CV+TB303 VCO- working?

[Phattline]

Hi, my plan is to build a:

TB303 clone, almost controlled by the SID-CV

VCO-VCF-VCA=> Analog

ENVelope LFOs and controlles=> Digital (transformed in CV)

If anybody knows the right Voltages and Lin/log of the 303 CVs…tell me.

I have made a Excel sheet, and saved it as Html, here you are:

http://www.phatline.at/XOXBOX/SID-303evaluierung.htm

If something is not right, or somebody have the answeres. please let me know.

Parts List for Germany:

I have already the Rare Parts (but this is a secret, until I have my parts  :-* )

http://www.phatline.at/XOXBOX/XOXBOXparts.xls

(this list is now not uptodate, since the whole project is in planing, but later, if it is finished, this list will be the final part list  )

The first shematics:

The orginal circuit (303)

http://www.phatline.at/XOXBOX/303.gif

The V-ca Section

Here is this is the inner circuit for the VCA chip:

[SLP]

anmerkung am rande: es heißt “to delete” 

[ganchan]

i’m interested in this but for now i don’t know much, i will report my infos.

[stryd_one]

I’m totally out of my area here, so I’ll just watch and smile. Good luck phattline, this is a cool idea!

[doc]

I dont understand a part of the VCA and gate—ääähm. What does Gate? Is gate a own Signal, or is it in the same signal path as envelope?

Gate is a simple On/Off - signal which is normally sended along with the CV. It is a “own signal”.

For example: If you press a key on a (analog) synthi it sends the CV on the CV-line and a ON on the GATE-line to the synthi. If you release the key Gate sends off. This signal is then used for signal forming stages, for example a ADSR to form the envelope. Or as a simple start/stop signal.

It is a simple control-signal.

Hope this helps.

greets

Doc

[Phattline]

In normal use the envelope is generated when the module receives a gate pulse or is triggered by a specific input.

_ Ok I think its like that: _

If on the Gain of the VCA is no Voltage, the VCA outputs no sound.

The Gain of the VCA, is controlled via the Envelope

The Envelope:

You press a key, and the keyboard send a “Gate on” Signal.

With this Signal the envelope starts (triggers):

Attack comes and the Voltage get higher, until Decay is reached.

Decay hold this Voltage as long a new Gate Signal comes.

If this is a “Gate off Signal”:

The Suistain comes, it gives a static signal, until Release comes (and acts like the decay)

Then the Release comes, and the Voltage goes down. (Release acts like Attack only invertet)

If this is a “Gate on Signal”:

I am not sure.

But if this so works, I think midibox SID can handle this. The ENV output on the CV board, have already integratet this. (correct me if I am wrong please)

Because the Midibox ENV is software based (?) and it already triggers the envelope with the gates? So I dont need any Gate signal on my layout because I use the digital ENV for my TB303.

2nd need is the Resonance Pot, I want it to CV. Since it is Stereo Pot. And feedbacks Signals, I need a simply dual VCA, or a simply VCR (voltage controlled resistor) which can handle this.

The one part of the Stereo part, mixes extra Accent to the VCF. The Other part of the Stereo Pot Feedbacks the Filteroutput to the Filter input or whereever :-).

So maybe the Resonance Pot-problem, can make with a single VCA, which only feedbacks the signal, the extra accent can be emulatet, since the Single VCA is driven via CV over the Midibox, it must be possible to add, by turning the RES-Encoder on the SID - to add a bit Accent to the Velocity CV-Out…but Since I am a analoge human I dont know if this possible, and if it is possible I dont can programm that :-.… So This must be a Dual VCA (op amp or what ever…)

Cool Idea is the

MB-sidechain

You take the basedrum amplify it, connect it with a yellow LED, and put on the LED a LDR, the output of the LDR must be amplifyed too, ant then you go in a MB-AIN.

Here you can duck the MB-SID-Volume-Envelope, and you have a sidechain VCA, between: good sidechaincompressors outthere working with VCAs!

The point where the Sidechain in the SID-application must be, is, always on last position!,

Meens:

If you route a LFO a Envelope and the Sidechain to the Cutoff of the SID.

the Sidechain, can reduce the Controll-voltage, to the minimum, elswere, the LFO would amplify it agin  8)

But this of course is in first thing a programming thing  , the analog circuit, would be so easy.

And If you want the sidehain to be mor linear:

You must take instead of LED and LDR, Transistors!

Amplyfiy it Rectify it,- put it in the AIN (but more of this later)

The Other Idea, would be take, the sidchainsignal, and trigger the envelope with it, but the upper idea is much smoother

anybody can explain what a audio buffer is? is this done with simply building a OPamp - amp???  ???

