Programming the Simmons SDS7 is a laborious task and to get a collection of patches can take days, weeks or even months. Hey, it might be an idea if you had a record of all your hard work, right? Well, here's something to help you with that. My Simmons SDS7 program chart is an easy way to make sure that all your SDS7 patch data is safely recorded.
There are several reasons why a record of your patch data may come in useful. When you tweak settings for example, you may need to refer to a reference, you may accidentally overwrite one of your favourite snares, or you may just want to create something new and a reference would certainly help you create that.
Designed to reside on your computer, you don't need any special software to fill in these charts. Adobe Acrobat Reader on Mac or Windows will work just fine. If you'd prefer a hard copy, then just print them out.
My Simmons SDS7 program chart allows you to record the following information:
Date
Patch number
Notes
Sample name of each module for up to twelve modules
All module parameters for up to twelve modules
You can try out my Simmons SDS7 program chart here or just download it here. Unfortunately for some (Adobe or Google) reason, the online pdf doesn't respect the tab sequence of the cells but humble me can't do much about that which is a bit annoying. You'll also soon realise that you can only input numbers between 0 and 255 into the parameter cells and I'm sure you know why that is! 🙂
Today is a BIG day. Today my test Simmons SDS7 is back in one piece! SDS7 serial number 70320 was finally put back together after several months of doing exactly what I bought it for… to develop a small range of peripherals for one of my favourite electronic drum systems. 😊
Back in December last year, I found a really nice SDS7 up for sale and having wanted one of these ever since I sold mine back in 1987 to help fund the purchase of my first SDX, I just wanted to get another one.
My early Christmas present to myself got me all smitten again and I had ideas to design stuff that would help keep this legendary instrument going for another forty something years. The only problem was that I didn't really want to develop stuff on the SDS7 I'd just bought, as it was immaculate.
Then in May 2024, a friend pointed me in the direction of a SDS7 that was up for sale relatively locally (London). It had some faults but having an idea what the problems were, I grabbed it for a really good price.
Subsequently, SDS7 #70320 became the platform on which I developed Pleiades lithium battery conversion and uniPulse MIDI to trigger adapter, Dark Matter modular switched-mode power supply, AMEP advanced memory expansion pack and NC-7 noise cancelling snap-in, all of which will be launching very soon. Indeed, I’m delighted to announce that SDS7 #70320 is running Pleiades, Dark Matter and NC-7. AMEP will be here very shortly. In fact, the pre-production PCBs should arrive today.
Using paper cut-outs to make sure that Dark Matter would fit into SDS7.
It's been a heavy few months and there were a couple of points during that period when I thought I’d been a bit too ambitious. Ed Rose (aka The Simmons Guy), Michael Buchner, Patrice Jacquot and my close friend Guy Wilkinson (of Super Synth Projects) have however, been so incredibly supportive. Without their help and encouragement, things would have taken so much longer and perhaps might not even have happened.
My test Simmons SDS7 is back in one piece and #70320 looks and sounds amazing. I’m just so pleased that it all worked out. Pleiades, Dark Matter and AMEP will be launched at the same time and very soon, like within the next couple of weeks, hopefully. 🙂
UPDATE - 16:00, 1st October 2024
Oh! Look what just turned up! AMEP pre-production prototype PCBs. Oh WOW!!
My NC-7 noise cancelling mod for the Simmons SDS7 is for those SDS7s that didn't get this mod factory fitted.
"Surely that can't be" I hear you ask.
Pictured below, is part of the Simmons SDS7 showing the quad op-amp, part of which is used to buffer the stereo outputs. Due to the mish-mosh of analogue, digital and power tracks on the back plane, Simmons was forced to come up with an easy retrofit solution to reduce specifically, CPU noise picked up by the stereo buss. Able to take advantage of a spare op-amp stage in the TL084 and dropping an 'aerial' on the rear of the back plane, inverted noise was mixed on to the stereo buss, thereby cancelling out the 'in-phase' noise. Highlighted in red is the pre-set pot and the two 10kΩ resistors which were part of that mod.
There are however, a few SDS7s out there that didn't get the mod! Pictured below, is my test SDS7 which I used to develop Pleiades, Dark Matter and AMEP and as you can see, it didn't get the mod fitted back in the day.
You'll also notice the absence of a small green capacitor, highlighted in yellow on the second image. This 47pF capacitor which is connected between pins 10 and 12 of the TL084, is sometimes soldered on the back of the back plane PCB. More about this later.
