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WIGGLING 'LITE' IN GUEST MODE

Befaco Even VCO
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Befaco Even VCO
CliffordMilk
I'm looking for an audio demo of the 'even' output from this module. Could someone out there point me in the right direction please?
thermionicjunky
Not the Befaco, but the same waveform from the Bergfotron Advanced VCO (with some phaser/VCF processing):

http://hem.bredband.net/bersyn/Ljud/Flutron.mp3

http://hem.bredband.net/bersyn/Ljud/Even,phaser.mp3
CliffordMilk
Interesting - thanks.
Richie Witch
I have a kit for one arriving today. Once I get the thing built, I'll try to post some audio samples.

Anything in particular you want to hear?
tallhouserecordingco
I'm interested in this module too - looking at ordering a kit myself. I've never built a DIY synth kit, but I've done several guitar pedals and a tube amp.
Richie, in addition to some audio samples, I'd be interested in your thoughts on the build.
Many thanks in advance!
Jumbuktu
I am interested in the kit. However, the 'Even' output looks like just another waveform. It would be interesting if there was some sort of CV control over the harmonic mix, but this doesn't seem to be provided.

The octave switch is a big plus, especially if this VCO is tracks as accurately as claimed.
chapelier fou
The octave switch isn't cv controlled, is it ?
CliffordMilk
Thanks. I was wondering what a sweep of the 'even' harmonics would sound like.
mbartkow
Mix a sinusoid with a sawtooth one octave higher, and presto - you have your even harmonic waveform. I believe this is how the waveform is actually derived in Befaco VCO.
thermionicjunky
mbartkow wrote:
Mix a sinusoid with a sawtooth one octave higher, and presto - you have your even harmonic waveform. I believe this is how the waveform is actually derived in Befaco VCO.


Yes, specifically a double-frequency saw derived from the same VCO core mixed with a sine with the proportion of 1:1.27.
Zanna83
I'm very interested in this module! I'm considering to realize a set of 4 for polyphonic pourposes.

Anyone who got the chance to try it ?
Richie Witch
Spent some time this weekend working on the kit, so here are some first impressions:

The kit is nicely organized. It comes with step-by-step instructions, organized by "bag". So you start by opening "Bag A" of the main board and follow the sequence given in the instructions.

The PCB is dense! In order to fit between components, the type on the board identifying the part labels is the tiniest I've seen, and in a couple of cases, the writing is defaced by the layout of the holes in the board. For example, R1 and R4 are unreadable. I had to reference the schematic to determine which location matched which resistor. I had some trouble distinguishing between 5' and 6's, and 8's and 0's because of the extremely small lettering, but usually worked it out by process of elimination.

There are a couple of surface-mounted component, and thankfully, they are pre-installed on the board. That was a big relief on a board this tightly designed.

The quality of the board and the components seems really good. So as long as you've got a good magnifier and have decent skills reading schematics, it's not a difficult build.

I would consider this an "intermediate" kit.
Zanna83
@Richie Witch :

Thank you for your review of the assembling phase. From your description it seems to me that i should be able to put together this module! w00t

However, before puchasing it i would like to read some impressions regarding its sound. For example i still don't understand if it's triangle core or sawtooth core!

Maybe it would be interesting to compare with other VCOs in the same price range. For example VCOb, Dixie II, Pittsburgh...
phonodyne
I'd also be keen to hear thoughts on the sound of it or, even better, hear some demos. It looks like a nice kit.

thermionicjunky wrote:
mbartkow wrote:
Mix a sinusoid with a sawtooth one octave higher, and presto - you have your even harmonic waveform. I believe this is how the waveform is actually derived in Befaco VCO.


Yes, specifically a double-frequency saw derived from the same VCO core mixed with a sine with the proportion of 1:1.27.

So is it a sawtooth core, then? I can't seem to find that info anywhere in the Befaco product details.
mbartkow
Based on the schematics, it's a classic saw core design, however a BJT is used to discharge the capacitor (instead of a commonly used JFET), which may have impact on the sharpness of the edge of sawtooth, hence it will impact the timbre slightly. This may also yield a small spike in the triangle waveform which will sound a little buzzy. These are only speculations based on personal experience with similar circuits, I don't have the actual module.
Randy
mbartkow is correct about the triangle.

http://www.youtube.com/watch?v=rv7wAsl5_-o

Randy
phonodyne
Thanks for the additional info and video. I'm considering building a pair of these. There aren't too many audio examples or opinions floating about yet, though.
Footkerchief
Any other opinions on this module? Size, price, and feature set all look good, but would need verification of the tracking, and audio demos.
Footkerchief
Surely someone has some opinions on this module?
jensu
I'm onto this aswell. Would be gret to get DivKid to make a series on the befaco modules. Even VCO and Rampage at least.
insula
jensu wrote:
I'm onto this aswell. Would be gret to get DivKid to make a series on the befaco modules. Even VCO and Rampage at least.


i have both modules, i'm going to try this week to make a demo-, let see how goes. MY ASS IS BLEEDING

besides the rampage module is a really cool and flexible complex evnvelope generator. nanners
jensu
insula wrote:
jensu wrote:
I'm onto this aswell. Would be gret to get DivKid to make a series on the befaco modules. Even VCO and Rampage at least.


i have both modules, i'm going to try this week to make a demo-, let see how goes. MY ASS IS BLEEDING

besides the rampage module is a really cool and flexible complex evnvelope generator. nanners


That would be really nice. The rampage seems like a bit of a no-brainer.
bonjourmyfriends
Could someone with this kit tell me the values for the pots for Fine Tune and Pulse Width?

I had PCBs printed, and I've got every part ready to order except the two pots - the values are not included anywhere on the schematic or instructions, although it does say that they're this type (PDF Datasheet).
galingong
bonjourmyfriends wrote:
Could someone with this kit tell me the values for the pots for Fine Tune and Pulse Width?

I had PCBs printed, and I've got every part ready to order except the two pots - the values are not included anywhere on the schematic or instructions, although it does say that they're this type (PDF Datasheet).


I have found nothing regarding those values, even in the CAD files.

Although I can make suggestions based on the circuit. Both of them are voltage dividers. Since the PW knob is connected to +12V and -12V you should be ok with a 100k linear.
The value of the Fine knob defines the range. On the front panel it says +7 and -7 (I guess that's a perfect fifth, 1 Octave total range). If you want to go for that, the pot value should be 10k linear.
galingong
I'd also like to ask something - what is component T_P_1 for? It's supposed to be a single pinhead on the control board, but I couldn't find it's counterpart on the main board, nor have I figured out it's purpose.
Ya-Neck
It's not a component it's a point for calibration
bonjourmyfriends
Thanks for the advice, that all makes sense.

galingong wrote:
I'd also like to ask something - what is component T_P_1 for? It's supposed to be a single pinhead on the control board, but I couldn't find it's counterpart on the main board, nor have I figured out it's purpose.


Good question, I hadn't noticed that. It's a 1-pin header on the control board, but on the main board the trimpot for V/OCT_LIN would be in the way. Nothing around V/OCT_LIN appears to connect to it on the schematic.

