Cheap Midi Add-on

[cheapthrill]

Back in the 80's, one of my close friends got an old DD-5 Yamaha drum pad (for Christmas I think). He eventually gave it to me. It has really cheesy sounding drums and I deemed it as a toy, but for some reason, I held onto it. Well, I was going through stuff in my garage last week and noticed something when I picked it up... what this? It has a MIDI out jack on it? With some help from some fellow vdrums.com members, I got it triggering via MIDI in my TD-8 module. It gave me ideas.

I installed a jack in it which allows me to plug in an trigger, somewhat like a primitive TMC-6. I only have the ability to add one trigger to my kit right now (because of limited rack hardware), so I made this tutorial showing how to install one jack into a DD-5. Of course, you could just as easily install four input jacks though.

First, take the bottom off with a screwdriver. I decided to remove the speaker and de-solder the DC battery wires for better access.
Drill a hole for the jack. It only needs to be a stereo jack and not a TRS jack. Solder on some wires, they should be about a 12 inches (30cm) long.


Remove screws which fasten the circuit board down and turn it over. There are places on the circuit board where the piezos from the little built-in pads are soldered at. Solder the other ends of the wires from the jack you just installed to the respective pad that you want the jack to share. I chose the bottom right-hand one because with MIDI function it has more capabilities. On the Yamaha, the colored wires are the grounds (not the black wires), so wire them accordingly.


At this point, you can fasten the board back on. Be careful to make sure that the power light lines up with its hole. To test it out to make sure that it works first, I fastened a few screws on around the on/off switch give it good contact and reattached the grounds. If you get power, unplug it again and refasten the rest of the screws.


Reattach the bottom and you're done. Here is a pic of it plugged into my kit.


The con with this model is that you have to leave the power on or you will have to reset your MIDI settings every time. The sensitivity can't be adjusted for the trigger, but it works well for triggering instruments without a lot of dynamics, such as a cowbell, woodblocks, etc.

This cost me nothing because I already had everything, but to buy a DD-5 on eBay is about $10 to $20 US dollars. This is a relatively cheap and easy way to increase your triggers. You can get a MIDI cable at Radioshack for under $10. I am sure that this kind of modification can be done with other cheap drum pads with a MIDI out jack as well, so I hope I stirred up some DIY imagination and saved a few old drum pads from ending up in the landfill.

[Hellfire]

That's using the old noggin. Great application of old technology. Actually, I did a write-up on my web site about this very subject. The yamaha DD5 is not the only DD module you can do this with. Just have a look at my old post:
Hack For A Drum Module?

[cheapthrill]

Originally Posted by Hellfire

That's using the old noggin. Great application of old technology. Actually, I did a write-up on my web site about this very subject. The yamaha DD5 is not the only DD module you can do this with. Just have a look at my old post:
Hack For A Drum Module?

Great minds think alike... seems like you are always a step ahead though!

I thought that the higher end Yamaha pads would probably be even better for this kind of modification, but I just happened to have a DD-5 laying around.

When you used them on your PC, did you have a means of adjusting trigger sensitivity and whatnot?

[Hellfire]

Originally Posted by cheapthrill

Great minds think alike... seems like you are always a step ahead though!

I'm not always a step ahead, but I do thank you for the comment.

Originally Posted by cheapthrill

I thought that the higher end Yamaha pads would probably be even better for this kind of modification, but I just happened to have a DD-5 laying around.

I like the DD-5, that's why I chimed in.

Originally Posted by cheapthrill

When you used them on your PC, did you have a means of adjusting trigger sensitivity and whatnot?

(Unfortunately) The DD5 doesn't have a trigger sensitivity like some of the other DD units, but if you are worried that the triggers being too hot, you can always build this to control the sensitivity:



Also, depending on what software you are using, you might be able to control the sensitivity through the software. (but I'm not 100% sure about that one)
BTW, If you need a manual for the DD5, you can find it here: http://www.usersmanualguide.com/yama...rtasound)/dd-5

[cheapthrill]

Hellfire, I like your sensitivity tuner. Is there an electrical component that can actually boost the sensitivity though?

[bogiesbad]

Nice recycling job. I believe a transistor amplifies the signal...might take a close look at the KRC to see how he uses a transistor...I'm pretty ignorant on electronics so I'm not sure if it would work for you.

[cheapthrill]

Originally Posted by bogiesbad

Nice recycling job. I believe a transistor amplifies the signal...might take a close look at the KRC to see how he uses a transistor...I'm pretty ignorant on electronics so I'm not sure if it would work for you.

Thanks Bogie. If anyone else wants to chime in, feel free.

[Hellfire]

Originally Posted by bogiesbad

Nice recycling job. I believe a transistor amplifies the signal...might take a close look at the KRC to see how he uses a transistor...I'm pretty ignorant on electronics so I'm not sure if it would work for you.

You could try that, however my understanding of the KRC is to make a piezo act like a switch, and if that is correct I don't think this would work. (But) It is definitely worth looking into.

Originally Posted by cheapthrill

Hellfire, I like your sensitivity tuner. Is there an electrical component that can actually boost the sensitivity though?

Unfortunately, I no longer have my DD5, but I would bet that you could jump a resistor or two on the PCB (of the DD5) to get a stronger signal. I'm saying this base on what little I can see from your pictures. If I still had my DD5 I would experiment down that road, but I don't, so unless you feel comfortable "trying" stuff I wouldn't do it.

The resistors I'm looking at are the ones near where the wire for the piezo go into the PCB. I would bet money that yamaha cut the input signal down with one or more of those resistors. The only way to check is to "jump" a resistor to find out. To do that you would need a small piece of wire with some alligator clips on it, but again I don't know if this could harm you DD5. So do it at your own risk if you do it at all.

