Presenting: Crowminius

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JanneI
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Post by JanneI » Sun Apr 01, 2018 3:38 am

I removed the R177 (between VCF and VCA) and took audio out of this point, it's normal level, so the low level output -problem has to be somewhere in the VCA, right?

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JanneI
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Post by JanneI » Sun Apr 01, 2018 4:31 am

Vca is current controlled, right? Anyway to test separate sections? +10v & -10v points are ok. Loudness t->ts jumpered, (+7,3v). Vca trimmers have effect, env works. Only the output is low level, even the A440. What should I look for?

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JanneI
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Post by JanneI » Sun Apr 01, 2018 5:51 am

Ok, I think I found the problem. R194&R195 should be 8.2ohm and I have 8k2. Oops :O

Yes, that was it! I didn't find 8.2ohm so I used 10ohm. Still much closer than 8k2 :hihi: :yay:

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ElSmurf
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Post by ElSmurf » Mon Apr 02, 2018 6:09 am

JanneI wrote:Ok, I think I found the problem. R194&R195 should be 8.2ohm and I have 8k2. Oops :O

Yes, that was it! I didn't find 8.2ohm so I used 10ohm. Still much closer than 8k2 :hihi: :yay:
Glad to see you figured it out!

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JanneI
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Post by JanneI » Mon Apr 02, 2018 6:44 am

ElSmurf wrote:
JanneI wrote:Ok, I think I found the problem. R194&R195 should be 8.2ohm and I have 8k2. Oops :O

Yes, that was it! I didn't find 8.2ohm so I used 10ohm. Still much closer than 8k2 :hihi: :yay:
Glad to see you figured it out!
Yes, learned a lot! Still one thing to fix, b50k for modmix (vr9) and used bom for laying out components so I used 24k, not 47k as it says on the schematic. It would really be nice if bom would also include these option, both on pot and resistor rows

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mutronic
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Post by mutronic » Fri Apr 06, 2018 5:55 pm

Aside from the stand-alone components, does the eurorack BOM differ that much from the stand-alone BOM for the crowminius?

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Staticcharge
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Post by Staticcharge » Sat Apr 21, 2018 8:24 am

mutronic wrote:Aside from the stand-alone components, does the eurorack BOM differ that much from the stand-alone BOM for the crowminius?
Did you get any response for this question?
I've just bought the v1.3 Eurorack kit from Modular Addict and there is little to no info on the DIY Euro build.

Additionally, The main boards are, as far as I know, the same boards for the stand alone.

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mutronic
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Post by mutronic » Sat Apr 21, 2018 4:40 pm

I didn't get a response to that question, but I figured out you have to do some excel wizardry and convert the csv files to make the BOMs they have posted on Modular Addict legible.

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Staticcharge
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Post by Staticcharge » Sun Apr 22, 2018 1:38 am

mutronic wrote:I didn't get a response to that question, but I figured out you have to do some excel wizardry and convert the csv files to make the BOMs they have posted on Modular Addict legible.
I think it's saved in an old version of Excel, but your right, after a little editing it does become clearer. I have the v1.3/1.31 version, have you got the same? Also the ATTINY85 IC does it require firmware?

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Staticcharge
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Post by Staticcharge » Mon Apr 23, 2018 11:34 am

Troubleshooter wrote:Finished the faceplate and measured and milled out some mod wheels

Image

Image

Image
I'd really like to see this once complete, looking good so far.

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evengravy
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TIS97 in the ladder

Post by evengravy » Thu May 24, 2018 3:42 pm

Hey Crow. I'm (slowly) building my 1.12 board and have some matched TIS97 transistors that I'd like to use in the ladder filter section. Apart from the orientation which is reversed from the 2N3904s the capacitors seem to be the same. Am I correct in thinking that I'll have to swap out the three 150R resistors for 220R if using TIS97.

I'd like to get the filter as close as possible to the original and I have these transistors anyway so I'd like to use them,

Thanks a lot, John

edit: oh, it looks like they're 150R in the original too...I'll just pop these in reversed then, the curve tracer shows quite a difference in characteristics between the 2N3904 and TIS97

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ElSmurf
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Post by ElSmurf » Sun Aug 05, 2018 7:32 am

Hoping someone still reads this thread, here's 3 issues I still have with my crowminius

1. All 3 square waves are asymmetrical, being 47-53%. All components surrounding the LM393Ns are correct. Is this normal? If not, what could be the issue?