You can see the hole and the trimpot just below the top left spacer on this picture.



EDIT: ^answered above we're not worthy
plogbidman
Very good great sounding VCO ! nanners
maciej83
Anyone knows if it tracks as good as advertised?
BugBrand
T_P_1 --- probably stands for Test_Point_1 - somewhere you can probe with a multimeter etc when calibrating the module.
Befacosynth
BugBrand wrote:
T_P_1 --- probably stands for Test_Point_1 - somewhere you can probe with a multimeter etc when calibrating the module.


BINGO!

It´s used to set the voltage refernece precisely to do the octaves selection.

maciej83 wrote:
Anyone knows if it tracks as good as advertised?.


if I tell you that it does. Could be considered advertising? meh
BigCranberry
One problem I'm having is that the transistor pair QQ_2, one of the surface mount componenets, keeps disconnecting. I will resolder, then after powering the module for a few hours, it will become disconnected again. This is extremely annoying considering it is placed underneath an IC socket which needs to be removed to access the component.

I'm going to try going at it with a heat gun at my office.

Any suggestions Befaco?
Befacosynth
BigCranberry wrote:
One problem I'm having is that the transistor pair QQ_2, one of the surface mount componenets, keeps disconnecting. I will resolder, then after powering the module for a few hours, it will become disconnected again. This is extremely annoying considering it is placed underneath an IC socket which needs to be removed to access the component.

I'm going to try going at it with a heat gun at my office.

Any suggestions Befaco?


Replace the socket for this kind of pins:



Makes accessing SMD way easier.

If problem persists, drop us a mail and we will fix it for you!
Befacosynth
BigCranberry wrote:
One problem I'm having is that the transistor pair QQ_2, one of the surface mount componenets, keeps disconnecting. I will resolder, then after powering the module for a few hours, it will become disconnected again. This is extremely annoying considering it is placed underneath an IC socket which needs to be removed to access the component.

I'm going to try going at it with a heat gun at my office.

Any suggestions Befaco?


Replace the socket for this kind of pins:



Makes accessing SMD way easier.

If problem persists, drop us a mail and we will fix it for you!
Chidori
Em, so this is probably a very stupid question...

Where do I connect my multimeter to ground(GND)? I see T_P_1. Is there another header specifically for ground? I'm having trouble wrapping my head around the concept of ground, so I'm guessing this should be obvious.
BigCranberry
Chidori wrote:
Em, so this is probably a very stupid question...

Where do I connect my multimeter to ground(GND)? I see T_P_1. Is there another header specifically for ground? I'm having trouble wrapping my head around the concept of ground, so I'm guessing this should be obvious.


Here is a link to the schem: http://befaco.org/img/Modulos/evenVCO/even_VCO_sch_v03.pdf

a good bet is to use any of the ground lugs on the 3.5 mm jacks. i think this vco uses these: http://erthenvar.com/store/image/data/jack_pin_out.jpg
Chidori
Perfect, thanks!

Any recommendation for a high frequency tuner plug-in? I tried using my TC Electronics Polytune, but it doesn't show the octave/etc. Then I switched to a free plugin called Lingot and am running audio out of the Even VCO into my M-Audio Fasttrack Ultra. I'm stuck on the last step of calibration. The tuner shows ~25hz for the frequency of the 1/4" wave and higher. Clearly it sounds like it's in the right range, but I can't seem to get an accurate reading by fiddling with the settings in Lingot.
bonjourmyfriends
I'm having trouble calibrating the tuning/voltage. The first steps are fine but when I get to the V/OCT_LIN steps for 1/4' octave, I can't tune the C7.

So C2 (8') and C5 (1') are both tuned perfectly to C, but when I get to C7 (1/4') the note is at C#, the V/OCT_LIN trimpot only makes a small difference in getting it closer to C, and I run out of turns on the trimpot before I can get there. What should I do? Change the value of this trimpot? Anything simpler I can do involving TUNE or the INIT trimpot?

I'm referring to the last page of this PDF, by the way.
solipsistnation
bonjourmyfriends wrote:
I'm having trouble calibrating the tuning/voltage. The first steps are fine but when I get to the V/OCT_LIN steps for 1/4' octave, I can't tune the C7.


I just had something similar happen, but it was tuned close enough to C7 that I didn't really care that much.

And then I hooked up a CV source and tried to play it and discovered that the calibration process had left the whole thing tuned to C# and I had to turn down the tune knob to get it to be in tune with my other stuff. So that was weird. I may try to recalibrate it tomorrow, but since the tune knob works to get it in tune with other things I may not bother.

Also, the parts that came with my kit were a little off-- it was missing the 3pf cap, and one set of 3 caps, and it came with 3 extra 10pf caps of a different type than the other 10pf caps, so that was confusing. Luckily I live someplace with good electronics stores, so I could easily get a replacement, and it was like a 15 cent part so I'm not too annoyed-- it was just confusing.

It sure sounds good, though. The PWM is really nice. I could just sit around holding down keys and modulating the PWM all night.
Richie Witch
maciej83 wrote:
Anyone knows if it tracks as good as advertised?

It took me almost an hour to calibrate it exactly, but once I did, it tracks to +/-0.5 cents or less, across all ten octaves. hyper

I patched mine into Ableton Live and used Live's native tuner plugin. Admittedly, I had to loop around the calibration procedure more times than I can count, but... every time I repeated the process, the tracking just kept getting closer, so I kept going until I reached that very precise measurement.
NekoNeko
Interested aswell,

how well does it handle fm?
hydrobert
bonjourmyfriends wrote:
I'm having trouble calibrating the tuning/voltage. The first steps are fine but when I get to the V/OCT_LIN steps for 1/4' octave, I can't tune the C7.

So C2 (8') and C5 (1') are both tuned perfectly to C, but when I get to C7 (1/4') the note is at C#, the V/OCT_LIN trimpot only makes a small difference in getting it closer to C, and I run out of turns on the trimpot before I can get there. What should I do? Change the value of this trimpot? Anything simpler I can do involving TUNE or the INIT trimpot?


i have the same problem... :-(

did u find the way to fix it?

and i had to turn the fine tune pot to +5 at the calibration ?

there were a few different parts in my kit :

capacitor`s :
2n2J 100 schould it be.. but i find only 2n2k 100?
.68j63 should it be but i find only .68k63 ?

and there are 3 E102M to much ? i used the normal 102 code ones ?
and there was no 10p capacitors with code 100J only 3 caps with the code 10 ...? i used this ones ?

did i made something wrong tilll here...?

then was one 100k resistor missing i only had one with 2 % tolerance not 1% like the others.... can that cause to calabrating problems?(put it on r45)

at the moment the sine wave looks very edgy with a spike and sound like the triangle wave?

i am sad ...i did 8 other diy kits before ..and no problems ...but this one wont let me sleep well..

i hope someone can help me..


greetz robert
bonjourmyfriends
hydrobert wrote:
bonjourmyfriends wrote:
I'm having trouble calibrating the tuning/voltage. The first steps are fine but when I get to the V/OCT_LIN steps for 1/4' octave, I can't tune the C7.

