DB25 Pin Out Question

[gustebeast]

I am looking to send separate string signals from my guitar into the H9000 using a Roland GK-3B pickup and a jerry rigged DB25 cable. The pickup has 6 hot signals, one ground and one shield.

Is this image an accurate representation of how the DB25 works on the H9000? I’ve highlighted the pins based on how I’ll connect them: red = hot, green = ground, blue = shield. I’m not sure if the shield is necessary or not, but I read that it’s best to wire it to the chassis, which should be in contact with the rim of the male connector. Is it okay to leave the cold and ground pins unconnected for the six hot signals?

[tbskoglund]

This is the correct representation of the DB25 input on the H9000, however, you would need to ground the cold pins when using an unbalanced input. Also, you may not be able to connect this pickup directly to the H9000’s inputs without a preamp or buffer depending on the output level.

There is another H9000 user who has been using it with hexaphonic pickups, I will send him a link to this thread and see if he has any suggestions for your setup.

[gustebeast]

For grounding the cold pins, could I wire together all the cold pins to a single wire that attaches to the green pin highlighted above?

 

Regarding output level (and maybe grounding too) I should note that these signals will be sent to MIDI Guitar which is a program that maps guitar signal to MIDI, so the tone of the signal doesn’t matter, it just has to be intelligible by the software. For gain I could use a THRU algorithm on the H9000 to apply gain, or maybe just digital gain in MIDI Guitar.

[vanceg]

Hello,

I’ve got pretty extensive experience using the H9000 as a hexaphonic processor, running 6 signals into it, one from each string, and I’d be happy to help with some detail here.

While I’m using a very different pickup than you, I am quite familiar with the GK-3 and GK-3b and might have some insight that is useful.

Indeed it is correct that you’d need to jump the cold pins together to make this work, but depending on the adaptor you are using that enables the independant outputs from the strings from the GK-3b, this may already be built into it.  Are you building this cable or do you already have it built?  are you perhaps using one of the commmercially available cable systems (like those made by Bill Bax?) or another breakout box?  Or are you simply building a cable?.   If the latter, where is your power and preamplification for the GK-3B signal coming from?  Are you sending 7V for the GK-3B down your 13pin cable?

Just FYI – I definately find that the signal coming out of my Cycfi breakout box is a bit low for the H9000 and I need to set the H9K to -10db input.  I know that the signal coming directly out of the GK-3b is signficantly lower and you may well have to amplify a bit more than will be provided by the GK3-B.

Those are my initial thoughts – But I’m happy to continue this here or on a private thread (it would be good to keep it public so others might search it out later).

 

[gustebeast]

I should clarify that my initial post was a bit of a simplification. I am actually using this with a 10 string pedal steel guitar, which has a narrower 8mm string spacing. The GK-3B is adjustable down to 16mm spacing, so I can cover the strings by staggering two of them (strings 1,3,5… and strings 2,4,6…). I would be happy to use a different pickup that is better suited for this if one exists.

My plan was to buy the GK-3B kit which has a pickup with a raw molex connector (6 hot signals, ground and shield). I would then take the wires out of the molex and merge them into a single 10 wide molex:

Note that I dropped one hot signal from each pickup (each one covers 5 strings) and I have merged 3 of the hot signals into a single wire so I can get it down to 8 (H9000 only takes 8 analog in). I would then buy 10 wires and a DB25 male connector and make my own DB25 cable which routes these signals to the correct pins.

I wasn’t planning on supplying power since I’m not using the actual GK-3 processing unit, just the pickups. I was hoping that a very quiet signal would be fine since I can just apply a lot of gain via -10db + THRU algorithm 24db in/out gain + gain in MIDI Guitar software. I imagine the signal will be very noisy but so long as it can detect the pitch of the notes that should be fine.

[gustebeast]

Bump, happy to discuss over email if that’s better – gusc @ llaway.com

[vanceg]

<p style=”text-align: left;”>I apologize – I got distracted and should follow up on this a little later today.</p>
I’d be pretty concerned about the signal level and noise without providing amplification for those signals from the GK3 b.

The dual GK3 b setup, while innovative, seems somewhat donkey as well.  Have you considered using a pickup system designed  for the number of strings your instrument has? Have you considered a Cycfi rig, for example?

if getting another pickup system is out of the question, then I’d recommend trying the single gk3b without any amplification/no 7v sent to the gk3-b and see if you get anywhere close to the level signal that you want out of this thing.

I’d strongly recommend taking a look at a Cycfi rig.  If that’s just not in the cards, you might want to try building or quitting a breakout box or cable that can provide the 7v for your gk3b.  It’s not all that tough to insert that 7v. And cables by Bill Bax and others can provide you with a prebuilt option.

 

 

[vanceg]

I inteded to write “seems somewhat WONKY….”  not “donkey”. Doh.

 

 

[vanceg]

Out of curiosity – Does this MIDI Guitar software you are using convert 10 channels of audio to MIDI or are you using two copies of the same app (each one with 6 string support)?

