Presenting: Crowminius

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mikefiction
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Post by mikefiction » Sun Jul 19, 2015 6:55 pm

I ordered a board a few days ago, just before they sold out :)

I'm excited to build this!

I think I'm going to go for close to a full sized panel with (mostly) the original placement - maybe throw the PWM stuff below the MOD section.

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wahee
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Post by wahee » Mon Jul 20, 2015 4:44 am

got a little bit further troubleshooting my build.

I changed the display for a Adafruit one and now get the Crowminius message and MIDI although just XXX with no midi input.

I have meticulously checked all resistors and discovered one that was wrong. A 220ohm but should have been 820ohm in the power supply. So hum is now gone.

All transistors and electrolytic caps are ok. Smaller caps still to check.

I still have no audio on the AUDIO high out.

very low audio on HEADPHONES out.
All oscillators seem to be sounding.
Although the ON and OSC VOLUME controls do very little!

so i'm thinking possible problem in mixer circuitry or VCA

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moogasm
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Post by moogasm » Tue Jul 21, 2015 1:59 pm

I trust Crow's expertise in specifying tolerances and matching but are there areas in the circuitry that might benefit from extra precision? I realize some of the inaccuracies add to the Minimoog magic but I find myself wanting to go to the extra effort of matching parts to improve performance. For instance, matching the octave switching resistors to 0.1%, the VCF ladder caps and the VCA differential pair transistors to name a few.

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wahee
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Success! (well mostly)

Post by wahee » Wed Jul 22, 2015 11:04 am

well after literally days of staring at each and every component on the board. We have success. I thought I was going mad. :zombie:


Midi is still not working. Just a regular pulse on the TX light. May be the 900 opto.

I used the Gate output from a Prophet 5 (The CV out on the P5 does not seem to change pitch - probably something to do with it's spec)

So I am getting a single note. All 3 OSC's and noise are working. Noise was a it of a issue as I had fitted a multiturn trimmer and it took a hellova lotta turns.

PWM and filter also seem funtional.

Pretty amazing sounding even uncalibrated with a single note!

so feeling happy

:party:

Image


custom panel from Schaefer AG, just a pity it's not totally matt black, plus I made the white markings too small, but looks ok once knobs on.

Image

TIP: avoid this knob, threads strip really easily, plastic crumbles

http://www.banzaimusic.com/Synth-knob-Synthie-1.html
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Pioneers
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Post by Pioneers » Thu Jul 23, 2015 10:05 am

wahee That looks great! I built the board very quickly but have been taking my time with designing my panel. I think I just about have it though.

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mikefiction
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Post by mikefiction » Thu Jul 23, 2015 10:26 pm

wahee - that panel looks really nice!

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Post by mrcase » Fri Jul 24, 2015 5:30 am

Will there be another run? I deeply hope so! This looks terrific!
and Techman, whats the name of those moog switches on mouser?

Cheers
M

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Altitude909
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Post by Altitude909 » Fri Jul 24, 2015 6:34 am

I still have 1 V1.1 board for sale if anyone missed out..

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wahee
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Post by wahee » Fri Jul 24, 2015 7:00 am

Pioneers wrote:wahee That looks great! I built the board very quickly but have been taking my time with designing my panel. I think I just about have it though.
wahee - that panel looks really nice!
cheers It was a bit of work to make the sub plate but it works well with the Moog panel. Just working on the PWM one now
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Techman
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Post by Techman » Fri Jul 24, 2015 12:23 pm

mrcase wrote:Techman, whats the name of those moog switches on mouser?
I got these switches from fellow wiggler Dimitree.

Still got a few issues to iron out with my unit:
Hf tracking of vcos needs adjusting
Calibrate ext 1v/oct
Calibrate filters and vcas
Check operation of midi modulation - adjust midi Vcf pot
Noise level low
Headphone noisy- regular ticking...& oscillator bleed
440hz gen noisy

But I'm on holiday so won't get a chance to investigate for a couple of weeks.
Had it at Synth Diy UK last weekend. It was well received and those more familiar with the Minimoog than I were nitpicking on some small details, which I took to be a good thing. :hihi:

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oldcrow
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Post by oldcrow » Sat Jul 25, 2015 12:26 am

I am opening up an August bare board run. See the usual site, link at http://www.cs80.com/crowminius

(Look for "order here!")

Crow
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wahee
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Post by wahee » Sat Jul 25, 2015 6:27 pm

got midi sorted out. Nothing wrong with the Crowminius, something with my controller keyboard. Perhaps its midi channel setup.