So C2 (8') and C5 (1') are both tuned perfectly to C, but when I get to C7 (1/4') the note is at C#, the V/OCT_LIN trimpot only makes a small difference in getting it closer to C, and I run out of turns on the trimpot before I can get there. What should I do? Change the value of this trimpot? Anything simpler I can do involving TUNE or the INIT trimpot?


i have the same problem... :-(

did u find the way to fix it?


Not yet, but it's a relief to hear I'm not alone! I did receive new trimpots in the mail, so I'm going to try a different value to see if that will keep the upper octaves in tune. I think it will work, since everything else in the calibration procedure is OK so far.

It's strange that everything else works, and the lower octaves can be calibrated up to a point... although I still can't use the module til I solve this. Finally have a bit of free time to experiment, so I'll give it a shot tonight and let you know if it works.

Smash!
bonjourmyfriends
It worked! Everything's in tune across all the octaves now. It took me an hour of calibrating. I changed the "V/Oct" trimpot to 50K. I still ran out of turns on the 50K trimpot the moment that everything became calibrated, so you may want to go to an even higher resistance, between 50K-100K.


hydrobert wrote:
and i had to turn the fine tune pot to +5 at the calibration ?


Don't worry too much about this. You can put the fine tune pot back down, as long as you continue tuning each octave to the same note. In other words, some of the time I was tuning every octave to C, some of the time I was tuning to G - as long as you pick one note and stick with it for a while. I believe the internal "Init" trimpot has the same effect as the external fine tuning knob. So if you run out of turns on the fine tune knob, you can also re-center your fine tune knob and then use the "Init" trimmer to get back to C.
hydrobert
bonjourmyfriends wrote:
It worked! Everything's in tune across all the octaves now.


great... we're not worthy


thanks for this info...

....i will try it today also ...i have a 100k trimpot to test....
atte
I just ordered one from thonk today. Will I need to swap resistors from what will be supplied with the kit to avoid trouble, or does the problems come from people using things not supplied with the kit?
Richie Witch
atte wrote:
I just ordered one from thonk today. Will I need to swap resistors from what will be supplied with the kit to avoid trouble, or does the problems come from people using things not supplied with the kit?

Curious about that myself... I used just what was in the kit and had no problems.
bonjourmyfriends
atte wrote:
I just ordered one from thonk today. Will I need to swap resistors from what will be supplied with the kit to avoid trouble, or does the problems come from people using things not supplied with the kit?


I made mine myself. Go ahead, you should be fine with the kit - it seems like nobody else is having problems.

I had the PCBs made and I sourced my own parts using the BOM extracted from the schematic Eagle files. It's possible that one resistor value got changed somewhere along the line, and the Eagle files didn't get updated while the kit did. Something like that.

It's possible it's my own fault too, maybe I put the wrong resistor in somewhere and I had to make up for the difference with the trimpot. I kinda doubt it though because I've now built two with this problem. At any rate, there is a cheap and easy solution now, and the VCO sounds great!

nanners
maltemark
I recieved a kit with the same mix of parts. if someone found out which parts are ok replacements and how to determine which not to use, i would be grateful. (i have not built it yet, so cannot say anything about tuning.

hydrobert wrote:
bonjourmyfriends wrote:
I'm having trouble calibrating the tuning/voltage. The first steps are fine but when I get to the V/OCT_LIN steps for 1/4' octave, I can't tune the C7.

So C2 (8') and C5 (1') are both tuned perfectly to C, but when I get to C7 (1/4') the note is at C#, the V/OCT_LIN trimpot only makes a small difference in getting it closer to C, and I run out of turns on the trimpot before I can get there. What should I do? Change the value of this trimpot? Anything simpler I can do involving TUNE or the INIT trimpot?


i have the same problem... :-(

did u find the way to fix it?

and i had to turn the fine tune pot to +5 at the calibration ?

there were a few different parts in my kit :

capacitor`s :
2n2J 100 schould it be.. but i find only 2n2k 100?
.68j63 should it be but i find only .68k63 ?

and there are 3 E102M to much ? i used the normal 102 code ones ?
and there was no 10p capacitors with code 100J only 3 caps with the code 10 ...? i used this ones ?

did i made something wrong tilll here...?

then was one 100k resistor missing i only had one with 2 % tolerance not 1% like the others.... can that cause to calabrating problems?(put it on r45)

at the moment the sine wave looks very edgy with a spike and sound like the triangle wave?

i am sad ...i did 8 other diy kits before ..and no problems ...but this one wont let me sleep well..

i hope someone can help me..


greetz robert
atte
Same here, I posted in another thread (https://www.muffwiggler.com/forum/viewtopic.php?t=156213), but here's my latest question repeated:

I'm doing the caps on main board now. I think I have sorted all out except 1x3p, 3x10p and 3x1n and I have the following left to choose from:



My best guess is that the top ones and the bottom ones are 1n (which ones do I use then, the lower ones?).

I guess the middle ones (marked with black felt tip) are the 10p ones, but I really can't read anything on them.

I assume the 3p, which according to the manual is redundant is simply not included, and should just forget about it.

How does that sound?
atte
Somethings not right with my first build (still waiting for the missing resistor in the mail from befaco for the second build).

I went through the calibration procedure and according to that, everything is fine. However when I send pitch cv to v/oct it's about 20 cents sharp for every octave up, which obviously is totally unacceptable. The cv source is a BeatStep Pro, my other oscillators tracks fine with v/oct from it.

I'm really clueless, what to do?
Befacosynth
atte wrote:
Somethings not right with my first build (still waiting for the missing resistor in the mail from befaco for the second build).

I went through the calibration procedure and according to that, everything is fine. However when I send pitch cv to v/oct it's about 20 cents sharp for every octave up, which obviously is totally unacceptable. The cv source is a BeatStep Pro, my other oscillators tracks fine with v/oct from it.

I'm really clueless, what to do?


I already replied to your mail, but will paste it here if this is happening to someone else:

This might be caused by damaged SMD resistors. Please measure their values. They are 120 Ohm 0.1% so they should be exactly same value (well, 0.12 ohm deviation).
You can also measure the voltages in each pin of the rotary encoder. The changes must be also exactly the same.

If this is not right, then the calibration procedure is done based on wrong octave changes so when using a CV input you have this behaviour.
atte
I only have an entry-level multi meter (Vellerman DVM851), so I don't trust it to be that precise. Anyhow, here are the measurements of the resistors under the octave encoder, clock-wise:

120.5
120.5
120.4
120.4
120.4
120.5
120.4
120.4
120.4

How does that look, taking into account that my meter might be (consistently) off?

I'm pretty sure I did the calibration to the point. Will try again later, though...

A few questions, to help me understand a bit better:

1) What exactly does REF_ADJ_1 do? I mean that might have been a bit off as well, would that have an impact on the tracking?

2) Is there any one trimpot that controls the tracking, or is it a combination of several things? I mean, the things I calibrated in the past more or less had one pot for base tune and one for tracking, but with the even vco, it's hard to tell what is doing what from the rather convoluted calibration procedure.

