MSA-T to Boss DR-55 question

[Brogram]

Hello,
I'm attempting to use the MSA-T to trigger the sounds of a Boss DR-55 drum machine. I have successfully uploaded this sysex message to the MSA:
F000015D0201013C013D033E013F01400141014201430001F7
I have tried this. And the example in firmware manual
"3-3"

I have the trigger connection points for the DR-55 but using these configuration I am only able to get the machine to start the currently selected pattern. Since I am new to electronics I'm not sure what kind of trigger pulse should be used to trigger the 4 sounds.
Any help would be greatly appreciated!:D

Cheers,

Eric

[John]

Ok...

When you send MIDI notes corresponding to other functions (not "pattern start"), does the MSA respond with an activity indication?

If not, we'll need to get your MIDI notes matched up with the SysEx configuration.

If you are getting an activity indication, then...

Which MSA output are you using for "pattern start"? I notice that the SysEx configuration uses a fixed length pulse for one output (mode 03h), but uses pulse-length-from-note-length for the other outputs (mode 01h):

F0 00 01 5D 02 01
01 3C
01 3D
03 3E
01 3F
01 40
01 41
01 42
01 43
00 01
F7

Perhaps you'll need to experiment with fixed pulse mode, and then with different pulse lengths. I haven't modded a DR-55 myself, so I can only provide some general ideas...

[John]

You might also try to contact lazenbleep (http://forum.highlyliquid.com/member.php?u=776)...he has done a DR-110 MIDI mod with the MSA-P (http://haha-fresh.blogspot.com/2007/11/dr-rhythm.html).

[Brogram]

In regards to the pattern start, I am using trigger 0A, and only triggered it because I stumbled upon a jumper wire (on the board) that corresponds to pattern start that is next to the individual drum sound connection points. In other words it wasn't my intent to use this trigger for that purpose, just thought I would let you know that I was able to at least get something to trigger.

In short, yes it does indicate activity but after I uploaded the new Sysex message only one note would show activity. (I switched something by mistake)


I notice that the SysEx configuration uses a fixed length pulse for one output (mode 03h), but uses pulse-length-from-note-length for the other outputs (mode 01h):

I got sloppy entering numbers when I left one output at Mode 03h :o

Thanks for all the help, I will try some different pulse lengths and see what happens. The diodes aren't needed for this type of triggering correct? Just the wire directly to the contact point?

Best,
Eric

[John]

Thanks for all the help, I will try some different pulse lengths and see what happens. The diodes aren't needed for this type of triggering correct? Just the wire directly to the contact point?


Diodes are not necessary. But you'll need to be sure that the drums are triggered when the contacts are grounded--when an MSA-T output is active, it is like a short-circuit to ground.

[Brogram]

Which contact point should the ground wire be connected to? Running from where to where? And that's one per trigger output correct?

[John]

Which contact point should the ground wire be connected to? Running from where to where? And that's one per trigger output correct?

Where are you connecting the MSA-T outputs, and how did you determine those locations? (was it a website, your own investigation, etc)?

Can you provide a diagram of how you're connecting the MSA-T?

[John]

This diagram shows what the MSA-T output terminal effectively does--in your application, the MSA-T output terminal is like a switch that connects the output to ground. The diagram assumes that MSA-T ground is connected to drum machine ground.

[Brogram]

So attached is the document I am using for the connection points. The jumpers all in a row are what trigger the sounds. Let me see if I understand what you are saying.... I'm a bit confused. If I only make the connection from the MSA-T output to the jumper wire connection on the DR-55 then when the trigger fires it grounds the output? Is that right?

Thanks for your patience!
-Eric

[John]

Hi Eric,

Let me see if I understand what you are saying.... I'm a bit confused. If I only make the connection from the MSA-T output to the jumper wire connection on the DR-55 then when the trigger fires it grounds the output? Is that right?


Yes. :) That's correct. You'll also have to connect the "ground" power terminal on the MSA-T to the logic ground on the DR-55 so that it will work properly.

So:


You'll need to make sure that simply grounding the DR-55's trigger points is the "correct" way to trigger the sounds. (I mention this because I'm unfamiliar with the DR-55.)
Then, you can test a trigger point on the DR-55 by grounding it manually (with a piece of wire or whatever).
If the manual method works, then triggering via the MSA-T output should work, too.


Hope this helps...glad to continue the conversation if you need more help.

[Brogram]

That's great thank you.
I just got the sounds to trigger which i'm very happy about :D
The cymbal may give me some trouble but we'll see.
I will need to try out different pulses now. I'm now powering the DR-55
directly from the MSA-T which is going to make things easier for me since I'm adding a jack for the power supply. Great MSA feature by the way!

I'll post which pulse length works well in case anyone else is going to give this a go.

Cheers,
Eric

[Brogram]

Ok... So I got it to trigger with this sysex message although there was a "bump" sound before the initial drum sound. Then for some reason it started triggering the sounds VERY quietly. So I tested out the manual method and that worked like a charm.

