try to discourage him?

it's not "odd" that i don't have a tb-303 in front of me, should i mention that i am kinda not very rich..
not that i don't want to have one, or be rich in that matter ;]

the samples that we use here in this discussion are not from an "unknown" source, you probably didn't read anything from the past ~30 pages here
either be helpfull or at least don't be offtopic

neotec · Post by **neotec** » Sun Oct 04, 2009 12:52 pm

antto wrote:neotec: well, the whole point in the square shaper is that it makes a "pseudo" out of the sawtooth, with variable PW (what you call duty cycle)
this wierdness is because of the HighPass filter before the tanh() shaper

Jup, have you looked at my screenshot? This is a simulation of the shaper circuit inside of the TeeBee with a 'perfect' sawtooth.

antto · Post by **antto** » Sun Oct 04, 2009 12:57 pm

yeah.. but there must be some filters involved there, this just looks like a normal pulse wave

mistertoast · Post by **mistertoast** » Sun Oct 04, 2009 2:18 pm

neotec,

So you put a "perfect" saw in as input? I wonder what happens to the output pulse is the saw is "imperfect" in various different ways.

antto · Post by **antto** » Sun Oct 04, 2009 5:04 pm

report: new approximate values for the 3 HP filters around the main filter
HPF1 DC Killer ~54Hz
HPF2 feedbackHP <somewhere between 70 and 140Hz> (i was using 128)
HPF3 ADC ~13Hz

HPF2 does not change the sound pretty much, mostly shapes the resonance across the cutoff range of the main filter

HPF3 acts as the external A/D Convertor or mixer or somethin.. (which can be altered by taste)

i think i got the square wave kinda close now, but there is something i don't like
little clicks pop up in one specific place
it's because of that i subtract one of the sawtooths with the "squared" (shaped) saw, and when i use bandlimited saw - the clicks can be seen/heard
maybe i need a little 1 pole LP to smooth that?

EDIT: and yeah, from the 3 HP filters i placed for the square-shaper circuit - i didn't use the last two (they stayed at 0Hz)
so only the first one is correct (the one that filters the saw before the tanh())

and since there are some more parts on the circuit that "look" like they might be filters, i suppose there could be a LP there (as neotec said)

Kriminal · Post by **Kriminal** » Sun Oct 04, 2009 5:11 pm

antto wrote:
Kriminal: will you tell us some facts or show us these "drawings" or anything else helpful?

i get the impression that you just look around and when someone is about to make something nice - you come in and try to discourage him?

it's not "odd" that i don't have a tb-303 in front of me, should i mention that i am kinda not very rich..
not that i don't want to have one, or be rich in that matter ;]

the samples that we use here in this discussion are not from an "unknown" source, you probably didn't read anything from the past ~30 pages here
either be helpfull or at least don't be offtopic

keep your wig on, im not having a go dear boy

all im saying is, how can you make an 'accurate emu' if you are just going by samples? drawings are all over the net, free...not some secret ones i have

i would have thought you had studied all those in great detail before you even started coding..?

cant you not find a person who has a 303 and use it for your 'tests' or something?

antto · Post by **antto** » Sun Oct 04, 2009 5:26 pm

ok, i knew this was personal again

Kriminal wrote: keep your wig on, im not having a go dear boy

all im saying is, how can you make an 'accurate emu' if you are just going by samples? drawings are all over the net, free...not some secret ones i have

i didn't say i'm making an "accurate emu" .. in fact, there is no "accurate <software> emu" yet available as VST (or the other popular plugin formats) to my knowladge
i'm sure someone might have already taken the whole circuit and processed it "virtually" but that's insane (cool tho), and probably not for realtime processing.. yet

i would have thought you had studied all those in great detail before you even started coding..?

no, i didn't, and i still learn more and more about that synth, and i think you know nothing about it, prove me i'm wrong?

cant you not find a person who has a 303 and use it for your 'tests' or something?

no, i don't know a guy who can give his TB-303 to me..
i doubt there is even a single unit here in my country

you wasn't helpfull.. again
i don't know why you act like that, but to me, it looks like your just jelous when someone is doing something cool that you can't do yourself
sorry for being so direct here

rv0 · Post by **rv0** » Sun Oct 04, 2009 6:22 pm

Kriminal wrote: cant you not find a person who has a 303 and use it for your 'tests' or something?

he has me, i have direct access to 2 303's and also indirect access to more than 10 303's (as almost any musician-friend i have owns between 1 and 5 303's.).
so imo he cant get any better than the situation now..

what would be great if someone with the correct 303 electronics knowledge could point of few things out
I don't mean "following schematics" style knowledge.. i mean people who know exactly what is going on in there, who know exactly how the analogue components behave on that particular pcb design..
people who know the differences between 303 revisions and such
I don't think such people exist.. Hell, even my 303 guru doesn't know everything about every series, although he has seen loads of different 303's in the past 15 or so years. He can still get amazed by another case design (with different pcb supports), or yet another pcb revision with errors.

because a schematic is.. well_ just a schematic.. and you dont make a good clone by just following it.. (see: x0xb0x)
none of the schematics i know of are a complete sources of information for any 303 made..

mistertoast · Post by **mistertoast** » Sun Oct 04, 2009 10:05 pm

The proof is in the pudding. I don't think that analysis of the output is a bad way to go. (Speaking of both how the waveforms look due to phase shifts due to filters, plus how the frequencies look in a DFT.)