[stryd_one]

[me=stryd_one]clueless[/me]

[Phattline]

more question about the midibox SID-CV:

Is there any preset setting in the SID what says: CV1=Cutoff CV2=Resonance usw…???

Or it doesent matter, because, it easy to edit in the SID-Application???

When I use digital switches ( dout modul remotes a switch, and the switch —switch audio)(8 are supportet?) which switch could that be?

What Voltage Controlled Resistor can I take? (aviable in the EU- germany-austria…) and has anybody have a shematic for that–thankz

[stryd_one]

Is there any preset setting in the SID what says: CV1=Cutoff CV2=Resonance usw…???

That should probably be routed via an AOUT module, you can see more discussion about that in the current thread about the ssm filter… but uhm… I thought you were doing a VCO?

When I use digital switches (din modul remotes a switch, and the switch —switch audio)(8 are supportet?) which switch could that be? I simply wire it on a din module? (maybe with a resistor between-yep..)

Momentary ons. You should really search the forum and wiki if you’re not sure on such things

What Voltage Controlled Resistor can I take? (aviable in the EU- germany-austria…) and anybody have a shematic for that–thankz

Search for ‘mbfx’ (don’t forget to follow and where necessary add tags) to find info on this.

[Phattline]

That should probably be routed via an AOUT module, you can see more discussion about that in the current thread about the ssm filter… but uhm… I thought you were doing a VCO?

no no no you dont understand me  ;)…I am still talking about CV and the TB303…so: Is there any preset setting in the SID what says: CV1 from the AOUT-MODULE

=Cuttofff---->

The SID application has already a preset setting for the encoders and the DIN modules for it  ----> is there a preset setting for the AOUT in the MB-SID Firmware??? 

I know that I need the aout module  :

The Tread titel is named CVTB303 VCOworking? because- my first question was, can handle the MB the current that a 303 needs? I think yes. But I have to CV the whole 303, except from the Envelope—that will do independet for VCA and VCF the SID envelopes and LFOs  ;D

When I use digital switches (din modul remotes a switch, and the switch —switch audio)(8 are supportet?) which switch could that be? I simply wire it on a din module? (maybe with a resistor between-yep..)

Momentary ons. You should really search the forum and wiki if you’re not sure on such things

No my fealure… I meant of course the DOUT modle. So I was talkin about the little small DIP-form- devices—the digital switches, that are switching, if they get a current—for exemple bya DOUT module. Of course I know what momentary switches I take.

Search for ‘mbfx’ (don’t forget to follow and where necessary add tags) to find info on this.

Thankz I will search

[stryd_one]

so: Is there any preset setting in the SID what says: CV1 from the AOUT-MODULE

=Cuttofff---->

Sorry my bad!

Yes, that’s the one in that thread about the ssm I mentioned…This one

-the digital switches

Ahh my mistake again! Yeh, what kind do you need? What signals are going through them? There are lots of different flavours. I guess the 4066 is the standard, but there are many types that are intended especially for audio.

Of course I know what momentary switches I take.

You would not have been the first person to ask

HTH!

[Phattline]

MBSID software:bJust activate the AOUT_INTERFACE_TYPE and (if using the bypass relay) set DEFAULT_J5_FUNCTION 3 (in the setup…asm, then recompile).

use the F2A function (found in the EXT menu of the Ensemble).

This routes everything you do with the SID filter(s) to AOUT channels 1-4.

Connect the Bypass input of the SSM module to one of the J5 gate outs.

This way you can set the filter active/bypass by checking/unchecking the respective option of the patch’s EXT page (S#1..S#8 depending where the bypass is connected).

The bypass state will also be stored within your patch, so when playing stored patches you can have patches using the ssm or the SID filter or both, without changing any wiring or patchbay or other kind of action.

Cutoff/resonance are controlled just like the normal filter, i.e. if you turn the cutoff/res encoders or, for example, if you set your modulation matrix to modulate cutoff from an LFO or envelope, this will affect both internal and external filter the same way. So the usage in all standard applications is transparent.

Why 4CVs for a Filter  ???

The switch is to select sqare- or saw-wave.

I want to do this via the Midibox, to store the setting for presets…but ok thats future sound…for this I must program a little I think… and I cant  ::)…but there is already a function in the sid for this… the waveform selecter switch…

The Voltages are:

12V and 8V  I switch audio, but of course powerfull audio  ;D

Hm the use who made the filter PCB- took a relais for his bypass-switch. With a Relais its easier to do, since you only need a dout-out-and nothing else. The sound will be untouched! http://parts.digikey.de/1/1/122391-relay-smt-dpdt-1a-5v-gullwing-g6k-2f-y-dc5.html

With that shematic: http://www.uni-bonn.de/~uzs159/switching.png

You have a CMOS or whatever switch, With that shematic, the distortion or the colouring of the sound will be hard limmetet.

