A love letter to Jenny: Tremolo and Key Tracking Mod

This JEN SX-1000 belongs to Stéphane in France, who wrote to tell me of the three mods he did. I have never seen two of them before – a Tremolo control, and variable filter tracking. Which would make Gordon Reid very, very happy.

So here is Stéphane’s letter:

„Hello, here are some modifications for the Jen synthetone SX1000. Nothing is disconnected. Components are added.“


Securing Jenny’s power supply

Pretty straightforward, this one: Replace the JEN SX-1000’s fixed power cable with an IEC socket. (Like weird German words? You’ll love this: In German, this thing is called a „Kaltgerätestecker“, more precisely, a „Kaltgeräte-Steckverbinderbuchse“, which translates to „Cold unit connector socket“. Don’t ask me.)

Jenny's backside

No problems here apart from cutting a hole for the socket; I used steel drills to mark the corners of the cutout and then cut the steel with my Dremel tool. Lots of metal dust but fast, and it did the job precisely.

A word on Jenny’s power supply: It’s extremely oldschool – a transformer and a diode bridge generating +/-18VDC, two 7812 regulators generating +12V and -12V, and another 7805 regulator generating the +5V supply rail from the 12V. If you would like your JEN to be a bit more eco-friendly I’d advise replacing those regulators by the 2931CT low-dropout type, but apart from that, there’s hardly any reason to look at the power supply – it’s rather solid and possibly not your primary concern if the synth does not work.

Could you also patch an Alesis IO Dock II?

Is it possible to retrofit an Alesis IO Dock II with an internal USB hub, just like I did with my IO Dock 1? TL;DR: Some have tried and failed – seems like Alesis deliberately switched the code for this hack off. 


This photo was sent to me by Blek in the Czech Republic who asked that very same question. He has taken a look inside his IO Dock II and noted that it features an all-new PCB, so my original hack won’t work. And of course there is no guarantee that the prerequisite for the original hack is still implemented in the IO Dock II: the ability to function not only as a USB bus host for the iPad, but as a USB bus slave device, with the iPad working as the bus master.

The good news is: It is simple to give it a go, as Alesis took extra care to label the locations of the USB bus signals:


So here is what you do to try it:

  1. Get a male-female pair of plugs matching the connector in question. Possibly a 12-pin version of these connectors, so as in the original hack, 2mm pin grid stripes could work. They are a bit hard to come by, but it is possible.
  2. Solder connections from male to female for all lines but 6 and 7 – the D- and D+ USB data signals.
  3. Get a suitable UBS2.0 hub – I used a Belkin F5U404; you might have to try a couple of hubs if that one does not work.
  4. Take the cable that is meant to connect the hub to the computer – it should have a standard USB plug on one end and a USB mini connector on the other end – and cut it in half. This is the only non-reversible action you are taking, but as it is easy to buy a replacement cable, there is not much harm done if it does not work.
  5. Take the cable half with the USB A-type plug, for connecting it with the computer. Solder the cable wires to the connector that goes into the IO Dock side as follows: Red (Vcc) -> pin 1, White (D-) -> pin 6, Green (D+) -> pin 7, Black (GND) -> pin 8.
  6. Take the other cable half with the USB mini-B plug for connecting to the hub and solder it to the iPad side, i.e. to the connector that is leading to the iPad connection cable. Once again, solder red to 1, white to 6, green to 7, and black to 8.
  7. Do some checking for connections and possible short-circuits. Believe me, it’s worth the effort.
  8. Unplug the IO Dock board connector for the iPad. Insert your freshly-made adapter.
  9. If it works, make a video of it. Become world famous. :)

Wiring diagram

Wiring the USB hub connector: Once again, the trick is having the iPad work as USB host rather than as a slave device, and the IO Dock as the slave rather than as the host. Use your hub’s connector cable, cut in half, and solder the color-coded wires to the connectors as shown.

