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Befaco Evan VCO opinion?
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Author Befaco Evan VCO opinion?
I'm hearing nice things about people's experiences with Befaco sound quality-
I'm eyeing the Evan (Befaco calls it precision) VCO. It looks like a bad ass, lil' something I'd like to build- Smash!

Does anyone have any feedback on it as a VCO, and/or their experience with assembling it?

The manufacturer's info provided looks tight, but objective opinion from wigglers would be tighter- please advise Animal!
I have built it, and I've found it to be a great compact little VCO. The rotary switch for octaves is really useful, you can kind of 'play' it too. 'Even' output is a waveform with octave overtones, which is a nice addition to the standard waveforms; I think it's sine like/double frequency ramp mix. I think the sine output has a slight, very short pulse at the top of it's peak that can't be trimmed out, but that doesn't bother me really.
I got one in route to me as we speak. Once I receive it, and get it assembled, I'll give you my verdict as to how it performs.
i love mine
I've got two of them going into a Befaco mixer. Easy to build and calibrate. Anything specific you want to check or ask?
Thanks for the feedback- this exact info is helpful in confirming what I thought (hoped) I might hear. SlayerBadger!

I was trying to decide on a smaller footprint DIY VCO to built next, and as much as it looks like this one would be the right fit for my needs, I was surprised by not seeing anything posted about it- good or bad.

I like the fact it's calling itself precision, and I'm a little curious how accurately it tracks those 10 octaves it claims... Not the most important need- great sound that is at least tracking in the mid/low range accurately, and most bang for the HP are my main concerns.

What's the deal with the 2 V/OCT inputs? does it combine voltages, or take the high only, or something else? hmmm.....

beer! Anyway, cheers folks, thanks for the info. I'm just going to assume the build is straight forward with no 'watch out for this' type stuff to be concerned with, because nothing was mentioned...

I placed my order just now Combine Overwatch
I had three PCBs made. Built the first, did all the resistors on the second, will decide what do do with the third depending on how it sounds. It was quite easy except for surface mount resistors, which also became relatively easy halfway through.

I'm still waiting for my power supply in the mail (I'm new to euro) but if everything works out I'll post my Mouser Project cart here. Feel free to chase me up if I don't do that within two weeks.
I agree to the thread,

I know the designer and I've seen grow this design, not in a day, it has been a job of years.

IC1 and components around are a very strong commitment to the stability of temperature. A decoupling of 1000 ohms, which sacrificed a good margin of PSU voltage towards the stability, just to the 10V, 10 octaves, proper to professional equipment, but with street components. I know this circuit and I remember we had talk about it. I studied this in instrumentation for electronic scales in a good metrology level, and is a little gem.

Not a cheerful design, born of divine inspiration. It is a job evolution from the previous VCO III, and previous II and previous I. There are many, many hours in here.

watch out for this?

Well, just is a VCO. It does not had things that, I think, are not needed, and as well believe that it decided his designer.

The drawbacks will only appear while another, with the same price, improved performance.

Oops! In my opinion as electronic designer.
Hey everyone!
my first post here..for sure not the last..

i´m new to eurorack! and i´m planing to do this VCO as my first build.
everything clear so far except the potiometer. can anybody tell me which resistances are needed and are the linear or exponential ?

thx a lot
Befaco usually all shaft potentiometers are linear 100K ohms for economy.
But although there are exceptions. Reviewing the schematic both are linear:

Fine-tune should be linear yes or yes, law is volt/octave.

PWM is same style, action manual entry by a CV, usually linear.
allright! thanks autocet!!
hello again,

another question which came up while planning...

i saw on pictures of the pcb that it seems like the pcb come with some pre-soldered parts.

looking on .brd file i can´t find them..

maybe anyone has a hint?!
From memory, there was a tempco under one of the ICs, and I think some precise resistors around the rotary switch. There may be more but I can't recall right now.
I think I've got a couple of these in my backlog box if anyone wants to do pcb trade
thanks guys!!

I had another close look to the schematics and i found it out.
there are some smd parts...(resistors, ic,...) that are pre soldered.
Built it nice and easily- no surprises, until I went to calibrate it...

