Highly Liquid Forum facebook twitter google plus rss feed

Go Back   Highly Liquid Forum > Discontinued Products > MPA

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-11-2012, 05:25 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default MPA 100k Enclosure and powering

Hello, I have just built the MPA and I am now in the process of putting it in an enclosure and finding a suitable power supply.

For the enclosure, I settled on a Hammond 1590BB enclosure which is 4.96" x 3.68" x 1.18". Is this big enough if I'll be using 4 1/4" TRS jacks on the pot outputs and only the midi in?

As for powering the MPA, I was wondering how long it lasts on a 9v battery? If not, I gues I would just use any 9v adapter that supplies more than 400ma ?

Thank you!
Reply With Quote
  #2  
Old 02-14-2012, 02:55 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Hi Sidewinder, welcome.

The hammond 1590 should be large enough for the MPA. The phone jacks might be a little tricky--usually it's hard to know for sure until you give it a try. Please let us know what you find out.

A 9V battery is a good power supply choice. Battery life depends a lot on the usage pattern for your application, but I would expect tens of hours as a rough guess.

More information about selecting a DC power supply can be found here:

http://forum.highlyliquid.com/showthread.php?t=447

Hope this helps.
Reply With Quote
  #3  
Old 03-01-2012, 10:27 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

Hi John, I have started putting the MPA in its enclosure and I have a few questions:

Could you please tell me the right order to connect the TRS jacks to the Potentimeter outs. The board that I have is the 100k version A with 2 leds. I want to use this to change pot values on my guitar effects pedals that have expression pedal inputs.I want to replicate expression pedals like the Roland Ev-5, the moog Ep-1 or the Ernie Ball Jr Expression pedal.

The only constant I can find is that the Wiper is the tip?

I saw this in another forum entry, is it correct?

Tip = Wiper
Ring = B
Sleeve = A

Am I right in assuming that A = minimum pot position and B = maximum pot position?

Furthermore, I mounted all my jacks onto the hammond aluminum enclosure, because this is metal, all the grounds of my TRS jacks are common. Is it going to be a problem? I also need to know whether the negative of the current needs to remain isolated or connected to the ground of the chassis. Currently I am using a 3 prong power jack and the negative and positive are isolated.

Finally, What is the sysex message that I need to send the MPA to program it properly for my purposes? All I'm using are the 4 Potentiometer outs.

I have read the firmware manual and this is what I get: I want pots 1 2 3 4 on channel 1 2 3 4 respectively using program change (mode 3) with 001 being the lowest pot value and 128 being the highest

ex: If I were controlling a volume pot, 001 would be inaudible and 128 would be full volume.

Since it doesn't need a controller number value I've left it at 00. I don't use the logic outputs but I don't see that there's a way to bypass programming them so I put then all on channel 5 using mode 00. Would this be ok? I will be using Sendsx 1.30.

//Header
F0 00 01 5D 01
//Potentiometer 1
01 03 00
//Potentiometer 2
02 03 00
//Potentiometer 3
03 03 00
//Potentiometer 4
04 03 0D
//Logic
05
00 00
00 00
00 00
00 00
00 00
00 00
00 00
00 00
//Footer
F7

Thank you kindly!

Last edited by sidewinder; 03-06-2012 at 04:30 AM.
Reply With Quote
  #4  
Old 03-07-2012, 06:55 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Hi Sidewinder,

Thank you for your patience.

Quote:
Originally Posted by sidewinder View Post
Hi John, I have started putting the MPA in its enclosure and I have a few questions:

Could you please tell me the right order to connect the TRS jacks to the Potentimeter outs. The board that I have is the 100k version A with 2 leds. I want to use this to change pot values on my guitar effects pedals that have expression pedal inputs.I want to replicate expression pedals like the Roland Ev-5, the moog Ep-1 or the Ernie Ball Jr Expression pedal.

The only constant I can find is that the Wiper is the tip?

I saw this in another forum entry, is it correct?

Tip = Wiper
Ring = B
Sleeve = A

Am I right in assuming that A = minimum pot position and B = maximum pot position?
I can't give guaranteed advice on the connections within the pedal, but here's an image that might help.

The difference between the "A" and "B" terminals is only how they relate to the wiper position and control value.



