Yamaha DTXpress/DTXplorer/DTXtreme

This might seem kinda crazy, but I purchased the game Rock Band which 
comes with a crappy electronic kit. One of the worst things about this 
kit is the bass pedal. Well, I own a DTXpress III and the back of the 
Rock Band kit has a 1/8" mono input. I tried hooking up the KP65 kick 
pad from my DTXpress kit up to it using stereo cables, mono cables, and 
mono to stereo, mono to mono adapters, etc and nothing seems to work. I 
don't completely understand how the kick pad works, but I'm guessing 
the problem is that it isn't a simple on/off type switch. So I would 
think I'd need to build something similar to Keith Raper's Piezo/Piezo 
to Piezo/Switch Adaptor but possibly in reverse? It would take the 
output from the KP65 and then create a single mono on/off signal that I 
could hook up to the Rock Band kit. I hope I explained things well 
enough. Is there anyone that can help?

--- In DTXpress@yahoogroups.com, "quique_777" <quique_777@...> wrote:
>

I will certainly try to help if I can, but I need some information on
the "Rock Band" kit.  Have you any details, links etc?

Keith.

Well there isn't much information out there. Best I can do is maybe

http://en.wikipedia.org/wiki/Rock_Band#Instrument_peripherals

and here are some of the current mods people have come up with:

One using a button and a kick pedal:
http://rockband.scorehero.com/forum/viewtopic.php?t=1692

This guy was able to get his DTXpress cymbal to trigger the kit so he
taped it onto his kick pad.
http://rockband.scorehero.com/forum/viewtopic.php?t=1888

and this person explains how he thinks the pedal that comes with the
kit works and how you could take apart the pedal to create your own
using a real pedal:
http://rockband.scorehero.com/forum/viewtopic.php?t=1909

So my goal is to get the KP65 to work with the Rock Band kit rather
than doing something silly like taping one of my cymbals to the kick
pad. Should be possible right? What's the difference between the
cymbal and the kick pad and can you make the kick pad work the same
way as the cymbal? Thanks for the help.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:

>
> --- In DTXpress@yahoogroups.com, "quique_777" <quique_777@> wrote:
> >
> 
> I will certainly try to help if I can, but I need some information on
> the "Rock Band" kit.  Have you any details, links etc?
> 
> Keith.
>

Well, I have uploaded my best guess to the files section as "Rock Band
interface".  The components aren't critical - use any general purpose
NPN transistor.  I can only guess at what's inside the Xbox/PS3, but I
am guessing a simple pull-up resistor internally.  The circuit has no
power so it won't be able to do any harm - it will just either work or
not.

There is no difference between the kick and cymbals in principle -
they both generate a voltage from a piezo.  However, there are subtle
differences apart from signal size.  There is an adjustment pot on the
KP65 - try turning it up.  The other differences are the ringing that
you get on the cymbal signal so it will generate positive & negative
pulses.  The KP65 is more damped, from memory.  So it may be
worthwhile reversing the connections of the KP65 (top to sleeve and
sleeve to tip) to swap the pulse polarity & see if that makes it work.

HOWEVER, I WOULDN'T RECOMMEND PUTTING PIEZO SIGNALS INTO EQUIPMENT
THAT ISN'T DESIGNED FOR THEM.  I know people seem to get away with it,
but there is a risk.  The voltages can be quite high and could blow up
what you are plugging it in to.  Something like my circuit provides no
power to the box, so can do no more than a switch.

Keith.

So I bought all the parts today and tried building the circuit and
couldn't get it to work. I have no idea whether it's me or not because
I'm really bad at all this, especially soldering. I bought double the
parts so I'm going to give it one more try anyways.

The input and output is mono correct? I tried using mono cables for
the input and output and also tried all combinations using stereo and
mono cables. I'm sure this should be pretty easy, but I half way know
what I'm doing in the first place.

I guess I'm going to have to give up soon, even though I wanted this
to work pretty bad. If for some reason you ever get ahold of this game
and one of the kits and can figure it out make sure to post on here
how you did it because I'm pretty desperate to get this to work.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:

>
> Well, I have uploaded my best guess to the files section as "Rock Band
> interface".  The components aren't critical - use any general purpose
> NPN transistor.  I can only guess at what's inside the Xbox/PS3, but I
> am guessing a simple pull-up resistor internally.  The circuit has no
> power so it won't be able to do any harm - it will just either work or
> not.
> 
> There is no difference between the kick and cymbals in principle -
> they both generate a voltage from a piezo.  However, there are subtle
> differences apart from signal size.  There is an adjustment pot on the
> KP65 - try turning it up.  The other differences are the ringing that
> you get on the cymbal signal so it will generate positive & negative
> pulses.  The KP65 is more damped, from memory.  So it may be
> worthwhile reversing the connections of the KP65 (top to sleeve and
> sleeve to tip) to swap the pulse polarity & see if that makes it work.
> 
> HOWEVER, I WOULDN'T RECOMMEND PUTTING PIEZO SIGNALS INTO EQUIPMENT
> THAT ISN'T DESIGNED FOR THEM.  I know people seem to get away with it,
> but there is a risk.  The voltages can be quite high and could blow up
> what you are plugging it in to.  Something like my circuit provides no
> power to the box, so can do no more than a switch.
> 
> Keith.
>