Well, I was going to implement the mod as per the original service bulletin but as it turned out, the track layout of the back plane version in my test SDS7 was different to later revisions and I wasn't able to drill the three holes for the pre-set without busting a track.
Then I had a thought; "Why don't I knock up a little snap-in PCB to do the job?" That way, anyone with a SDS7 that didn't have the noise cancelling mod installed, could also benefit. 🙂
Snaping into the IC socket that the TL084 is in and taping the aerial on to the rear of the back plane, means that NC-7 can easily be installed in a few minutes.
Of course it's not quite that straight-forward. The noise cancelling circuit has to be 'tuned', hence the pre-set pot. Instructions on how to do that are in the installation manual and that process also takes only a few minutes.
The two through-hole resistors of the original mod, are replaced by SMD 0805 resistors that are situated underneath the IC on NC-7. That 47pF capacitor I mentioned earlier, is also superfluous as on the underside of the NC-7 PCB is a SMD 2010 47pF capacitor. Hence, if the original capacitor is indeed soldered to the rear of the TL084, it must be removed.
Irrespective of where the 47pF is located, it should be removed as NC-7 has a 47pF on-board.
NC-7's aerial wire can't simply flip over the back plane PCB. That's because one of three guides guide in the SDS7 top-case secures the back plane PCB exactly where the aerial wire needs to be. The wire I chose for the NC-7 aerial wire is CAT5/6 cable strand so it's solid. If it catches into the guide of the top-case, it'll break. Hence, the aerial wire has to go to one side.
In a similar manner as the original mod, the aerial from NC-7 is hot-glued to the rear of the back plane in between the edge connectors for modules 9 and 10 and across the stereo outputs busses.
So while looking into the infamous SDS7 noise and testing my NC-7 noise cancelling mod for the Simmons SDS7, I thought it might be an idea to actually record this annoying phenomenon.
The video below shows the effect on overall noise level, as the NC-7 noise cancelling mod is gradually tuned in. Check out the VU meter on the right.
WARNING!!!! The signals have been amplified so TURN DOWN YOUR SPEAKERS
Below is a spectral capture of the noise and the effect of the NC-7 noise canceller. As can be seen, tuning in the NC-7 noise cancelling mod, reduces noise between 3kHz and about 11kHz but doesn't do anything for lower frequency noise.
There's one other thing... In fact, you may already have noticed, that instead of using a TL084, NC-7 is fitted with a newer NJM2060. This device is of a much higher specification than the humble TL084. Since two stages of this quad op-amp are used to buffer the stereo buss, having a quieter device will no doubt improve things a little. 🙂 Having said that, I'm not sure the difference will be too noticeable with all of that other stuff!
NC-7 is handmade in Hemel Hempstead, Hertfordshire, United Kingdom, only a few miles from St. Albans where Simmons used to based and where I used to work.
I do not keep NC-7 units in stock and each NC-7 is built to order.
This Simmons SDS7 battery leak occurred because the battery wasn’t charged regularly.
Recently in, was a Simmons SDS7.This is my second most favourite electronic drum systems of all time, after the Simmons SDX. In fact, you can read how much I love this instrument here.
Anyway, this SDS7 was apparently just fine a couple of years ago but when the owner recently got it out of storage, there was no sound. Powering up but otherwise completely dead, only the voice-card name illumination seemed to be coming on with nothing showing in the programmer display. Well, I had a pretty good idea what was wrong with it.
Like a lot of music technology at the time, the pre-MIDI Simmons SDS7 used NiCd (nickel-cadmium) batteries to back up its memory. Some manufacturers like Cheetah, continued to use NiCads all the way up to the end of the eighties, perhaps even a little later. Unlike lithium batteries which soon took over, NiCads need to be regularly charged. If left uncharged for an extended period, NiCd batteries die and WILL LEAK.
Fortunately, the Simmons SDS7 was built with vertically mounted PCBs. Despite the fact however, that there was also a version (like this one) which, instead of having a single battery soldered directly to the memory-board, used a triple AA battery holder (3 x 1.2V in series = 3.6V), battery acid managed to leak out over those already old solder joints, tracks and components. I soon noticed for example, that the C̅E̅ line was down and in fact there were several other issues preventing code from running and therefore not allowing the machine to boot.
There was also, a fair bit of damage to tracks on the rear buss-board (marked up as 'SDS7 BACK PLANE'), which couldn't be resolved by cleaning alone and which required some hot-wiring. Annoying but to be expected.
