Author Topic: 5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?  (Read 1340 times)

haddimudd

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« on: January 09, 2012, 10:17:53 AM »
Has anybody done this? Going direct from the Series II 5-Pin XLR output to 2x 3-Pin-XLR inputs of a recording device (mixer console or - as in my case - an Edirol FA-101 (http://www.rolandus.com/products/productdetails.php?ProductId=702)) and make use of its phantom power instead of using the DS-5R or batteries?
 
Would any Y-cable do or do different wirings exist that I need to take into account? I found some wiring info here: http://www.dvinfo.net/forum/sony-xdcam-hd-cinealta/88803-5-pin-xlr-wiring-configuration-2.html
 
Does the same wiring apply to the Series II 5-Pin XLR?
 
Can anybody recommended any readily available cables? Or maybe just a simple Y-adapter (w/out cable) to be used with the cable I already have?
 
Thanks a billion!
 
Hartmut

sonicus

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #1 on: January 09, 2012, 11:03:55 AM »
Hartmut,
           Here is the PIN OUT for the ALEMBIC 5 pin
pin 1 ground
pin 2 neck pickup
pin 3 bridge pickup
pin 4 +V
pin 5 -V
 
      You need either active or passive DI coupling .
1) Find an Alembic IN-2(passive transformer DI coupling)
OR use 2 Alembic F-1X preamps ( they have a nice XLR DI )
OR get a multi channel DIRECT BOX such as the PROCO -4A  (passive transformer DI coupling)
(i have one , it works well)  
http://www.musiciansfriend.com/pro-audio/pro-co-db-4a-quad-direct-box/151518000000000?src=3WWRWXGB&ZYXSEM=0
 
 I have tried all the above with out problems
 
     Viel Spass !  
 
       Wolf

JimmyJ

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #2 on: January 09, 2012, 12:22:01 PM »
Hartmut,
 
Wolf correctly described the pin-out.  Although I don't fully understand phantom power I believe the current draw required for these instruments is too high to be powered that way.  The power supply that comes with the instrument provides +/- 18VDC and would be the best way to operate.  Or you could pack a ton of spare batteries...  
 
Since the instrument's audio output is also unbalanced you would not gain any advantage by wiring it directly to XLRs. You could do as Wolf says and use DI boxes ... but before you add more pieces to your recording rig you should try plugging directly into the 1/4 inputs of your audio interface.  
 
And I suggest trying inputs 3-8 on the back, bypassing the device's internal preamp.  Your Series-II should be able to provide enough level to make that work, using the master volume on the instrument to lower it.  This would be your cleanest way in.  
 
If there is not enough level that way (remember you can adjust the trim pots on the back of the instrument) then next try 1/4 into the front and experiment with the Hi-Z/Lo-Z switch to see which way works best.  
 
The 3rd way would be to use DI box(es) and the mic inputs.
 
Good luck!
Jimmy J

sonicus

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #3 on: January 09, 2012, 01:05:10 PM »
I like Jimmy's suggestions as well.
 
The Alembic Series  I/II  +/- 18 V through the cable should not be confused as Phantom Power because it is NOT.   There have been various specs on Phantom Power over the years . Currently 48V is the popular standard.
 
  All voltages specified are DC
 
(Message edited by sonicus on January 09, 2012)

dfung60

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #4 on: January 09, 2012, 05:19:42 PM »
The adapter you're asking about isn't trivial to make.  The problem here is that the 3-pin XLR mic connections expect a balanced signal, but the stereo outputs that come out on the 5-pin Alembic XLR are unbalanced signals.  They just happen to be on a similar family of connectors.
 
The Alembic outputs have a hot and ground conductor.  That's like a regular passive bass plus a buffering preamp that makes a low-impedance output that eliminates interactions from cables and the amp front-end.  
 
That's different than the balanced wiring of a microphone.  On a mic, the signal is carried on a matched set of conductors and is completely separate from the grounding and shields.  At the signal source and mixing board end there are transformers that recover the signal by recreating the difference between the +/- signal conductors.  Inside the mic cable, the +/- conductors are twisted together tightly.  If the cable passes through an electromagnetic field that would cause hum, both the +/- wires pick up the noise, but the differential combination at the receiving end will remove anything that wasn't at the source.  This kind of noise reduction doesn't work with unbalanced connections (like an instrument).
 