Previously I had suggeted that you might look into the Cycfi line of multichannel pickups as they can be configured to support a wide variety of string counts and spacings.  I do note, though, that they are 10mm wide.  So if you had 8mm string spacing that you are trying to deal with, even with a Cycfi system, you would need to stagger the pickups so that you could achieve the string spacing you need.    The Cycfi breakout box could absolutely supply you with 10 independant string outputs, though.  And they would be at the right level to run into/through your H9000.

It sounds like you are planning to simply use your H9000 as an audio interface here – running the 10 string signals directly into the computer where you are going to use a computer based app to convert from pitch to MIDI.  Is that right?  Where would/might the H9000 processing come into play here… or should I not even consider it as you are just trying to use the hardware you have on hand as a multichannel A/D?   Might you consider a simple 16 channel auido interface just for this purpose?  Or utilizing two external pitch to midi converters (roland GR series perhaps?) and runnign each of your GK3B into one of those?

To be frank – The H9000 seems like massive overkill and not quite the right tool for the job if you are doing pitch to midi conversion and really just want a 10 channel A/D for pitch to MIDI.    There must be more to this picture.

Interesting issue and I’m happy to continue to share my thoughts..  Hopefully they are at least somewhat helpful.

As an aside – have you seen this project?  https://paglieresteelguitars.com/. It’s a proper pedal steel, but the string bending is digital.   It’s using an embedded processor to do the pitch shifting… but I know for sure that the H9000 can (and does) do this really well.   I have a 6 string version of a “pedal steel” bending program for the H9K that I use on my normal guitar a lot and I love it.  I’m a crappy player, but it’s a lot of fun.   I’m positive someone who could really play pedal steel would really be able to make a digital bending system sing well!

 

 

[gustebeast]

MIDI Guitar can only convert one audio channel to MIDI, but it has a VST version, so I can load 8 instances of it into a DAW like Mainstage and send each one it’s own string. I did a test run by sending my pedal steel to the 5.1 DiatonicShifters algorithm and routing each note of a 7 chord to a different instance of MIDI Guitar https://www.youtube.com/watch?v=IPAsXy2YPOU

For the dimensions, the main concern is height. Ideally I would like to fit the new pickup between the neck and the strings, which is only 13mm. For that I wouldn’t want the pickup to be taller than 10mm. I sent an email to Cycfi to see if that’s possible with some customization of the hardware but I’m not optimistic. My MSA pedal steel does feature a quick change pickup so it’s possible I could get a setup where I remove my normal pickup and slide in the MIDI one, but that would definitely be a downgrade in convenience. If a GK-3B approach could fit under the strings and still output a signal good enough for MIDI Guitar, I’d pick that for sure.

Although for now I am only planning to use MIDI at home, I’m only interested in investing if I know I could later use it at gigs as well. My H9000 lives with an ASP880 in a 3U gig bag which features a decently sized side pocket. The plan (assuming I am taking good advantage of MIDI and want to take it on the road) is to have the H9000 do the A/D conversion, send it to a mac mini that lives in the pocket, then get back a final mono synth signal. I’m open to any approach, but any additional devices need to fit in that side pocket alongside a small computer, and any other MIDI conversion software/hardware needs to support separate string pitch bends (key for pedal steel). Note that I don’t want to use the ASP880 for this project because I am already using the inputs at home for jam sessions.

Your thoughts are much appreciated, I’ve already learned a lot, and am curious if you have any more ideas. The eletro-pedal steel is very cool, curious to see how it develops.

[gustebeast]

I cut a DB25 cable today and tested it with the H9000. I am finding that the original image I posted is not accurate as far as the input assignment goes. What is labeled as input “1” is actually input “8”. I do see that the ground/hot/cold labels are accurate though.

[gustebeast]

I cut a DB25 cable today and tested it with the H9000. I am finding that the original image I posted is not accurate as far as the input assignment goes. What is labeled as input “1” is actually input “8”. I do see that the ground/hot/cold labels are accurate though.

[gustebeast]

Ah I think the issue is that I am working off a male plug but the image is for a female plug. That’s why it’s flipped.

[gustebeast]

gustebeast wrote:

however, you would need to ground the cold pins when using an unbalanced input

 

I just tried this with a cut DB25 spliced to a TS jack. If I short the ground and cold pins the signal comes through with a noticeable hissing sound. If I leave the cold floating it comes through clean.

[vanceg]

I seem to recall that when I initially built an unbalanced version of the DB25 connector for use with the H9K, I had problems when I grounded the cold pins too. That said, what I ended up doing was just buying a commercially available DB25 to 8x 1/4″ TRS cable and then plugged the 1/4″ TRS into a standard unbalanced 1/4″ TS output…. and it worked just fine.    I am not at my system right now but I suppose I could/should go check to see if the R ing is grounded.,

 

[gustebeast]

I have a  DB25 to 8x TRS cable as well. Plugging that into my guitar yields the same hiss. That connection does the same ground+cold short.

Strange if you found that it didn’t make a hiss. How much gain are you applying via the H9K? I assume you’re using the higher gain setting on the inputs from the settings panel plus some extra gain within the FX chain.

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