Isn't that the ultimate goal? Surely the circuit info can inform the pursuit, but in the end it's the results that count.

There have been several commercial attempts, and several of them have already been surpassed by antto, it seems to me. And some of them DID dig into the guts of the 202.

I think antto has the advantage of being relentless, and of being driven by his desire rather than a profit motive.

antto · Post by **antto** » Sun Oct 04, 2009 10:49 pm

thanks toast
i still don't rely on the circuit at 100% ..rv0 has a good point there, about different revisions and stuff..
but it is like a guide, and i believe my gut feeling only
looking at the waveform surely helps alot
i am pretty sure that if i had a real TB-303 hear in my hands, i would just play with it and waste time, instead of coding and staring at scopes..

both AudioRealism and d16 have messed with TB-303s for sure ;]
not sure about what attention the guys payed and what approach they used
i like AudioRealism's result, even that d16's looks more "accurate" on the scope (well, most of the time)
and CPU Usage is unbelievable, so, i'll never beat that
but my goal is probably a little bit different
they were doing emulation, i'm not, i am just doing whatever i can to achieve similar sound/waveform/functionality/behaviour of the synth, while still adding some new wierd stuff
i will dig hard into some parts of the 303 that i think are very important (like the oscillator, which drives the whole thing afterwards) and i might neglect some others (like the exact behaviour of the pattern editor, and the front panel layout (wtf))

all that time i was trying not to start a new track with this "unstable" version, but i couldn't resist, i started at least 3 tracks
one of my motives is to finish the synth, so i can finish these tracks, and satisfy my 303 desire (you know, i am searching for the 303 sound since ~2001!)
this is enough, tho, i have lot's of other motives to keep pushing this project

and i'm sharing all the results of my analyzis
Kriminal, you better not say a word if it's going to be off topic

mistertoast · Post by **mistertoast** » Sun Oct 04, 2009 10:58 pm

"both AudioRealism and d16 have messed with TB-303s for sure ;] "

I was thinking Muon's Tao. Which is nice, but doesn't seem to nail everything. No offense to Dave & Muon, as that was a very early attempt, and processors were much slower then. I really like Muon and kinda feel sorry for them with all the heat directed at them.

Also, I would try not to be distracted by Kriminal's delivery. He is a smart guy and makes a lot of good points.

antto · Post by **antto** » Sun Oct 04, 2009 11:15 pm

haven't had the opportunity to play with Muon Tao, can't say anything
if Kriminal is a smart guy, then he hates me or something?
or he *really* knows the secrets of the TB-303 and is bored by looking at us poor mortals trying to discover something he knows for years?
nah.. he hates me ;]

mistertoast · Post by **mistertoast** » Sun Oct 04, 2009 11:38 pm

antto wrote:haven't had the opportunity to play with Muon Tao, can't say anything
if Kriminal is a smart guy, then he hates me or something?
or he *really* knows the secrets of the TB-303 and is bored by looking at us poor mortals trying to discover something he knows for years?
nah.. he hates me ;]

No! He hates everyone!

VSTJuNkiE · Post by **VSTJuNkiE** » Mon Oct 05, 2009 2:36 am

antto wrote:haven't had the opportunity to play with Muon Tao, can't say anything
if Kriminal is a smart guy, then he hates me or something?
or he *really* knows the secrets of the TB-303 and is bored by looking at us poor mortals trying to discover something he knows for years?
nah.. he hates me ;]

Nah, Krims just a (master)"baiter". He'll just spew off some B.S. comments to get ya goin'.

You just keep on workin' on yur stuff antto. Let Krim have his fun in another thread.

And no, I hav NOTHING against Krim as he's actually helped me out a couple of times.

Later

antto · Post by **antto** » Mon Oct 05, 2009 4:01 am

thanks guys

btw, i just found out that we've all wasted our time, and there is already "the most accurate software emulation"
http://www.pulsecodeinc.com/DB-303/
they have "scanned" the knobs of a real TB-303 into a 3D modeling program!

just kidding ;]

Open303 - open source 303 emulation project - collaborators wanted