3) Should I do anything about C22, right now there's just nothing soldered there?

4) When I first put the even in the case there was a solder bridge between legs of C14 (or was it C16), causing my PSU to now provide -12V (IIRC). I immediately shut the power off and by visual inspection found the solder bridge and fixed it. From then on the even seemed to work as expected until the end of the calibration procedure, when I tried sending it v/oct. Could that have damaged something?

When I receive the missing resistor for the other build, it will be interesting to see how the other even behaves after calibration.
BigCranberry
i completed my second build of this module and i'm having one issue. all the wave outputs (except square) are greater in amplitude than they should be, based on the schematic and my other module. the outputs are ~8V-p instead of ~5.6V as the schematic indicates. i've checked all the component values of the saw core circuit (IC2B, IC4A, IC2A, and associated passives) and they are correct. i've also performed the calibration several times but it doesn't seem to affect the output level.

any idea what might be causing this? the first module i built was a V0.3.3 while this one is a V0.3, could that make a difference? according to the schematics the voltage levels for the saw core of both versions are the same.

this wouldn't be a huge deal, but the increased amplitude of the saw core increases the amplitude of the triangle and thus causes the sine wave to distort. i'd also like both my befaco VCOs to behave the same.

i suppose i could modify the gain of IC2A, but i'd rather identify the root of the problem.

any help is appreciated!

here is a link to the schematic for reference: https://befaco.org/img/Modulos/evenVCO/even_VCO_sch_v03.pdf
BigCranberry
BigCranberry wrote:
i completed my second build of this module and i'm having one issue. all the wave outputs (except square) are greater in amplitude than they should be, based on the schematic and my other module. the outputs are ~8V-p instead of ~5.6V as the schematic indicates. i've checked all the component values of the saw core circuit (IC2B, IC4A, IC2A, and associated passives) and they are correct. i've also performed the calibration several times but it doesn't seem to affect the output level.

any idea what might be causing this? the first module i built was a V0.3.3 while this one is a V0.3, could that make a difference? according to the schematics the voltage levels for the saw core of both versions are the same.

this wouldn't be a huge deal, but the increased amplitude of the saw core increases the amplitude of the triangle and thus causes the sine wave to distort. i'd also like both my befaco VCOs to behave the same.

i suppose i could modify the gain of IC2A, but i'd rather identify the root of the problem.

any help is appreciated!

here is a link to the schematic for reference: https://befaco.org/img/Modulos/evenVCO/even_VCO_sch_v03.pdf


turns out it was a bad resistor (R10) in the output amp of the sawtooth d'oh!
420troll
[quote]
A few questions, to help me understand a bit better:

1) What exactly does REF_ADJ_1 do? I mean that might have been a bit off as well, would that have an impact on the tracking?

2) Is there any one trimpot that controls the tracking, or is it a combination of several things? I mean, the things I calibrated in the past more or less had one pot for base tune and one for tracking, but with the even vco, it's hard to tell what is doing what from the rather convoluted calibration procedure.
[quote]

i have had luck adjusting REF_ADJ_1 to help get common tracking between the octave switch and the cv tracking of a beatstep pro but after 20 min the tracking is out again i wonder if it could be my power supply in the case fluctuating? going to have to monitor that. i noticed that all my meters were a little different when i adjusted REF_ADJ_1 to 1.504 it was perfect for about 20 min.
atte
420troll wrote:

i have had luck adjusting REF_ADJ_1 to help get common tracking between the octave switch and the cv tracking of a beatstep pro but after 20 min the tracking is out again i wonder if it could be my power supply in the case fluctuating? going to have to monitor that. i noticed that all my meters were a little different when i adjusted REF_ADJ_1 to 1.504 it was perfect for about 20 min.


So your even is not stabilizing? Sounds like mine, one of my evens is in Barcelona for investigation, although Befaco haven't been able to track down (or as far as understand, even reproducing) the issue yet.
420troll
atte wrote:
420troll wrote:

i have had luck adjusting REF_ADJ_1 to help get common tracking between the octave switch and the cv tracking of a beatstep pro but after 20 min the tracking is out again i wonder if it could be my power supply in the case fluctuating? going to have to monitor that. i noticed that all my meters were a little different when i adjusted REF_ADJ_1 to 1.504 it was perfect for about 20 min.


So your even is not stabilizing? Sounds like mine, one of my evens is in Barcelona for investigation, although Befaco haven't been able to track down (or as far as understand, even reproducing) the issue yet.


ya i put it in another case with different power supply (tip top zues, instead of dopfer diy.), re calibrated after warm up that takes about a half hour in the case. i can see the tuning rise with the temperature over a half hour till its stable, but then it starts to fall as it cools, when i take it out to calibrate. it seems super sensitive to heat, i thought it was supposed to be super stable but i have had no luck, :( each day i go back to it it is way off! 30 cents over 3 octaves today after it was perfect for hours yesterday? Dead Banana
Befacosynth
420troll wrote:

ya i put it in another case with different power supply (tip top zues, instead of dopfer diy.), re calibrated after warm up that takes about a half hour in the case. i can see the tuning rise with the temperature over a half hour till its stable, but then it starts to fall as it cools, when i take it out to calibrate. it seems super sensitive to heat, i thought it was supposed to be super stable but i have had no luck, :( each day i go back to it it is way off! 30 cents over 3 octaves today after it was perfect for hours yesterday? Dead Banana


Thanks a lot for this feedback! The more data we have the better to perform some testings over here.

We are testing with Atte's VCO and a couple of other VCOs here in the lab. We are definetly facing an issue here and still did not found a satisfactory answer.

Stay tunned for some extra info, hopefully soon confused
FiltroMan
A BOM
https://docs.google.com/spreadsheets/d/1g4JD5RutYXlQ7D7ybxdso7Vra4tFtW BkU9zFE5gYpRk/pubhtml?gid=0&single=true&widget=true&header s=false
Is there any more hidden component ?

R115 shown in the schematic as 1k 1% but in manual as 50 0.1% , I'm not sure about this .
It works? 667-ERA-S33J102V
JJCS88
I have had trouble getting the v/oct to track. I have the octave select working, but then the v/oct trimmer does nothing.

I read earlier in the thread replacing this with a higher value 100K trimmer might work.

I have spent so long trying to get this to track properly. I have already tried replacing the SMT resistors.

(I also had the issue of the received components not matching the BOM)
420troll
JJCS88 wrote:
I have had trouble getting the v/oct to track. I have the octave select working,


(I also had the issue of the received components not matching the BOM)



thats exactly how mine was working till i noticed the heat in the case was changing the tracking, my temporary fix is now to hard sync it to tip top
s z3000 to get it to track!
I really wish we would hear back from befaco about this. when i last posted he told me he had 6 units in the shop with the same issue he was trying to figure out but haven't hear anything for months now? i would feel bad selling it since its messed up don't really know what to do Dead Banana help
maltemark
Also curious to hear back, I'm having a hard time tuning mine and getting it to track
Daisuk
Damn. I was thinking about building one of these next - so what's the status on this? Is there a general tracking issue with this VCO?
float32
I had the same tracking issue - calibrate for the octave selector, but then v/oct is sharp ~20c per octave. I think I've figured it out. The v/oct summing resistors are 100k, and the octave selector is .5v/oct, so its summing resistor should be 50k. The v/oct inputs have 100k 0.1% resistors but the selector has a 50k 0.1% in series with a normal 1k 1% (R115). I just jumped R115 and recalibrated and now I'm getting much better tracking, about +/- 15c across 10 octaves.