Although the memory-board was okay, some tracks were badly damaged on the rear buss PCB. The one highlighted in red had completely perished and only the white trace was left.
Above you can see that I'd already jumped one track but there were another eight which although buzzed out okay, I really didn't like the look of. One in particular looked as though it had completely succumbed to battery acid.
Technical literature on really old machines like the SDS7 is thin on the ground. Techs often have to make do with copies that were scanned many years ago on what would now be classed as, low-resolution scanners. I therefore, decided to make myself a little reference diagram.
Unlike the image above which is a standard 1920 x 1280, the original pdf document is pretty big but without going to that kind of trouble, I'd be shooting in the dark. In the end, I actually decided to install my wires around the back of the back plane PCB.
You'll notice in the two images above, that the polarising key in the CPU card edge connector (P13) is somewhere where it shouldn't be and that the key in the edge connector to the right (that takes the memory-board) is missing altogether. In fact, there was a polarising key on one of the voice-cards that was also out of place and so the card didn't work properly.
Anyway, while I was buzzing things out on the back plane, I carried on cleaned up the memory-board.
The battery holder can't be salvaged but I have other plans anyway. I've made a start on cleaning up the memory-board. You may notice that I changed the two grey battery wires. They are now colour-coded!
When I say "cleaning up the memory-board", it actually took several days to buzz out connections and hot-wire tracks that had been damaged by battery acid. After all that, this SDS7 finally managed to consistently boot but there was another problem; the data encoder was unresponsive. Grr... The problem turned out to be a simple but very annoying, dry joint under a buffer that reads the signal off one of the optical receivers. Phew...
My own SDS7 is serial number 71722. The serial number on the back of this one was #70320. If sequential, that's 1,402 units difference. More than just a batch or two!
Indeed, as I went over the insides of this SDS7, it became apparent that it was quite an early version. It had the optical encoder as opposed to the electrical contact type. The polarising keys in the edge connectors on the back plane were the small bits of black plastic type, instead of the yellow clip types used later. There were also various wire jumpers on the CPU-board that aren't on later revisions.
On a side note... There was also some work to do around the back of the unit as the socket pins although not corroded (because they can't), were very black and so needed a good clean.
The XLR pins on the audio outputs were black so needed a good clean. I think I'm also going to have to do the XLR receptacles on the pad inputs.
The lid was smacked in at the front and was also badly scratched and lots of areas that showed corrosion.
Removing the creases on a piece of metal like this is a time consuming task but it'll be worth it. This SDS7 is otherwise in pretty good cosmetic condition.
After several days (or perhaps two weeks) of patient straightening with a combination of heat, G-clamps and weights, I took it to a local company to be sand blasted and powder coated. They said that they didn't think they'd be able to match up the leatherette finish but when I collected the lid a week later, I was blown away. This top case looks like it just came from the factory! WOW!!!! 😮
I was absolutely delighted with the results of sand blasting and powder coating this old Simmons SDS7 top case. It wasn't just the colour. They got the shade and texture bang on. THANK YOU Chiltern Blast Cleaning!
So, back to batteries... Amongst instruments like the afore mentioned Cheetah MS6 and true vintage gems like the Sequential Circuits Prophet V, a Simmons SDS7 battery leak is something I've seen quite a few times over the years, or should I say decades. Don't think that everything can be fixed. It took me two years to concede that the last Prophet V I had in with a leaked battery wasn't salvageable. It's incredibly sad and something that would potentially 'brick' an iconic piece of vintage music tech' so please take note: If you have a piece of old gear like this, do check what kind of battery it has. If it's got a NiCd battery, then make sure it's charged regularly.
! ! ! WARNING ! ! !
Floating around on the Internet, is a post of someone who's substituted a NiCd battery with a lithium battery in (coincidentally), a SDS7. PLEASE DO NOT DO THIS!
Memory retention is designed for specific batteries. The chemistry of a lithium battery is very different to that of a NiCd battery. For a start, the former can't be charged and if you try to do so, you may end up with getting more than your fingers burnt... literally.
For over thirty-five years now, equipment has been designed to take batteries like the CR2032 which we're all familiar with and which outputs 3.0V. Older NiCd batteries are rated at 3.6V. That 16.7% difference can sometimes be significant.
