J.Haible's Living VCO for Eurorack [Build Thread]

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ashley27
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Thu Apr 30, 2020 9:11 am

Hey, I have the Barcode edition black PCBs, VCOs rev 1.3, Driver rev 1.1. Pic attached of what front panel I'm using, I've just finished my build.

I've attached an MP3 recording of the fuzzy sound I have sitting on top of my sine wave outs from all 3 VCOs. Anybody know what this could be? Something on the Driver board somewhere presumably. This is probably my cleanest build to date, everything just seems to work apart from the sine wave niggle, fault finding should be simple enough I guess although I'm new to reading schematics.

Other questions I have are........

- why would two 1V/Oct ins on the driver be useful?
- what calibration can I do for the driver?
- is the vibrato depth supposed to only be useful from 12 o'clock onwards?

Thank you in advance!
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by sduck » Thu Apr 30, 2020 10:31 am

I'm not really hearing a problem with that file - but I didn't play it really loud. Use a scope, see if you can see anything out of the ordinary. Does it do it if you don't use the driver section?

There are numerous ways one might use 2 v/oct ins. Say you're playing a sequence into one of them, but want a transposing voltage also, then you could use the other one. It saves a mixer.

I don't know enough about the Barcode version and it's calibration options to help you. With the r*s version you can adjust/calibrate the octave up and down switch range.

There are some mods for the vibrato knob - it's been a while since I built mine, so don't remember the specifics. Look in a) the original thread on electro-music.com, b) the r*s version build thread here, and c) earlier in this thread. Or perhaps someone will see this and know.
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Thu Apr 30, 2020 1:56 pm

It’s a good quality recording. Listening to the audio file you can hear the high pitched buzz I’m taking about quite clearly. Also what is the driver out for?

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by SyndieBot2000XL » Thu Apr 30, 2020 5:30 pm

ashley27 wrote:
Thu Apr 30, 2020 1:56 pm
It’s a good quality recording. Listening to the audio file you can hear the high pitched buzz I’m taking about quite clearly. Also what is the driver out for?
Oof, yeah, I can hear it using headphones. Not really sure what’s going on there, but mine doesn’t do that.

The driver out is for chaining other VCOs to the driver - saves you a mult, and lets you apply the portamento and vibrato to external voices.
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by cafe-de-la-jungle » Sun May 03, 2020 1:07 pm

Hi Guys,

Do you know if random source is going to make another run o their living vco kit?

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Fri May 15, 2020 9:27 am

Can anybody help with my sine wave issue that I have. It relates to my first post at the top of this page. I'm struggling with it. Thanks!

For example does anybody know where the sine converter is on the driver PCB Barcode rev 1.1? Is there one or three separate converters? I'm guessing one as I have the same problem across all 3 VCOs.

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by SyndieBot2000XL » Fri May 15, 2020 1:10 pm

ashley27 wrote:
Fri May 15, 2020 9:27 am
For example does anybody know where the sine converter is on the driver PCB Barcode rev 1.1? Is there one or three separate converters? I'm guessing one as I have the same problem across all 3 VCOs.
There are definitely three separate converters - each one has its own i/o, two trimpots, resistor network, and a pair of transistors. If I recall correctly, it isn’t important that these transistor pairs be closely matched - I didn’t do any matching in mine.

Have you tried powering it from different PSUs with the same result?
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Mon May 18, 2020 7:41 am

SyndieBot2000XL wrote:
Fri May 15, 2020 1:10 pm

There are definitely three separate converters - each one has its own i/o, two trimpots, resistor network, and a pair of transistors. If I recall correctly, it isn’t important that these transistor pairs be closely matched - I didn’t do any matching in mine.

Have you tried powering it from different PSUs with the same result?
Could that make a difference? I only have one supply so I haven't tried it no. I have a clicksandclocks DIY supply, never had a problem with it.

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by SyndieBot2000XL » Mon May 18, 2020 5:42 pm

ashley27 wrote:
Mon May 18, 2020 7:41 am

Could that make a difference? I only have one supply so I haven't tried it no. I have a clicksandclocks DIY supply, never had a problem with it.
The type of supply that gives me trouble with this module is far less robust than that one - that looks pretty solid, probably isn't that.