Now for some fun math! The 100k v/oct summing resistors result in 10uA/octave into the summing amp. With R115 in series with the 50k resistor, the octave selector gives 0.5V / 51kohm = ~9.8uA/octave. If you calibrate to the octave selector, then adding 1V to a v/oct input would multiply the vco frequency by 10/9.8 = ~1.02 which is 1224 cents, or 24 cents above the octave, which is pretty close to what we observed before the fix w00t
Befacosynth
Sorry for the lack of communication over here..... seems we are not passing by muffs as often as we should!!

We have been investigating all mentioned issues with Even VCO since a few months and driving us nuts... so here some updates.

About tracking issues, we have a workaround in place and will implement definitive fixes on next version.

THIS:

float32 wrote:
I had the same tracking issue - calibrate for the octave selector, but then v/oct is sharp ~20c per octave. I think I've figured it out. The v/oct summing resistors are 100k, and the octave selector is .5v/oct, so its summing resistor should be 50k. The v/oct inputs have 100k 0.1% resistors but the selector has a 50k 0.1% in series with a normal 1k 1% (R115). I just jumped R115 and recalibrated and now I'm getting much better tracking, about +/- 15c across 10 octaves.

Now for some fun math! The 100k v/oct summing resistors result in 10uA/octave into the summing amp. With R115 in series with the 50k resistor, the octave selector gives 0.5V / 51kohm = ~9.8uA/octave. If you calibrate to the octave selector, then adding 1V to a v/oct input would multiply the vco frequency by 10/9.8 = ~1.02 which is 1224 cents, or 24 cents above the octave, which is pretty close to what we observed before the fix w00t


Quite sharp, float32!! cool
This is the workaround in place and what has been changed in current VCO documentation!
Question: are by any chance these 15 cents deviation located in the last three octaves? in our tests there is one cent in octave 7 and 2 - 8 extras on 8th and 9th.
float32
Yep the biggest deviations are in the lowest and highest octaves. I recalibrated after waiting for the module to warm up in my case and was able to get even better tracking than before.
drmarble
Befacosynth wrote:

Quite sharp, float32!! cool
This is the workaround in place and what has been changed in current VCO documentation!
Question: are by any chance these 15 cents deviation located in the last three octaves? in our tests there is one cent in octave 7 and 2 - 8 extras on 8th and 9th.


Yes, float32, thank you for the analysis and the suggested fix! I just finished building an Even VCO the other day. After verifying that the updated documentation from Befaco now officially says to jumper R115, I went back to mine and did that modification.

After many tuning attempts, however, I am still getting poor results on pitch tracking across octaves.

Befaco, could you explain which parts of the perfomance are going to be the most affected by temperature? Is the "width" trimpot's effect going to vary with temp? Or just the baseline "init", i.e. absolute tuning, parameter?

Also, has anyone gone in and modified their Even VCO by adding thermal paste to the key temperature-sensitive components?
drmarble
After poking around a bit more on the schematic, I pulled up the PCB files to see where QQ_1 and T_SENS are positioned. So they're the pair of SMD parts that were under IC2. Should they get some heat sink compound piled on top of them?

Granted, I'm new to using tempco parts – but as-is, I don't see how the two parts would be in thermal contact, just sitting side by side on the board.

And was the idea of placing them under IC2 just to save space? Or is it important for QQ_1 and the tempco to be thermally bonded with IC2?


EDIT: Or maybe the idea of being under IC2 is to put the matched transistor pair and the tempco in a little cave together, to reduce (cooling) air flow across them? And if so, would sealing the edges of the "cave" (with compound or heat shrink or something around the IC socket) further reduce frequency drift?
drmarble
I didn't have any "heat sink compound" around, so I decided to build a "breeze shield" around IC2. Got the idea from here:
http://musicfromouterspace.com/analogsynth_new/ELECTRONIC_PARTS/Matche d2N3904_MFTempco.php

Here's a pic:



Full post on it here:
http://fishboytech.tumblr.com/post/157581166963/added-a-heat-shrink-br eeze-shield-around-ic2-on
bonjourmyfriends
I just jumpered R115, changed one of the SMD resistors near the octave selector, and now there's no sound coming out of my module from any of the waveform outputs. It had been working for a year.

d'oh!
bonjourmyfriends
oops
drmarble
bonjourmyfriends wrote:
I just jumpered R115, changed one of the SMD resistors near the octave selector, and now there's no sound coming out of my module from any of the waveform outputs. It had been working for a year.


Something else must have gone wrong. Even without any voltage coming from the octave selector section, there would still be other sources of CV, and sound would still come out.

Did anything get switched around with the power connectors, after you took the module out to solder it? (The Even VCO has power polarity protection diodes, so you most likely wouldn't have damaged anything even if you did plug the power in backwards.)
bonjourmyfriends
drmarble wrote:
bonjourmyfriends wrote:
I just jumpered R115, changed one of the SMD resistors near the octave selector, and now there's no sound coming out of my module from any of the waveform outputs. It had been working for a year.

Did anything get switched around with the power connectors, after you took the module out to solder it?


Nope, it has a keyed header so it'd not really possible to plug in backwards. I checked a couple points with the multimeter and both panels were receiving power - turned the front pots and saw the voltage change accordingly.

Really all I did was remove and jumper R115 and replace R117 with a more accurate SMD resistor. Checked those with a multimeter as well and there was continuity.

So what could make the sound disappear from all five jacks while it's all apparently still powered?
dlabtot
Have you contacted Befaco? They are actually pretty awesome.
Varthdader
So, one more case of an EvenVCO not being able to calibrate properly.

I get to C5 on the ´1 octave by having my Freq. knob out of center, running out of turns on the trimmer pot. Center of freq pot gives me C4.

I go though the calibration chart provided in the last page of the build doc, and manage to get the `1 and `8 steps tracking C, but can´t tune `1/4, the trim pot runs out of turns between G and A

Tried contacting Befaco, but had no reply so figured maybe somebody around Muff´s had a clue as to how to tune this pup.
Varthdader
So, Befaco are still silent on how to properly tune my Even.

I am about to get some 100k trimmers to replace the ones in the kit in the hope this gives me enough adjustment to be able to dial in the tuning.

I hope I don´t damage anything with this, my Even is working fully (apart from not being calibrated)
destroysound
drmarble wrote:
I didn't have any "heat sink compound" around, so I decided to build a "breeze shield" around IC2. Got the idea from here:
http://musicfromouterspace.com/analogsynth_new/ELECTRONIC_PARTS/Matche d2N3904_MFTempco.php


Also having pretty drastic temperature drift problems here:

- Take it out of the case and the tracking immediately gets wonky and the pitch drops at least 50 ct.
- Tune it up and adjust the tracking outside of the case, everything is good until I put it back in.

