I posted some instructional YouTube videos about cleaning switches
and replacing slide pots on an Oberheim DXa.
Here, here and here.
Updated the installation
instructions for the DMX MIDI board with new photos
reflecting new version of board.
I completed the fabrication on a new batch of end panels and they are
now ready for finishing.
I have run out of walnut panels for the time being. I hope to get a new
batch started in a week or two.
By the way, I have quite a few used panels available, including
several of the plastic DX panels. Used walnut panels are half price ($10
each) and plastic panels are available for free for as long as the supply
lasts. Shipping is extra in both cases.
The new DMX
MIDI boards are in, and with successful testing, they are
ready to go!
After 11 years, I have decided to raise the price of the DMX MIDI Board,
but for the extra money, you get:
- On-board lithium battery to replace the old, leak-prone NiCd battery.
- Optional MIDI Thru output (Select either MIDI Out or MIDI Thru, or
add an optional third MIDI jack for both).
- Secure hold-downs for the the Electrongate MRAM board, in case you
want to do away with batteries altogether.
New DMX MIDI boards have been ordered and should arrive in about two
weeks. This is a new revision and includes some nice new features.
1) There is an option for a lithium memory backup battery on the MIDI
board, eliminating the old NiCd battery which was prone to leakage and
required periodic charging.
2) Mounting holes have been added to the board to securely support the
MRAM board option which allows eliminating batteries completely.
3) Components to support an optional MIDI Through jack have been added.
A potential hardware bug has been found in the DX MIDI board REV. 1.01
version only). The symptom of the bug is a doubling of the recording and
playback tempo when using the internal DX clock source.
I've already notified Stretch owners by email, but
if your Stretch DX is showing this problem, it may be corrected by
replacing the 74LS32 IC (U4) on the MIDI board with a 74HC32. I will be
glad to send a new 74HC32 at no charge to owners of a DX Stretch with the
Electrongate MIDI interface.
If your Stretch is not showing this symptom, no changes need to be
Added a pictorial showing how I make the walnut end panels sold with DMX and DX MIDI kits.
See it here.
Added DSX ECOs (Engineering Change Orders) and revision 3.01 software operation guide to the OB Files page here.
Added DSX Service Manual to the OB Files page here.
Added DX factory sequence tape image here.
Added photos showing Prophet 5 installation for MKC-1 MIDI-Keyboard
Added DX Owner's manual (rev.1) and Stretch manuals here. (Thanks to Edward Chen
for providing the scans!)
New details about the tap tempo version of the MCC-3 have been posted here.
At the request of Forat Electronics, the copyright holder of the original LinnDrum samples,
I have removed the Linn samples that were previously available on this site. Sorry for the inconvenience, but
you can still get programmed Linn EPROMs from Forat.
Related to the math error mentioned below, all the WAV file samples in the
EPROM sound libraries have been updated with corrected versions.
Updated Promenade to correct a math error in conversion of bin to wav files. New version is 1.03.
Added a "reggae snare" sample to the DMX/DX samples page.
New DX/DMX MIDI jack plates, ready for painting.
The link I had for the DX User Manual on another web site was broken, so I posted a new cleaned-up copy of the
manual here. This is the second edition of the manual, covering the
DX with factory MIDI, as well as units with the Electrongate DX MIDI upgrade.
I added a new product page for the MKC-1, a MIDI to Keyboard Converter.
This board can be used to add simple MIDI control to older Oberheim synths (OB-X, OB-SX, OB-Xa) and the
SCI Prophet 5.
New DX/DMX walnut end panels are here! In this photo, you can see them
after sanding, before drilling the holes and routing the openings for
MIDI jacks. The panels are sorted into three piles based on which side has
the best appearance: left side, right side or two good sides.
Added Matrix-12 voice board OS images and moved all other ROM images to a new
Many people have asked me about replacement voice boards for the DMX. I'm glad to announce that I now
have these available. The design is based on the original 1554 single-EPROM voice board with a few
minor improvements. The basic sound playback circuitry is identical to the original, so the sound
is the same.
The boards will work with the original 24-pin 2732 EPROMs, but the new board also supports 28-pin 2764
EPROMs with two 4K samples that can be selected by a switch, either directly attached, as shown
here, or through the external control voltage connector.
Check it out!
The new professionally machined and silk screened cases for the
are in! Check out photos and information here.
PayPal ordering and further information coming soon.