Maybe double check that nothing is touching that shouldn’t be - the switches to turn tracking on and off can make contact with the back of the driver pcb very easily, I had to put a bit of tape on mine to insulate it.

Other than that I would reflow everything on the driver board and check to make sure the ICs are functioning properly and well-seated in the sockets.

I’m sorry I can’t be more helpful, but I’m a bit of a noob and usually need some help troubleshooting stubborn problems myself.
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Tue May 19, 2020 4:12 am

SyndieBot2000XL wrote:
Mon May 18, 2020 5:42 pm

Maybe double check that nothing is touching that shouldn’t be - the switches to turn tracking on and off can make contact with the back of the driver pcb very easily, I had to put a bit of tape on mine to insulate it.

Other than that I would reflow everything on the driver board and check to make sure the ICs are functioning properly and well-seated in the sockets.

I’m sorry I can’t be more helpful, but I’m a bit of a noob and usually need some help troubleshooting stubborn problems myself.
Ah! One thing I've noticed is that I have nothing connected to the 0V connections on the VCO boards. Presumably something should be connected here? Should the VCO boards be grounded to the Driver board using this? Thanks so much for the help! Two noobs bashing heads! :doh:

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Wed May 20, 2020 6:05 am

If anybody is able to chip in on this I'd greatly appreciate it. Just need to know where the 0V outputs on the VCO PCBs are wired to. Thanks

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by SyndieBot2000XL » Wed May 20, 2020 12:33 pm

ashley27 wrote:
Wed May 20, 2020 6:05 am
If anybody is able to chip in on this I'd greatly appreciate it. Just need to know where the 0V outputs on the VCO PCBs are wired to. Thanks
I left the 0v pads on the voice cards empty - ditto the saw and pulse pads that are scattered across the boards. I think these pads may have been a holdover from an earlier revision of the voice boards, before the driver card was implemented. It’s all documented... somewhere...

I’m starting to remember how truly shambolic the documentation is for this project.

One thing I forgot to ask - do you have all four (3 voice + driver) pcbs on one stretch of ribbon cable? My build did not like it when I did that. I have the VCOs all daisy chained on one ribbon and the driver on its own.
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Thu May 21, 2020 4:29 am

I'm using individual power cables, nothing daisy chained. It's not the end of the world as I can easily filter out the problem, I'll try a few more things. Thanks again!

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Thu May 21, 2020 11:07 am

Attached is a pic showing what I'm hearing
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by sduck » Thu May 21, 2020 11:37 am

That looks pretty good actually. No wonder I didn't hear anything.

Take a good look at the triangle out - you might see a short downward spike at the top of the waveform. I expect that's what's causing this, as the sine is derived from the triangle. I don't remember where or what, but there's a possible fix for this over in the other living vco build thread. I think it involves a cap of some kind placed in parallel with a resistor - you'll have to search back a bit for it - sorry I can't be nore help than that!
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by Leverkusen » Thu May 21, 2020 12:27 pm

The cap did indeed fix the sine wave for me. Unfortunately the other waves are more distorted now. But I am okay with that for now since I like my sines pure but can accept other wave forms to have some character. I'll have a look at it again when I find time to examine why I cannot tune all three osc's in a way that the Pots look the same...

EDIT: here is the link, first post on that page. viewtopic.php?f=17&t=150988&start=350

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Thu May 21, 2020 4:49 pm

Great to read the above two comments, also to discover there’s another thread! Thanks indeed

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Tue Jun 02, 2020 1:15 am

Does anybody know where the 2.2nF cap goes in parallel to a resistor somewhere in an attempt to fix the spike? In relation to the Barcode rev 1.3 VCO PCBs. It's labelled RT2A, B and C in the random source BOM and is a 20k resistor. Thank you.

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by whyfarer » Mon Aug 24, 2020 7:34 pm

I got my hands on a badcode pcb + panel set. I'm close to done sourcing parts for it. Can someone help me with the tempco deets? I've seen both 1k 3300ppm and 1k 3500ppm thrown around. Synthcube sells both: 1k 3300ppm from ankaeohm and 1k 3500ppm from krl/bantry. Is one preferred over the other? many thanks

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by finnurbjarna » Tue Sep 15, 2020 5:47 am

the control board on mine has stopped working after spending a bit of time unused.

Any tips on how to troubleshoot that? The oscillators are still fine - just wont track through the driver...

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