I've been letting it warm up periodically between taking it out and making fine adjustments which gives me a couple of octaves of tracking. But it sure would help not to have to do this little dance. drmarble, did this fix help you at all?
drmarble
destroysound wrote:
drmarble wrote:
I didn't have any "heat sink compound" around, so I decided to build a "breeze shield" around IC2. Got the idea from here:
http://musicfromouterspace.com/analogsynth_new/ELECTRONIC_PARTS/Matche d2N3904_MFTempco.php


Also having pretty drastic temperature drift problems here:

- Take it out of the case and the tracking immediately gets wonky and the pitch drops at least 50 ct.
- Tune it up and adjust the tracking outside of the case, everything is good until I put it back in.

I've been letting it warm up periodically between taking it out and making fine adjustments which gives me a couple of octaves of tracking. But it sure would help not to have to do this little dance. drmarble, did this fix help you at all?


Ah, that fix didn't really help a ton. It just slows down the effect of cool air a little bit, but the drift itself isn't improved over the longer term.

There's a bunch more about my attempts to understand the tempco circuit used by the Befaco VCO here:
https://www.muffwiggler.com/forum/viewtopic.php?t=177712

I haven't had time to revisit the troubleshooting for a while, but with the help of Muffwiggler member "guest", I am basically re-engineering that part of the VCO, and will be replacing the tempco resistor and some other supporting parts.

It's all a bunch more time and effort than I had planned spending on a VCO which was supposed to be super accurate and stable. It has great features but a massive Achilles heel. Oh well, at least it's an education...
RawMaterial
Just built a kit from Synthcube. Had no trouble building the kit, all the parts were present and instructions were clear. I was able to calibrate the module by following the instructions, however when I plug in a v/oct cv source, it does not track accurately. It would only track the octave rotary switch. I then calibrated again using the instructions, but instead switched between c1-c5 using v/oct cv rather than the octave rotary and got it to track perfectly, but then it would not track the octave rotary switch. So it seems I can track one or the other, but not both. What am I doing wrong?
donpachi
RawMaterial wrote:
when I plug in a v/oct cv source, it does not track accurately. It would only track the octave rotary switch. I then calibrated again using the instructions, but instead switched between c1-c5 using v/oct cv rather than the octave rotary and got it to track perfectly, but then it would not track the octave rotary switch. So it seems I can track one or the other, but not both.


Don't know if you saw this on page 1 --- did you jumper (short out) R115?

float32 wrote:
I had the same tracking issue - calibrate for the octave selector, but then v/oct is sharp ~20c per octave. I think I've figured it out. The v/oct summing resistors are 100k, and the octave selector is .5v/oct, so its summing resistor should be 50k. The v/oct inputs have 100k 0.1% resistors but the selector has a 50k 0.1% in series with a normal 1k 1% (R115). I just jumped R115 and recalibrated and now I'm getting much better tracking, about +/- 15c across 10 octaves.
drmarble
donpachi wrote:

Don't know if you saw this on page 1 --- did you jumper (short out) R115?


That was my 1st thought too...

If the pitch is tracking well with an external V/oct CV source, then congrats, you got a tempco circuit that is performing reasonably well. Luck of the draw I guess.
RawMaterial
Total bonehead move on my part. I had read up on the tracking issue and jumping R115 before I even received the kit, then promptly forgot all about it, as the build went so flawlessly. It didn't even occur to me that I missed that step until you guys mentioned it. Thanks!
It's peanut butter jelly time!
Randy
I did the R115 mod, still no luck on this. It worked for awhile 'though. Now, I can't get better than a major 6th interval out of the octave switching and less than 2.45V from TP1.

I have replaced the LM336 as well. Befaco tells me the centre pin of the LM336 should be 5V but it is also 2.45V. This is an odd one.

Randy
Oblivion
So . .. what's the consensus on this module? Go or no-go? Looks awesome at first blush, but then a bunch of problems cropped up. All solved?
drmarble
Oblivion wrote:
So . .. what's the consensus on this module? Go or no-go? Looks awesome at first blush, but then a bunch of problems cropped up. All solved?


Tuning problems not solved yet. See details here: https://www.muffwiggler.com/forum/viewtopic.php?t=177712

Manufacturer expressed to me that they want to revisit the design, to address these issues... so I'd check in with them to see where they are in that process, before ordering one.
Oblivion
Thanks, drmarble. Had a line, but I'll pass for now. I've got enough wonky gear.
Cloudstache
drmarble wrote:


Manufacturer expressed to me that they want to revisit the design, to address these issues... so I'd check in with them to see where they are in that process, before ordering one.


If there's a serious design flaw, it's not cool that it hasn't been announced more openly by Befaco and that these are still being sold today. I'm sure I'm not the only sucker who bought a second kit to try to figure out what went wrong with his first build.

Are there a lot of people building it and having no tuning problems?
bchampion96
Cloudstache wrote:
drmarble wrote:


Manufacturer expressed to me that they want to revisit the design, to address these issues... so I'd check in with them to see where they are in that process, before ordering one.


If there's a serious design flaw, it's not cool that it hasn't been announced more openly by Befaco and that these are still being sold today. I'm sure I'm not the only sucker who bought a second kit to try to figure out what went wrong with his first build.

Are there a lot of people building it and having no tuning problems?


Tuning on mine hasn't been completely perfect. I've got the tracking reasonable, but it does go out of tune when out of my case/with temperature. Using the fine tune, fixes it mostly. Definitely not 100% accurate, but for sequences spanning 3 octaves, it'll do okay for me! Just finished uploading my video on the chap!

https://youtu.be/QiFMECYU4Ds
bchampion96
Just got an email through from Thonk that Befaco are sending out (free of charge) an add on to Even VCOs for better temperature stability. Will update when mine arrives! smile
Dancing_Bananas
Cloudstache wrote:


Are there a lot of people building it and having no tuning problems?


I built one in a workshop, two more were also build, and all three worked fine. Calibration took a little longer than expected maybe, but that's it.

bchampion96 wrote:


Just got an email through from Thonk that Befaco are sending out (free of charge) an add on to Even VCOs for better temperature stability. Will update when mine arrives! smile


Please do, I'm surprised this hasn't been announced louder.
bchampion96
Dancing_Bananas wrote:
Cloudstache wrote:


Are there a lot of people building it and having no tuning problems?


I built one in a workshop, two more were also build, and all three worked fine. Calibration took a little longer than expected maybe, but that's it.

bchampion96 wrote:


Just got an email through from Thonk that Befaco are sending out (free of charge) an add on to Even VCOs for better temperature stability. Will update when mine arrives! smile


Please do, I'm surprised this hasn't been announced louder.


Yeah, I can't find anything about it on befaco's website. Just the email I got from thonk
Richie Witch
Dancing_Bananas wrote:
I built one in a workshop, two more were also build, and all three worked fine. Calibration took a little longer than expected maybe, but that's it.