Something I will do from now on will be to snap a picture of the PCBs before they are stuffed. I couldn't find any pictures anywhere on the web for this one, and it delayed my calibration because the pots cover the labels of which is which once installed. d'oh!
For future reference-

top right pot is the input voltage calibration
top left is volts per octave calibration
left side is range
left side on the control board is the tune

After dorking around with that a bit, I dialed it in. I think it's a great piece!

I agree with Eloc on it being 'playable' with the octave knob. It is, indeed what I hoped it would be. Nice work Befaco!! applause

Next up- the Rampage? or maybe the spring reverb... hmmm.....

We are a bit delayed with audio and video demos about our modules. Sorry fo that wink

Here you can see a Befaco vs analog4 jam.
You have two even VCOs passing thru a BF-22 and controlled by Rampage retriggering. CV and gate is sent from analog4.
Then reverb efect is added in the elektron box.
Hope it provide some info and sounding capabilities of both modules smile

[EDIT: Jump to 1:25 to skip spanish speech]
Bananallama! Bananallama! Bananallama! Bananallama! Bananallama! Bananallama! Bananallama!
I've just built Even VCO from a full kit (purchased from Thonk). Mini review below.

Packaging: Good, easy to find each component. One standoff nut was missing, so I had to dig out a replacement from my nut box, no big issue. One extra resistor was left unused. I first thought it's for some option, but it's not mentioned in the manual, so probably just a packing glitch.

PCBs: Beautiful hand-drawn traces. Nice large soldering pads are easy to solder. It's nice that they've put so large pads even in such dense board. (Some other unfortunate manufacturers use board density to justify tiniest pads). Basically, a great job placing everything on two small (8HP wide) boards (largely thanks to using 1/8w resistors).

One decision I'm not sure about is sandwiching SMT parts under a through-hole chip. While it allows to minimize board size, in theory it might make troubleshooting or repair difficult.

Manual: Minimalistic but sufficient. However one point is (IMHO) not covered well in the manual, so I want to add a suggestion to new builders: When soldering inter-board connection headers, first install the headers (don't solder yet), then secure the boards together using standoffs and screws, only then solder the headers. This way the headers end up aligned (with each other, and with standoffs). The provided manual does not say this, but if you first solder the headers and then try to connect the boards, you may find the headers are misaligned.

Nitpicks: Standoffs are few mm longer than headers. Tuning pots are distributed on two sides (left an top), rather than accessible from one side. I used more washers than provided in kit to properly align the front panel (due to rotary switch being taller than pots/jacks).

Also note that this VCO uses 1/8w resistors, so if you build from PCB using standard 1/4w resistors, you'll have the joy of soldering ~65 of them vertically.

I haven't used it much yet, but it seems working great so far. Tracking seems good. Overall, a beautiful module, and "even" waveform is a nice addition.

To the OP or moderator: Please fix spelling of "Even" in thread title, so that the thread will be searchable.
I built a Befaco Even Vco at one of their workshops at The London Music Hackspace -

The workshops at Music Hackspace are held regularly even if it is not listed there should be one coming up.

It was very easy to solder together with step by step instructions. I didn't need any help building as I had already built a couple of their modules. But if you need any help they are there - and they tested and calibrated it for me. I am very happy with the sound quality and range. It stands up well next to my other oscillator the Z3000. I will think about building another one this year.
I'm in the middle of the build doing the resistors, just wanted to make sure regarding what I think are R18, R19 and R17, is the following correct:

screen shot of .brd.

Cool overlooked that file, thanks!

EDIT: Downloaded the files from befaco, did a google search for "CAD linux", downloaded/installed eagle and opened the .brd file, and WOW. Makes it almost too easy to identify the location of parts on the PCB (and support my OCD-ish frantic for making sure everything is correct).

Thanks a lot for pushing me to this, I can't believe I didn't find this before d'oh!
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?
Either of the top and bottom rows (102) will work for 1nF, use the ones that fit the hole spacing best. It's hard to make out the middle row but it looks like they say 10 on them so they're your 10pF caps.
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