You should also double check when buying batteries as many unscrupulous or perhaps just ignorant retailers advertise NiMH (nickel metal hydride) as NiCd and lithium-ion as lithium. In all fairness, sometimes it's just not clear. As we all know, a Google search for example, will often throw up results that are close to your search term so please check before you buy. Yes, I know it's frustrating, especially when NiCd batteries are becoming increasingly more difficult to procure but please don't be tempted to take the easy option. Batteries are all different. Even those that can be charged, have different charge rates, depending on their respective chemistry. Charging circuits for NiMH batteries for example, are usually designed to measure the status of the battery, thereby dynamically reducing the current that's being fed into them. This is NOT the case with NiCd charging circuits. If you substitute NiMH into a system that normally takes NiCd, then you stand the risk of overcharging the battery. This might not be disastrous but will reduce the lifespan of the battery.
APLOGIES TO SELLERS
If you're considering buying a Simmons SDS7, please do also consider asking the seller to show you a picture of the memory-board. My apologies in advance to anyone selling a Simmons SDS7.
AND FINALLY...
It's quite difficult to find information on the Simmons SDS7 and so I thought it prudent to offer some useful links for those interested.
For a start, if you're in the US, you need The Simmons Guy on your side. Ed is not just knowledgeable and experienced, he's methodical, tidy and VERY helpful. Just one thing; because of all that, he's amazingly busy!
Ed (The Simmons Guy) is also very active on social media and it's worth checking out his Facebook page and his YouTube channel. In fact, in amongst his videos, you'll see my own SDS7 #71722 before I bought it from him, LOL. Ed, where on earth do you get the time?
This site has a lot of really useful SDS7 information and may be of help to those who just need a few facts.
And of course, there's the Simmons Virtual Museum which also has a few useful resources.
UPDATE - 30th May 2024
Since writing this article, I'm delighted to advise that the SDS7 featured above, is now fully up and running! 😀
It took a while and as I focused my attention on the memory-board, actually there were a couple of tracks on the back plane that slipped my eye. Grr...
Since posting however, I've had a few more older items in with completely leaked out batteries.
If you think they look bad, then you wouldn't want to see the insides of the machines that these all came out of! One of them had to be scrapped as it was totally unsalvageable.
I often get asked, which part of my carrier was my favourite. Well, to be honest, if you’re into music, it’s a bit like someone asking which is your favourite band or song. The seventies and the eighties were very exciting times. As an electronics engineer wanting to leave defence and branch out into music technology however, the eighties were truly magic. Indeed, my time at Simmons Electronics Plc in particular, well "kid in a candy store" comes to mind! Fast, hi-tec and an amazing bunch of people, Simmons was one of the many cool electronics companies around, uniquely being the only British electronics manufacturer at the time, to have an office in Tokyo.
What used to be the old Simmons factory in St. Albans (picture taken September 2021). Above the main entrance / reception area and at the top of the stairs (to the left of where it says 'Marshall Volkswagen') there used to be a massive Simmons drum kit.
Within a few months of starting with the company, I was very familiar with machines past, present and future and working on them daily wasn’t always enough. I ended up buying a SDS9, a SDS7, an EPB, a couple of SPM 8:2s and I even bought a Silicon Mallet. And then, in 1987, 'we' released SDX and I just had to have one! Fully expanded (and costing a small fortune), SDX was capable of holding a whopping 8MB of RAM. Well stupid me, I decided that 8MB wasn't enough for drums and cymbals so I ended up buying two fully loaded SDXs, both complete with pads.
Here are my two Simmons SDXs from many years ago, in a previous (life) studio. I still have them and hope I can get them back into my studio soon.And here's an old snap of my 'small' kit. This expanded to double-kick, a few SDX ZI cymbals and a lot more toms. Geesh... What was I thinking? I'm not even a drummer!
Young and stupid (I think I've confessed to such already), I sold my SDS7. I can’t remember why but it might have had something to do with buying the two SDXs which if memory serves me correctly, started at 13,000 GBP each for like the basic version which only had 2MB of memory and fewer pads. Little did I know that years later, selling my lovely SDS7 would be a decision I'd regret and so my long quest to find a really nice replacement began.
In recent years, I'd regularly check out the usual auction sites and scour the Internet looking for a nice SDS7. Well, over thirty years after selling the one I bought while at the company, I finally found one that looked too good to be true.
I'd heard about a Simmons tech in the US called The Simmons Guy and the unit I found was one that he was selling. That in itself, immediately made me feel comfortable as from what I've read, this dude seriously knows his stuff. The thing is that apart from being totally functional, this particular example, looked in really good condition.