I just uploaded a tutorial video on YouTube showing how
to clean a volume fader on a DX or DMX.
Added a DSX test EPROM image..
Added schematics for the DXa.
Added a DX FAQ for frequently asked questions about the Oberheim
DX drum machine.
Added DSX OS ROM images to the OB-Files page.
Added links to some OS ROM images in the OB-Files page.
Posted some Drumware and Digidrum samples here and here.
The 100th Electrongate DMX MIDI upgrade is ready to ship!
Removed non-working Google Friends link. Added some missing dates to
older blog entries with the help of the WayBack Machine.
switch board parts layout drawing to the OB Files.
Promenade, a Windows application from
Electrongate is now available for download or purchase on
CD-ROM. Promenade is an interface program for the Oberheim
Prommer, and supports data transfer, remote control of reading and
programming EPROMs and has a nice visual interface.
Prommer owners, give it a try and let me know how it works for you.
Added patch descriptions to OB-Xa patchbook index page
Added Am6070 DACs to the products page
Added scans of all the ECOs I could find relating to the Oberheim Xpander
Added a schematic for the DMX memory expansion board to the OB-Files page.
I added a page comparing the DMX and
If anyone sent me email on Friday (October 28), could you please re-send
it? My mail server was down all afternoon and I may have lost some emails
that were sent in the afternoon.
The Stretch features on the new DX MIDI board work perfectly. The long
ribbon cables that connect the Stretch to the DX main board, combined with
the higher clock speed of the MIDI board
Z-80, caused problems when installing the older DX MIDI upgrade in Stretch
DXs. The new board is designed to eliminate the noise on the address and
data lines that caused the problem. The redesign also moves the RAM chip
that was previously moved to the Stretch board, back to the DX main board,
for better battery backup reliability. The Stretch cables now plug into
sockets on the MIDI board, rather than the DX main board.
Jimmy Gillan for the loan of his Stretch DX for my testing!
The parts have arrived and DX MIDI kits are available again. The new
board works great, and I will be building some more this weekend.
I hope to test the Stretch features on the new board in the near future.
While waiting for DX MIDI parts, I did some work on Promenade, my
Prommer interface program. The new version is almost ready for release
and supports lots of neat new features, like saving and loading .BIN, .WAV
and .HEX files with automatic conversion from WAV to BIN and vice versa.
Drag and drop is now working, to make it easy to load sound
files. Clicking on the waveform display will now play the selected sound
through the PC speakers.
Watch this space for more news soon!
The PCBs for the new DX MIDI upgrade have been ordered and should be here
I've been working an a new PCB layout for the DX MIDI upgrade, since I ran
out of boards from the last batch and needed to correct some errors in the
I have decided to eliminate the built-in MRAM option, for a few
Adding MRAM to the DX is still an option by installing a MRAM board on top
of the MIDI upgrade, or directly into a factory stock DX.
- It was expensive and not many people were really interested in it.
- The lithium battery system in the DX really works pretty well as it
compared with the NiCd battery system in the DMX.
- It made the MIDI upgrade PCB layout more difficult.
I am also adding a Stretch interface option to the DX MIDI board
that should eliminate a couple of problems with the Stretch that turned up
when people installed the old DX MIDI board in their DX Stretch units.
Watch for the new DX MIDI board in the products section, coming soon!
Yay! I found a source for the Am6070 DAC ICs that are used in the DMX and
DX and bought a bunch of them, so I have them in stock now. That means
that I will have a few more 1554 (single EPROM) and cymbal #1 voice boards
available for sale.
New in the products section: The
(CV-to-MIDI box) and MIDI
Clock Converter (MIDI clock to clock pulse gadget). Check them out!
New in the DMX
EPROM images department, Beat Kick and Beat Snare
samples have been
I just added a new version of the addendum to the DMX Owner's Manual for
revision 4 firmware (MIDI). This is a 17 page document with details
about the new edit parameters and describes lots of stuff you may not have
known your DMX was capable of.
For example, did you know that you can use "tap tempo" to set the tempo
on the DMX? In the document, it's referred to as "Cue Tempo," but it's
basically the same thing.
And did you know that you can save and load the sequences and songs in the
DMX over MIDI?
I encourage current owners of MIDI DMXs (including those with the
Electrongate MIDI Upgrade) to download
this PDF document and find out what the DMX is capable of!
I added a link for Google friends at the bottom of this page.
