the Mox Philter..analog toolbox based

[moxi]

ok, I will give more precisions after, this first is for the fun, an to remember how things was at the beginning..  ;)

let say that most of the cabling is still missing  ;D

[stryd_one]

Could it be, that someone is building the Sherman-killer that I've imagined so many times?  ;D

[moxi]

and the labelling of the panel:

the panel is hand made, I just did the design in FPD, then print it 1:1, and use the paper sheet to locate the drill point on the panel.

the delay is a BBD one , the final mixer is inspired from the oakley filtrex, center position of pot give no sound, clockwise set the signal up and with + phase, anticlockwise do the same but phase reversed, that allow some other filtering result when mixing phase inverted and in phase signal of the dry and philtered signal

the preset handler is not done at this time, but I hope i will success doing a one-push=recall function/double-push=save.

the lfo give sine, square and saw

I think all of this can be done more easily with the SID software, but I like complications :P

[stryd_one]

I'll take 4. ;D

I think all of this can be done more easily with the SID software, but I like complications :P

Yeh well maybe this might be more flexible, and I wouldn't have to give up a SID channel :)

Looking forward to seeing this one grow! MP3's!! ;D

[nebula]

Looks awesome!

What is "CV distributors"??

[moxi]

cv distributor is from a schematic from musicfromouterspace.com.

the thing allow to multiply 4 time each incoming cv channel. so with one cv output of the aout, I can load all parameter of one cem chip (cut, rez, bal and vcaOut).

then param from different mod source are mixed together before the cv input of the cem.

[moxi]

hi,

Zaoum is its new name,  Majakovsky!

now, the panel artwork is done, next step will be the lazertran printing  :P

finaly, I've changed some things, mainly to be able to tweak independantly the two cutOff... the bbd delay and drive have been removed , to fully use all what is possible with the CEMs chips .

sounds come soon, friends... ;)

[Twin-X]

kut is another word for vagina in the Netherlands :)

[moxi]

kut is another word for vagina in the Netherlands

..that make the beast more sexy!  ;D

in the same time "vib" could stand for "vibro", that is a motorized toy our ladies sometime use..  8)

it's an organic box, I assume..

[moxi]

hi,

I'm now twinking more the app (analog_toolbox) and have done some change , as I'm learning more..

maybe someone can help me here:

I've added two more EG to the apps, in the rough way : I've duplicated the code two more time, one eg after one, creating beside all registers and variable needed.  all seems to work, but it's said that this eg is called each 1ms from a mios timer..

does my way could be suitable with no critical timing problem, or should I try to merge the 3 eg prog so all the attack first are processed, then the 3 decay, etc...?

thanks.

[stryd_one]

For those who missed it, we talked about this in the chat, and moxi is going to test some timings with his scope, and then we'll see how it goes :)

[moxi]

yes, and thank again Stryd, I will do the bunch of test saturday.

[Rio]

nice moxi..

how does it sound? Have you notice background noises in CEM3378 filter and which Schematic/Plan you use for that or can you show your pcb?

Because i'm interessted to reduce that background noise at much as possible in my solution.

Greets Rio.

[moxi]

for the perf mesurment, I've set a led on when entering the MAP_tick function, then light it off when the function end. The scope show that there is about 20ms between two iteration of the function, a lot more (60ms!) when tweaking the knob.. :-\

I will try to optimise the mapping so each mapping flags won't need to be checked if there is no change since the last call (maybe an unique flag tested at the beginning)

then, a little video of the LFOs on a scope, no sound for the while...

<object width="425" height="355"><param name="movie" value="http://www.youtube.com/watch?v=Dojcf-BK4aA&hl=fr"></param><param'>http://www.youtube.com/watch?v=Dojcf-BK4aA&hl=fr"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/watch?v=Dojcf-BK4aA&hl=fr" type="application/x-shockwave-flash" wmode="transparent" width="425" height="355"></embed></object>

lfo 1 alone, with different waveform, then with its rate modulated by lfo2 value, then modulated by lfo2 with its rate modulated too by lfo3 value...

how does it sound? Have you notice background noises in CEM3378 filter and which Schematic/Plan you use for that or can you show your pcb?

the filter sounded weel in the first testing, with the schematic as showned in the cem3378 pdf. no backround noise, but I use a nice ready made PSU ripped from a roland keyboard. I use BB OPA2132 aop for the main out and wima capacitor on the filter.

[stryd_one]

The scope show that there is about 20ms between two iteration of the function, a lot more (60ms!) when tweaking the knob.. :-\

It looks a LOT faster than that on the video!

[moxi]

It looks a LOT faster than that on the video!

yes, and I use the same TIME/DIVISION (10ms/div) for the two tests.

for the timing test, I can see on the scope an high level signal at the Dout pin (when in the MAP_tick function) with a duration of about 1/4 division, and a low level (the time MAP_tick end to its next execution) of about two divisions, or more when tweaking or activating some parameters.. ???

but I'm reworking the way butons and pots are handed. For the EG's, I have replaced the pots by encoders (no need for a "pot-over" function, so), and as I'm learning, the code become shorter :P

I post next test soon!