You actually can connect the two conductors of an unbalanced connection to a balanced input, but you won't gain any of the normal benefits of the 3-wire connection.
 
The adapter you want to make would basically be two DI boxes.  The transformer or active circuit in the DI box is what makes the conversion from unbalanced to a differential signal.  You could put a DI transformer in the bass, but if you wanted to keep stereo out, you need even more pins on the connector.
 
On the Alembic 5-pin connector, there are two unbalanced, lo-z + signal outs, a common ground, and +/- remote power from from the power supply.  The onboard batteries are a perfect power supply - since the power comes from chemistry, there's no opportunity for hum to leak in.  Putting the AC power supply in the blue box lets Alembic make a super-high quality filtered power supply with low noise.  This is really a remote power supply since there are dedicated power wires in the cable.  
 
A phantom power supply is a clever trick that takes advantage of the differential microphone connection.   They actually pump 48VDC power down the microphone signal lines.  The microphone can be powered by connecting to the signal lines, but when you take the difference between the signal lines, the DC power is cancelled out.  Many mixing boards provide enough power to power your bass, but you can't be sure of that.  Microphones usually only need a small amount of power to charge a mic element, but your bass is powering a bunch of preamps, and maybe LEDs too.
 
David Fung

haddimudd

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #5 on: January 10, 2012, 01:04:21 AM »
Thanks a lot, guys!  
 
Well, long story short: I have no (i.e. can't use) batteries on my Series II (reasons as mentioned here: http://club.alembic.com/Images/411/10807.html?1314758340) and my DS-5 introduces a constant (not a directional) hiss which I was trying to avoid by avoiding the DS-5 in the first place and by making use of phantom power of the FA-101 instead, but as you taught me now life is never that easy. Thanks a lot, David, for your in-depth explanation!
 
Wolf, of course I don't have an IN-2, but thanks a lot for pointing that device out to me as I had never heard of it before. I read through all the reference threads by now. Sounds interesting enough.
 
For the suggested F-1X solution (I do have one, but not two) I would need to use my DS-5 to power my electronics again and, as mentioned above, that's what I am trying to avoid and seeking alternatives for.  
 
When you suggest a DI-box, isn't that what I have with my Edirol FA-101 already or would it give me something different (besides the extra inputs which I don't need)?
 
So, no going direct without battery power or DS-5/IN-2?  
 
Needless (or maybe not so needless) to mention that without batteries my bass doesn't have a 1/4 jack output either, only the 5-Pin output. I guess I was an idiot when deciding to have the bass built without the option of using battery power.
 
Hartmut

JimmyJ

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #6 on: January 10, 2012, 09:41:26 AM »
Hartmut,
 
We need to further explore the audio problem you describe when using your DS-5, because connecting that way should be dead quiet...  
 
You say hiss and not hum, yes?  Hum would mean a ground disagreement between devices or some induced pickup interference, but hiss...   Did you try to play a note?  Is it possible the gain of either the instrument or the interface was incorrectly high?  Master and PU volumes are up to normal levels?  Do you set the Q-level controls set to extreme boost?
 
Describe that problem a bit more for us.
 
And now, here is a geeky alternate way to power your WILD looking axe.  I only mention this because it's possible but it is unlikely that this method would yield a different result from using your DS-5.  So before you go this direction we need to get to the heart of the issue...  
 
There have been a handful of Artists who have needed to play their Series instruments wirelessly.  If you ever saw the strap used to do that ... it looks like an ammo belt (and like you need MORE weight to carry around!)  But you CAN build a battery powered DS-5 if you want.  +/-18 means at least 4-9V batteries or if you wanted to go crazy you could use 6-6V motorcycle batteries.  You would still use your 5-pin cable in this case but the instrument would not be connected to mains power.  Again, I'm only mentioning this because it's an alternative way to power your instrument BUT I do not believe this would solve your problem...
 
Tell us more.
 
