OptoKey Minimoog D contacts now in production

[thealien666]

Something about the feel of the Ensoniq keybed never felt right to me.

Understandably so. In order to stop the travel of each note precisely, as it is pressed down, they used sort of a flat round rubber disc about 1/8" thick and 1/2" diameter under each note. That resulted in a "whacking" noise each time a note was stopped physically on its way down. That made for a noisy key action. The aftertouch worked by pressing each note further down by squeezing that rubber pad and bringing the metal plate still closer to the coil.

Another side effect of the limited technology of the day, was the relatively slow scanning of all the 61 notes (around only 20-30 times per second) which resulted sluggish polyphonic aftertouch response. Also, each signal from each coil had to be converted to digital data in real time, in order to know the position of each metal plates at all times. The relatively slow micro-controller (8 mhz) was very busy doing all this.

With today's high speed/low cost technology, this system could be much improved. And another way of stopping the travel of each note, perhaps near silently, could be implemented.

[Kevin Lightner]

I worked on Ensoniqs back when they were still around as a company.
All I recall is update after update being published and either new roms being sent out or requesting the entire main PCB sent back to them.
They didn't support component level repairs. Warranty stations were required to swap boards only.
If you wanted to replace a component and be paid for warranty work, you had to call them and explain it to obtain an authorization.

If I recall, there was a common problem with VFXs where the entire keyboard would suddenly die or make a "crash" sound with every note playing.
I think their cure was to wipe down the PCB "coils" with alcohol and usually install a new rom or add capacitors.

I didn't like the keyboard either.
They were a lot like what switch makers call a positive action, often found in lever switches.
After you reached a certain point of travel under spring tension, a key would feel like it just fell the rest of the way down.

When I worked at Roland US, we bought or borrowed an Ensoniq Mirage to take a look at.
(we probably sent it to Roland Japan afterward to do the same.)
The first thing we noticed is that the patch display would flicker wildly and this was "normal" for it.
I recall one engineer saying "couldn't they have afforded a couple latches?" (meaning 8 bit latch chips.)
Instead of data being sent and held to the individual LED segments of the readout, it was part of their programming loop.
Looked horrible.

[thealien666]

...the patch display would flicker wildly and this was "normal" for it.
I recall one engineer saying "couldn't they have afforded a couple latches?" (meaning 8 bit latch chips.)
Instead of data being sent and held to the individual LED segments of the readout, it was part of their programming loop.
Looked horrible.

The Prophet 5 from Sequential Circuit has a similar behavior...every time you tweak a knob or simply play the keyboard, that patch display (and all the panel LED) flicker. Even though Dave Smith used latches... That poor Z80 is working very hard in there...

EDIT Although I must agree with you, that the Mirage was a rather prototypical piece of engineering, to say the least...

[drogoff]

I always thought the Ensoniq contacts were capacitive, not inductive.
Either way, they too had their problems sometimes.

Kurzweil MIDIboard had a capacitance contact system. Ensoniq was inductive. Both lent themselves to a cost efficient poylphonic aftertouch system.

Are you sure? I thought it used Hall-effect - also contactless - which gave the velocity and pressure sensing.

I'm pretty sure the new VAX77 does the same.

[Kevin Lightner]

Are you sure? I thought it used Hall-effect - also contactless - which gave the velocity and pressure sensing.
I'm pretty sure the new VAX77 does the same.

Do you mean the Kurzweil or the Ensoniq?

I recall a synth that used a hall-effect (a magnet and magnetism sensor) for aftertouch.
Just one tho, probably because of their price.

I've also had good experience using optical sensors for aftertouch.
At least one of the Polyfusion keyboards used a single optical sensor and shutter to do it, but the entire keyboard was pivoted. (!)

Isn't the SCI T8 and/or Synclavier optically sensed for every key, at least for key closures?

[MC]

Are you sure? I thought it used Hall-effect - also contactless - which gave the velocity and pressure sensing.
I'm pretty sure the new VAX77 does the same.

Do you mean the Kurzweil or the Ensoniq?

I recall a synth that used a hall-effect (a magnet and magnetism sensor) for aftertouch.

That would be the Ensoniq.

The Kurzweil MIDIBoard was a capacitance system developed by Hal Chamberlin. Each key had a deformable rubber hammer that contacted a conductive plate. As you applied pressure, you increased the surface area of the hammer to the plate, thus varying the capacitance. That's how they implemented polyphonic aftertouch. Only the MIDIBoard had it. I talked to Hal at a NAMM show - who was still at Kurzweil - and encouraged him to revive that system.

Apparently Dave Luce at (1980s) Moog developed a hall effect contact system using a crystal element under each key but it never got into a product.

At least one of the Polyfusion keyboards used a single optical sensor and shutter to do it, but the entire keyboard was pivoted. (!)

The Moog Liberation used an optical sensor with a shutter. Under the keys was a stiff actuator that was pivoted and moved the shutter. It was quite effective. The Lib would had been a great MIDI controller, but there's no easy way to retrofit it so I sold mine.

Isn't the SCI T8 and/or Synclavier optically sensed for every key, at least for key closures?

Yes it was.