If you connect the MPA output and the pedal "action" is reversed, the solution is to simply swap the A and B connections. Hope that helps.

Quote:
Furthermore, I mounted all my jacks onto the hammond aluminum enclosure, because this is metal, all the grounds of my TRS jacks are common. Is it going to be a problem? I also need to know whether the negative of the current needs to remain isolated or connected to the ground of the chassis. Currently I am using a 3 prong power jack and the negative and positive are isolated.
It would be very difficult and irresponsible for me to comment on this without seeing schematics of your wiring scheme.

For certain, I can say that you must take a look at that MPA hardware user manual and review the MPA hardware user manual, which can be downloaded from the product page.

How are you powering the MPA?

Quote:
Finally, What is the sysex message that I need to send the MPA to program it properly for my purposes? All I'm using are the 4 Potentiometer outs.

I have read the firmware manual and this is what I get: I want pots 1 2 3 4 on channel 1 2 3 4 respectively using program change (mode 3) with 001 being the lowest pot value and 128 being the highest

ex: If I were controlling a volume pot, 001 would be inaudible and 128 would be full volume.

Since it doesn't need a controller number value I've left it at 00. I don't use the logic outputs but I don't see that there's a way to bypass programming them so I put then all on channel 5 using mode 00. Would this be ok? I will be using Sendsx 1.30.

//Header
F0 00 01 5D 01
//Potentiometer 1
01 03 00
//Potentiometer 2
02 03 00
//Potentiometer 3
03 03 00
//Potentiometer 4
04 03 0D
//Logic
05
00 00
00 00
00 00
00 00
00 00
00 00
00 00
00 00
//Footer
F7
The sysex looks good to me. Nice work.
Reply With Quote
  #5  
Old 03-07-2012, 08:46 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

Hi John. As of yet nothing is wired. I have version A of the board all built and ready to be placed in my hammond box.


My aluminum box has the 4 TRS jacks placed in with a female 5 prong midi jack and a 3 pring power input jack. All I have left to do is relay the jacks to the mpa board.

I will be powering it with a 9v positive tip 1000ma adaptor.

My TRS jacks will be wired like this:

Tip = Wiper
Ring = B
Sleeve = A

the power jack will simply be wired with the tip to the + and the negative to the G as it states in the manual for revision B. then my midi jack will be wired to the Midi in as indicated in the manual. Is there anything else I have to think about? Do I ground the power to the chassis? And like I mentionned, since my 4 jacks are physically touching the chassis, they all have the same ground.

Last edited by sidewinder; 03-07-2012 at 09:27 PM.
Reply With Quote
  #6  
Old 03-08-2012, 12:09 AM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Quote:
Originally Posted by sidewinder View Post
Hi John. As of yet nothing is wired. I have version A of the board all built and ready to be placed in my hammond box.


My aluminum box has the 4 TRS jacks placed in with a female 5 prong midi jack and a 3 pring power input jack. All I have left to do is relay the jacks to the mpa board.

I will be powering it with a 9v positive tip 1000ma adaptor.

My TRS jacks will be wired like this:

Tip = Wiper
Ring = B
Sleeve = A

the power jack will simply be wired with the tip to the + and the negative to the G as it states in the manual for revision B. then my midi jack will be wired to the Midi in as indicated in the manual. Is there anything else I have to think about? Do I ground the power to the chassis? And like I mentionned, since my 4 jacks are physically touching the chassis, they all have the same ground.
I think it's ok that the 4 jacks share the same ground. Ultimately some trial-and-error will be required.

Grounding of the MPA power supply to the case probably isn't necessary, but again, this may be a matter for trial-and-error. It's hard to discuss the complete picture without a proposed wiring diagram an without knowing the internals of the other devices connected to ground.

I'm not an expert on grounding issues by any means. If you contact the authors of these threads, you may get some very sophisticated answers. These guys are very knowledgeable and might be willing to give some advice:

http://forum.highlyliquid.com/showthread.php?t=384
http://forum.highlyliquid.com/showthread.php?t=428

Hope this helps.
Reply With Quote
  #7  
Old 03-08-2012, 12:20 AM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

HI John. Thank you for the reply. Basically the only thing going into this chassis is the MPA, there is no other wiring to speak of. I'm using the MPA as a midi controlled expression pedal. It's just the MPA in an aluminum box with 4 Trs jacks, a power in, and a midi in. The midi signal is coming form a Musicom Labs EFX MKIII pedal switcher and the output is going to some diamond pedals like the memory lane 2 and the halo chorus to control the feedback levels, rate and delay time by midi.

