Will it work? Should I do it?
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Posted on Jan 13, 2009 02:32 pm
Doug Babbitt
Sound as good as you play
Member Since: Dec 23, 2008
I'm planning on removing the monitor mix from my FOH console's aux channels.
My motivation is to put control of the monitor mix on the stage. The band I've worked with up till now was accustomed to running both monitors and FOH from the stage and they would like to regain control of the monitors. Also, I can foresee the day when I would have another sound tech, with one of us on FOH and one just off stage running monitors.
I also figure I can make the band carry the entire monitor part of my rig. Now that's control.
Anyway, this raised the question of splitting signals. The lowest cost per channel for a purpose-built mic splitter appears to be about $28. I've been looking for deals on the Art S8, but $220 seems to be about as low as it goes.
After thinking about it for awhile, I wondered if I could get the same result with a DI, specifically the Behringer DI800 ($90 or $11/channel). Here's the concept, ready to be dissected, deflated, and/or debunked if it stinks:
1 - Continue running all signals from the stage to my console, which has 16 primary channels (not counting the aux returns).
2 - Tap into those signals at the channel inserts, sending to the DI's input and returning the unaltered signal to the console from the DI's link out. The signal could also go from the DI link through a processor before returning to the console.
3 - Take the balanced signal off the DI and route it back through the snake (I have plenty of channels) and from the stage box to the monitor mixer.
Comments?
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Jan 13, 2009 06:18 pm Well I think that your over thinking the whole problem.
I take it that you have a budget on this project. Having a bunch of DI's will eat through that budget very rapidly. Also, if all of the signals are not line level, then your loosing signal to one of the boards.
Are you handy with a soldering iron? The easiest and cheapest way to do this,is to add a monitor tail to your snake.
It is nice to have all of the splits ISO transformed. But, that will set you back more then a few penny's. So, just leave off the ground wire off of each of the channels going to the monitor board.
Find a 25' foot piece of multi paired 22 gauge wire. One that has the same amount of pairs that your snake has already.
You will need a romex connector that is the same size as the wire that you are adding. And a piece of kellom.
Open up your stage box, and solder the new wire in right over top of the exciting wires that are there. The only thing is, you do not want to add the ground to the monitor split. Leaving the ground off will help keep your monitor split quite. By adding the ground in, you could cause a ground loop going through the monitor board. Which will hum and buzz.
Just remember what color wire you put on each of the pins of the XLR's in your stage box. You don't want to have the polarity reversed going to the monitor board. Example, if the pairs have the colors of Red, Black, and ground. Then put the Red on pin 2 and the black on pin 3. Make sure you do the same for the XLR's that will be on the side that plugs into your monitor board. But, on the XLR's that plug into the board, make sure that the ground is attached there. It will make what known as a ground drain.
If you wish to go this route, let me know. I will help you find the pieces that you need at a decent price.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Jan 13, 2009 09:13 pm Rob has got it right on. That is how we were doing it way back when. It worked a charm and was an easy way to get the job done.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 13, 2009 09:31 pm I wasn't thinking that I'd be losing any signal. If I understand the "link out" on the DI, the signal returning to the console should be identical to the original signal. I figure the DI will do its job and the balanced out to the monitor console will be good too, with a ground lift button if necessary.
I've never done soldering, but it's something I know will be important at some point, so learning isn't a problem. On the other hand, taking into consideration the time and materials to do 16 channels as you describe, would I be better off just dropping $200 for a pair of DI800s and patch cables?
If the signals are ok, I'm thinking $200 for a "plug and play" solution isn't bad.
Here's a link to the owner's manual for the di: www.behringerdownload.de/DI800/DI800_ENG_Rev_B.pdf
Jan 13, 2009 10:30 pm Hey Doug. Sorry to say that is not going to help in your situation.
A DI, stands for Direct Injection. What this means is, that it takes a high impedance, high gain signal, and converts it to a lower impedance, low gain signal.
