JD-800 Aftertouch Modification

Use the full range of aftertouch without straining your fingers.

DISCLAIMER:

This is a Mod to the JD-800 circuit. Do it at your own risk.

Photo: Gwydion Elderwyn

All JD-800 users knows we need to put a lot of pressure to use the aftertouch.

As someone sayd: one needs to stand on the keyboard to get an effect.

I took here the work of two great guys from the JD-800 Tech group. As I know, they had many messages about this work and here is the result with comments from both.

Preben Friis, synth lover an expert in electronics who explain how to do a simple mod to make the aftertouch become better, really light to play.

Gwydion Elderwyn, a guy who have great merits and a lovely work and story.

From now, I merge material from both and something more, including one or two words of mine.

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The Idea:

Preben:

In basic, just change how the circuit "feel" the input value.

A 270 kOhm resistor across R27 will make it possible to use full range of aftertouch without straining your fingers.

R27 position.
Photo: Gwydion Elderwyn

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Please read all the comments before doing anything you will repent! (LOL)

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Researching:

I poked around with a multimeter on the aftertouch circuit today. The pressure
ribbon starts out at 150 kOhm and by full pressure it is around 1 kOhm...

Shunting the ribbon will make it possible to move the threshold to make it start
earlier but will not make it more sensitive.

Preben

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CAUTION:

This is a modification you can do inside the JD if you are comfortable with a soldering iron that makes the aftertouch much more responsive.

This mod might require to unsolder a SMD resistor ... not something for people with ten thumbs.

For sure you can ask an electronics technician to perform this modification.

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About opening the JD-800:

Removing all screws may do your internal components fall.

You must remove only the screws AROUND the bottom and two screws in the center line, they are at 1/4 from side, and may be you can see a few bigger hole where thy fit to.

Sometimes the bottom have some "dust" acting like glue to.

Photo: Gwydion Elderwyn

How to remove the panel.
JD-800 Manual. (click to enlarge)
Source: Roland Co.

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The Solution:

Original post: groups.yahoo.com/group/JD-800_Tech

Preben:

Thanks to Gwydion Elderwyn I received exactly what I needed to calculate and test a better modification of the aftertouch circuit in the JD-800.

The short version: 

Change resistor R27 to 120 kOhm instead of 220 kOhm. Done.

The long version:

Since SMD components are very difficult to remove, and I did not have any SMD components at hand, I chose to solder a 270 kOhm resistor parallel with R27. 

R27 is located on the mainboard in the left corner right by the ribbon cable to the keyboard.

The picture shows my "huge" resistor piggyback on R27. It is not very pretty, but it works! 

Image by: Preben Friis

 

Actually the picture shows a 100k resistor, which was the first one I tried, but that made the aftertouch sensitivity too light. I could easily press the aftertouch from 0 to 127 with my pinkie finger. The 270k resistor is in my opinion the best value. If I use my pinkie with this value it allmost hurts to press it to max. Feel free to experiment - Reasonable values are in the range from 100k to about 1M

Find a soldering iron with a very thin tip and add a little solder to the two pads on R27 first. Then cut and bend the legs of the new resistor to fit across it and add a little solder blob to the legs of it. Hold the new resistor in position with a set of pliers and touch the iron to the legs of the resistor. This should melt both solder blobs to one and the connection is made. Repeat for the other side.

The smaller the better: 

A 1/8W resistor would be preferred over a 1/4W. 

Smaller resistors have thinner legs and that makes them easier to solder to the SMD resistor.
(Acutally I'm currently using a 1/2W resistor and it is BIG!).


The tolerance does not matter much. You can use 220k or 180k if you really want to use the full aftertouch range when playing monofonic lines.
 

An alternate idea:

Marc (daemons_ca) also suggest using a trimmer instead of a fixed resistor:

What I'd like to do instead on this mod is replace the resistor by a lower value, cut the trace next to it and connect a 500Kohm trimmer pot with modding wire (26-28Awg) and have it adjustable. 

I imagine not every aftertouch ribbon has exactly the same value, so this would make it tweekable. Nice thing is if the value of the ribbon changes in time, all you have to do it open it up and adjust it a little. The fixed resistor is there as safeguard so the value doesnt go below a safe value and draws too much current.

Also, I would not connect a pot in parallel with the current value. The response of the pot would not be linear at all, and hard to adjust. 

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Another mod using the same idea:

See that was placed a wire connecting the potentiometer (at left) to position R27 in the circuit board.

Foto: Yuri Alfons Peeters Charlotte

Remember to power off before you solder anything... 

If you connect the resistor properly without shorting anything there is no risk involved in this modification. The current in the pressure ribbon will be double from around 40 uA to 80 uA, but those currents are still very far from anything that can destroy any components.

I can tell you, that a well adjusted aftertouch is almost like getting a new synth. Many of the factory sounds is way more fun to play around with, when you can change the sound by a light pressure. 
For example, try for instance patch I-22, Classic Sweeper .. 

Thanks again Gwydion Elderwyn, I couldn't have done this without your help :-)

Have fun.