[stryd_one]

for the timing test, I can see on the scope an high level signal at the Dout pin

Ahhh.... Don't use the DOUT pin, drive a spare pin on the PIC.... otherwise your timing is a representation of the DOUT chain speed too :)

TK (and I) usually use the touchsensor pin for this.

[moxi]

hum... yes, does this mean that the Dout routines takes an amount of time it's important to take into account?

back tonight to give new result..

[stryd_one]

Well in theory it should update the DOUT every 1ms so that would quantise your output to ms resolution, but in practice it's possible that they don't update for some other reason... Better to be safe :)

[Rio]

@moxi: what is weel? and really no background noise? i've used a +/-15V trafo and used ripple filter + 7805,7905,7812,7912 to get +5V,-5V,+12V,-12V, which i used to feed the filter+AOUT_LC.

Damned that i can listen to a sweeping noise in background...i don't know what i do wrong.

[Rio]

And additional i can measure a constant high oscillation on a oscilograph (but i don't hear that)...

What could be the reason for that oscillation?

@moxi: do you measure something like that too?

[moxi]

hi,

the night i've announced was a bit long..;sorry 8), the app is now near to be finished (I need to do some improvment cause now the code don't fit in a pic18f452, probably cause of my crappy c coding!)

let me some more days to finish that and replugg the cem in the box, so you will ear what I mean about "no noise" (the cem3378 are given for a 70db s/n ratio, so by the way, a really little background noise can be ear, but nothing boring)

about oscillation, I've said somewhere else, when testing for the first time my cem3378, that it was abble to generate sound by itself when tweaking the cv's in a probably too important range... it seem that the cv voltage was not the thing that lead to that, it's probably something related to an innapropriate "impedance" or current drained, but from my side, I mix many cv before loading the cv input of the CEM, so I was thinking that the problem come from this mixing stage.

It's not a problem for me as the filter work well in an enough large range, I take it as an nice add. feature  :)..

but if you don't ear this oscillation, you can say, as I do, that all work fine!  :P

I will try to look at that on the oscilloscope as soon as it's possible, maybe it's a thing that happend with all chips?..

about my zaoum, here is what I've done during this long night:

- the 3 LFOs now can be synced to an internaly generated bpm (without any interpolation, bpm is based on the mios_timer @ 1ms, so it will probably not being so exact ..). if synced to bpm, lfo's rate knob are used to set the bpm divider (64/1, 32/1, 8/1...up to 1/16),

- the two first LFO get a fourth "waveform" parameter: called "free", in this case, the encoder act as a controler one : you do the waveform yourself!

- the 3 LFOs can be synced to note (the cycle start with midi note event (or restart if new note event)

- the 3 LFOs can be modulated by any of the 4 EG's (i.e. saturated by EG's values)

- now there is 4 EGs

- EGs sustain can be driven by velocity..

- different MIDI channels can be selected for each EG

- now there is 4 EG's..

- a TWIN mode : the variation of the second cutoff follow the variations of the first one

- a MIDI mode: to drive the filters with MIDI CCs, I think I will do a vst interface later...

- EG can be triggered by audio signal (side input or filter input), with a Threshold knob (I use an audio to trigg circuit, I still have to adapt the trigger signal to send it into a DIN input...will see if that can work)...

nothing else.. ::)

...for the while ! ;D

[stryd_one]

Rad. I was poring over those chips last night too, must have been something in the air :)

[Rio]

i've tested 4 of the cem3378 chips. All sounds in the same way. I can listen to a sweeping noise in background at all...

But the chips are connected like in pdf schematic of cem3378.

If i press my fingers on the chip...this sweeping noise will be more or less boosted.

The second noise is a repeating sound in background, like a train drives on the rails.

Third, i can measure a constant high frequency on osciloscope if i switch the psu on. That high frequency modulates the sound waves to thicker ocillations.

..but besides of these facts, the sound of the filter is allright. Only that noises are anoying and not useful for studio recordings etc..

I believe the reason could maybe my psu... i don't know..

[moxi]

If i press my fingers on the chip...this sweeping noise will be more or less boosted.

maybe for that you can try to improve your ground circuit, make larger traces and design your circuit in "star", with all ground line reaching each other the nearest of the start point at the PSU. I cannot help you here cause I use a nice PSU ripped from a roland keyboard.

The second noise is a repeating sound in background, like a train drives on the rails.

sound like what I get too, but only when cv's set at full...what the frequency of this sound on the scope? if 50hz (or 60hz if your are in USA), we can suspect some side amplification of the 240v buzz? else, maybe  the DACs generate transient noise, the max 525 datasheet say that:

Digital or AC transient signals between AGND and

DGND can create noise at the analog outputs. Tie

AGND and DGND together at the DAC, then tie this

point to the highest-quality ground available.

Good printed circuit board ground layout minimizes

crosstalk between DAC outputs, reference inputs, and

digital inputs. Reduce crosstalk by keeping analog

lines away from digital lines. Wire-wrapped boards are

not recommended.

..but the original Aout pcb seems to be already well designed in this way... maybe you use a diy "Wire-wrapped" board ?