Got the Crowminius tuned up using a program from the net. Musical Tuner.

all OSC's between +- 4 %. With multiturns it would be better, but sounds fine.

working on other trims

also got my PWM panel nearly done, display to mount.

working on case




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Last edited by wahee on Sat Jul 25, 2015 7:19 pm, edited 1 time in total.
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Techman
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Post by Techman » Sat Jul 25, 2015 7:09 pm

wahee wrote:got midi sorted out. Nothing wrong with the Crowminius, something with my controller keyboard. Perhaps its midi channel setup.

Got the Crowminius tuned up using a program from the net. Musical Tuner.

all OSC's between +- 4 %. With multiturns it would be better, but sounds fine.

working on other trims

also got my PWM panel done
Nice :tu:

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Noiseconformist
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Post by Noiseconformist » Mon Jul 27, 2015 7:26 am

Techman wrote: those more familiar with the Minimoog than I were nitpicking on some small details
I'm sorry to hear that! :hihi: :lol:

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Pre-Buit

Post by redragebrian » Mon Jul 27, 2015 9:29 am

Hey Oldcrow, this is really brilliant. I'd love this but don't have the skills to build it. I'd be really interested in mounting one inside this case with a larger custom built faceplate:

http://www.thomann.de/ie/boschma_cases_mic_9_case.htm

So my question is, will you offer a fully built version of this as SMT or TH that I can then fit inside this case with the knobs and switches mounted on a separate larger panel?

Will you offer some sort of a graphics file with a pre-done layout that can be used as the basis to design a custom faceplate?

Regards

Brian

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Techman
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Post by Techman » Mon Jul 27, 2015 10:45 am

Noiseconformist wrote:
Techman wrote: those more familiar with the Minimoog than I were nitpicking on some small details
I'm sorry to hear that! :hihi: :lol:
I'll re-phrase: 'provided some useful feedback' - thanks Michael :hihi:

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mikefiction
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Post by mikefiction » Mon Jul 27, 2015 3:17 pm

Got my board today! Haven't seen it yet as I'm not home :)

Is there a Mouser cart? I've looked through the tread a couple times and I failed to spot one?

If not, no big deal, I can make my own - just would be much faster and probably more accurate :)

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oldcrow
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v1.2 SMT

Post by oldcrow » Mon Jul 27, 2015 7:08 pm

My Crowminius SMT v1.2 (version bump for SMT) bare boards are here. I will hand-build the first one to verify everything works then it is off to my SMT shop to spend a week setting up the machines to build the SMT portion.
There are still some through-hole components: mostly pots, switches, jacks and a couple parts that need to be mounted with heatsinks, etc.

More later,

Crow
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moogasm
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Post by moogasm » Mon Jul 27, 2015 7:16 pm

Are there areas in the circuitry that might benefit from extra precision? I realize some of the inaccuracies add to the Minimoog magic but I find myself wanting to go to the extra effort of matching parts to improve performance. For instance, matching the octave switching resistors to 0.1%, the VCF ladder caps and the VCA differential pair transistors to name a few.

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Re: Success! (well mostly)

Post by groove » Tue Jul 28, 2015 2:59 am

wahee wrote:well after literally days of staring at each and every component on the board. We have success. I thought I was going mad. :zombie:
Congrats to you and everyone else on your progress and the success of your builds!

I haven't started my build yet, but I can imagine how it must feel to power things up for the first time and have a bunch of issues, as well as how it must feel to get your first sounds out of it.

Curious: what cabling did you use for your rotary switches, and are you happy with it?

redragebrian
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Post by redragebrian » Tue Jul 28, 2015 4:27 am

Thanks for the reply Oldcrow. If you're taking names, can you put me down for a pre-built SMT model?

Will this have the pre-programmed midi module chip installed?

Thank you!

Brian

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Noiseconformist
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Feedback!

Post by Noiseconformist » Tue Jul 28, 2015 4:34 am

Speaking of Feedback ... 8-)
Anyone normalised the (an) output to the external input?

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Post by sk23 » Tue Jul 28, 2015 12:03 pm

Hi Crow,
I would like to have some info about the midi implementation (no CV) with the your pre programmed MCU.
1) Does the velocity MIDI control affect the VCF?
2) Does the pitch bend MIDI control affects all 3 VCOs?
3) When 2 MIDI notes are overlapped does this generates a slide between the 2 notes? (not a fixed glide)

Thank you!

redragebrian
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Post by redragebrian » Tue Jul 28, 2015 1:03 pm

Sorry Oldcrow, another question.

Would a TH version be better in terms of future repairs by my very capable synth tech?

I'm trying to avoid having to hire someone to build the synth from scratch, hence my interest in the SMT version. But I don't want to end up with a synth that requires specialist SMT repair tools.

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Re: Feedback!

Post by Techman » Tue Jul 28, 2015 2:36 pm

Noiseconformist wrote:Speaking of Feedback ... 8-)
Anyone normalised the (an) output to the external input?
You tried on mine with a patch lead from lo output to ext audio in. How does it compare to your Mini?

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