Preben Friis

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The Circuit and the mods


Draw and commented by Gwydion Elderwyn.

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As we say here in Georgia, WEEEEEE HAAAAAA!

Thanks Preben!  This mod was easy and it works great!  I used the 270k and find the aftertouch to now be similar to my K2000.

Most excellent.  Kinda makes you wonder why Roland didn’t get it right in the first place.

Jim Combs
www.touchxtone.com

 

 .'.

The Roland JD-800: A Great Synth - Short History and Specifications

Roland JD-800 Programmable synthesizer

Year 1991

"Combining stunning digital sound and sophisticated digital technology with a natural feel and warmth reminiscent of analog instruments, the JD-800 was an instant sensation."

When the JD-800 appeared in 1991, Roland was the first to announce a new trend in the 90's: editability and overview.

The JD-800 become instantly a mega-classical keyboard.

All sliders are dedicated editors just like the original analog synths.

Based on sampling technology, it's a great synthesizer for guitar-like, analog bass or string/pad sounds.

Internal ROM based with CD quality waveforms are combined to build sounds.

Almost patches was created by Eric Persing.

This synth become the synth of choice in just about every studio around the world.

It also can be used to control the JD-990 module.

This keyboard is an extremely programmable digital synthesizer that retailed for $3000 when it was first introduced.

Release Date 1991-1996

Price list (1991 year): Us$2895 (USA), DM 4580 (German) 

Units produced: 24.000 

Digital Programmable Synthesizer with analog user surface.

Real-time controls

Great overall sound.

It´s really beautifull.

Keyboard

61 keys, Velocity, Channel aftertouch, 4 velocity curves

Polyphony 24 voices

6 Parts Multitimbral (Multi mode): 5 part multitimbral + drum mode

Sound memory:

64 internal RAM patches storage positions plus 64 Rom-card

Oscillators

ROM based digital synthesizer

Tone generation:

S+S (Sampling and Synthesis) with resonant filters.

6 MegaByte ROM with 108 PCM Waves, expandable by PCM Rom Cards.

CD Quality waveforms

24 db Filters

108 internal source waveforms:

• 13 Analog waves
• 22 digital waves
• 10 samples
• 16 percussion samples
• 9 overtones
• 4 piano's
• 17 attack transients
• 6 wind samples
• 9 noise
• 2 effect samples

You can also add waveforms from ROM plug-in cards.

Controls:

Keyboard: Good action 61 keys, fast, light, and smooth, with velocity, channel aftertouch, 4 velocity curves. 

125 buttons, knobs and sliders on the front panel, being 75 dedicated for sound editing. All this sends out recordable sysex! You can control the JD-990 with it.

Displays:

• 1 2x22 characters-LCD,
• 1 2x16-characters-LCD,
• green or orange backlight.

Tone Processing functions:

Envelopes:

• Pitch
• TVF - Time Variant Filter (18 bit)
• TVA - Time Variant Amplitude

WG - Waveform Generator

Dynamic filters and Amplifier,

2 LFOs · with 5 waveforms

DSP Effects processor:

2 Effect chains

1x Mono

1x Stereo

• Phaser
• Distortion
• Spectrum
• Enhancer
• Chorus
• Delay
• Reverb
• 3 Band EQ

Cards:

From Roland Roland JD-800 Turbo facts:

• SL-JD80 Series:

A diverse library of Waveforms and Patches ranging from Acoustic, Dance and Rock drums to Strings, Brass, Pianos and even Accordian. Each set contains both a Waveform card and a Data card with 64 patches which utilize the sounds on the Waveform card.

• SO-PCM Series:

These cards contain new Waveforms for use with either the JV or JD-series synthesizers. The JD-800 can use these Waveforms cards to enhance its internal library and allow users to build new Patches.

SL-JD80 SERIES

These are the original Jd-800 sets. Each have two cards, one for patches and one with waveforms.

• SL-JD80-01 Drums & Percussion STANDARD
• SL-JD80-02 Drums & Percussion DANCE
• SL-JD80-03 Rock Drums
• SL-JD80-04 Strings Ensemble
• SL-JD80-05 Brass Section
• SL-JD80-06 Grand Piano
• SL-JD80-07 Guitar Collection
• SL-JD80-08 Accordion

The JD can use waveform PCM cards from JV series.

SO-PCM SERIES (see note bellow).

• SO-PCM-01 Piano Selection
• SO-PCM-02 Guiter & Brass
• SO-PCM-03 Rock Drums
• SO-PCM-04 Grand Piano
• SO-PCM-05 Accordion
• SO-PCM-06 Baroque
• SO-PCM-07 Orchestral FX ** (not for the JD)
• SO-PCM-08 Country/Folk/Bluegrass **  (not for the JD)

Important note about the SO-PCM cards. 

This series of 1 and 2 Mbyte cards for the JV-80, JV-880, JV-90, JV-1000, JD-800, JD-990 and JV-1080 consists of incredibly high-quality sounds that take advantage of these instruments' powerful capabilities. Each card contains patch data and wave data, so you can instantly get at these great sounds.
** 2 Megabyte cards - not compatible with the JD-800. So the SO-PCM-07 and SO-PCM-08 waveforms cards does not work with the JD.
SO-PCM cards provide waveforms AND patches for all models except the JD-800 so you only will have new waveforms to create patches. 