--- In DTXpress@yahoogroups.com, "quique_777" <quique_777@...> wrote:
> The input and output is mono correct? I tried using mono cables for
> the input and output and also tried all combinations using stereo and
> mono cables. I'm sure this should be pretty easy, but I half way know
> what I'm doing in the first place.

Yes, mono cable is correct - use the tip & sleeve to connect to the
circuit.

I don't have access to an Xbox/PS3 but if you have a multimeter you
could check what the voltage is across the switch when it is all
plugged in, and what the voltage is when the switch is pressed (zero I
assume).   Let me know if you can find that out.  Unfortunately, while
I have loads of equipment which would help me sort it out, I don't
have the game or any games boxes (just a DTXpress)!

Keith.

Well I got it working pretty well. I tried out a lot permutations of
your circuit using a breadboard. The way I had the input and output
hooked up I had to change both tip and grounds for each one and that
made a huge difference. With R1 in the circuit it won't work at all.
The other huge difference comes from the diode. Without the diode it
doesn't work well at all either. The circuit works almost perfectly
with just the transistor and the diode only. VR1 and R2 really don't
seem to make a difference. Sometimes it seems to help and other times
it seems to be worse. It isn't perfect though and I don't know why.
Every few hits it screws up. I've tried messing with the knob on the
kp65 and playing with VR1 and it doesn't seem to help. I don't know if
there is anything that could be done to make it any better? It works
really well, but it still isn't completely perfect. As for the voltage
I believe I read somewhere that the Rock Band kit uses 2.5v for the
pedal input.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:

>
> --- In DTXpress@yahoogroups.com, "quique_777" <quique_777@> wrote:
> > The input and output is mono correct? I tried using mono cables for
> > the input and output and also tried all combinations using stereo and
> > mono cables. I'm sure this should be pretty easy, but I half way know
> > what I'm doing in the first place.
> 
> Yes, mono cable is correct - use the tip & sleeve to connect to the
> circuit.
> 
> I don't have access to an Xbox/PS3 but if you have a multimeter you
> could check what the voltage is across the switch when it is all
> plugged in, and what the voltage is when the switch is pressed (zero I
> assume).   Let me know if you can find that out.  Unfortunately, while
> I have loads of equipment which would help me sort it out, I don't
> have the game or any games boxes (just a DTXpress)!
> 
> Keith.
>

It is almost impossible to diagnose what is happening without seeing
some signals.  However, I am suspicious that you have got it working
for the wrong reasons.  While I don't know what is in the game box, I
do know what the KP65 signals are like and if it doesn't work with R1
in the circuit then there is something wrong.  I think you are
possibly coupling the piezo signal directly into the game box input
through the transistor/diode, rather than using the transistor as a
switch.  

Keith.

I was wrong again. Your circuit works as is with everything. I just
have to flip the output and ground for the 1/4" mono jack. It still
misses hits every couple though. I'm going to go ahead and solder one
up now with brand new parts and see how things work out. Thanks for
all the help. I'm a pretty big newbie when it comes to all of this.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:

>
> It is almost impossible to diagnose what is happening without seeing
> some signals.  However, I am suspicious that you have got it working
> for the wrong reasons.  While I don't know what is in the game box, I
> do know what the KP65 signals are like and if it doesn't work with R1
> in the circuit then there is something wrong.  I think you are
> possibly coupling the piezo signal directly into the game box input
> through the transistor/diode, rather than using the transistor as a
> switch.  
> 
> Keith.
>

Remember to adjust the KP65 pot as well.

Keith.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:
>
> Remember to adjust the KP65 pot as well.
> 
> Keith.
>
I'm attempting this mod myself and am running into similar issues.  
KP65 just doesn't feel responsive enough or misses hits when using 
it.  It's pretty good with your circuit but not perfect.  I've tried 
a few different variation with no luck including increasing the 
resistance across R2 and removing R1.  I've also swapped the polarity 
on the KP65 side but didn't seem to do much.  I'm very confident my 
circuit is implemented as designed in the .pdf

What I know is the Rock Band controller (drums) outputs 2.14v on the 
center post and registers a hit when connected to the collar (at 
anything under ~10kohms resistance).  What I don't know is how long 
the connection/short needs to be for the controller to recognize a 
hit.  The foot pedal for RB using a magnetic reed switch which 
grounds once the magnet in the pedal gets close to it and stays 
grounded until it is let up.  So even if you have the fastest foot in 
the world there will be a several millisecond window where the 
circuit is closed.

