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Working on fixing the 'session logged out' issue - please log out and log back in as there is a new cookie name. It MAY be worse for a while, sorry. We'll see... I'm working on it. Thanks

Presenting: Crowminius
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... 36, 37, 38 [all]
Author Presenting: Crowminius

Pioneers

I took a break on this project and now I'm back, trying to calibrate. It certainly seems rather involved. hmmm.....


sk23

Hi guys, I'm sorry to insist, but anyone could hep me?
thanks

sk23 wrote:
Hello,
I've a working Crowminius v1.1.
I would like to control via midi:
1) pitch bend
2) mod wheel
3) filter cutoff

With the actual firmware those control don't work via midi (I use the standard 4 pin DIN connector, no CV).

Someone can explain me please if it's possible to implement, and how, those functions.

Thank you

Regards



ElSmurf

Perfect, thanks! That was the last puzzle piece for me.

oldcrow wrote:
To disable the pitch wheel, you want to "lock" a DC voltage into the pitch wheel node of the CV input summing amp. The easiest way is to just use a couple of 10K resistors where the pot would go, one from CW to center, and one from CCW to center. This places 5V on the pitchwheel node, which is needed to get other things into the correct default range. -Crow



Pioneers

I'm curious if this sounds like the correct way to calibrate:

Set Range to 16
hold low A and adjust the zero trimmer
hold high A and adjust scale trimmer
(repeat for all oscillators)

Set Range to 2
Hold low A and adjust zero trimmer.
Hold high A and adjust comp trimmer.
(repeat for all oscillators and also repeat above)

I feel like every time I try this I keep messing up the previous settings and seem to be just going back and forth from in tune to out of tune.


ElSmurf

I tested the power supply yesterday and I get a good +/-10V. Tried to start the calibration process today, but it appears OSC1&3 are dead. OSC2 has sound and responds to range, freq and waveform changes, as well as the PWM.

Checked all switches and connections, and they look good. Swapped out the ICs between OSC1 and OSC2 one by one, which changed nothing. The only big difference I measured between corresponding ICs on all three OSCs is pin 1 of the LM393Ns (IC8,13,18). On OSC2 I get a steady -5.3V, on the other two I either get 0V or -9.9V. It just jumps from 0 to -9.9 on the two dead OSCs - for no apparent or audible reason. hmmm.....


Any ideas what this could be, before I start checking all values and solder joints?


*edit* Just scoped the oscillators and I find no waveforms on the OSC1&3 ICs. When I touch pin 1 of IC5 and IC12 with the positive probe of my DMM, OSC1 resp. OSC3 produce sound, and respond to the waveform switch, but not the range or frequency controls. OSC1 responds to PWM also. I'm getting closer!


oberling

Hi sk23,

as far as i understand the source code the filter mod is already implemented (lines 308-312). It uses the second DAC-channel (first for Pitch CV) and you must set switch#1 to low and switch#2 to high for it to work on CC#11. If switch #1 and #2 are low it will respond to Velocity (lines 265-266). If switch #1 is high it responds to aftertouch (lines 315-318). So Filter modulation should be covered already.

The Mod Wheel is implemented as a PWM-DAC already as well (lines 302-306). For that to work you'll need to have the vactrol circuitry installed.

PitchBend might be implemented in software but will be not as smooth (if usable at all) opposed to using a dedicated DAC as in v1.1.3.

oldcrow implemented both ModWheel and PitchBend using a dedicated second DAC and some OpAmps for v1.1.3 so basically we (with older revisions) would only have to have some additional PCB to implement these things, wire it up correctly to our PCB (flying wires alert) and use a corrected version of the firmware - which seems not to be available as of now. However implementation should be straight forward.
The effort to design such an additional PCB has already been undertaken by mrmrshoes some posts back by just straight forwardly exporting the necessary differences between schematics v1.1.0 and v1.1.3 onto a new PCB.
This is not yet in production and currently lacks a 5.1k resistor... we'll see how that works out...

tldr: mrmrshoes and I are also on it... but it'll take time Mr. Green

sk23 wrote:
Hello,
I've a working Crowminius v1.1.
I would like to control via midi:
1) pitch bend
2) mod wheel
3) filter cutoff

With the actual firmware those control don't work via midi (I use the standard 4 pin DIN connector, no CV).

Someone can explain me please if it's possible to implement, and how, those functions.

Thank you

Regards



sk23

Hi Oberlin,
thank you very much for your reply.

Everything is clear now.
Please guys keep us updated!

Cheers


jimfowler

For anybody who hasn't already populated their boards, do yourself a HUGE favor and use multi-turn trimmers...especially for the oscillator tuning section.