Sorry for my rather artistic impression of the adapter, hope it gives you the right idea. Pin 1 is to the left, pin 12 to the right. IO Dock side is up, iPad connector side is down.

Just to be sure:

  • I’d strongly advise you to solder and try out the adapter rather than soldering any wires to your IO Dock. It is a good thing to keep that sort of stuff reversible. For this reason, don’t start dremeling before proving that it actually works…
  • …which I won’t guarantee you. Mind you, I don’t even own an IO Dock any more. If you start doing this, you should know what you are doing.
  • Please understand that the base for this hack is a feature that Alesis seems to have implemented deliberately into the first IO Dock (see Dan Radin’s comment): the ability to work as a USB slave to the iPad, in addition to normal operation, where the IO Dock works as a host for the iPad. If the IO Dock does no longer do that, you can try to rotate the USB hub, but that’s about it.
  • Please write me back with your experiences. Please don’t get on my tits with any attempts to make me do this hack for you, or repair your IO Dock if anything went wrong. (Oh my god – I just realize that bullshit warnings are obviously contagious.)

It’s worth giving it a try, isn’t it?

Thanks to Blek for allowing me to use his pictures.

Adding a slightly odd sub-oscillator circuit to Jenny

Let’s start with some good news: Jenny’s here to stay with me, so I can start some serious modding. The single VCO and the filter design make it hard for her to growl credibly, so I tried to make her bark and her bite a bit tougher, using bits and gates from my basement supplies: adding a sub-oscillator, and pre-filter overdrive.

Jen SX-1000 oscillator/mixer section


The sub-oscillator is simple and has been done by many great modders: You add a divider circuit to produce a one-octave (or two-octave) square-wave sub-oscillator and feed the signal to the unused „Off“ terminal of the noise selector switch (over a 100k resistor so that the sub-osc signal is not overly loud). So now when the noise generators are switched off you can use the noise dial to add some deepness.


Reviving Jenny, or: contacts cooked to life

An Italian beauty, fallen on hard times – starting her career as a budget singer, forced out of business, living in a basement for more than a dozen years – and come to my house by accident. Now I am trying to get her back in shape – and to make her voice fuller than it has ever been. Her full name is JEN SX-1000 Synthetone, but she is affectionately known as Jenny.

Jen SX-1000 Synthetone after basic cleaning. Some pot caps missing.


Matrix-1000 Brain Surgery

Shot of opened Matrix-1000 with freshly socketed CPU, runningDremeling and ripping out the brain of a 25-year old vintage machine – I was so Frankenstein yesterday. Luckily, it worked, being the first step to a much improved Oberheim Matrix-1000 running with – at least – doubled system clock, and patched firmware. This takes up the work of Gligli who was the first to hack a faster CPU into the Matrix, and tries to take it one step further. 

Hacking a vintage instrument – my favourite guitar player calls this cruelty. Yet there are good reasons to do it: As I’ve mentioned before, the Matrix‘ CPU is actually too slow for what it tries to achieve, but the 8-bit 6809 chip could only be clocked to 2 MHz in its fastest version, and this is it.

So Gligli, a hacker from France known for his Prophet-600 firmware rewrite/retrofit, had the idea of using a 6309 CPU, a chip from the same era that, while maintaining drop-in compatibitily, offered faster instructions and could be overclocked to 4 MHz. So he replaced the CPU and the main oscillator, patched the firmware and – it worked.

Yet there are some issues with Gligli’s solution, in my humble opinion. The Matrix‘ peripheral chips are designed to work at 2 MHz; by doubling the CPU clock, they have only half the time to read or write data to the bus. Not all of the hardware is up to this; Gligli’s solution is simply writing everything twice, and that seems to work, but it’s not very trustworthy.