I only have an auto-ranging digital multimeter so it is hard to tell 
what the circuit is doing when hooked up.  Perhaps the connection 
from the transistor is so fast RB has a hard time detecting the 
circuit is being closed.  Any suggestions on how to keep the 
transistor in the closed state longer?  I would guess a cap or even 
the use a Darlington pair might work but I'm a novice at circuit 
design.

Thank, Jeff

Jeff,

If it is the speed of the pulse then you need to try adding some
capacitance to the output (transistor collector).  If the rock band
input impedance is 10k ohms then something like 1uF on the output
(collector) to ground is worth a try.  It is a bit of guesswork but
100nF to 10uF is the likely range that would work.  Too high and it
will stop working altogether (the capacitor will stop the output being
pulled down).  Too low and it will have no effect.

Keith.

Getting the kick pedal to work is actually rather simple. Just get a
stereo to mono plug and plug it into the rock band kit, from there
plug a stereo cable from that into the output in the DTXpress brain
where you would plug headphones in. Then plug a stereo cable from the
bass pedal to the DTXpress brain and set the switch in the back to
MAC, done! Enjoy =).

--- In DTXpress@yahoogroups.com, "Chris" <mr_whoggie77@...> wrote:
>
> Getting the kick pedal to work is actually rather simple. Just get a
> stereo to mono plug and plug it into the rock band kit, from there
> plug a stereo cable from that into the output in the DTXpress brain
> where you would plug headphones in. Then plug a stereo cable from the
> bass pedal to the DTXpress brain and set the switch in the back to
> MAC, done! Enjoy =).
>

Makes no sense to me!  The MAC switch is to do with the "to host"
connector - what are you plugging into there?

Keith.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:
>
> Jeff,
> 
> If it is the speed of the pulse then you need to try adding some
> capacitance to the output (transistor collector).  If the rock band
> input impedance is 10k ohms then something like 1uF on the output
> (collector) to ground is worth a try.  It is a bit of guesswork but
> 100nF to 10uF is the likely range that would work.  Too high and it
> will stop working altogether (the capacitor will stop the output being
> pulled down).  Too low and it will have no effect.
> 
> Keith.
>
 
Thanks for the info Keith.  I'll give that a try as soon as I get the 
parts.  I'll assume the cap goes in series from the collector.  I also 
verified that the ground coming out of the RB kit is actually a ground 
(connected to the USB ground) with zero impedance on it.  Your circuit 
works rather well as long as I give the KP65 a pretty hard kick.  
Although once in a while it will miss a kick in a series when hitting 
at the same force.  The only thing I can think of is that the piezo is 
dropping below the trigger voltage before the RB controller can 
register the kick but again it is just a guess.  If I get well tuned 
circuit I'll post it up here.

Jeff,

I have put a new circuit in the files section to make it clear where
the capacitor goes.  If you use a polarised capacitor then the
positive side should go to the collector.

Keith.

--- In DTXpress@yahoogroups.com, "Keith" <keith@...> wrote:
>
> Jeff,
> 
> I have put a new circuit in the files section to make it clear where
> the capacitor goes.  If you use a polarised capacitor then the
> positive side should go to the collector.
> 
> Keith.
>

Ah I didn't see your post until just now.  I figured out where it 
needed to go, I was just going to post what I did.  Since the KP65 
already has a 1k resistor and a trimpot, the circuit is more 
responsive without R1 and VR1.  If you are building your own trigger 
you would want to have at least a 1k resistor and trim in the 
circuit.  I experimented with different caps and 1uf to 4uf seems to 
be a pretty good range.  No missed hits and the sensitivity is 
excellent.  I also found that the 2N3904 transistor felt a little 
better than the 2N4401 but both work well.  Light taps will now 
consistently be recognized by RB.  I have the trim all the way up on 
the KP65 without double hitting but still plenty sensitive.  I also 
created a Darlington pair circuit with caps and it felt about the 
same as the single transistor circuit with cap. 

Keith thank you very much for taking the time to draw up the circuits 
on what is pretty much an off topic subject.