This was my experience as well. The module has worked perfectly since I found the bus pin I forgot to solder. hihi Calibration took about an hour. Yes, it's long and tedious and I had to cycle through the flow chart about 20 times, but patience paid off. The thing tracks perfectly (+/- 2 cents across 8 octaves) after a 20-minute warm up. I have an L-1 tuner that I keep connected to it just to be sure.

During the warm-up, I've seen as much as a two-and-a-half semitone drift, but once it's warm, I've had no further issues.
bchampion96
Here's a link to the changes you need to make with the upgrade kit (which hasn't arrived yet). SMT stuff in there as well which is not good news for me. Never done any before :(

https://www.befaco.org/docs/Even%20VCO/Tempupgrade/EvenVCO_Temp_Upgrad e.pdf
Uvula_Fluorentine
I just received a new Even VCO kit from Modular Addict and it included the components for the thermal stability upgrade. It looks like it still involves changing out the SMT resistor.

It came with pre-mod instructions. The proper instructions for full assembly with the upgrade are at:

https://www.befaco.org/docs/Even%20VCO/Even_VCO_V3.3_assemby_manual_te mp_upgrade_.pdf
imre
Does anyone have a check on the current situation with the kit?
I don't really feel like picking up this kit on the basis of what I've read here, but the situation might've changed?
zorglub76
Hi guys,

I've just finished building the new version of Even VCO, and I'm having problems with calibrating it. It looks like the range is ~3 octaves whatever I do with WIDTH trimmer.

Also, it looks like the trimmers INIT and WIDTH are doing the same job. I set C5 on 1' with INIT, then go to 8' and turn WIDTH all the way to lower the current tone by 5-6 semitones. But when I switch to 1' again C5 is now lowered by the same 5-6 semitones - so WIDTH does not change the range but just shifts the tuning the same way as INIT.

Can anyone suggest what might have gotten wrong with this build? (Btw. I was able to adjust ref. voltage to 1.500V)
zorglub76
And now I found another problem - sine output outputs triangle signal at half the voltage of that from the actual triangle output (square and sawtooth are ok):




I thought that maybe my cheap oscilloscope messed something, so I let Humpback self-oscillate, and I got a nice sine wave:
metabaron24
I am about to build the Even VCO from a full kit. I'm a little nervous about it, it's only my second build and I've read all the stuff about tracking problems and there are a number of revisions to the assembly.

The latest one is for the temperature stability update and it calls for an SMT part to be replaced, it's the temperature sensor under the IC. All the other changes are resistors which is easy.

Now I don't think I can do that myself, too scared of SMT sad

Is that part critical for the update?
Or put differently: Does it even make sense to use the other resistors of the update version and not change the temperature sensor or would I mess up more that way?

Just at the beginning of my journey help
zorglub76
metabaron24 wrote:

Now I don't think I can do that myself, too scared of SMT sad


No worries. All the SMT stuff came presoldered (at least on my board). You should find tempco at the place where some IC should go, and there should also be several smd resistors around the rotary switch.

EDIT: Do worry.
I've just taken a second look at that update document, and it seems that I'm screwed up. I thought that my version (3.3) came with already updated sensor and all... How on earth will I desolder a smd that is already below the IC socket.....
zorglub76
I was under impression that they updated the board and presoldered components when they announced this:



But now I see that they didn't update BOM, upon which I was sourcing the components. Not sure what to think...
metabaron24
I didn't buy mine from them directly but from a shop in the Netherlands, which must have had a pre-upgrade version. My PCB also says V 0.3.3. wich still doesn't mean the temp sensor is the updated one. My component bags also had the old resistor selection. These are the only changes regarding parts: the SMT sensor and a few resistors (5 I think)

I contacted them and they were super helpful. In my case it is relatively easy because I haven't started building yet. I'm going to send in my main PCB and they will replace either the temp sensor or just sent me an updated one instead. (plus they will send the few updated resistors) So the only downside is that I can't start soldering today.
There's also a fun system of Befaco coins to pay for the postage back to me.

Knowing myself, while I'm at it I'll probably pull the trigger on another PCB/panel combo from them nanners
metabaron24
Just took a look at the BMO. As far as I can tell it's updated, so if you've sourced your parts recently you should be fine. It's easy to tell by the temp sensor.
metabaron24
Also the question is: If you have an assembled version that is nicely tuned and tracks well, why bother getting an update? It's not that they weren't usable as stable VCOs before the update, at least that's my impression from reading here.
zorglub76
I bought PCB/Panel on September 26. The BOM I used was from October 17, and that BOM had outdated components....

I actually don't care much for tracking. I do this for a hobby, and I'm interested in using modules for autogenerative music, so, for me unstable VCO is a plus hihi

But I'm annoyed by the two problems I mentioned before - getting only ~3 octaves of range and getting triangle wave from sine output. That's why I'd like to rule out any BOM related issues before trying to debug the module.
zorglub76
Looks like I've got good news for you.

I didn't change the tempco that I got on my 0.3.3 board, but changed everything else (IC's and resistors). I didn't want to wait for those two weird resistors (4.22 and 95k3), so I soldered a few in parallel and measured them - I got 4.2 and 94k9.

I tuned the oscillator to C5, and started measuring frequency. This is what I got so far (left is the time in hh:mm, right is the frequency in Hz):

00:00 - 523.2Hz
00:12 - 527.2Hz
00:25 - 526.7Hz
00:38 - 526.6Hz
00:45 - 526.7Hz
00:53 - 526.6Hz
01:00 - 526.6Hz

I guess that it became stable now, but I'll still run it for some time. It drifted for 11.5 cents, and it seems that it takes about half an hour to stabilize, which is exactly what Befaco stated in their tuning manual.

The other good thing is that now (after changing ICs and resistors) the range that I have is much wider than before. The bad thing is that the range is still wrong. Now whenever I turn the switch I get two octaves down or up instead of just one.

This means that already at 4' I'm getting just 32Hz, and at 1/4' it goes ultrasonic. Ref voltage is still 1.500V, and I didn't need to calibrate that one.
metabaron24
What a weird resistor this is, isn't it. 4.22 Ohms is unheard of. But there we go Resistance is just the result of an equation.

@zorglub: What IC's did you replace? IC2 and IC3 with the LF412? I have those in my bag. Or did you take even fancier ones?

Nicely done just doing it and getting stable results. Way to answer a question. I should develop a more experimental approach. Maybe after my fifth build.
zorglub76
Yes, in the old BOM, IC2 and IC3 were TL072, so I now replaced them with LF412.

Now I see that the schematics file is offering some more ways of checking if everything works properly (exact voltages for each position of the octave switch, oscillator graph in different points etc.). I'll try to check my build using that.
Richie Witch
metabaron24 wrote:
Also the question is: If you have an assembled version that is nicely tuned and tracks well, why bother getting an update? It's not that they weren't usable as stable VCOs before the update, at least that's my impression from reading here.

Yeah, I agree with you. I feel bad for everyone who has had problems, but mine works great after a 10-minute warm up. I built mine about two years ago.