So I’m planning to install a CPU with a custom clock generator that is using asymmetrical cycles to give the peripherals more time to read and write. (I’ll have to build in new oscillator circuitry anyway, as I happened to buy 63C09E CPUs, which rely on external clock generation.) And there’s always the possibility to go even further and replace the CPU by a modern programmable logic chip, an FPGA, that can be loaded with a 6809-compatible core clocked even higher and has proper slowing-down logic to interface the old hardware. More on that later, suffice it to say that I simply want my Matrix’s CPU in a socket. And be it only to be able to revert to the original chip.


Next Project: Korg R3 Aftertouch Hack

Not there yet, but it’s in reach: An Aftertouch, e.g. channel pressure control, retrofit for the Korg R3 synth.

Korg R3 under press


I really like the Korg R3. No, there’s more: I bought it second-hand out of very rational considerations, and ‚ve come to love it deeply. There are people who don’t like it for its plastic housing, for the limitations in comparison with its more expensive sibling, the Korg Radias, others hate it simply for not being a first-generation Microkorg. In my experience, it’s an excellent virtual analog synth capable of doing massive bass as well as very unusual pads. It’s versatile, it’s compact, it’s cheap, and it sounds great. And unlike the Microkorg, it’s got a proper keyboard, albeit without aftertouch.

For some reason, the MIDI Thru jack in my R3 stopped working today, which is bothersome, but also a welcome excuse to open the R3’s housing and take a look inside. I had this idea of equipping it with an aftertouch sensor for even more variation and liveliness in playing. And now I’m confident it would work, although I won’t be able to do the mod for some time.  Weiterlesen

Insert ___ here – new connections for an old mixer

Look: My little old Behringer Eurorack MX1604A mixing console has four insert jacks now, just what you need for a four-channel compressor. After a day spent with sick kids, a little soldering and drilling felt just right.
I have been shopping on eBay. Looking for a reverb to go with my rediscovered Oberheim Matrix synth, I acquired a rack containing a Lexicon MX, and a four-channel compressor. Lucky me.
This is when I noted that my mixer has no inserts.
Well, I fixed it. Took me about 3 hours. You need: 4 6.3mm stereo jacks, shielded 3-wire cables, soldering iron and being prepared to use it, a 12mm steel drill.


QuNexus: Kein Hack, ein Tipp…

…wer eine Tasche sucht und bei den DJs und im Computerladen nicht fündig wird: Querflötentaschen passen! (Es muss ja nicht die mit dem Hermelinsackhaarsamtfutteral sein.)

QuNexus in einer billigen Querföltentasche chinesischer Provenienz.

Ansonsten: Der QuNexus hat inzwischen einen deutlichen Versionssprung gemacht – und demnächst wird sich hoffentlich mal Zeit finden, die Analogausgänge auszutesten. Mit einem Korg Monotron Duo! Muhahaha!

Proof-of-concept: Alesis IO Dock bekommt einen Hub

iPad im IO Dock - macht das Midikabel am wackeligen Camera Connection Kit überflüssig

iPad im IO Dock – macht das Midikabel am wackeligen Camera Connection Kit überflüssig

Am Alesis IO Dock führt kaum ein Weg vorbei, wenn man mit dem iPad Musik machen möchte. Zugegeben: man kann Verstärker auch an den Kopfhörerausgang anschließen, und für die Verbindung zum Midi-Masterkeyboard sorgt auch die Kombination aus Camera Connection Kit und einfachem Midi-Adapter. Wirklich betriebssicher ist das nicht, dafür sorgt allein der 30-polige Apple-Stecker. Das IO Dock gibt dem iPad nicht nur eine stabile Heimstatt, in der es mit Strom versorgt wird, es bietet vor allem exzellente Audio-Ein- und Ausgänge in stereo, einen regelbaren Kopfhörerausgang, Goodies wie Phantomspeisung für Kondensatormikros und Midi- Ein- und Ausgänge. Unverzichtbar.