--- In DTXpress@yahoogroups.com, "jdamph" <jdamp@...> wrote:
>
> --- In DTXpress@yahoogroups.com, "Keith" <keith@> wrote:
> >
> > Jeff,
> > 
> > I have put a new circuit in the files section to make it clear where
> > the capacitor goes.  If you use a polarised capacitor then the
> > positive side should go to the collector.
> > 
> > Keith.
> >
> 
> Ah I didn't see your post until just now.  I figured out where it 
> needed to go, I was just going to post what I did.  Since the KP65 
> already has a 1k resistor and a trimpot, the circuit is more 
> responsive without R1 and VR1.  If you are building your own trigger 
> you would want to have at least a 1k resistor and trim in the 
> circuit.  I experimented with different caps and 1uf to 4uf seems to 
> be a pretty good range.  No missed hits and the sensitivity is 
> excellent.  I also found that the 2N3904 transistor felt a little 
> better than the 2N4401 but both work well.  Light taps will now 
> consistently be recognized by RB.  I have the trim all the way up on 
> the KP65 without double hitting but still plenty sensitive.  I also 
> created a Darlington pair circuit with caps and it felt about the 
> same as the single transistor circuit with cap. 
> 
> Keith thank you very much for taking the time to draw up the circuits 
> on what is pretty much an off topic subject.
>

I am glad it is now working.  The 2N3904 has higher current gain at
low currents, so that may be why it is a little better.  I guess there
is some debounce on the switch inputs which was making it miss short
pulses.

The subject is not too far off topic - it has part of a DTXpress kit
in it!

Keith.

--- In DTXpress@yahoogroups.com, "jdamph" <jdamp@...> wrote:
>
> --- In DTXpress@yahoogroups.com, "Keith" <keith@> wrote:
> >
> > Jeff,
> > 
> > I have put a new circuit in the files section to make it clear where
> > the capacitor goes.  If you use a polarised capacitor then the
> > positive side should go to the collector.
> > 
> > Keith.
> >
> 
> Ah I didn't see your post until just now.  I figured out where it 
> needed to go, I was just going to post what I did.  Since the KP65 
> already has a 1k resistor and a trimpot, the circuit is more 
> responsive without R1 and VR1.  If you are building your own trigger 
> you would want to have at least a 1k resistor and trim in the 
> circuit.  I experimented with different caps and 1uf to 4uf seems to 
> be a pretty good range.  No missed hits and the sensitivity is 
> excellent.  I also found that the 2N3904 transistor felt a little 
> better than the 2N4401 but both work well.  Light taps will now 
> consistently be recognized by RB.  I have the trim all the way up on 
> the KP65 without double hitting but still plenty sensitive.  I also 
> created a Darlington pair circuit with caps and it felt about the 
> same as the single transistor circuit with cap. 
> 
> Keith thank you very much for taking the time to draw up the circuits 
> on what is pretty much an off topic subject.
>

Hi, sorry I didn't get to reply to your e-mail you sent earlier
jdamph. I've been on vacation until today. I was wondering if you
could put up the working circuit diagram that you came up with
including part numbers? I had to have my Rock Band drum kit replaced
and they didn't send me a kick pedal back and so now I need to get
this working more than ever. Thank you so much for figuring this out.

Just use the B diagram Keith provided in the files section without R1 
and VR1.  

Parts for Yamaha KP65 drum trigger (radio shack part number):
1x 1.0µF 35V 20% Dipped Tantalum Capacitor (272-1434) or any other 
1µF-3µF cap. I stole one from a bad power supply 
1x 1M-Ohm resistor (271-1356)
1x NPN transistor 2N3904 (276-2016) or 2N4401 (276-2058).  I felt 
that the 2N3904 worked better but who knows.  
1x mini-board cut down to ¼ (part #276-148)
1x shielded cable with 1/8" headphone plug stereo or mono (42-2387) 
www.radioshack.com only had stereo so I wired the black to the shield 
where to make it a mono cable.
Optional: 1x Enclosure box for the project; (270-1801) 
Optional: 1x three-conductor 1/4" stereo phone jacks (274-312B) 

If you are making your own trigger:
1x 1K Ohm 1/4-Watt Carbon Film Resistor (271-1321) - R1 in Keith's 
diagram
1x 100k Ohm VR (271-284) – VR1 in Keith's diagram.
1x Piezo Element 1500-3000Hz (273-073)

Take a look here http://www.rockband.com/forums/showthread.php?
t=11121&page=4 to physically build the components, just don't 
use any 
of the diagrams there.  

I also used a 1¼ hole saw (metal cutting bit) in a drill press to nip 
two semi circles out of the KP65 stand.  This is to allow the kp65 to 
fit over the back support bar of the RB drums I removed the bar 
closest to me.  I made the holes in the stand just behind where the 
stand meets the upright (if that makes sense).  You could probably 
just use a grinder since you don't have to take much out of the 
stand.  I'll post a diagram and pictures if I have time.

-Jeff 
This post is supplied as is with no written or implied warranty and 
I'm not responsible for any damage you do to your RB drums, Xbox, or 
yourself.