crOwBX 8-voice

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ultravox
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Post by ultravox » Sun Sep 08, 2019 3:40 pm

whomper wrote: I had to eliminate some of the 1n SMD caps on the carrier board to get the envelope working (Attack, Decay and Release) and a few changes I've posted elsewhere.
Nice work! Can you give more details on which caps were eliminated and the other changes to get it working?

Any sound clips?
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Post by whomper » Mon Sep 09, 2019 1:17 pm

ultravox wrote:
whomper wrote: I had to eliminate some of the 1n SMD caps on the carrier board to get the envelope working (Attack, Decay and Release) and a few changes I've posted elsewhere.
Nice work! Can you give more details on which caps were eliminated and the other changes to get it working?

Any sound clips?
I did eliminate all 1n SMD caps that connect to VCA and filter envelops on the carrier board (those that connect to the 3rd board set of pins). I also eliminated all other 1n caps that connect with other pins just in case.

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Post by ultravox » Mon Sep 09, 2019 1:51 pm

whomper wrote:
ultravox wrote:
whomper wrote: I had to eliminate some of the 1n SMD caps on the carrier board to get the envelope working (Attack, Decay and Release) and a few changes I've posted elsewhere.
Nice work! Can you give more details on which caps were eliminated and the other changes to get it working?

Any sound clips?
I did eliminate all 1n SMD caps that connect to VCA and filter envelops on the carrier board (those that connect to the 3rd board set of pins). I also eliminated all other 1n caps that connect with other pins just in case.
Thank you for the info.
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Post by jpeterman » Fri Sep 13, 2019 2:51 am

Have all of you guys that ordered from the last batch receive your boards by now? Seems like whomper has ironed out the kinks on the latest board, but has anyone done a build with the 2.3.2 boards (the one for euro, sold on modularaddict)?

I'm considering doing the modular, single voice build, and upgrading to 4 voice if boards ever become available again/if this project is still being supported

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Post by kynsi » Fri Sep 13, 2019 5:24 am

It looks like his kickstarter-project is still eating up all his available time:


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Post by whomper » Sat Sep 28, 2019 8:55 am

Here's a quick sequence of me playing with the CrowBX knobs as the sequence fires along. You can hear filter sweep, filter with envelope mod, a few filter types (V2.4) SQR with PWM and hard sync

Two cards are playing, each one different sequence (L and R).

https://soundcloud.com/erezyaary/crowbx-sequence

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Post by ultravox » Sat Sep 28, 2019 2:43 pm

Thanks whomper, I finally get to hear what the crowbx sounds like today.
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Post by Nuclues » Sun Sep 29, 2019 6:43 am

Thanks Whomper. it sounds really sweet

Question :

Is there a way to test the voiceboards, without using the hostcard?
All my voicecards have no sound from the oscillators, but I can hear the filter is working

all the best from Nick

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Post by whomper » Sun Sep 29, 2019 7:48 am

Nuclues wrote:Thanks Whomper. it sounds really sweet

Question :

Is there a way to test the voiceboards, without using the hostcard?
All my voicecards have no sound from the oscillators, but I can hear the filter is working

all the best from Nick
Thanks, the synth sounds real good, has that 'warm' sound that complements my other synth very well.

As for your cards, there is a way to test each card placed on main board one by one, but that requires soldering a few parts differently, which is why I never attempted to debug cards like that.

As you have no sound out, can you trace with a scope or DMM in Hz mode (scope preferred if you have one handy), and follow the signal path? Current schematics are good for this procedure. See whether audio leaves the voice card at all.

I changed on carrier board R2 and R3 to 4k7 and removed R34 and R158. This provided higher output volume.

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Post by Nuclues » Sun Sep 29, 2019 9:54 am

I've been testing with and without the Hostcard ( with 5 v+ on the Gate) with no output at all, except I can hear the filter. But now I will try to troubleshoot my hostcard and make the modifications you and Chrutil suggested. Think it's time to finish the project :) Did you replace R34 and R158 with a Wire or just leave it?

all the best from Nick
Thanks Whomper- you're a truly fellow wiggler

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Post by whomper » Mon Sep 30, 2019 3:45 am

[quote="Nuclues" Did you replace R34 and R158 with a Wire or just leave it?
[/quote]

I have left it as is, i.e. nothing connected.

Please also observe from my previous comments regarding carrier board R51 and R28 are now 100K, R2 and R3 are now 4K7. This should bring output voltage to proper level.

Do you ave a scope to trace signal across its path?

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Post by Nuclues » Mon Sep 30, 2019 1:17 pm

whomper wrote:[quote="Nuclues" Did you replace R34 and R158 with a Wire or just leave it?
I have left it as is, i.e. nothing connected.

Please also observe from my previous comments regarding carrier board R51 and R28 are now 100K, R2 and R3 are now 4K7. This should bring output voltage to proper level.

Do you ave a scope to trace signal across its path?[/quote]


Super Whomper, i'll leave it open

Well, I haven't done any modification yes, on the hostboard or backplane, but I will read the thread again and remember your previous comments.


Nope, I haven't got a scope yet- but I will try to borrow a scope.. Guess, I should start to scope around the opamps for signal.

