Current status

Well, don't I feel silly? Haven't updated this in nearly a year now... hard to believe.

Since last writing, Endangered Audio has apparently done a complete re-spin of the PCB board. I haven't seen it, but this is good news. While I felt that the board construction was fine, a few things were placed on it rather awkwardly, it seemed. Hopefully it better meshes with the schematic, and that the documentation has improved as well. Fingers crossed that the power & CV stuff is a bit cleaner as well. Unfortunately it seems that the PCB is no longer available on its own from EA, but only as a kit (with all the main components), but perhaps they will sell them individually upon request. All that means that what I've previously written (and would have written) is mostly moot, I'm afraid.

Anyhow, I did complete my Gristleizer, and it sounds great! I wanted it to be a table-top model with the knobs on the top - at least for me, that makes a lot more sense given how I work both in the studio and live. Final assembly was a bit awkward; the PCB was designed to have the pots fixed to it - in my case, they were going to be on a different panel entirely than the one where the PCB would be mounted. Granted, part of the difficulty was surely due to the fact that this was the first thing I've built go to in an enclosure... at home they've just been fun little projects, and at work they've been prototypes connected to various things on my desk. However, everything eventually went together. Hopefully it all stays. ;-)

Not the most beautiful thing (or the greatest picture), but it works great. The first trials were running my MS-10 through it, and the VCA worked some crazy magic on the sounds. When tweaking the controls (particularly the rate), I could definitely hear elements of that distinctive TG sound. The VCF is great too, though more subtle than I would have expected.

When I built this, I got enough components to make a second one. If I get around to starting on a modular synth later this year, I'll definitely try to get a second PCB and make a Gristleizer module. If/when that happens, I'll be sure to better document the process and post it here!

Populating the PCB

First, apologies for the lack of photo evidence... my digital camera has certainly seen its last days.

The PCB is pretty easy to populate; everything is nicely labeled, and no components are too close to each other. Everyone has their own way of preparing parts and soldering them, so I won't go into that. In general, I added components based upon the height of their profile, saving the biggest things for last, as well as those that wouldn't move around.

The resistors came first, as there's so many and they're so simple. After that, I added the diodes. Two of the three different diode types have thicker leads, so they're a bit hard to lay completely flush.

Following those I did the IC sockets and the two on-board pots. I really should have done it in the opposite way, as the sockets have a slightly higher profile than the pots. But it all worked out fine. Following that I did the capacitors, and finished with the transistors, since they're the most sensitive (and stay pretty well fixed when you've got the board upside-down and are soldering).

If you don't want the CV capabilities, you should add a jumper between CVIN and CVOUT at this point. I wanted that functionality, so left them clear until instructions would arrive...

All things considered, this part was a pretty easy assembly. Connecting the PCB to the switches, pots, and AC jack will be the next step...

The Parts

If you've ordered the Gristleizer PCB, you've surely received the BOM (bill of materials). In general, it has the part numbers for most components, some from Mouser and some from Jameco. They're both easy to order from, and everything comes packaged in nice little plastic envelopes, all labeled.

For all the resistors, capacitors, diodes, ICs, transistors, pots, switches, etc. I ordered what was on the BOM. Actually not 100% true... one of the caps was out of stock, but it is easy to order one with the same specs.

For the knobs I ordered Jameco 264946. They're a bit larger, and I like the look.

For the audio jacks I ordered Mouser 568-NYS229L, since I didn't want on-board jacks.

And for the enclosure I ordered Jameco 209358. It is a 7.5 x 9.8 x 3.2 inch case. Rather big, yes, but that is what I wanted, especially for mounting the knobs, switches, and audio jacks on top.

I also ordered IC sockets for all of the ICs. Though hardly required, it just provides a nice peace of mind.

With the exception of the case & knobs, I actually bought enough parts to make 2 Gristleizers. If I like this one enough, I'll grab another PCB to build into the modular synth I'm planning to start... sometime...

The PCB

Once you have your PCB, you should also have your documents from Endanged Audio... including instructions, schematic, and bill of materials. The one thing currently missing from the documentation is the CV In/Out support. I have some info from Todd at EA that I'll be posting, but if you don't want CV support, all you have to do (and you _have_ to do it!) is add a jumper from CVIN to CVOUT on the PCB.

It seems like a nicely prepared PCB: it is nicely labeled and isn't too compressed -- good for a DIY project.

There are a couple issues that I do have, however.

First, I wish that it had more mounting holes (is that what you call 'em?). Right now, there is only one. The expectation is that the rest of the board will be supported by on-board audio jacks. There's nothing beneath either audio jack, with the exception of the battery ground lead... so, since I'm not using batteries (and they're not recommended) I'll be drilling through both of the audio jack sections later.

Second, I wish there was a 2nd LED to indicate effect on / bypass disabled. There is an LED for the LFO, but I'd really like two LEDs... one for the LFO and one for effect-on, as on Chris Carter's original.

I'm hoping that a future respin of the board will solve my first issue.

An Introduction

Hey kids!

I've built this blog as a resource to those assembling Gristleizers from the PCB.

For those who aren't aware, the Gristleizer was an effects unit used by Throbbing Gristle in the late 1970s & early 1980s. Built by member Chris Carter, they were based off of initial designs by Roy Gwinn published as the "GEP" in Practical Electronic. More information on this can be found on the links to the side here.

In April of 2009, Endangered Audio emerged from the folks at Smashing Guitars in North Carolina. Their first product was a new version of the Gristleizer. Initial copies of this were available at Throbbing Gristle shows in Chicago in 2009 (during their first US tour since 1981!). They're now available directly from Smashing Guitars, but you can also order just the PCB!

For me, the PCB was the ideal buy -- personally, I wasn't too keen on the faceplace of the new version, and I'd rather have all the controls and audio jacks on the top of the unit. So, I bought a PCB and the rest is (or will be) history.

A few comments first...

I'll try to provide pictures where possible, but bear in mind that I started the assembly before I decided to create this blog. So, at this point, the PCB is mostly populated. My camera has also been having issues, but I'll do my best (and maybe steal my girlfriend's camera a bit).

I don't plan on publishing the Endanged Audio schematic, so don't ask. They redesigned it from the original schematic, and Chris Carter's changes.
Unless they decide to publish it, I consider it their property.

I'm not an electrical engineer, and this is my first real DIY audio project. My background is in computer science and I'm a software engineer... so I've had to take plenty of electrical engineering courses with the worst professors ever, and I've had to interface with a lot of circuitboards in some jobs (like laser tracking systems). Basically, what I'm trying to say it that I understand schematics and the practical parts of assembly, but I don't quite "get" electronics as much as I'd like to. So... I might not be able to answer all of your questions.

And, finally, a few thanks...
First, to Throbbing Gristle. Your music, especially "Heathen Earth", has been an inspiration for many years. Not to mention the influence of PTV, Coil, and C&C. Your soundtrack performance in Los Angeles in April was amazing.
Second, to Chris Carter, for inspiring my interest in "DIY electronics" -- even though it has taken until now for it to manifest in any real way.
And third, to Todd at Smashing Guitars, for his advice and assitance in the assembly of my Gristleizer.