[thealien666]

OptoKey is here ! (yesterday)

First impressions: very high quality product, as far as electronics is concerned (I'm a long time electronic hobbyist). High quality socket used for main PIC chip, high grade infrared reflective opto sensors (Vishay Telefunken TCRT1000) with visible light filtering imbedded, very high quality of assembly, meticulous attention to detail (ultra high 16 bit D/A resolution for CV), a 1 amp capacity voltage regulator that supplies only about 50 ma of power (stays cold and will never, ever fail), all the 44 sensors precisely the same height on their boards, the CJ connector has its wire ends protected with shrink wrap, the MIDI connectors are robust high quality Switchcraft.

In other words, its built to outlast the Mini itself.
My Minimoog is from 1975, and everything is still original in it (with the exception of the 3 electrolytic caps and 4 diodes on the rectifier board, replaced as a preventive measure even though were still good enough).
It is working exceptionally well (excluding the keyboard contacts obviously), because Bob Moog designed it to last a lifetime. Kevin Lightner seem to have embraced Dr Moog's philosophy, and that's a really good thing. But, as with many Moog products, it isn't cheap.

If you own a Ferrari, don't expect to buy cheap parts to fix it. It probably won't work for long and it's not worth it.

Addendum: finished installing it. Everything went smoothly. But it does require patience and care to align everything properly. Also, my white levers (the plastic pivot that comes in front of the IR sensors when you press a note) were tarnished and I had to lightly sand them (with very fine sand paper) to bring them back to their original white color. I also discovered that all my bushings were installed upside down by whoever did the job of replacing them before me. Not a problem, as they're easy to flip, but still it added extra time and effort since every key had to be removed and put back.

In a typical installation, you only need to remove 8 keys to have access to the holes to install the sensor bars. As Kevin mentions, in his well documented installation guide, the longest part is to adjust the sensors position carefully as to get consistent response and no misfires. Easy to do, but time consuming.

Other than that, it's working flawlessly, as expected. The touch is even a little lighter, which is a bonus.

All in all, extremely satisfied with the results. It's worth every single penny, even if it takes a lot of them to buy it.

As a side note: having spent a fair amount of time installing it, the additional cost of having Kevin install it for you might be worth it, if you aren't that good with your hands.

The only thing left to do for me, is to perform a slight touch-up recalibration of the oscillators, since the OptoKey is generating much more precise pitch CV, compared to the old resistors on the original contact board. But that's easy.

[Voltor07]

OptoKey is here ! (yesterday)

First impressions: very high quality product, as far as electronics is concerned (I'm a long time electronic hobbyist). High quality socket used for main PIC chip, high grade infra-red reflective opto sensors (Vishay Telefunken TCRT1000) with visible light filtering imbedded, very high quality of assembly, meticulous attention to detail (ultra high 16 bit D/A resolution for CV), a 1 amp capacity voltage regulator that supplies only about 50 ma of power (stays cold and will never, ever fail), all the 44 sensors precisely the same height on their boards, the CJ connector has its wire ends protected with shrink wrap, the MIDI connectors are robust high quality Switchcraft.
/snip/
It is working exceptionally well (excluding the keyboard contacts obviously), because Bob Moog designed it to last a lifetime. Kevin Lightner seem to have embraced Dr Moog's philosophy, and that's a really good thing. But, as with many Moog products, it isn't cheap.

As a fellow customer of Kevin Lightner, I have to say that none of the above statement surprises me. I will agree that Kevin builds stuff to last, and the workmanship is superb. I think we can all agree that Kevin is definitely the best in the business of restoration and modification of analog synthesizers.

[thealien666]

A 3 minute video of my Mini before, and after the OptoKey.

http://www.youtube.com/watch?v=0Lz_czsD ... e=youtu.be

[Voltor07]

Wow! Your keyboard was in really bad shape! It wasn't even TRYING to track!

[thealien666]

Wow! Your keyboard was in really bad shape! It wasn't even TRYING to track!

Yeah, even though I spent many hours when I bought it cleaning the buss bars and contact springs and had managed to get it working better than this, when damage due to corrosion is done it's only a matter of time before problems come back to haunt you.

That's why I felt it justified to spend a lot of money on a permanent solution.

BTW, in this video, in the first part (before the OptoKey), I show the best way for someone who would want to check the condition of a Mini's keyboard contacts: holding down the highest note on the keyboard and playing all the other notes in sequence. Since the Mini is low note priority, you can have an idea if the contacts of all the other notes are strong enough to "steal" the one from the last note. On mine it wasn't the case anymore, obviously.

That's also a reminder, for anyone who would be tempted to buy a Mini on eBay or anywhere else, that for any vintage electronic instrument it's always preferable to be able to check it out in person before buying.
I was lucky to have found mine locally and could try it out, because the keyboard was in even worst shape than this (many notes not even playing at all) so I got a really good deal with a low price.

[Kevin Lightner]

Alien666,

Thanks so much for the kind review and video.
I'm glad the Optokey installation went well.

Kevin

[thealien666]

You're very welcome, Kevin.

[thealien666]

The OptoKey in action (from underneath the Mini). Has a Terminator look to it... (the camcorder was able to pick-up the infrared light from the sensors)

http://www.youtube.com/watch?v=WP_Rb-Gi30o

[Logodave]

Alien,

Thanks for the installation report. I was kind of waiting to hear how it went. Also the videos are
excellent reference material.

Great product Kevin, might have to order one soon.

Laterz,
D