By “somewhat popular” demand (having been asked for the schematics “several” times) we have made a PCB and kit available for the circuit we use to add 1V/Octave scaled input to the ElectroComp EML-100 and EML-101 synthesizers.
The EMLs use between 1.2 V/Octave and 1.4 V/Octave (varying from one unit to another) with an offset of between 4.2V and 4.6V. Our board allows you to feed in conventional one volt per octave control voltage from another synth, controller keyboard, sequencer, etc. and scales it up so that the EML’s second-voice oscillators (Oscillators 3 and 4) can track it. Using a sequencer especially opens up amazing possibilities for this already very powerful synth!
Our original version of this circuit just performed the summing and amplification and required the installation of a new external switch to turn the mod on and off. Our new version uses a multiplexer to automatically perform this switching task when a plug is inserted in the CV input jack. This means that it can be completely invisible– no hole needs to be drilled, and the synth functions 100% as original when nothing is plugged in.
The mod can be used on both versions of the EML-101. On the later version that has a “Sequencer” jack, the Sequencer jack becomes the 1V/Octave input, and on the earlier version, another jack can be selected to be the new 1V/Octave input (we use CM3).
We are looking for someone to help us take photos of the installation in an EML-100 in exchange for a free PCB or kit so if you have a 100 and are interested in the mod, please get in touch!
The PCB will come with schematics, bill of materials and detailed installation and tuning instructions with lots of full color photos. The kit will come with all of the above plus all required parts and the jack already partially wired (because this is probably the thing people are most likely to mess up!)
One interesting thing about restoring vintage synths is that almost every instrument that we work on has been worked on by another tech at least once before. And it seems that more often than not, those other techs were… not great. We see a lot of bad work, but my favorite examples also feature a very special element of absurdity. Here are some recent highlights:
The owner of this ARP 2600 got it in an insane trade in the late 80s… in exchange for a Peavey keyboard amp and a TR-505! A lot of it had never worked in the entire 30 years he had had it.
When we do restoration of an ARP that’s in bad shape, we’ve learned that there’s really only one good way to approach it. We basically strip it down to its bones and do everything we possibly can in one fell swoop before even trying to test different systems. It ends up being so much more efficient that it actually costs less than taking a more step-by-step approach.
Because I am now one of those people who thinks they are very busy, I am just going to share a “quick tip” today.
In one of several Odysseys that we rebuilt recently, the “Proportional Pitch Control” pads (otherwise known as PPC, those three spongy white pads that Mark III Odysseys have) were so bad that no amount of cleaning could revive them. I finally was forced to look for another solution, and tried using some FSRs (force sensing resistors) and the results were great.
This was Bell Tone’s first Polivoks job, though not my first Russian synth repair as I have a UDS MARSH drum synth of my own. My goals were basically to “assimilate” this Soviet-era Russian for life in the modern United States and correct a few issues with the keyboard.
Remember when we used to do a blog post and try to think of something to say about every Juno 106 we worked on? It’s a good thing we stopped because this is the 31st Juno 106 that I (Alison) have personally restored, not to mention the ones that Darian has done.
I’ve been surprised by how many people have seemed to enjoy reading the Bell Tone Synth Works blog and now feel bad that it has been neglected so much in recent months. So what happened to the blog? Basically, the blog is a victim of its own success. I started the blog when I started the business and didn’t have many clients, to sort of get our name out there, make our site more findable on Google and prove to prospective clients that I knew what I was doing, aware that as a somewhat young woman working in a field undeniably dominated by middle-aged and older men, my knowledge and skills might be met with skepticism, conscious or subconscious. I also wanted to store my notes on my repairs somewhere so that I could refer to them later, and figured I might as well put them where other people could find them too.
Now, partly thanks to the blog and our YouTube channel but also to a great extent due to word of mouth and our growing reputation for doing good work (which is great), we have so much demand for our work that I often feel like I can’t spare the time it takes to write here.
One thing we find in almost every 1980s Roland we work on is crumbly, dirty “dust shields” or “dust protectors” on the sliders (aka faders) of the panel board. These gaskets were cut from thin black EVA foam sheets and were meant to protect the sliders from dust. However, 35 years later, they have dried out and are falling apart, their fragments actually falling into the sliders and making their crackly and intermittent behavior much worse.
This was a pretty big mod project that Darian finished a few weeks ago on an ARP Avatar, the ARP guitar synth which is mostly just a keyboardless Odyssey with a bunch of guitar-processing junk that no one cares about. That’s just a fact. Anyway, several years ago New England Analog developed this kit to break out a lot of the CV input points and modulation sources of the synth’s architecture to 1/8″ jacks mounted on a single long PCB, and now that New England Analog has closed, a new version of the kit is available from Retroaktiv. Continue reading “ARP Avatar – Retroaktiv patch bay kit installation and the vintage synth modding controversy”