It had a parallel pass threw. But, that pass threw is an unbalanced signal. At the same level as the input device is sending it.
The other output that is the balanced out on the back of the unit. Is the low level output.
YOU CAN NOT RUN A REGULAR MIC INTO A DI. IT WILL NOT WORK!
A dynamic mic produces it's own voltage. That voltage is very, very low. Around -20 - -30 dB. That is roughly around .50 mv. A DI is ment to take line level signals. +4 db, which is 1.23 volts. And then the DI either pass the signal to a FET (Field Effect Transistor) or a transformer. Either one drops the level from 1.23v to .50mv.
You can not use this as a splitter box. There are slitter boxes out there that will do this. Once again, they are not all that cheap. It's around $250 to $350 for 4 channels.
Some more reasons as to why not are:
The pass threw is unbalanced, and
still has the same ground attached.
This will cause a ground loop.
The output level is at mic level.
This will be a gain reduction for
What ever board that it is going to.
The mic that they show in the
instructions, is a high Z mic.
That means that it takes a 1/4"
cable for the input. A mic such as
a SM58, is a low Z mic. It does not
work with a 1/4" cable. So, it will
not work with this DI.
You need to separate the ground from
each of the boards. Otherwise you
will create a ground loop.
I know that this looks like a cheap solution to your dilemma. But it will cause more problems then you know, if you try to use it as a splitter.
Jan 13, 2009 10:47 pm Doug, I'd like you to try using one of the DI's that you already have.
Just use to do one channel as a splitter for right now.
And I want you to use a condenser mic for this experiment.
I don't think that I am explaining this right. I think that this experiment will do more justice in explaining this.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Jan 13, 2009 11:01 pm No, and No. Heres why:
If you notice, the insert is after the mic pre, which means every time you make an adjustment to the input trim, you would change the send level to your DIs. Dont try to re-invent the wheel here, the whole free world does the job just fine with a split. either put a split in your snake as Rob suggested or get a 16 channel splitter with short tails, plug one side into your snake and the other into your monitor board. Its really the correct way to do it, dont spend 500.00 trying to save money on a 250.00 job.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 13, 2009 11:01 pm Great idea. If I was thinking, I'd have done a test before asking.
Just to be clear, remember that I'm planning on running the original mic signals into the FOH console and tapping into them at the channel inserts, which are after the preamps. I don't know enough to understand whether the signal is high gain or high impedence at that point, but I was thinking it would similar to any other unbalanced signal when it passed through the DI, which would then create a balanced copy of the signal suitable to send back to the stage.
In any case, I'll do a test and see what it sounds like.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Jan 13, 2009 11:09 pm Rob, try to explain to him the insert is after the input pre....
Jan 13, 2009 11:28 pm Yeah Doug, I think your a little lost on how low voltage electricity works.
You can not use the insert as a pre amp. It does not work that way. And a single point insert is an unbalanced input.
Furthermore, a transformer needs two secondary windings to balance a signal.
Just passing it through a transformer does not automatically create a balanced line.
If you run a signal right into your board, you have no gain control of that signal. Plus, you have an open ended opamp at that point. Which will act as an antenna, and add noise to your channel.
The biggest thing, is that phantom power will not pass in a DI. This is why I want you to try a condenser mic for the experiment. A transformer can not pass DC PERIOD!!!!!
Brother, trust us. We are not leading you astray. We are not trying to make you spend a whole bunch of money here. We are not trying to mislead you in anyway shape or form. We really know from which we speak. And we are telling you, a DI will not do what you are looking for.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 14, 2009 07:30 am Thanks for being patient. I know that if I'd tried this thread at most other forums I'd have been flamed into submission by now.
I'm sorry if I'm coming-off as argumentative or questioning anyone's knowledge or motives in my posts. It's always tough to express the proper tone with the printed word.