In einem Punkt ist das IO Dock einem Camera Connection Kit allerdings unterlegen: es bietet keine Möglichkeit, zusätzliche USB-Geräte einzuschleifen. Bei mir wäre das ein kleines Masterkeyboard namens M-Audio Axiom; man kann es entweder über die klassische Midi-Schnittstelle anschließen – wobei es seinen Strom dann über ein klassisches 12V-Steckernetzteil bekommt – oder einfach über USB: dann hat das Keyboard nicht nur Anschluss, sondern wird auch gleich über die USB-Speisespannung mit Strom versorgt. Man muss nur darauf achten, einen USB-Hub mit eigener Stromversorgung zwischenzuschalten, weil das iPad auf alle größeren Verbraucher äußerst allergisch reagiert.

1 Netzteil sparen, 1000 neue Möglichkeiten gewinnen

Wäre es nicht schön, das Keyboard direkt an das IO Dock anschließen zu können und auf diesem Weg ein Netzteil (a.k.a. „Wandwarze“) loszuwerden? Leider hat das Dock den falschen Stecker: An den eingebauten USB-B-Stecker (das sind die fast quadratischen, wie sie sich in Druckern und externen Festplatten finden) muss man irgendwo einen Computer anschließen. Ein USB-Bus braucht nämlich einen Master – einfach nur einen Hub anzustöpseln würde nicht reichen. Was aber auch heißt: es gibt leider keine einfache Möglichkeit, weitere USB-Peripherie anzustöpseln – sei es ein weiteres Audio-Interface, sei es eine Kamera, sei es ein Keyboard. Spätestens, wenn mein von mir via Kickstarter stolz mitfinanzierter Superluxus-Musik-Controller kommt, ist das kein Zustand mehr – der hat nämlich ohne Zusatz-Hardware gar kein Midi mehr, und ich wäre gekniffen.

Deshalb reifte in mir schon länger die Vorstellung, dem IO Dock mit einem kleinen chirurgischen Eingriff einen Extra-Hub zu verpassen. Der könnte Geräte wie mein Keyboard problemlos mit Strom versorgen – und für ausreichend Anschluss sorgen. Seit heute weiß ich, dass das nicht nur eine theoretische Möglichkeit ist: man kann den Hub zwischen iPad und Dock einschleifen – und wie beim Camera Connection Kit ist das iPad dann der USB-Master. Das IO Dock funktioniert wie gewohnt, aber man kann weitere Geräte anschließen und aus dem Hub mit Strom versorgen. Das lässt sich alles sogar bequem ins IO Dock einbauen!

Testweise frei verdrahtet: Ein USB-Hub "im" IO Dock

Testweise frei verdrahtet: Ein USB-Hub „im“ IO Dock

Loopy HD erkennt das Dock ohne Probleme - trotz zwischengeschleiften Hubs.

Loopy HD erkennt das Dock ohne Probleme – trotz zwischengeschleiften Hubs.

Wie das lief, darüber demnächst mehr. Detailliertes Howto und Video folgen, wenn der Einbau fertig ist.

Nebenbei: Wahnsinn, was sich alles getan hat, als ich mich über die Unstimmigkeiten der Musiksoftware auf dem iPad ausgemährt habe. In diesem Dreivierteljahr sind viele der Probleme, die ich beschrieben habe, verschwunden; die Software ist erwachsen geworden. Man kann ihr regelrecht beim Reifen zusehen. Und großen Anteil daran haben Einzelkämpfer wie der Loopy- und Audiobus-Entwickler Michael Tyson. Wie die sich mit ihrer Nutzergemeinde austauschen, um Bugs auszubügeln und neue Features zu erfinden, ist großartig. Wäre doch nur Apple auch so offen – dann wäre uns der zu nichts kompatible Steckverbinder im neuen neuen iPad erspart geblieben, es würde weiter ins IO Dock passen und ich hätte mir mit Sicherheit eins gekauft – die zusätzliche Prozessorleistung kann man für Musik gut brauchen. Seufz.