# DSP1124 Midi Commands?



## Glimmie (Apr 26, 2012)

Does anyone have a list of the complete Midi command set for the DSP1124? I want to be able to control the sub woofer level from my Irule based HT remote.

I have a DOS Midi control application library I wrote in the late 1990s for a Symetrix processor. Low level hardwrae programming is what I do so that's not a problem. Irule communicates to my DOS based HT automation system and trhis is where I plan to drive the DSP1124 from. 

The commands in the 1124 manual seem incomplete. From my rather limited experience with Midi there needs to be a manufacture byte and model byte?

Anybody have any info on the Midi protocol for the DSP1124?


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## JohnM (Apr 11, 2006)

Your Midi sequence will start with the code for the function in the Midi chart shown in the manual plus the Midi channel (lower 4 bits). For example to select the 'Engine' send the code for Control (0xB0) plus the Midi channel (so for Midi channel 1 the channel code is zero, so you would use 0xB0, for Midi channel 6 would use 0xB5), then the code for 'Engine' (12, 0x0C) and then either 0, 1 or 2 to select coupled, left or right.

*Edit*: P.S. there is no level control in the BFD, though I suppose you could use a very broad filter and tweak its gain.


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## Glimmie (Apr 26, 2012)

JohnM said:


> Your Midi sequence will start with the code for the function in the Midi chart shown in the manual plus the Midi channel (lower 4 bits). For example to select the 'Engine' send the code for Control (0xB0) plus the Midi channel (so for Midi channel 1 the channel code is zero, so you would use 0xB0, for Midi channel 6 would use 0xB5), then the code for 'Engine' (12, 0x0C) and then either 0, 1 or 2 to select coupled, left or right.
> 
> *Edit*: P.S. there is no level control in the BFD, though I suppose you could use a very broad filter and tweak its gain.


Thanks.

But what about the start byte and end byte. I don't have the code in front of me but doesn't Midi need a start byte and end byte. I seem to remember 0xF0 and 0xF7.

There is a gain control setting listed but I'm not sure what it does.


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## JohnM (Apr 11, 2006)

Glimmie said:


> But what about the start byte and end byte. I don't have the code in front of me but doesn't Midi need a start byte and end byte. I seem to remember 0xF0 and 0xF7.


Might do, what I gave was the message content, won't your library add whatever wrapper is required?



> There is a gain control setting listed but I'm not sure what it does.


That is the gain of an individual filter.


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## Glimmie (Apr 26, 2012)

Ok I can probably figure that out but it's a moot point if there is no way to control overall gain of the DSP1124. I'll have to build an outboard box using a VCA to do that.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Why would you need to do that?

Regards, 
Wayne


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## Glimmie (Apr 26, 2012)

Wayne A. Pflughaupt said:


> Why would you need to do that?
> 
> Regards,
> Wayne


Well we can calibrate out HT systems until the cows come home but there is plenty of material out there that was not mixed properly. Sometime the sub is too hot and sometimes not hot enough. Hence I want the ability to tweak it outside of it's level calibrated setting on the fly. I also have one of those DBX 120A Subharmonic Synthesizers that extends the low end. This is useful for old recordings that don't have enough low end but you certainly don't want it permanently in the calibrated path.

So here are my sub woofer options selectable via IRule remote

1) NORMAL - Calibrated levels and response.
2) OFF - Mutes the LFE channel.
3) +10db - This kicks in 10db of gain for disks that were mastered with LFE -10db - common BluRay problem.
4) VAR - Allows gain to be varies from -95db to +31db.
5) SYNTH - Inserts the DBX 120A into the LFE feed after the DSP1124.

In addition to the LFE/SUB options I can also turn the LCR on and off to check the surrounds, and insert DBX 3BX units in and out of the LCR feeds as needed on old films and shows. This switching is done with an outboard relay box so when the various processors are out of the path, they are OUT!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Glimmie said:


> Well we can calibrate out HT systems until the cows come home but there is plenty of material out there that was not mixed properly. Sometime the sub is too hot and sometimes not hot enough. Hence I want the ability to tweak it outside of it's level calibrated setting on the fly.


Got it :T Basically you want to control the gain of the subwoofer signal chain (I use one of these for that purpose). However, that is not the function of an equalizer.

Still, it looks like you already have that ability...


> So here are my sub woofer options selectable via IRule remote
> 
> 1) NORMAL - Calibrated levels and response.
> 2) OFF - Mutes the LFE channel.
> ...


... so I’m left wondering what the “outboard box using a VCA" will do for you.

Regards, 
Wayne


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## Glimmie (Apr 26, 2012)

Wayne A. Pflughaupt said:


> ... so I’m left wondering what the “outboard box using a VCA" will do for you.
> 
> Regards,
> Wayne


Note my list of LFE/SUB control capabilities is not completed yet in hardware. Will be in about two weeks I hope!

Basically the same thing as the box you use. That is provide a remote controllable gain control. In my case i will use RS232 because that's the easiest in my system. I was hoping to have the 1124 also be the gain control but since it has no MIDI command for overall gain I need another box in the chain. I have also though about just using the LFE gain setup on my Lexicon MC8. I can access that vua RS232. But it doesn't have enough gain range.

I'm an EE in the broadcast/film industry and custom black boxes are one of my specialties. The box will have a good Burr brown VCA chip (a PGA2310) and a microcontroller.


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