Here is the code I was using.
F000015D0201033C033D033E033F0140034103420343005BF7

:confused:

[John]

Ok... So I got it to trigger with this sysex message although there was a "bump" sound before the initial drum sound. Then for some reason it started triggering the sounds VERY quietly. So I tested out the manual method and that worked like a charm.

Here is the code I was using.
F0 00 01 5D 02 01

03 3C
03 3D
03 3E
03 3F
01 40
03 41
03 42
03 43

00 5B

F7


Ok, so at this point it looks like you're using a fixed-length output pulse for all MSA-T outputs except for output #4. Did different pulse lengths affect the result?

Do you have a diode between the MSA output and the DR-55 (as the schematic you posted seems to show)?

[Brogram]

Yes, different pulse lengths did effect the result but there was usually this thump sound before the drum sound and I wasn't able to fine a pulse that triggered the entire snare voice (even with very long pulses).
But then it started only triggering a very faint drum sound.
I'm not using diodes from the outputs just going directly to the board with one wire. About grounding... If I have the DR-55 Powered by the MSA-T using the + and G outputs does this mean the signal should be grounded? Or is there more wiring that I'm not understanding?

Thanks,
Eric

[John]

If I have the DR-55 Powered by the MSA-T using the + and G outputs does this mean the signal should be grounded? Or is there more wiring that I'm not understanding?


Are you powering the DR-55 from the MSA 5V output?

Or are you powering it from the same supply as the MSA and simply using the MSA power input terminals as a connection point?

The logic ground inside the DR-55 may not be the same as the ground on the power supply--so you're correct that this may be an issue.

You might try using a separate power supply for both the MSA and the DR-55, then connecting MSA ground to DR-55 logic ground (from a point inside the DR-55). This may change your results...

[Brogram]

I'm powering it via the MSA 5V output since that is closest to the amount of power the DR-55 needs. I'm unfamiliar with the term "logic ground", where would this usually be on the board? I was thinking the strap soldering points which hold the pots down to the board.

When you say to run the MSA ground to logic ground are you referencing the 5v output ground or running a wire from the input ground?

[John]

I'm powering it via the MSA 5V output since that is closest to the amount of power the DR-55 needs.

You're powering the DR-55 thru the DC input jack, correct? Hmmm...what is the input voltage specification to the DR-55? If it's higher than 5V, this could be causing problems.

I'm unfamiliar with the term "logic ground", where would this usually be on the board? I was thinking the strap soldering points which hold the pots down to the board.

What I mean by "logic ground" is the ground supply trace for whatever IC(s) happen to be involved in the triggering of sounds. This could be, but is not necessarily, the same as the negative terminal of the power supply and/or grounding for the pots & other parts on board.

If the "ground" for the IC that accepts the trigger signal is at a different voltage than what the MSA is using for ground, it could explain the unusual behavior.

The easiest way to investigate is to power everything down and poke around with a continuity tester.

When you say to run the MSA ground to logic ground are you referencing the 5v output ground or running a wire from the input ground?

Ground onboard the MSA is the same whether from the power input terminal or power output terminal. So you'll have to connect either one to the "correct" ground on the DR-55.

Please keep in mind that all of this is speculation, because I haven't worked on a DR-55 before. ;)

[Brogram]

Hi John,
So I just got back to attempting this project and I think the problem seems to be the grounding issue. On the schematics it appears the IC says something like 6V for ground (See attachment). The IC is labled TC5501P-1
Any ideas? Thanks for your help!
-Eric

[John]

Hi John,
So I just got back to attempting this project and I think the problem seems to be the grounding issue. On the schematics it appears the IC says something like 6V for ground (See attachment). The IC is labled TC5501P-1
Any ideas? Thanks for your help!
-Eric

Hi Eric, I believe the "6" on the diagram is just the identifier for the IC...it is not a voltage figure. The diagram does not appear to show the pin number for the ground connection of the IC.

Maybe you can post some photos and/or diagrams of your wiring?

[Brogram]

Ok here is my attempt at a diagram. The drum machine still fires when directly touched by the ground from the MSA but is extremely quite when triggered by the 0 wire (as I said before). Could this mean the MSA is putting out a very small voltage from the 0 output?

[Brogram]

Also I found this schematic I believe showing pin 8 as the ground for the IC.
I have tried it out as the ground point as well with the same result...
Thanks,
Eric

[Brogram]

Not sure if it's important but if I have the 0 output connected to one of the trigger points and then touch the ground from MSA to pin #7 it triggers that sound continuously. When I touch the ground to #8 it does nothing.

[John]

Hmm, not sure exactly what to tell you. The diagram in post #8 is actually not completely accurate---the MSA-T output is pulled down to the ground voltage plus about 0.7V. So maybe the voltage difference causes the "quiet" triggering.

[Brogram]

Is there anyway to fix that difference? Any components that can be changed or added?
Thanks

[Brogram]

I'm pretty puzzled by this since triggering the drum machine manually with the MSA works fine.
Also since it was triggering the sounds loud before via "output 0" and then all of a sudden started triggering them quietly. Anyways don't want to trouble you too much. Thanks for all your help.

[John]

The best advice I could give is just to do more trial-and-error. You could try triggering via a relay, and then use the MSA-T output to trigger the relay...