Thanks Whomper

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Re: crOwBX 8-voice

Post by randel » Thu Jan 16, 2020 8:57 am

FYI:

https://www.kickstarter.com/projects/ab ... ynthesizer

I'm hoping that I can re-use my crOwBX voice cards in this, so I don't have to build them again...

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Re: crOwBX 8-voice

Post by jimfowler » Fri Jan 17, 2020 8:49 pm

What’s funny is that I emailed those folks some time ago asking if they had a diy project in the works and they said no.

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Re:

Post by jvq » Tue Jan 21, 2020 3:51 am

Chrutil wrote:
Thu May 09, 2019 11:03 am

Does anyone have keyboard tracking working?
See my post in the other thread: http://www.muffwiggler.com/forum/viewto ... 5#p3005985

It's a host board bug.

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Re: Re:

Post by jvq » Tue Jan 21, 2020 3:58 am

jvq wrote:
Tue Jan 21, 2020 3:51 am
It's a host board bug.
To elaborate a bit more: the key tracking CV ought to have a buffer so that when it's 5V, it doesn't matter how many voice cards its driving. But it does not have a buffer, it's just the 5V rail coming through a resistor. The more voice cards it drives, the more the voltage sags below 5V to the point where it does nothing. You probably followed the silkscreen and put a 33K resistor next to the key tracking switch. That should be 4K7 if you are using the host board to drive 4 voices. With 8 voices, maybe even less.

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Re: crOwBX 8-voice

Post by jvq » Tue Jan 21, 2020 4:01 am

Another cross-post: if you used linear pots on your host boards, some of your pots are tapered wrong, and you might want to mod that. http://www.muffwiggler.com/forum/viewto ... 6#p3187326

It's much easier to make envelope changes and LFO rate changes if you don't have the wrong taper on their pots.

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Re: crOwBX 8-voice

Post by jvq » Mon Mar 16, 2020 5:25 pm

I'm working on expanding my 4 voice to an 8 voice now. I got frustrated matching AS3310 EG's and the "equivalent circuit" on my old voice cards so I hacked my old voice cards to use AS3310's too. https://crowbx-6d48f4aa5932532a5cd4216f ... v-mod.html

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Re: crOwBX 8-voice

Post by jvq » Mon Apr 13, 2020 3:07 am

Collecting notes about the 8-voice backplane: https://crowbx-6d48f4aa5932532a5cd4216f ... plane.html

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Re: crOwBX 8-voice

Post by ultravox » Mon Apr 13, 2020 4:25 pm

jvq wrote:
Mon Apr 13, 2020 3:07 am
Collecting notes about the 8-voice backplane: https://crowbx-6d48f4aa5932532a5cd4216f ... plane.html
Fantastic! I'm looking forward to following your progress.

I've been putting together an 8-voice BOM but it's not complete. I like the way Roman at BlackCorp does his BOM's and I made mine using the same format.

Cheers
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Re: crOwBX 8-voice

Post by Chrutil » Wed May 27, 2020 2:28 pm

Hi all,
Just my annual check-in on this project.
I still only have two of my cards built, but I did build a digital test harness for it so I can now test the voice cards and experiment with additional programmability features and such.
Here's a first test video of the thing in action:


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Re: crOwBX 8-voice

Post by ultravox » Wed May 27, 2020 3:56 pm

Nice work Chrutil, keep it up!
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Re: crOwBX 8-voice

Post by JanneI » Wed May 27, 2020 5:58 pm

Good job Chris!

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Re: crOwBX 8-voice

Post by Chrutil » Sat May 30, 2020 5:12 pm

Thanks guys!
Turns out I have a problem on my cards.
Both voice cards experience the same problem on both oscillators.
The problems shows up as a 'frizzle' or instability around 130Hz-150Hz or 150Hz-180Hz (depending on voice card and oscillator).

Here is a demonstration of the problem. It first starts around 44 seconds into the video.



It should be noted that this is not dependent on the CV sent in, I can repro with no CV sent in - it is strictly dependent on the frequency, and I can reproduce it with no incoming CV just by tweaking the Init Freq trimmers. It happens on both Saw and Pulse waves.
The CV mix coming out of pin 1 on A1/A2 (LT1013) and into the FMB3904 seems stable.
Since it reproduces the same on both voice cards and both oscillators I suspect the use of FMB3904, and I'm wondering if I should try to find some LM3046MX, which is an alternative component that can be used - but before blindly trying to replace components that I'd like to hear if someone else have experience something similar, or have any suggestions on what to try?

Thankful for any suggestions!
C

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Re: crOwBX 8-voice

Post by Chrutil » Sun Jun 14, 2020 7:46 pm

Qapla'

Got a set of LM3046M in the mail and replaced the FMB3904 on one oscillator and the frizzy artifacts are gone!
Yay, I'll jump on replacing the remaining three on my two voice cards and come back with the results.

It does seem that the FMB3904 won't work in the crowbx - or maybe that was just my batch, but four out of four had artifacts in the 130Hz to 180Hz range so I'll certainly be putting LM3046's in the rest of mine. I got mine from Mouser (512-FMB3904).
The LM3046M are obsolete and I went to ebay gambling that they wouldn't be fake, and they weren't (at least the one I tried works).
This is the listing, fwiw: https://www.ebay.com/itm/5-PCS-LM3046M- ... 3764360998

Thanks,
C

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