Jimmy J

JimmyJ

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #7 on: January 10, 2012, 10:10:42 AM »
One other thing - after reading a bit about your double bass...  You mentioned that you might like the idea of having the different necks output to different amps instead of having always stereo pickups.  I think that could be done as a mod without too much difficulty.  Setting it up so the fretted neck output would appear in mono coming from output A and the fretless neck would come from output B.  It would involve a few summing resistors and a bit of internal rewiring but it's certainly possible.  Just a thought.
 
That bass is a work of art!
 
Jimmy J

dfung60

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #8 on: January 10, 2012, 11:32:14 AM »
Hartmut -  
 
Aha!  From your description, I think your DS-5 is bad.  
 
If you've ever looked inside, you'll see there's not much in there (I only have the little blue ones).  The AC line cord goes into a transformer which tweaks the voltage.  The secondary output of the transformer goes to a tiny square component mounted on the back wall of the DS-5.  This little box is a rectifier which converts AC into DC.  The DC supply goes into the two enormous capacitors which store up power to smooth out the supply, then it's off to the 5-pin connector.
 
When you have a hum problem that's not directional and won't go away, it means that the rectifier has probably gone bad.  Inside the rectifier there are 4 diodes.  They must be a precisely matched set or residual AC will leak through (that's called ripple).  In audio systems, the ripple is usually hum at the line frequency.  
 
I'd contact Alembic about getting the power supply checked out, and you should be in business again.   It's probably the cheapest part inside the DS-5 (if the part is even $10, I'd be surprised).  
 
You should have them do the fix though. You can get an unpleasant shock from those capacitors when they're charged up.  And if you mess up the replacement of the rectifier, it will blow up your electronics and neck LEDs when you power the bass up!  So you definitely want to get this fixed before it gets worse.
 
If you're adventurous or have a geek friend, you can confirm the problem with an oscilloscope.  If you attach a probe to the DC power wire in the bass, you should see a dead flat line on the scope.  If you see bumps at your line frequency (60 or 50 Hz), that's the hum from your bad rectifier.
 
David Fung
 
P.S.  I saw your bass while it was in the final stages at the mothership.  I was up in Santa Rosa and stopped by Alembic to say hello.  Ron grabbed me and said you've GOT to check this out...  The wood and finish work was done, but only part of the electronics were in.  Awesome!

sonicus

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #9 on: January 10, 2012, 01:32:09 PM »
I think David Fung is on the right track .  I was thinking my self that it could be a power supply problem as well . Just like he wrote .

JimmyJ

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #10 on: January 10, 2012, 04:59:12 PM »
As long as it's hum he's taking about (I guess that's why he said non-directional...) it certainly could be a problem with his DS-5.  It could also simply be a ground disagreement between his Alembic PSU / his Roland piece / and his computer...  
 
Does this noise occur with the DS-5 and an amp?
Jimmy J

Bradley Young

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #11 on: January 12, 2012, 04:39:33 PM »
Or DS-5 and Headphones?  I'm convinced that I have issues that are getting introduced somewhere between my DS-5 and my amp.
 
If you go straight to headphones, and there are no issues, it eliminates the DS-5 from being the sole cause.
 
Bradley

811952

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #12 on: January 12, 2012, 05:34:06 PM »
Perhaps it's just a bad cable?  Check the ends for broken connections and wiggle it to see if that changes anything or makes any noise.  A loose ground wire at either end could make it pickup any hum in the room, especially dimmers and such.  If it's the cable, I'd just cut a foot off of each end and re-solder the A5 connectors.  It's worth checking I think..
 
John

sonicus

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #13 on: January 12, 2012, 05:53:17 PM »
Before any cutting of a cable is done it should be checked for continuity, Each conductor one at a time. There are many ways to check for continuity , A Multi-meter ; VTVM, VOM or DVM. You can use the resistance scale on a meter . If you do not own a multi meter then  Battery and a light bulb in a series circuit . If the bulb does not light on there is NO continuity . Don't cut anything before you test continuity .
Thank you very much __ LOL __

811952

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5-Pin XLR stereo output to 2x mono 3-Pin XLR direct input?
« Reply #14 on: January 12, 2012, 06:55:40 PM »
Yes, don't cut it unless it's bad!
 
John