I take it that it should work just fine by connecting the power jack, trs jacks and midi as instructed in the manual and that no extra steps need to be taken to ground the chassis to the board then.

I'll let you know how it turns out.

Thanks
Reply With Quote
  #8  
Old 03-13-2012, 08:10 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

I just finished installing the board in it's enclosure and the power led lights up fine. But the activity led does nothing upon power up, Is this normal? Is it supposed to blink when it powers on or is that only the new version?

When I connect it to my interface, I use Sendsx to send the sysex info and the activity led does not light up at all.

I am using a cheapo interface, this one:
http://www.ebay.ca/itm/140714378543?...84.m1497.l2649

Sendsx says : sent 35 bytes when I send the data but the MPA does not react.

It looks like the interface that Wabbitguy claims doesn't work with Sysex. I have ordered a breakout cable for my Presonus Firebox which will allow me to use its built in interface, and I have also ordered the other cheapo interface with the treble cleft that Wabbitguy says works, this way I'll be able to elminate the interface as the problem. But do you get the feeling that the MPA itself isn't functioning properly?

By the way, my MPA has 8 dip switches and not 4. Is there anything I need to do with these dip switches??? The sysex code already designates which channel I'm sending program change on for eahc of the 4 outputs so aren't the dip switches useless in this case?

If this thing works I think a lot of guitarists would find it extremely useful
I really hope you can get back to me on this, Thank you!

Last edited by sidewinder; 03-14-2012 at 04:25 PM.
Reply With Quote
  #9  
Old 03-16-2012, 02:05 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

Man I really wish I had the answer to these questions before I spend more cash on a new interface. Anyone???
Reply With Quote
  #10  
Old 03-16-2012, 02:35 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Hi sidewinder, thanks for your patience.

First, I recommend doing a MIDI signal test as described here:

http://forum.highlyliquid.com/showthread.php?t=241

...it is written for the MSA, but applies equally to the MPA.

You can also loop the MIDI signal from the MPA MIDI Thru back to your computer, and see if SendSX displays incoming data that is the same as what is being sent. (Don't forget to select the correct MIDI interfaces in the SendSX "Midi In" and "Midi Out" menus!)

I am in the process of importing old product documentation (like for the MPA Rev A that you have) to the forums. I will be posting Rev A documentation here soon.
Reply With Quote
  #11  
Old 03-16-2012, 03:02 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Performing the test on the MIDI Thru is the only way to confirm that the MIDI signal is getting through to the MPA.

For the DIP switch, positions 1-4 specify the channel. DIP switch positions 5-8 are ignored unless you have a very old MPA. What was the purchase date for your MPA, and what is the serial number on the microcontroller IC?
Reply With Quote
  #12  
Old 03-16-2012, 03:42 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

The MPA is in the enclosure and the wire isn't long enough for me to Pull it out and see the serial number.

I purchased it about a month ago from a gentleman who built it but never used it. I am not good enough in soldering so it was convenient for me to buy one that was pre-built. You were also out of the 100k version so I had no choice but to find one elsewhere.

when you say that the dip switches set the channel, what channel would that be? I want each pot on a different midi channel so I need more than just one, which is why I use the sysex to configure it.

Since it was pre-built all I can say is it looks well built and the power led does light up. Should the activity led blink when it powers up? I know the manual for the newer version states this but mayeb the older version is different.
Reply With Quote
  #13  
Old 03-16-2012, 03:51 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Quote:
Originally Posted by sidewinder View Post
The MPA is in the enclosure and the wire isn't long enough for me to Pull it out and see the serial number.

I purchased it about a month ago from a gentleman who built it but never used it. I am not good enough in soldering so it was convenient for me to buy one that was pre-built. You were also out of the 100k version so I had no choice but to find one elsewhere.

when you say that the dip switches set the channel, what channel would that be? I want each pot on a different midi channel so I need more than just one, which is why I use the sysex to configure it.