I'm sure this has been mentioned before but it bears repeating in my opinion.


ElSmurf

If anyone has an idea where to start looking, any help would be greatly appreciated. Transistors have correct orientation, btw.

ElSmurf wrote:
I tested the power supply yesterday and I get a good +/-10V. Tried to start the calibration process today, but it appears OSC1&3 are dead. OSC2 has sound and responds to range, freq and waveform changes, as well as the PWM.

Checked all switches and connections, and they look good. Swapped out the ICs between OSC1 and OSC2 one by one, which changed nothing. The only big difference I measured between corresponding ICs on all three OSCs is pin 1 of the LM393Ns (IC8,13,18). On OSC2 I get a steady -5.3V, on the other two I either get 0V or -9.9V. It just jumps from 0 to -9.9 on the two dead OSCs - for no apparent or audible reason. hmmm.....


Any ideas what this could be, before I start checking all values and solder joints?


*edit* Just scoped the oscillators and I find no waveforms on the OSC1&3 ICs. When I touch pin 1 of IC5 and IC12 with the positive probe of my DMM, OSC1 resp. OSC3 produce sound, and respond to the waveform switch, but not the range or frequency controls. OSC1 responds to PWM also. I'm getting closer!



Update : I reflowed pretty much every solder joint of the OSC and CV sections, with no change to the problem. I'm starting to suspect the LM348 is faulty - could this produce these results? I already ordered some new ones, so I'll know soon enough...


SynthOSphere

jimfowler wrote:
For anybody who hasn't already populated their boards, do yourself a HUGE favor and use multi-turn trimmers...especially for the oscillator tuning section.

I'm sure this has been mentioned before but it bears repeating in my opinion.


Instead of what?
Can you please be more specific or point me to a post that is?
I haven't yet started to populate as I haven't even bought my parts....

Thanks!


ElSmurf

SynthOSphere wrote:
Instead of what?


Instead of single turn trimmers, which would probably be a real PITA to calibrate the oscillators with.


Pioneers

I agree about the multi-turns. I wish I had used them now that I'm trying to calibrate. I'm thinking it will be difficult to get the single turns out now.


ElSmurf

Finally figured out the problem yesterday. I doubt anyone will encounter the same issue, but I'll share for historic purposes.

When I first started to populate the board, I solder the through-hole tempcos flat on the board. When I figured out they needed to touch the 3046s, it seems I had some desoldering rage, and fried the traces between the tempco and pin2 of the 3046 for VCO 1&3. Two tiny copper wires between the tempco leg and the SMD pad later, and the synth worked like a charm.
nanners

Today I sorted out some wiring mistakes between the front panel and the board, and looks like I'm all set to start calibrating tomorrow. I'm also planning on writing down the tuning procedure, based on the text file provided by medbot earlier in the thread.


ElSmurf

Two questions :

1. I can't seem to get enough base voltage to tune OSC2, I run out of turns on the ZERO trimmer to get it up high enough to be in tune with the other two oscillators, with the OSC2 FREQ pot in the middle. I got it to scale across all octaves, but the Frequency knob is set to about +1 (30° past center) on the front panel. Would lowering the value for R53 help?

2. When I compare the waveform on the volume pots to the one I get from the main outputs, the final waveforms look very rounded. Is this normal behavior? Frequency knob is FCW, emphasis and contour FCCW.


hreggi89

Things seem a bit quiet here lately so I don't expect much help, but I'm still gonna post this for the off-shot that someone here reads this and can help me.

I've finally finished assembly but I don't get any sound from the synth itself. I get the test-tone on all outputs, all LEDs seem to work (except phase and tx even though I send MIDI signal to it, also tried changing phase jumpers. are they supposed to light up?) and the Gate LED lights up when I send signal from an outside source. I'm thinking the problem might exist in the filter or amplifier section because I get no signal from any of the oscillators, noise source or external audio in. If this is the case, where should I continue troubleshooting?

I have other things to do for the next couple of days so I won't be able to look into the problem much myself, if I get any headway I'll post here immediately.


ElSmurf

hreggi89 wrote:
Things seem a bit quiet here lately so I don't expect much help, but I'm still gonna post this for the off-shot that someone here reads this and can help me.

I've finally finished assembly but I don't get any sound from the synth itself. I get the test-tone on all outputs, all LEDs seem to work (except phase and tx even though I send MIDI signal to it, also tried changing phase jumpers. are they supposed to light up?) and the Gate LED lights up when I send signal from an outside source. I'm thinking the problem might exist in the filter or amplifier section because I get no signal from any of the oscillators, noise source or external audio in. If this is the case, where should I continue troubleshooting?

