the story so far: searching for a DIY pad solution

good question. i really don't know.

more than anything i would consider it similar to some kind of skinned percussion. the lightest touch makes a sound. it redefines the often posted "BANGIN THEM PADS!!!!!!!11111"

i've pretty much solidified my underlying sensor design. that's the most important part of this whole solution. if people want to still use the rubber pads, it's all good - they still make for a better feel than the original shaky glue method. as of now, i just want to try a few new materials.

also, the more layers of foam, the longer the resistivity curve.

something a bit more permanent would be my cup of tea, like 16 pieces of the velostat cast in, say, silicone rubber, so there's no glue that can dry out and come apart a few years down the line, but that's just me. if you wanted to go that route, you can get frontpanelexpress to make you a mold to your own design. i've done buttons with a mold made by them and designed by me.

something a bit more permanent would be my cup of tea, like 16 pieces of the velostat cast in, say, silicone rubber, so there's no glue that can dry out and come apart a few years down the line, but that's just me.

oh, SHT son
i know where to get home-cureable silicon
that's a GREAT idea, very sturdy.

the only physical problem being the underside between the velostat and the contacts, as the silicon would have to be thin, but it should be ok given that it'll be under compressive load. if you need any help designing a mold for said method, drop me a pm.

k, so i'm a step further. i have a design (very simple and durable, with no moving parts) that uses velostat and vinyl. the velostat rests directly on top of the sensor, and does not trigger until you press down on it.

i then put a soft rubber (or foam depending on whatever's more available) spacer down in between the vinyl/velostat surface and the pads. on this, i place the rubber pads 1 at a time (i wish they were all on one sheet, wtf)

slap the cover back on and i'm good to go.

what i noticed at first was a "sticking" sensation. the pads would sense velocity well enough, but then when i removed my fingers the pad would still be triggered as if my finger was still there.

the issue was suction. the pads were totally sealed. to solve this i took a razor blade and slit each corner diagonally a little bit, so air can flow. the sticking problem was taken care of.

this design is good because the velostat doesn't move (it cant, it's stuck in an unmoving layer of vinyl). the only issue right now is one pad that acts funny, but i'll figure out what's going on with that soon enough. otherwise, the results are great, it feels good and responds predictably. no ghost notes show up in the sequencer when i record w/ tc off, and no low-velocity double triggers replace my notes when i record w/ tc on.

and to boot, it uses the original pads, too.

pretty good. i'm gonna give this design a week or two to see how well it holds up udner constant use. i'm about to go on winter break, so i'll be on this thing hours a day.

i'll check in again later.

sounding like your almost there nym, well done. remind me: why did you have the foam there? was the velostat too sensitive on its own with just the pads? also: if one of the kind people with an mpc half-k could measure the size of, and distance between, each pad, there could be a simpler solution if anyone (Akai or VST) releases a pad sheet for the 500, in that you could buy two sheets, and cut a column of four pads off one side, and use that with a full pad sheet. might make the re-assembly easier for those with missing link type hands. just a thought....

i dont own a 1000 (yet) nor seen the inside of one... but can't a regular Pad Sheet be made and solve the problem?

no, the pads are all individually self-contained units on the 1000, so you'd have to make your own PCB with all the contacts for the pads on, and then do what nym is proposing.

Antonym wrote:what i noticed at first was a "sticking" sensation. the pads would sense velocity well enough, but then when i removed my fingers the pad would still be triggered as if my finger was still there.

the issue was suction. the pads were totally sealed. to solve this i took a razor blade and slit each corner diagonally a little bit, so air can flow. the sticking problem was taken care of.

re the sticking problem: i think if you look at the original design, the pads were pretty much sealed, so when the foam you're using allowed air to flow when the pad was hit, and slowed the air going back in again when the pad went to rebound, the issue, in my view, is that the air was allowed to escape in the first place, not that it can't get back in quick enough. my main concern is the slit you've cut with a razor blade. sharp corners in any material propagate cracks when the material is subject to flexing. rubber is no exception. if totally sealing the pads is not an option (which, i believe, is the better option), a little round hole would be FAR better than a slit. try getting hold of a leather hole punch.

remind me: why did you have the foam there? was the velostat too sensitive on its own with just the pads?

the foam (or layer of rubber, which is my case) is there for this reason: say i were to put the rubber pad directly overtop the sensor/velostat/vinyl. the lip (the edge of the rubber pad) holds the pad itself up overtop the sensor. nothing is touching the velostat. this means that you must put your finger against the pad and push it in order to trigger a hit. this is why the mpc1000 pads have been described as "hollow."

i am attempting to remove the aspect of the moving part as much as possible. putting a layer of foam or rubber down acts as a buffer layer. the pads go on, the case goes on and gets screwed in - this secures the pads and pushes em down. now, the lightest touch makes a very light trigger, which is exactly what i want. i want these things to register a hit from a stiff breeze. i've got it to the point where if i'm recording in a pattern and my hand accidently brushes a wrong pad, i have to go in and delete that note. this is the way i like it because you can bang the pads or just touch them depending on your desire- truly expressive.

as for the cut corner: since the pad is no longer supposed to rebound, i am not worried about the cuts compromising durability. admittedly there is more i can do here. ideally, i would be able to find a very thin, soft layer of foam or better yet rubber that i could cut up and put into the pads themselves, so that they don't have to be pushed down at all.

i've learned the following things in the last couple days:

1-velostat should be directly touching the sensor at all times, but not adhered to it, rather sandwiched to it.

2-the less movement the better. the fingertips should be what moves, not the composition of the pad. this is what would cause longterm durability issues.

3-the softer the medium in between the rubber and the sensor, the softer notes you can trigger. different rubber has a shore hardness - that is to say that a tire is harder than say a rubber ball. it's best to make some kind of gradient in between the rubber of the mpc pads and the very sensitive velostat/sensor sandwich.

i spent about an hour last night playing the pads and had great result. i put an attack velocity envelope on and it sounded great with varied velocity. there are a couple things i need to look at, but we're in really good shape here.

regardless of my success, i am not gonna say i have THE ANSWER til i've tested it enough personally and had a beta guy (distorted) do it himself and test it as well for a time. however, i'm willing to say that this thing is going to make a lot of people really happy. it's so nice to be able to play pads without full level on - do you realize that i've only really played my mpc with full level? all my drums from every song i've put online from my mpc - this is going to open up a wonderful world of dynamics.

if you fill up the 'hole' in the pads themselves, i think you run the risk of decreasing the dynamic range of the pads. you will be converting the design to work on the reduction in resistance (with pressure) of the velostat/copper interface, rather than the area of said interface changing with pressure. the whole point of the rubber dome on the underside of the pads is to create a small initial contact patch, which then increases in size with additional pressure. removing the effectivness of this dome will mean you have a large area contact patch whatever force you apply to the pad. i have no idea whether or not this happens in reality, but it might be worth looking into: ie dropping set objects onto the pads (eg a range of coins) and measuring the response. that way you can accurately judge the effectivenes of each change you make to the design.

just my 2 pence, ignore at will.

Ya Doin' It!!!!!!


I can't wait til you post the method to fix these mofokin pads!!!! They R Dyin' slowly but IT DONT STOP THE FUNK!!!!!

gunmetal pm me your address

The Home Improvement Thread brought to you by Nym the Tool Man (pissss...$50 will go a long way towards getting an MPC with pads you don't have to repair...)