DX MIDI News:
The DX MIDI upgrade is now available with built-in Magnetic RAM, so you
can combine two upgrades in one. The instability problem has been fixed
and after several days of continuous testing, I've decided it's ready to
release. Place your order here.
The glitch in the MKC-1 is fixed. Everything is now working perfectly
with the OB-X. In theory, it should also work as well in the OB-SX, OB-Xa
and OB-8, since all of these use the same keyboard interface method. I'm
pretty sure the MKC-1 will also work with Oberheim TVS and FVS systems.
The first MKC-1 prototype is up and running. I'm testing it on an OB-X at
the moment (thanks to B.C. who loaned me his). It seems to be working
very well with the OB-X, with only a minor glitch in the top octave of the
keyboard, which I should be able to fix without too much trouble. The
keyboard pass-through is working fine, and MIDI in and MIDI out are both
working as well. I still need to test the local control on/off and
onmi-off functions, but it's looking good.
The price for the MKC-1 will be $129, and once I get a few more built
and tested, I will put an ordering link up on the products page.
My first tests with the DSX led me to discover that the DSX firmware
version I have (3.04) doesn't support an external keyboard as described
in the owners manual. It looks like I will need to work on a modified
version of the DSX firmware in order to make the MKC-1 work with the DSX,
and that will take some time.
Ten MRAM boards are complete and tested. I made a small modification to
this batch, which I think will result in improved reliability.
DX MIDI kits are now sold out. Expect 1-2 weeks delay.
A new batch of MRAM boards is almost ready.
DMX MIDI kits are sold out. Expect 3-4 weeks delay if you order one.
Update: I just ordered printed circuit boards for the new MKC-1
(MIDI to keyboard
matrix converter), which will emulate an external keyboard in the Oberheim
well as adding MIDI keyboard control to any of the older non-velocity
Oberheim synths (OB-8, OB-Xa, OB-SX, OB-X and possibly even
the SEM based systems. I expect boards to arrive in about a week, and if
all goes well, testing will begin shortly after that. The firmware is
written, just awaiting hardware for testing.
MRAM News: I have parts for more MRAM boards now and just need to
finish assembling and testing them. Maybe this week...
A new batch of walnut end panels have arrived. I recently finished
building more DMX MIDI kits and still have some DX MIDI kits in stock.
I'm currently building more Magnetic RAM boards.
I did a custom modification of a DMX last week which added a Sync24 (DIN
sync) output to the DMX. I tested it with a Roland TR-606 and it worked
pretty well. I'm thinking of
adding this as an option on future DMX MIDI upgrades, or perhaps as a
Oberheim Prommer owners: I'm working a Windows application that
you transfer data files to and from your Prommer so you can program
EPROMs. All you need is a Prommer, a MIDI interface for your
computer and two MIDI cables. I should be releasing this program soon.
If anyone is
interested in testing a preliminary copy, let me know.
There is a new version of firmware for the DX MIDI kit which fixes a
problem in the Stretch DX. This version will ship with all future DX
MIDI kits, but current owners do not need to upgrade unless they have
a Stretch DX. Thanks to Bruce Forat for helping me find and fix this problem!
Now accepting DX and DMX repairs again. Contact Paul to
arrange shipment of your machine to San Jose, California. |
overhaul price for either machine
is $89, which
includes switch cleaning, new battery if needed, minor repairs and return
shipping via UPS within the USA. Some repairs may require specialized
parts or extra labor at additional cost. Turnaround time is usually
one week or less.
Electrongate is moving! |We are temporarily unable to accept
machines for repair. This situation should change within a couple
of weeks. Please do not send any shipments to the old
address. Please contact Paul White to
arrange shipment of your DMX for repairs or upgrades.
I am withdrawing the MRAM option for the DX MIDI board due to some
reliability issues. The basic DX MIDI upgrade is working fine, but the
PCB layout of the MRAM section turns out to have some problems. Sorry
DX MIDI upgrade news: |
I shipped the first five DX MIDI upgrade
kits this morning! More should
be ready to go out tomorrow.
Now in the accessories product page: DSX ribbon cables to connect your
DSX sequencer to your classic Oberheim synthesizer.
Work is progressing on a DX MIDI upgrade. Watch this space for an announcement soon!|
My stock of 1554 DMX voice cards is starting to run very low, so I am
designing a replacement voice card that will sound just like the
original (using the same filter circuit), but will have more options for
different EPROM sizes and be easier for the user to configure. Stay tuned
for more info.