2. The output signal looks very different on scope than the actual waveforms pre-filter, all are sloped and rounded. VCF and VCF Range trimmer are open. Is this normal behavior? If not, what could be the issue?

3. The Zero trimmer on OSC2 is maxed out but doesn't get the osc high enough for tuning with the osc2 tuning knob in the middle. I'm assuming lowering the value for R53 would remedy this, is this correct?

Thanks in advance!

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Troubleshooter
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Post by Troubleshooter » Tue Aug 07, 2018 1:52 am

Hi StaticCharge. Here it is.
Image
Image
Image
It has a few extra bells and whissles like an extra LFO as found in the Moog Reissue. It also has a tune pot on the back for the fixed frequency of VCO3 so you if you switch of the keyboard following of VCO3 you don't have to disturb the bigger VCO3 tuning pot and you can simply play the "OSC 3 CONTROL" switch in a musical way...Velocyty is patchable in the back to whatever you whant and it has an attenuator on the back. I have also built in a distortion cirquit located in the external input (true bypassable) great for making the filter feedback trick a bit more interesting sounding. Sonicaly the synth matches the reissue perfectly. You have to match it by ear however not by sight. The range of the pots it a bit diffrent here and there.


-

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ElSmurf
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Post by ElSmurf » Tue Aug 07, 2018 8:03 am

Gorgeous build, Troubleshooter :hail:

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Troubleshooter
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Post by Troubleshooter » Wed Aug 08, 2018 8:02 am

ElSmurf wrote:Gorgeous build, Troubleshooter :hail:
Thanks, about your 3 problems: I wouldn't care much about the unsymetrical waveform neither would I worry about the shape after the filter. If the results sound fine it's OK. Changing the resistor as you suggested is also the best solution for your scaling problem. If you need me to make some measurements for your reference (voltages, waveshapes) then please specify on what components and in what controlpanel setting, notes etc... I will make them if I can reach them on the component side.

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Boogie
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Post by Boogie » Wed Aug 08, 2018 9:53 am

Troubleshooter
Great, Beautifull, etc. etc... :hail:

I must admit I didn't read all 40 previous pages, so maybe my question is already answered, but may I ask where you got the keyboard from ?

Thanks
Boogie
-------------------------------------------------------
“Digital generated ‘analog’, is missing its analog soul and therefore isn’t analog any more.”
Jupiter 8 clone: https://www.muffwiggler.com/forum/viewt ... p?t=209322
Minipops 7 clone: https://www.muffwiggler.com/forum/viewt ... p?t=199360
ClapTrap clone: https://www.muffwiggler.com/forum/viewt ... p?t=202248
www.nabla-instruments.com

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Troubleshooter
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Post by Troubleshooter » Wed Aug 08, 2018 7:30 pm

Boegie

I bought the key bed and midi electronics @ newgroove.it
https://www.newgroove.it/vendita/doepfe ... cable-set/

I had to cut out the 5 lowest keys to go from 49 to moogs 44 key. It's Not too hard to do that.

Are you planning to build my clone? I have vector drawing available in DXF format. (Done everything on my DIY CNC). PM me if you want those.

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Boogie
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Post by Boogie » Thu Aug 09, 2018 4:48 am

Troubleshooter

Great work you did on a DIY CNC.

I am mainly looking to buy key beds.
Thanks for sharing the URL info. :chug:
-------------------------------------------------------
“Digital generated ‘analog’, is missing its analog soul and therefore isn’t analog any more.”
Jupiter 8 clone: https://www.muffwiggler.com/forum/viewt ... p?t=209322
Minipops 7 clone: https://www.muffwiggler.com/forum/viewt ... p?t=199360
ClapTrap clone: https://www.muffwiggler.com/forum/viewt ... p?t=202248
www.nabla-instruments.com

lowell513mx
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Post by lowell513mx » Sun Oct 14, 2018 4:28 am

Hammond case, screen printed graphics, heaps of hours... Some point going to replace the stock wood cheeks with a better quality Australian wood ones.

Image[/img]

gruvsyco
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Post by gruvsyco » Mon Oct 15, 2018 9:29 pm

lowell513mx wrote:Hammond case, screen printed graphics, heaps of hours... Some point going to replace the stock wood cheeks with a better quality Australian wood ones.

Image[/img]
That looks absolutely perfect!

