Living VCOs for Eurorack

There’s a tribute panel and a PCB set for the 3VCO boards plus the VCO driver board for sale over at Muff’s:

It seems the whole thing is Open for orders until 12/10/14! That’s December 10th, date formats are a jumble…

There’s been a lengthy discussion about ethics and the stated by JH himself (RIP) fact that he wanted his designs out there being built by DIY:ers. Seems that the consensus at the moment is that this is kosher and it is a kick-ass VCO. I read that @kvitekp said that these are among the best sounding VCOs there are out there so I figured that it would be sad if people missed out.

@piscione has written over there so it’s good to see that more Mutable denizens are on for some linear detune goodness.

@fcd72: you don’t do Muff’s do you? Holler if you want a panel/PCB set and I’ll order an extra.

very interesting project.
34hp is huge, but then this triple vco does seem huge, too. :slight_smile:
so i’m very tempted to join in.

(btw, i’m called “bartleby” over at muff’s and

We are so close, we don’t even need to PM :wink: Im in!

@fcd72: You got it sir! :slight_smile:

This, the past weekend’s sale over at SynthCube, and the clarke68 panel for the Serge resonant EQ makes me yearn for another row of Eurocrack. Nom nom nom! Plus, there’s a couple of Happy Nerding modules heading my way… Yarr!

Image from

I’m doing a 30hp panel.

Oooh, is there a design up somewhere? Guess I could peruse the Muff thread, but I couldn’t be arsed as it’s a Wednesday.

Edit: Never mind, this seems to be it

I take it that the compact panel requires 9mm pots? I love me the reassuring savings you get from 16mm pots, but 4 hp is nothing to be sneezed at.

tries to quickly close his eyes while feverishly hitting the Back button

Resistance is futile.

in fact, after some more thought i think i’ll pass on this one.
the module looks to be rather deep, i.e. skiff-unfriendly. and it doesn’t seem to be doing much that i couldn’t do with 3x 555 vco plus a buffered mult and maybe a bunch of attenuverters.
plus my backlog is big enough already.
but if you have enought rack space in a sufficiently deep rack, i’m sure it’s a cool module…

Well, there’s this linear detuning feature plus some other goodness in how the VCOs are driven, plus the VCOs themselves. I doubt that you can replace that with the 555 VCOs. That said, the 555 VCOs are a masterpiece in simplicity vs features and they do sound nice.

But yeah, I have a feeling this may not be the most skiff friendly module ever conceived. However, I’ve heard (and played with) the Living VCOs and they are up there on the way nice scale.

@Jojjelito, nice hunting! Mine is going to require the 9mm pots, I’ll just place a huge order to Tayda when I’m ready for stuff. The Muff’s gang decided the 9mm pots were too expensive but since I’m only building one, I figured I’d rather pay a bit more for a smaller panel.

The PCBs from the first run are 63mm wide. Not sure if that fits in a skiff but they are small PCBs. If you mounted them flat to the panel instead of at a right angle, you could make it very shallow. More wiring 'though.

I’m currently going through some of what is on my bench to get ready for the Tayda order. I’ve bitten off more than I can chew, but there’s the Living VCO, the Stroh Modular Ultrafade (doing this as a dual), YuSynth Minimoog filter, NonLinearCircuits VCO (again as a dual), a pair of Miss 10 modules and a Wogglebug. Also a half-done Barton quantizer and a Stroh/J3RK sequencer (Dustin Stroh is really nice guy). Oh, and a non-working dual 258J that has been driving me nuts.

@piscione: Good choice of modules there! I like the J3RK stuff, I usually get it through SynthCube as I remember the old days when he bit off more than he could chew for a while. I have the J3RK mirror core VCO to build and it seems like a wild discrete PLL-based take on the big ole 259, albeit with a Lockhart folder instead of the classic folder used in the 259 and the Easel. I have RomanF’s take on that however, so it’s not like I miss out :slight_smile:

In fact, I have nearly all the clarke68-panelized modules except for the TabulaRasa, which is said to have some bugs. The 258J sounds massive! I wish I was at home and had mine within reach…

Ok, I would be interested in this living VCO module. There is something to be said about the principles that underline how it works. Yes, an oscillator that has a linear to exponential pitch conversion does sound better for some reason.

Does anyone have the cost of the BOM for this project? 30 to 60 USD for a panel and PCB set, seems great. Now what about the rest?

BoM as PDF are found here:

Apart from a LM13600 IC for the driver board and a CA/LM3046 each for the VCO boards (3x) there’s mostly ordinary, cheap and more or less passive stuff, plus the pots and some trimmers to consider.

The 3xVCOs take 4x3 trimmers, that can be a bit of cost, plus 6x ferrite beads. Also 3xLM311, 3xTL074 and 6xTL072. Oh, and 3x 1k TC, the cheap Panasonic SMD variants (0805) are said to be fine, these are somewhat cheap and cheerful at Mouser. The VCO driver board adds 8x trimmers and a LM13600 plus 2x ferrite beads. Plus 2x TL074, like that matters for the cost :slight_smile:

Hmm… I will wait a bit and think about this as I will not be able to get to building it soon anyway. I just like these types of VCOs, and wouldn’t mind a modular one in the future.
If I can figure out a way to get the BOM cost down significantly, I may just get one anyway. :slight_smile:
I know I have the TL072 and LM13600 as well as most of the passives. Not so much all the proper pots or trimmers.

Do you have LM3046s at hand? i can trade for LM13600s

@audiohoarder, I tend to be of the same mind as you but I’ve recently decided that if I see a set of PCBs that seem interesting, I’ll buy a set or two anyways. If figure the cost of the PCBs is relatively low and they don’t take up too much space, and since some of these are either never available again or the time between runs can be quite long, I might as well get them.

The cost of parts can be daunting but the more stuff you build, the more of an inventory you tend to collect. I’m never in a hurry so I tend to order from Tayda or other Asian suppliers (on Ebay) rather than Mouser. Self-sourcing can be a chore but for the price of a few resistors I can get 100. This is good and bad of course, because I have ended up with more resistors than I will ever use.

The deciding factor for me is usual the availability of a panel, because making my own aluminum panel is a bit of a task. For the larger projects, like the Living VCO, I figure I’ll take the chance because I didn’t like the available panel. I may end up buying blank panels for the smaller stuff and just drilling the holes for pots, jacks and switches myself. I use laser waterslide decal paper for the labels and clearcoat before mounting everything.

@piscione: I have not read though the whole thread at Muffs yet, is there a picture of what the final aluminum panel looks like? That was one of the main reasons I was interested in this run.
I agree with you on sourcing parts. That is pretty much what I was thinking.

@fcd72: I still have plenty of both kinds of those ICs. I’m totally not a stranger to slipping you some in a padded envelope :slight_smile: Got enough weird semiconductors to be able to take on anything but that pesky Yamahahaha key scanning IC…

@Jojjelito&fcd/Frank - can I sneak in on your order? Ordering it by myself would slap a shedload of taxes, fee’s and other unpleasantness onto my life, something I’d rather avoid…(Thanks Danish customs, for your retardedly low import/duty free limit of a whopping 80DKK, or 8£/10€… .)