I just found out that the DMX Files were mentioned in this article in The Guardian,
written by David McNamee. Thanks, David!
The Magnetic RAM upgrade has now been successfully tested and is
now available for the Oberheim OB-Xa synthesizer!
Thanks to German Hernandez for his assistance,
The Magnetic RAM upgrade has been successfully tested and is
now available for the Oberheim OB-8 synthesizer, as well as all versions
of the DMX and DX drum machines! Check the products page for ordering information.
New! Magnetic RAM
for Oberheim Z-80 based products (DMX, DX, OB-8, OB-Xa, OB-X, DSX).
The circuit boards are in, and the DMX version is tested and working correctly!
This upgrade replaces the battery RAM with a new magnetic RAM technology -- no more battery replacements, no more battery
leakage, no more memory loss due to dead batteries. A small circuit board plugs into the Z-80 socket and the Z-80 is
moved to the Magnetic RAM board. The old RAM ICs and battery are removed. That's it! No soldering required.
This board will work with all versions of the DMX, including the MIDI version.
The MRAM board has been successfully tested on three versions of the DMX,
the DX, DXa and now the OB-Xa and OB-8.
|Sequential Circuit Drumtraks EPROM images now available here.
|New samples on the DMX EPROM image page:
Electric Kick, Electric Snare 3, Long Hi Hat, Long Noise and Scratch.
Visit the new Friends of
page! If any of my customers or other friends would like to be added to
the list, just drop me an email.
Due to the battery price increase, the cost for a
DMX tuneup is
going up to $89.
|Batteries! We now have replacement lithium
batteries with solder pins as used
in the Oberheim DX, OB-X, OB-Xa and OB-8.
|Due to a price increase from my supplier, the cost of replacement
DMX/DSX batteries has gone up.
Check out the new product page -- you
can use PayPal
to buy cool DMX accessories! Click the link at the top of the page.
|New Electrongate products, now in production --
- DMX Trigger Box DTB-8 -- A rack-mount interface that allows
the DMX with external trigger pads such as those made by Roland or
Simmons (not included). The DTB-8 features eight 1/4
jacks on the front panel, each with an LED trigger indicator.
A custom cable connects from the rear panel to the Molex
on your DMX. Trigger sensitivity is adjustable by means of
a trim pot for each individual channel.
Powered by an internal 120/240V AC power supply. $279
- DMX Trigger Box DTB-10 -- like the DTB-8, but with the addition
two multi-trigger inputs that allow triggering any combination of drums
with a single trigger pad. The combinations are set by DIP switches.
- UniTrigger UT-1 -- A simple MIDI trigger box that accepts a
or variable resistance trigger input and produces MIDI note-on/note-off
A multi-turn pot sets the base MIDI note number, and a 0 to +5 volt
control voltage (CV) input allows
setting the MIDI pitch at 1 volt per octave. Features LED
power and trigger
indicators and a pitch select knob on the front panel. The rear panel has
a DC input jack, MIDI In and MIDI Out jacks, 1/4 inch CV and Trigger Input
- Click Box CB-1 -- Give your drummer a click track to
keep time with
your MIDI sequences. The CB-1 is like a synthesizer with only one sound
-- any MIDI note-on received on the selected MIDI channel produces a
click. The tone of the click is determined by the note-on velocity, so
you can emphasize the down beat. Just add a track to your MIDI sequence
with a note every quarter note and assign it to the CB-1 MIDI channel.
Direct output to headphones is through a 1/4 inch stereo jack, or send the
output to a mixer or amp for more volume. An analog volume control sets
the level. An LED on the front panel blinks with each click, and the
rear panel features MIDI In, MIDI Thru, DC power in and the headphone
output jack. $99
THUMBSCREWS! We now have a supply
of those cool
for the front cover of your DMX or DX. These make it easy to open your
drum machine to change EPROMs or voice cards without using any tools. A
set of two thumbscrews
is available for $5.00, including postage to anywhere in the USA.
Click here to order.
KNOBS! We now have replacement
volume slider knobs for the DMX available. These are exact
replacements, newly manufactured by Rogan, the company that made the original knobs for Oberheim. The same knobs are also
used on the Oberheim DX (and Stretch).
Click here to order.
Added link to panel
cutout diagram for end panel modification on the DMX MIDI installation instruction page
Just added: Oberheim DX schematics and part layout
Started blog on this page.
DMX picture is colorized, "In color" added to page title.
DMX Files goes online with a black & white image at the top of the page.