Memory Cards

You can save memory data using standart M-256E cards or compatible as the M-512E. Note, using the M-512E won´t give you double memory.

The cards save patch data only, not waveforms.
It is not possible to create nor save waveform data in the JDs. 

Connections:

• Mix Out - mono (L+R);
• Direct Out - Stereo (L/R);
• MIDI In, Out, Thru;
• Hold pedal (damper);
• Expression pedal input assignable to Volume, Pan, Modulation, or Aftertouch;
• Headphone;
• Card Slots for Patches and PCM data.

General:

Power source: AC100V (50/60Hz) (need an internal technical procedure to change). 

Electric power consumption: 25w

External size: 1040 (W) ×420 (D) ×108 (H) mm

Weight: 15 kg

Optional:

Roland M-256E Ram Card

Roland M-512E Ram Card (only 256kb used)

Roland DP-2 damper pedal

Boss FS-5U momentary type footswitch




Roland EV-5 Expression Pedal

Roland EV-10 Expression Pedal

Differences between JD-800 and JD-990

The JD-990 is the Supermodule of the JD-800. It have extended capabilities and is a "big plus" to any setup.

• Expanded wave ROM (6MB vs. 4MB)
• Ability to use a 8MB expansion board
• 4 additional outs
• True stereo engine
• Osc sync
• Cross-mod (FXM)
• Osc structures that allow ring mod and serial dual filters
• Additional LFO waveforms
• MIDI CC control of parameters
• Tempo-sync delay
• Polyphonic portamento
• Performance memories
• Additional multi-timbral slots
• One patch can keep full effects in multi mode.

Thanks to Ian and Don Solaris for this part.

Important notes and disclaimer:

This is a fan-page.  I have no relation with Roland Corporation.

This page was done because I found myself lost and I start to colect info around the world. All information I found is posted here.

Please, don´t write asking how to do something. Save your time and go directly to the user foruns and sites.

.'.

Roland JD-800 Filters and Aftertouch

Two videos by moretacos1. Visit is page at Youtube, there are lots of good material.

Mean while, I selected two:

Great Filters. Program or just move the sliders as you want.




Atertouch:

An user Roland JD800 experience

Here a interesting testimony from a Roland JD-800 owner, posted recently at JD-800 Tech group relating some troubles and happiness with the JD:


Hi to the tech board. I have had the pleasure of owning a JD800 for several
months now and am totally obsessed over it. The JD800 is one gorgeous keyboard
all around.

Keys I have used extensively for projects in the past included: Korg Microkorg
(went through 2 of these before the tiny keys got to me this year), Korg Karma,
Korg Triton, Yamaha S03 (stolen one night), FM7 softsynth and Sampletank
softsynth.

I have moved on from my band days, and now only have the JD800. It can make up
for all of the prelisted synths, although these days a good VA like Korg's
MS2000b would be essential to have too with a digital. Honestly I like the
stable sound of digital oscillators as well, it's another kind of sound tool,
that gives your monophonic lines a "Synclavier"-like feel.

That brings me to the next point - the JD800 feels alive when you are playing
it. I can't describe it, it simply feels like no other synth I have played.
Sure, first thing I remember about the Korg Karma was it having an excellent
keyboard, but to me and the way I was using my tools back then, it was down to
being a killer preset machine. Whereas the JD800, you start playing on sounds
you normally would shun because they just sound like something from the outer
limits! I got the JD800 to finally own a "true synth". I have no regrets, the
JD800 is a very expressive and touching keyboard. The phaser reminds me of the
phaser from the ARP Quadra.

I really want to get deeper into it but I don't have that much time to practice
synth programming. I was always a preset hound but this board is making me want
to get that aspet of it together. I will be trying out the often mentioned
patches on the internet this week.

When I got it of course it needed some good TLC, it was kinda filthy. Contact
cleaner, compressed air and all that. One of the waveforms for the parts in
multi-mode, #4, was wildly going in and out of tune. Sometimes, some patches
using that waveform would sound horrible because of the detuning. A factory
reset was needed to fix that! Never read about this happening to anyone so I
thought I should mention it.
Next I saw the sliders start changing values on their own, though not full-on
possesed mode. Thanks to all the sources on the net I was able to get it open
and clean the entire thing well. It passed all the diag tests, and the
aftertouch is the only quirk on it now.

Otherwise it plays like a dream, and it probably is, as Roland's newer gear
after the JV and XV stuff IMHO does not have the same charm, uniqueness or power
that Roland gear of the past has. One things for sure, they all are unique and
sound unique. Of the newer stuff I liked the Juno Stage, though I have not
played a Fantom yet. The guys at YouTube in the comments are always going back
and forth on Fantom vs. JD800.
V-Synth is interesting in a way since you can use the sample feature to
literally create your own oscillators and voila its a ROMpler, a JD-8000 with no
sliders lol. We'll see how they respond to the newer competition.

By: gdanielak