My continued questions and pushback are an attempt to learn. I could accept your professional advice without really understanding, but that won't help me solve the next problem myself.
Let me try that test tonight and post the results.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Jan 14, 2009 06:36 pm No flaming here, at least by the well known and level headed.
HRC isn't about being uppity, although I might seem that way at times.
Your in good hands with these two for sure.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Jan 14, 2009 09:34 pm Doug, from what Ive seen, everyone here is on your side, I havent seen anyone attempt to lead you astray. If I seem abrupt in answering a question for you it is because im just trying to save you time/ effort/ money/ heartache/ or embaresment (sp?) at a gig. If there is something I know from experience wont work, Ill tell you flat out. If you have a good idea, Ill tell you that too. for this thing your trying to do, If I, at my day job, got to a gig and someone was feeding the stage mix through inserts with DIs, Id totally freak, demand they got a splitter, or go digging in the truck and drag in my own stuff. Im not saying in an emergency it wouldnt work, Im saying in good professional practice its not done. Your thinking though, and thats good.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 15, 2009 09:50 am Thanks guys. I have no worries that you're on my side. That's why I joined here and nowhere else.
So I didn't have time to do Rob's "experiment" last night, due to several hours spent driving. However, the driving time gave me an opportunity to think over my little scheme in detail.
I won't go through the exact signal path and why/how everything matches up, but I'm convinced it will "work," in the sense that both FOH and monitor consoles will get mic signals. I say "work," because it's clear to me that it's not an optimal solution.
Here's how I see my way v. Rob's way:
My Way - Gets a second signal that has passed through 3 amps (FOH console pre, DI transformer, monitor console pre), plus 100ft. of cable, on its way into the monitor mixer. Each stage will add noise and the potential for other problems, including ground loops. I would expect to hear a difference in signal quality due to these factors.
Rob's Way - Splits the original unmodified mic signal and sends it directly to each console. Both consoles get a mic signal that is slightly weaker than normal due to the split, but still "clean." It's highly unlikely that the split would compromise the sound in a way that would be noticeable in a live environment.
Am I getting closer?
Now, I'm wondering if I can execute Rob's concept another way. I have 2 ideas, please comment:
1 - Can I split the mic signals in a patchbay?
or
2 - For each mic, could I use a "splitter cable" that goes from a single XLRF to two XLRM? If yes, I'm thinking that I could open the XLRM on the monitor side and remove the ground.
Jan 15, 2009 10:58 am Well, on my way, the signal is the same at both desk. You do not lose any strength. It's the same as when it leaves the mic. You are not running over a 1000 feet of cable. So the ohm load of the cable is not a factor.
The last way that you describe, is what a normal splitter does. Just in a splitter, there is a 1:1 transformer in there. That keeps the the ISO split side from seeing ground. And phantom power can only come from one source at that point. They mark them as Direct and ISO split. What ever board is on the direct side is your phantom master. The other, you can turn on the phantom all day long, it will not go anywhere.
A patch bay is a one to one connection. there really isn't a split there. Patch bay's just move the signal to other areas on your board. Without the need of climbing into the back and physically moving it.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 15, 2009 11:35 am Idea #3 - Would it work the same if I opened my stage box and wired together 8 pairs of the existing XLR connectors, just + and -, leaving out the ground? The mic signal goes in through one connector and passes through its original channel on the snake to FOH. The signal also jumps to the paired connector, from which a cable takes it to the monitor console. Could the original wiring to FOH be left on the paired connector for use as another split? I'm assuming at least the ground should be removed.
Idea #4 - What if I made the split at the FOH side? I have an incoming mic signal on a snake channel, which normally gets plugged into the console's mic input. I could take one of my unused snake channels and wire it (again + and -, no ground) into the mic signal inside the XLR connector housing. This provides the original signal at FOH and makes a second available at the stagebox connection via the formerly unused channel.