So, on 11th December I bit the bullet and today (20th December) my new Simmons SDS7 serial number 71722 arrived.
I was recovering from my first bought of COVID but I simply couldn’t contain my excitement. It took me a while to get through the superb packaging. Of course #71722 is a US unit and therefore the transformer is wired for 120V operation. In such incredible condition, I reluctantly opened the unit and converted it to UK 240V, which included stepping down the fuse.
My new Simmons SDS7 on the bench and powered up for the first time and after its conversion to UK 240V.
The Simmons Guy is 'Ed Rose'. We got to know each other pretty well, while I waited for my new Simmons SDS7 to arrive. Such a lovely dude, he threw in so much with this unit including a beautifully discrete Tubbetec uniPulse MIDI conversion on a 3.5mm socket, loads of EPROMs, a patch-changer and many internal tweaks such as EPROM size selectors on each voice card and the hi-hat fast decay mod'.
These lonely SDS9 pads have been on the landing of the new studio for months. It's like they've been waiting for something...
Launched in 1983, the SDS7 didn't have MIDI. In fact, the first MIDI keyboards, the Roland Jupiter 6 and the Sequential Circuits Prophet 600 only appeared that year and even the MIDI Manufacturers Association wasn't established 'till 1985. Indeed this was a very exciting time.
Fitted with a Tubbutec uniPulse MIDI to CV converter which I have to say, has been done quite discreetly, #71722 can now be triggered via MIDI IN. Even the hi-hat open / hi-hat closed can be controlled via MIDI controller 18. Tubbutec supplies a configurator for Windows and OS X. With no MIDI Out though, things are a bit 'one-sided'. Having said that, the uniPulse hardware is fitted with a momentary switch which allows the system to 'learn' (and memorise) the incoming MIDI channel. A very convenient touch.
1983 Simmons SDS7 with Tubbutec UniPulse MIDI to CV.
All trigger inputs and audio outputs are on 3-pole XLRs. In the case of the audio outputs, one might be forgiven for thinking that they're all balanced. Unfortunately, that's not the case. In fact, being high-impedance as well, I've wired things to accommodate a couple of active unbalanced to balanced converters between the SDS7 and my Yamaha DM-2000 mixing desk.
I would normally have got this racked up but #1722 is in such amazing condition that I decided it should have pride of place.
I've also hooked up the SDS7 to a TP-Link Kasa smart power outlet and a schedule has been created which powers on the SDS7 every Monday at 12:00 mid-day for a couple of hours. That way, the NiCd battery receives regular charging.
Simmons SDS7 #1722 in its new home.
At some point, I might consider modifying the memory back-up battery circuitry so as to take lithium batteries, similar to the modification I offer as part of my external power supply package for the Cheetah MS6.
What the google hook-up also means however, is that I can say "Hey Google, switch on my SDS7" and guess what happens! 😮
LAST WORDS
How practical will my new Simmons SDS7 be for contemporary music production? Who know! Who cares!! What I do know is that I will be using it and I'll absolutely love using it. Yes, it's a huge chunk of mega nostalgia for me but I'm a firm believer in keeping the creative process fun and that's totally subjective.
UPDATE - 28th December 2023
I'm totally over COVID and #71722 is now MIDI'd up to the rest of my studio. For the time-being, stereo outputs are going directly to my Yamaha DM2000 and I AM SO HAPPY!!!!!
My new Simmons SDS7 responded immediately to MIDI and sounded just as I remember back in 1986 (ish). Oh boy! I'm gonna have some fun with this. 😀
NOTE: While I wait for my active unbalanced to balanced converters to arrive, the stereo outputs from the SDS7 are running unbalanced to my DM2000 and I have to admit that I can't believe how quite this box is. While I don't recall having any particular noise issues with my original SDS7 back in the day, it's a well documented fact that some SDS7s did / do suffer from what was referred to as CPU noise. In fact, Simmons developed a rather ingenious 'noise cancelling mod' which took advantage of a spare op-amp. A piece of wire strapped to the back of the 'back plane' PCB acts as an aerial, picking up the so-called CPU noise, which is then inverted and mixed back on to the stereo buss. This particular SDS7 however, is really very quiet. The DM2000 meters will show up failing chorus chips in something like a Roland JX-8P which might not be immediately apparent on the monitors and yet the unbalanced audio outputs from my new Simmons SDS7, aren't showing anything when not played. To be brutally honest, I didn't expect that, especially from a machine that's forty years old.