Since it was pre-built all I can say is it looks well built and the power led does light up. Should the activity led blink when it powers up? I know the manual for the newer version states this but mayeb the older version is different.
...the serial number is what will allow me to figure out what firmware version you have, and what the LED behavior should be.
Reply With Quote
  #14  
Old 03-16-2012, 03:55 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

Are there any other indicators? I still have the assembly notes that came with the board. I can tell you just by the placement of the components. there's quite a big difference between the current board and the one thatI have in terms of amount and placements of components. I'm just worried I might break some solder points or conenctions if I try to take everything out and unscrew the jacks but if that's the only way I'll give it a shot.
Reply With Quote
  #15  
Old 03-16-2012, 09:21 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

HI John, the serial numper of my MPA is : 001586 . Does this mean that it is normal that the activity led does not flash upon power up?

Do I need to do anything with the Dip Switches with this version MPA to send a sysex to it properly?

I'm using my preonus firebox midi out. When I connect the in and out the sysex is properly mirrored on the in. So I don't think it's the interface.


But the power led does light up however.

Here Is my wiring scheme:


Last edited by sidewinder; 03-20-2012 at 01:51 AM.
Reply With Quote
  #16  
Old 03-22-2012, 01:04 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Hi Sidewinder,

You have a very old (5+ years) version of the MPA. I have posted the sysex spec here:

http://forum.highlyliquid.com/showthread.php?t=772

If this still does not help you to get the board configured, then we really must try a MIDI thru test to eliminate MIDI wiring as the source of the problem. That is:

Computer MIDI Out -> MPA MIDI In
MPA MIDI Thru -> Computer MIDI In

Let me know if this helps.
Reply With Quote
  #17  
Old 03-22-2012, 02:07 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

Hi John, thank you for posting the specs on the old version.

I tried using this Sysex:

F0 00 01 5D 01
01 03 00
02 03 00
03 03 00
04 03 00
00 00
F7

And nothing works.

Should the led on this version blink 3 times when it powers up?
Was the wiring scheme that I posted ok or should the sleeves of my jacks be floating (using plastic jacks) so that they not all be relayed?

I think I'm going to give up on this project because I'm starting to think the board I got prebuilt is a dud nd even if I get a new one I don't know if my wiring is right.

Thanks for your help though, I had hope when I saw that it used a different Sysex.
Reply With Quote
  #18  
Old 03-27-2012, 06:57 PM
John's Avatar
John John is offline
Moderator
 
Join Date: Jan 2009
Posts: 3,007
Default

Let us know how things go with the new board.
Reply With Quote
  #19  
Old 04-12-2012, 01:54 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

Hi John, I've gotten the new board and I finished installing everything. The board woks! It does what I want it to. But I still have a problem.


I'm using plastic stereo 1\4" jacks and a plastic DC 2.1mm jack to keep everything Isolated

I have the Sleeve connected to the A, the Tip on the W and the ring on the B. This works for me and it sounds perfect when I use a battery.

When I use a power supply I get horrible ground noise and distortion.

I'm using a voodoolabs pedal power to power up the MPA. It's negative center 9v. I just have the center pin connected to the G and the outermost pin connected to the + .

I tried adding another wire from the center pin and soldering it to the enclosure (hard to do because the solder doesn't stick to the aluminum enclosure very well). Nothing really changed. Then I soldered all the sleeves of my TRS jacks to a connecting wire and I tried to solder the tip of that to the enclosure. I never got it to stick to the enclosure but still when I tested it, the ground noise was gone. I still get a weird distorted noise though on the repeats of my delay (I'm using the MPA as a digital expression pedal to control the mix and feedback level of my analog memory lane 2 delay from diamond pedals). Even when I touch the aluminum enclosure with the tip of the wire connecting all my sleeves, there is no change in the distorted sound but the ground noise is gone.


Please help.
Reply With Quote
  #20  
Old 04-13-2012, 02:19 PM
sidewinder sidewinder is offline
Junior Member
 
Join Date: Feb 2012
Posts: 23
Default

I've done all tests I can think of by grounding the negative lug of my power adaptor to the enclosure, as well as the sleeves of my 4 stereo jacks and I still get distorted sound when I play through my guitar. However everything is perfect when I use a 9v battery.

It's the weirdest thing... I'm using a 500ma negative tip 9v adaptor. Any idea why the battery would work perfect but any power adaptor causes distortion/clipping in my audio path??
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 02:44 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.