Recently, I was using the square wave output as a test signal for a mixer I refurbished, and only once, over the course of an hour, did the oscillator drift from 1.0k Hz to 999.8 Hz (after the warm-up, of course). That seems pretty stable to me, so I'm gonna pass on the update.
zorglub76
Had a big progress solving the issues with Even VCO w00t

It turned out that the stability fix also fixed my tuning problems.

Before applying the fix, I had awful tuning (about half the octave for each turn of the switch). Also, changing Width worked the same as changing Init - you set VCO to play C5 note, switch octave and get F5. Turn the width to get G5, set switch back to octave below, and get D5....

Then I changed everything according to Stability Update document EXCEPT tempco. Somehow I thought that the new and the old tempco had the same resistance and different ppm (turned out that the old one was, I think, 10k, and the new one is 100Ohm). Now Width trimmer worked OK, but I was getting 2 octaves on turn of the switch.

Now I changed tempco and also changed all the resistors around it (R1, R3, R6) with 0.1% tolerance ones, and I can finally tune the VCO properly applause

Now I have a new problem - V/Oct plays two octaves up. When I play C3, I get C5.

Also, I'm still getting triangle wave instead of sine.

Btw. shout out to Befaco support, which had a lot of patience with me, and helped a lot with debugging.
giantreptile
noob question: where/how do I hook up a volt meter to test voltage of even vco? It says hook up to T_P_L GND. but not sure where that ground is if the module is plugged into power supply.

context: updating old version with new upgrade kit supplied by Befaco. wasn't expecting all the de/soldering, but here goes nuthin'!
metabaron24
It says connect Voltmeter between T_P_1 and GND. T_P_1 is a test point on the PCB very close to the Width trimmer. For ground I use the the metal distance piece next to it. Works fine.

Good luck.
retoid
Started building the EVEN VCO recently and have run into a few issues. A couple of the IC sockets had to be dremeled out a little in order to allow them to fit over the pre-mounted SMD components. This was the case for 2 of them.



Another issue I am running into is that this red film cap is supposed to fit into C7 but it looks to have the incorrect footprint on the PCB and the cap legs are super short. Anyone else run into this issue? Any advice?

[/img]
retoid
Ended up barely able to make it fit by using some small needle nose pliers.
gbel
Damned... just pulled a trigger in one of those... What was the outcome? Did you get it Calibrated easily?
jfprimeau
I've finished my build a few weeks ago, and so far I am super happy with it. The calibration process was not too painful, and it is stable as far as I can tell by ear with I use it musically.
retoid
gbel wrote:
Damned... just pulled a trigger in one of those... What was the outcome? Did you get it Calibrated easily?


Yeah got it all working and tuning/calibration was a breeze. Not much tuning was needed.

jfprimeau wrote:
I've finished my build a few weeks ago, and so far I am super happy with it. The calibration process was not too painful, and it is stable as far as I can tell by ear with I use it musically.


Same here, I really like this VCO a lot.
HorseyWindpump
Just finished building my Even VCO (V3.3)

Mostly fairly painless, except for the part where I am meant to mount the main PCB to the control PCB. There is not nearly enough space for both one of the ferrite beads, and the 'INIT' trimmer. My solution was to desolder the ferrite bead and mount it on the other side of the PCB. Has anyone else run into this problem?

Hopefully it's visible enough in the middle of this photo - you can see there's no way the ferrite bead could sit underneath the trimmer:

oliq
Just finished building an Even VCO too. The kit was very good (from Thonk), clearly labelled parts all well organised and the order of components made sense. First kit I've done that didn't have pictures or diagrams of parts, just the list and part numbers but it was still pretty clear.

It's running, calibrates well and sounds great (huge sawtooth!), but I have one problem...

My sine wave output is silent. The even output also just sounds like a sawtooth an octave up from the saw output. From what I've read here the sine is needed to derive the even waveform so that makes sense. I've located the parts in the sine circuit using the schematic and double check the values and the soldering. The only one I haven't checked is the SMD transistor under the IC. I assumed it was OK as it came pre soldered to the board.

@BigCranberry you posted that this part wasn't soldered correctly on yours, did you have the same problem?

I'm not looking forward to removing the IC socket to get to this part... any other suggestions before I do?
oliq
Just for anyone else with the same problem I had - I fixed it.

It was indeed the surface mount transistor in the sine circuit (under the IC on the bottom left of the board). I ended up cutting the IC socket so it became two strips, which revealed the surface mount part. I carefully heated each leg to reflow the solder and that fixed it.

Now have a sine wave and the great even waveform - which is actually really sweet with it's bottom end and higher harmonics, so glad I got it working.
gbel
Hey guys, I'm having trouble with my build basically everything `works` I was able to calibrate the vco, it tracks quite reasonably, all cvs, inputs and outputs are working but the waveforms are not how they are supposed to be...
The sine wave is almost a square
The triangle is almost the same as sine but with a little peak

Even output is like a double triangle with something at the bottom

Sig Zag seems almost ok

And the Square has a little wiggly

Any Ideas? Thanks in advance.
gbel
WOrked out the be the triangle circuit, there was a short underneath the IC socket legs 1 and 2 very frustrating which cause the whole Ordeal.

All is good now and I'm an even bigger fan of Befaco smile
TheRealQuestionable
Sup guys, im new to the modular world, and electronic world, sooooo SUPER NEWB Miley Cyrus
This is my first post, I already read through this whole article to see if similar issue, some similar but none the same. This is my first Modular and i have only been now into modular/known it exists for 5 weeks. so that being said pls excuse my uber n00bness.

SO
I have built, its working all g. In the tuning process now and havnt gotten far till i have troubles LOL
Im stuck on the section of selecting one on the rotary switch and Adjusting INIT to C5
the highest i can Adjust too is Ab4 with 6cent. Litterally wont go any higher no matter how much i spin the INIT trimpot.
So I read through here and saw that someone said Width works the same, so i tried adjust the width, didnt really work the same at all... just upped/downed the tune by a few cent until it too had no more effect.
IM OUTA SPINZ!
i can get the it to C5 when i adjust the TUNE pot to around +3. Buuuut the tuning instructions say to set it at middle. Keen to hear a response. Stoked to be part of this collective. super keen for a life further filled with Modular! (seriously how did i only discover this a few weeks ago?)

THANKS! Rockin' Banana!
also if you havnt gathered im very bad at simplifying text. I over explain to avoid confusion. love it baby.

OH also would getting a much bigger Trimpot be the solution? Would defs prefer to not have to pull apart and re solder. but also okay if i have to.
oliq
Just to add to this thread about the incredible tuning on this thing. I've been using at the main VCO in a lead sound fora track I've been working on on and off for several weeks. In all that time I haven't had to tune it, the tuning is seriously solid on this thing.
loresdef
Hi all,

I just wanted to add here that i build the Evenvco (rev 3,3) this week and allthough when calibrating / tuning, it did run off a few 0,1 cents per few seconds (after a few minutes 2/3/4 cents) when calibrating. But after finishing the tuning procedure its really stable and tracks tight over all octaves!


For people wondering about the red film cap (c7), i just squeezed it in there, it should fit when bending the legs!
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