They say: if you switch the whole current thru the cmos, the sound will coloured! So the need a big circuit for one switch:  :o

of course with the Railais I have the orginal sound! But its mechanical  : , one error change more  >:( , but ok, its much easier, and cleaner.

[stryd_one]

4 filter CV = 2* cutoff, 2* resonance (it’s for stereo pairs I guess!)

You might like to look at the TI and AD sites for audio switches.

[drsyncenstein]

Hi, I did not read all of your post so maybe i’m talking bullshit, but

if i’m correct you do not use the an6562 opamp as powersupply. There is nothing wrong with that, but many people think that the crappy powersupply in the tb303 is the reason the thing sounds so squelchy. Your tb clone might more clean than you like. Second, for switching the audio you can use a cd4066 of 4016, they do that in many synths, i think also in the tb. I attached a piece from the prohet 5 schematic where they switch each wave independent from each other with a cd4016.

[Phattline]

Hi, I did not read all of your post so maybe i’m talking bullshit, but

if i’m correct you do not use the an6562 opamp as powersupply. There is nothing wrong with that, but many people think that the crappy powersupply in the tb303 is the reason the thing sounds so squelchy. Your tb clone might more clean than you like. Second, for switching the audio you can use a cd4066 of 4016, they do that in many synths, i think also in the tb. I attached a piece from the prohet 5 schematic where they switch each wave independent from each other with a cd4016.

cool thankz. that is good that I only need one part(and its not mechanical–yes!)

A qestion to this, I should use the 4016? or I can use both(the 4066)?

And a 4016 can only switch one? or more?—The reason why I ask this:

The SAW and SQARE Wave OSCillators cannot be mixed (without audiobuffering…and with two VCOs that would be 2x2=4 audiobuffers-to much PCB-place would be needet), so I need a toogle switch… If this not exist I must take 2 but I am happier with one 

To the supply, I will take the orginal.

But the Rectifier Diodes will be stronger, because, I also drive there a 78S12 79S12 78S09 78S05 …  ;D

A fiew persons meant that when the 12V stage and the 5.333V stage are in the same OP-amp- the Temperatur drive whould be eliminatet, so if it drives, it drives alwasys together… or so…

[drsyncenstein]

You can use either.

There are 4 switches in one package.

But there is already a cd4066 in the x0xbox, maybe there are switches left in it.

Look a the datasheet: http://www.fairchildsemi.com/ds/CD%2FCD4066BC.pdf

To toggle; you’d have to toggle the 4 switches in the 4066, no problem if you have enough dout lines from the midibox.

But if you have no space for a quad opamp and some resistors to make 4 simple summing amps, then I doubt you have space for a 4066.

[Phattline]

I now already use 2 buffer amps, to mix the VCO1 and the VCO2 (since I build two TB303 VCOs) I thougt I will mix them with CV like on this shematic:

Signal A is the switched VCO1 with SAW or WAVE…Signal B  is the same only for VCO2

It is a cool Idea to switch the seperatly, but then I must have 2 more puffer amps…

But a qestion If I use 4 switches and 4 Buffer amps, where I can mix them… it is the same shematic wright? only with 4 buffer amps…in thwo groups, yes of course Signal A=switchabel SAW and SQAURE…The REason I cant fade them, is, that I have only 8CVs and they are still to “unzureichend” “insuffizient”  :-[

[stryd_one]

the 4066 is the standard

4066 is an improved 4016… If you’re going to go this route (As I said, I’d check out the analog devices stuff too, as they’re specifically designed for carrying audio, but anyway…) then you may prefer the 74HC4066 over the CD4066 as it is much cleaner.

Phattline: Any chance you could shrink the pics a bit?

[Phattline]

Phattline: Any chance you could shrink the pics a bit?

done  the whole topic is cleared up (from my side)  8)

Here the pinout of the 4066

[drsyncenstein]

I’m no electronics guru, but i guess you could mix the signals in a simpler way.

See: http://www.wisc-online.com/objects/index_tj.asp?objID=SSE3403

Notice that the signal is inverted, but that should not matter.

You’d have to reduce the output of the summing stage, or you’ll get overload in the next tb303 stage.

Also, you do not need a cv to switch the cd4066, you can use a din out from the midibox. I made a simple drawing to show it.

For the din out’s, I’m sure stryd_one knows more than me about it.

Another thing, the opamp you use is pretty fast, they oscillate pretty easy. I’d stay in tb style and use a 4558, tl07* or a ne553* if you are more into hifi.