I have other things to do for the next couple of days so I won't be able to look into the problem much myself, if I get any headway I'll post here immediately.


It has been quiet here lately, I hope Crow hasn't forgot about us mortals here.

First thing - did you measure the voltages at the OSC and filter ICs or at the PSU to make sure you have a good +10V/-10V? Do you see CV and gate activity when sending MIDI into the synth?


hreggi89

ElSmurf wrote:

It has been quiet here lately, I hope Crow hasn't forgot about us mortals here.

First thing - did you measure the voltages at the OSC and filter ICs or at the PSU to make sure you have a good +10V/-10V? Do you see CV and gate activity when sending MIDI into the synth?


Thanks for the prompt reply ElSmurf, I tried to answer yesterday but I'm juggling a 20th century music history final I have tomorrow and troubleshooting the synth (which I'd much rather spend my time doing).

I am picking up current going through the oscillators and noise volume pots but low levels of voltage which is opposite to my semi-modular synth which outputs less current, but I've got no idea what values to expect from the board and I haven't measured any of the ICs for that reason. I am thinking that voltage delivery might be my current problem, seems that the P10V trim pot doesn't do anything unlike the N10V pot, I can trim that one between DC -7.2V and -9.2 but the P10V is stuck at 6.9V, I measure this between the power transistors Base and Collector, Emitter outputs 0.6V no matter what. I don't know how that PSU circuit works so I don't know where else to measure or what to expect. I'm gonna take a closer look at the P10V trim pot when I find time.

Regarding MIDI, synth doesn't appear to answer any incoming MIDI signal, gate light doesn't go off unless I input gate signal from another synth, but is it supposed to? The atmega chip seems to work at least partially since the Test Tone is generated there, the LM7805 is getting an input of 8.5V and outputting 5V so the digital part seems in order.

Another thing I want to mention quick, I used SPDT switches on all the three wire switch connections (going for a synth box) instead of DPDT, I'm 95% sure that isn't a problem but I just wanted to throw it out there to make sure.


ElSmurf

How are you powering the synth? Looks like getting a good +/-10V should be your highest priority now.

Also, SW8 and SW10 require a DPDT switch, you can use SP for all the other switches.

hreggi89 wrote:
ElSmurf wrote:

It has been quiet here lately, I hope Crow hasn't forgot about us mortals here.

First thing - did you measure the voltages at the OSC and filter ICs or at the PSU to make sure you have a good +10V/-10V? Do you see CV and gate activity when sending MIDI into the synth?


Thanks for the prompt reply ElSmurf, I tried to answer yesterday but I'm juggling a 20th century music history final I have tomorrow and troubleshooting the synth (which I'd much rather spend my time doing).

I am picking up current going through the oscillators and noise volume pots but low levels of voltage which is opposite to my semi-modular synth which outputs less current, but I've got no idea what values to expect from the board and I haven't measured any of the ICs for that reason. I am thinking that voltage delivery might be my current problem, seems that the P10V trim pot doesn't do anything unlike the N10V pot, I can trim that one between DC -7.2V and -9.2 but the P10V is stuck at 6.9V, I measure this between the power transistors Base and Collector, Emitter outputs 0.6V no matter what. I don't know how that PSU circuit works so I don't know where else to measure or what to expect. I'm gonna take a closer look at the P10V trim pot when I find time.

Regarding MIDI, synth doesn't appear to answer any incoming MIDI signal, gate light doesn't go off unless I input gate signal from another synth, but is it supposed to? The atmega chip seems to work at least partially since the Test Tone is generated there, the LM7805 is getting an input of 8.5V and outputting 5V so the digital part seems in order.

Another thing I want to mention quick, I used SPDT switches on all the three wire switch connections (going for a synth box) instead of DPDT, I'm 95% sure that isn't a problem but I just wanted to throw it out there to make sure.



evengravy

Hi, Just getting around to populating the TH 1.1(?) version.

I've no need for the MIDI functionality at all, I have plenty of options for sequencing with CV and want set it up for 1V/Oct CV input only.

Are the parts that can be left off the PCB in this case (MIDI DAC Parts) listed somewhere? The MCU and DAC are pretty obvious but resistors etc. I'm not sure.

I can always populate them and trim for 1V/Oct I suppose but I'd rather drop a Teensy MIDI/CV board in here down the line and save the space for it.

Thanks a lot!


ElSmurf

evengravy wrote:
Are the parts that can be left off the PCB in this case (MIDI DAC Parts) listed somewhere? The MCU and DAC are pretty obvious but resistors etc. I'm not sure.


The only useful thing I can tell you is that if you want the 440 reference tone, you'll have to populate the Atmega section anyway.

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