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ElSmurf
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Post by ElSmurf » Wed Jan 09, 2019 3:14 pm

Troubleshooter wrote:
ElSmurf wrote:Gorgeous build, Troubleshooter :hail:
Thanks, about your 3 problems: I wouldn't care much about the unsymetrical waveform neither would I worry about the shape after the filter. If the results sound fine it's OK. Changing the resistor as you suggested is also the best solution for your scaling problem. If you need me to make some measurements for your reference (voltages, waveshapes) then please specify on what components and in what controlpanel setting, notes etc... I will make them if I can reach them on the component side.
@Troubleshooter, for some reason I have overlooked your reply until now, my apologies for not reacting any sooner.

A little update - I used a 100k trimmer to find a better value for R53, and ended up using a 86.6k resistor. Now OSC2 can be tuned with the frequency knob at center. I also discovered I had soldered in a 100k at R145. Since I used a RevLog pot for VR8, removing that resistor solved the Emphasis problem.

I've been fiddling with the VCF Scale and Range trimmers some more, totally ignoring the calibration process as outlined in the original MM manual, and now the filter closes and opens up completely, depending on where the Contour amount knob is positioned. Which is good enough for me.

The mystery of the asymmetrical waveforms still persists.

Looks like the ramp wave is bent in all 3 oscillators, on scope you can actually see that it's not a straight line going from max to min, and it doesn't cross middle line where it should. This translates to the square wave not being symmetrical, since the LM393Ns use the ramp to generate the square AFAIK. Since all 3 osc show the same behavior I'm wondering if anyone else has seen this on their scope. The only thing I can think of is that I'm using ICs with different specs, but this problem is a bit above my paygrade anyway.
Last edited by ElSmurf on Thu Jan 10, 2019 10:27 am, edited 1 time in total.

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devinw1
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Post by devinw1 » Wed Jan 09, 2019 3:57 pm

ElSmurf, that looks beautiful. Nicely done! :hail:

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Troubleshooter
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Post by Troubleshooter » Sun Jan 13, 2019 6:47 am

ElSmurf wrote:
Troubleshooter wrote:
ElSmurf wrote:Gorgeous build, Troubleshooter :hail:
Thanks, about your 3 problems: I wouldn't care much about the unsymetrical waveform neither would I worry about the shape after the filter. If the results sound fine it's OK. Changing the resistor as you suggested is also the best solution for your scaling problem. If you need me to make some measurements for your reference (voltages, waveshapes) then please specify on what components and in what controlpanel setting, notes etc... I will make them if I can reach them on the component side.
@Troubleshooter, for some reason I have overlooked your reply until now, my apologies for not reacting any sooner.

A little update - I used a 100k trimmer to find a better value for R53, and ended up using a 86.6k resistor. Now OSC2 can be tuned with the frequency knob at center. I also discovered I had soldered in a 100k at R145. Since I used a RevLog pot for VR8, removing that resistor solved the Emphasis problem.

I've been fiddling with the VCF Scale and Range trimmers some more, totally ignoring the calibration process as outlined in the original MM manual, and now the filter closes and opens up completely, depending on where the Contour amount knob is positioned. Which is good enough for me.

The mystery of the asymmetrical waveforms still persists.

Looks like the ramp wave is bent in all 3 oscillators, on scope you can actually see that it's not a straight line going from max to min, and it doesn't cross middle line where it should. This translates to the square wave not being symmetrical, since the LM393Ns use the ramp to generate the square AFAIK. Since all 3 osc show the same behavior I'm wondering if anyone else has seen this on their scope. The only thing I can think of is that I'm using ICs with different specs, but this problem is a bit above my paygrade anyway.
I checked and saw the same shapes as you discribed.
Here is a little demo of how my instrument actually sounds, just 5 sounds including a short FM FX thing in the end:

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ElSmurf
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Post by ElSmurf » Sun Jan 13, 2019 9:35 am

Troubleshooter wrote: I checked and saw the same shapes as you discribed.
Here is a little demo of how my instrument actually sounds, just 5 sounds including a short FM FX thing in the end:
It does sound lush and gorgeous, asymmetrical waveforms or not... Can't wait to put mine through its paces.

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ElSmurf
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Post by ElSmurf » Sun Jan 13, 2019 9:39 am

I decided to call it a day and close her up. She's fully functional and sounds right. Time to make some music!

Image

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