I'm just trying to think of all of the different ways that I can establish the electrical configuration you recommended. One or the other may work better for us, based on the way we operate.
Thanks again. All the feedback is very much appreciated.
Jan 15, 2009 11:54 am Idea #3 is what I was suggesting all along. You can make as many different tails as you want. Normal is three. On long tail for FOH. One short tail for monitors. And one medium tail for recording.
FOH must still have the ground attached. You need this for phantom power. All others the ground is left off. You just might run into a situation where the wires, just don't physically fit any more. No more room left an the XLRF pins.
When that happens, you can use what is known as a bus bar. But that takes a lot of time and patience.
You can also use splitters ("Y") cables out at FOH. You just have to mark which side of the split has the ground removed. Doing it that way, takes a lot of cable. A long pair to FOH, and a long pair going back to monitors. It's nicer just to have the split already built into your stage box.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 15, 2009 12:46 pm I think my #3 and #4 are slightly different than you are understanding. Rather than adding a new tail from the stage box or new returns from FOH, I'm talking about connecting existing channels that are already in the box and snake, but not needed.
It may help to understand that I plan to have the stagebox and monitor console right next to each other.
Let's say I split 4 mic signals under scenario #3. On the box, the channel 1 connector is next to 5, 2 next to 6, 3 next to 7 and 4 next to 8. Inside, I would connect the +/- of each adjacent channel and disconnect the existing ground on 5, 6, 7, 8. Mics connect to 1, 2, 3, 4, go through the tail to FOH and phantom power is available back from FOH to the mic. External cables connect 5, 6, 7, 8 to monitor console mic inputs (no ground, so no phantom power coming back). Channels 5, 6, 7, 8 would still have their connection through the tail to FOH, except without the ground.
Connections under #4 could be essentially the same, except pairing the existing tail connections at the console end with each other (1 to 5, 2 to 6, 3 to 7, 4 to 8).
I figure I have 8 extra channels in my snake, so I could do 8 splits to the 8 mic inputs on the monitor console. I figure I'll need some solder, raw wire if I go with #3, and either 8 XLR cables or a short 8 channel snake to go from the stage box to the monitor console.
Sound right?
BTW - Thanks, I'm learning.
Jan 15, 2009 01:30 pm Yeah, you can do that. It just doesn't leave with any room for future expansion. But, doing it that way will work.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 15, 2009 07:41 pm I take your point as far as maintaining room for expansion. There's no rush, so I'll mull it over before committing to one plan or another.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Jan 15, 2009 11:18 pm
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Jan 15, 2009 11:28 pm
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Jan 16, 2009 07:17 am Hey Monmixr - Did you notice there was already one bid on that splitter listed on ebay? One guess who placed the first bid.
That's absolutely perfect for me if the price stays low.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Jan 16, 2009 09:24 am I hope you win it cause its made to do exactly what your doin.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Feb 13, 2009 11:36 pm Doug, just wonderin if you won the split, and if so how lifes treating you with the new gear.
Doug BabbittSound as good as you playMember
Since: Dec 23, 2008
Feb 19, 2009 11:06 am I didn't win the splitter snake we looked at. As an alternative, each channel that requires a split is getting a simple 1 fxlr to 2 mxlr cable splitter located at the stage box. Each mic or other cable connects to the fxlr on the splitter, one mxlr connects to the stage box and the other mxlr connects to a cable running to the monitor console, with the ground dropped at the console end of the cable. I got a bunch of extra mic cables when I bought my SM58s, so that part of the solution was essentially free.
At some point I expect to need a more formal solution, but so far my guys have only asked for vocals (5) in the monitors, so it's manageable.
monmixrIf 50hz 60 will kill ya.Member
Since: Jan 08, 2009
Feb 19, 2009 07:22 pm Yea, I see guys using the xlr Y cables to split to a mix wiz for in ears and it seems to work fine. Sorry ya didnt win the splitter, that would have rocked.