[cheapthrill]

Originally Posted by Hellfire

I would bet money that yamaha cut the input signal down with one or more of those resistors.

That is a good point. Removing a resistor or two seems like the most likely way to improve the sensitivity. I looked at how the piezos are adhered... they are fully glued onto the backs of the rubber pads (which are metal!) and they hardly flex at all. Replacing them would not be worth the hassle, so I'll try removing a resistor eventually.

[Hellfire]

Originally Posted by cheapthrill

That is a good point. Removing a resistor or two seems like the most likely way to improve the sensitivity. I looked at how the piezos are adhered... they are fully glued onto the backs of the rubber pads (which are metal!) and they hardly flex at all. Replacing them would not be worth the hassle, so I'll try removing a resistor eventually.

What is the sensitivity of your external trigger? For the internal triggers it makes sense that the sensitivity may be lower because of the way the piezo mounted, but that shouldn't matter for your external triggers. I also realized that I stated to "jump" the resistors. Doing that would create a short, most likely making the piezo not work at all. Once you do that at least you will know which resistor to cut out at that point.
(sorry about that)

[cheapthrill]

Originally Posted by Hellfire

What is the sensitivity of your external trigger? For the internal triggers it makes sense that the sensitivity may be lower because of the way the piezo mounted, but that shouldn't matter for your external triggers. I also realized that I stated to "jump" the resistors. Doing that would create a short, most likely making the piezo not work at all. Once you do that at least you will know which resistor to cut out at that point.
(sorry about that)

When I said "remove a resisitor" I didn't mean literally take it off the circuit board. I knew what you meant by "jumping" and that is what I should have said, sorry to confuse.

I can't adjust sensitivity for external triggers on the module while they are running though MIDI, or at least haven't found a way to yet. Both internal and external triggers go through the same circuit at the same point on the DD-5, so the circuit itself could use a boost for both.

[Hellfire]

Originally Posted by cheapthrill

When I said "remove a resisitor" I didn't mean literally take it off the circuit board. I knew what you meant by "jumping" and that is what I should have said, sorry to confuse.

I can't adjust sensitivity for external triggers on the module while they are running though MIDI, or at least haven't found a way to yet. Both internal and external triggers go through the same circuit at the same point on the DD-5, so the circuit itself could use a boost for both.

The rolling eyes were meant toward me. (not you) What I was trying to say is that you are correct. A resistor needs to come out to get more sensitivity, not get shorted like I stated. (I was backwards )

I ask about your external trigger, because you stated this about the internal:

Originally Posted by cheapthrill

I looked at how the piezos are adhered... they are fully glued onto the backs of the rubber pads (which are metal!) and they hardly flex at all.

My point was that your external trigger piezo is most likely not mounted that way, so I would have thought your external trigger to be a slight more sensitive. (but then again I'm guessing because I'm not doing it myself) This is one of those times that I wish I had the equipment to try what you are doing so I could be more helpful.

[cheapthrill]

Originally Posted by Hellfire

My point was that your external trigger piezo is most likely not mounted that way, so I would have thought your external trigger to be a slight more sensitive. (but then again I'm guessing because I'm not doing it myself)

You know, HF, I plugged it into my tom trigger and it wasn't anymore sensitive than the internal pads to my surprise. I am thinking that jumping some resistance will help both external and internal triggering and allow me to plug in some triggers with a more dynamic range through the Yammy device.

[cheapthrill]

Originally Posted by Hellfire

Unfortunately, I no longer have my DD5, but I would bet that you could jump a resistor or two on the PCB (of the DD5) to get a stronger signal. I'm saying this base on what little I can see from your pictures. If I still had my DD5 I would experiment down that road, but I don't, so unless you feel comfortable "trying" stuff I wouldn't do it.

The resistors I'm looking at are the ones near where the wire for the piezo go into the PCB. I would bet money that yamaha cut the input signal down with one or more of those resistors. The only way to check is to "jump" a resistor to find out. To do that you would need a small piece of wire with some alligator clips on it, but again I don't know if this could harm you DD5. So do it at your own risk if you do it at all.

Your logic makes perfect sense, but is incorrect. There are two resistors in between several diodes and the points at which the wires (from the piezos) connect to the board... the first one was 47K, the other 22K. I tried removing one and/or both resistors and also replacing one or both with resistors possessing much different ohms (1M, 150K, 55K, 10K, 1K). The first resistor could be omitted, but the second couldn't. Nothing yielded the most sensitivity like the original resistance. However Yamaha made this, it seems that their set up allows the ideal current from the piezos. Maybe sensitivity is still tweakable elsewhere on the PCB, but I have no idea where or how.

[jman 31]

Look at the resistor. If one end actually goes to ground then you need to increase the resistance, therefore decreasing the amount of voltage that is dissipated to ground. I can't tell anything from your pictures, but with the outcome you described it sounds like you are actually letting more signal be dissipated to ground when you jumper it. you will actually have to remove the resistor to increase it with one of a higher rating because the lowest value is what it will be if you jumper it with another resistor and won't do you any good. Sorry if that doesn't make sense, I will try to explain it better if you need me to.

DIYaudio.com is a great place to learn about audio. With their help I have built several guitar headphone amps that used an op amp to increase the signal. Transistors will work also, but you will need to build an amplification circuit, not just add a transistor.

Jman

EDIT: sorry just reread your post and it looks as though you already tried resistors of a higher value. Post some closer pics if you can.