Question on Mic Splitter

[sissybum]

We run a video recordering room and our worship center, there are about 48 different mic inputs ( band-chior-pastor) right now we use Y-splits to run them to 2 different mixing boards. I would like to clean up this area and make a Mic splitter box.
Question 1. Should I run line transformers inside the box. They cost a lot of money?

2. If I do run Transformers can I run 2,3 or 4 inputs through one transformer. When you buy a splitter box they have 1 transformer for each input. Again big money~~~. We are not a big money church. I am trying to build a nice unit at low cost. Any help or ideas out there thumbsup

[David Kulka]

The way it's wired now, do you have mics "hard wired" to 2 boards at the same time? Usually that doesn't work very well. You wind up with ground noise, weird frequency response, etc.

Line transformers and mic splitter transformers are totally different animals. A line transformer can't be used with a mic.

Mic splitter transformers are used to connect one mic to 2, 3, or 4 preamps at the same time. Yes, they are kind of expensive. The better ones are made by Jensen and start at about $50, in quantity. JENSEN TRANSFORMERS, INC. - MICROPHONE SPLITTER TRANSFORMERS

I didn't quite understand your second question, but all splitters have one input, and multiple outputs. Each mic splitter transformer can only be used with one mic.

Sometimes used splitters show up on ebay, that might be a way to find a good deal and save having to build anything.

[sissybum]

Yes we come out of the snake on stage into a Y-split then into mixing boards.
Yes I am talking about Splitter Transformers. What is the reason you can't hook up more than one input to a transformer. I would think it would cut out noise-static from any input that was running through it. Thanks for your help..

[David Kulka]

Originally Posted by sissybum

What is the reason you can't hook up more than one input to a transformer...

I'm afraid that I don't understand your question. The purpose of a mic splitter transformer is to connect a mic to two or more inputs, and this is the way it's meant to be used.

Can you re-phrase your question?

[soundrick]

For a 2 way split, you need 1 tranny for each mic output.

Basically, from each mic output, you'll be going into one console direct and the other console via the transformer's secondary.
So, a 2-way 24 input split will have 24 transformers.

For a 3-way split, you would need transformers with 2 secondaries. One direct, 2 via the transformer.

This isn't hard to wire up, but still, with the information you've given, you may want to just buy one. Transformers are expensive, and cheap ones aren't even worth the effort.

[aussie_techie]

Originally Posted by David Kulka

The way it's wired now, do you have mics "hard wired" to 2 boards at the same time? Usually that doesn't work very well. You wind up with ground noise, weird frequency response, etc.

huh? its done all the time and works fine in most settings.

to the OP, the best solution without spending money on quality transformers or active splits is just to spend time to work out the best way to run things and to clean up your foh/monitor areas.

oh and read up on how transformers and any other devices you arnt familiar with work so you know what to ask for when/if you revisit the issue.

[Vitalis]

Originally Posted by sissybum

Yes we come out of the snake on stage into a Y-split then into mixing boards.
Yes I am talking about Splitter Transformers. What is the reason you can't hook up more than one input to a transformer. I would think it would cut out noise-static from any input that was running through it. Thanks for your help..

Well, first of all, you have to understand why a transformer is needed in the first place and then your questions will become clear to you. The transformer actually performs a number of functions - all of which you absolutely need. One function is to isolate one output from another. The way you have it now, the mic is being expected to drive both inputs - which it was not designed to do. Both FOH and monitor boards are drawing current from the mic which causes it's voltage to drop to a lower level than if it was only driving one console. Therefore, both mic pres will have to be turned up further than they would normally need to be, causing noise.

Second, because both consoles are now connected in parallel across the mic, the total impedance the mic sees is only half of what it needs to see in order to deliver it's specified frequency response. In other words, because there is now a greater load on the mic, it's high frequency responce will start to roll off at an earlier frequency than it should, causing the sound to be dull.

Third, because the mic has to drive two inputs, it can only drive half of the cable length that it normally could. This also causes high frequency loss.

Fourth, again because the mic is driving two inputs, any change in input parameters of one console will influence the other console as well. If for example, one console is providing phantom power to the mic, this can effect the other console's input, or, if one console has noise or RF on it's input, this will carry over to the other console.

I'll bet you that if you listen to a mic on an instrument and then disconnect the "Y" feeding the monitor board, that the sound will greatly improve.

At any rate, the transformer split will solve all of the above mentioned problems by, first of all, allowing the mic to see the correct load impedance, which is usually around 1 kilo Ohm per leg. If you "Y" it, it will only see 500 Ohms per leg. It will also provide the necessary isolation between consoles to prevent loading and to prevent ground loops.

What you need here is NOT a splitter transformer because a splitter has one input and two output taps - you don't want your FOH signal going through the transformer. So, all you need is just a single, balanced in/balanced out transformer per stage box input. The way to connect it is simply to tap off the plus and minus "legs" of the mic input on the stage box and feed that tap to the monitor board. In other words, your mics will all feed straight through to your FOH console and the monitor board inputs will be fed from the transformer outputs. The two issues you need to pay attention to are that the transformers have a high enough input impedance, say about 10k Ohms, so as not to load down the mic at the split point. These transformers also should have an output impedance of around 150 to 200 Ohms so that the monitor console will see it's correct source impedance. Sescom transformers are inexpensive and are certainly good enough to feed a monitor board. Don't buy Jensens because you will never actually need all the specs that they deliver.

Now to your questions.

1. "We run a video recordering room and our worship center, there are about 48 different mic inputs ( band-chior-pastor)..."

Well, that doesn't mean that you are using 48 mics at the same time. Figure out how many mics you need at any one time and just concentrate on making splits for those.

2. "... right now we use Y-splits to run them to 2 different mixing boards. I would like to clean up this area and make a Mic splitter box."

I would look for a splitter on the web and not try to build it yourself. Try Sescom. I know they make transformers, but I don't know if they make splitter boxes.

3. "Should I run line transformers inside the box."

The answer here is yes, the box will shield out noise and interference, but like I said, don't try to build this yourself. A lot of guys think it's easy to build stuff, and it's not. All you need to do is make one mistake and you can end up with a pile of worthless junk that you just wasted the church's money on. You have to have the perfect plan when you start out, plus many years of project building experience behind you. You have to be at the level where if you make a mistake, you can troubleshoot and correct it. I just completed a project recently where I added phantom power to a old Shure M68 mixer. Well, when I first turned it on it didn't work. As I began to study the problem I discovered that I had made about three fatal mistakes - that thing didn't stand a chance of working LoL! But, hahaha, I worked through the problems and got the thing working. I'm only lucky that it runs on a relatively low voltage otherwise I would have blown the whole thing up and myself along with it. So, my motto is; DON'T TRY THIS AT HOME.

4. "They cost a lot of money? / We are not a big money church. / "When you buy a splitter box they have 1 transformer for each input. Again big money~~~."

Write to one of these TV Evangelists, you know, these guys who are buying airplanes and boats and big mansions, with the money they steal from the Christians, and ask one of them to help your church out. Fat chance of that huh?

But, If you want to do it right then yes, it's not going to be cheap.

I realize that it takes a good amount of technical understanding to grasp what I have said here, but I believe that as a sound tech, you absolutely have to understand this stuff. There is a website called "Church Sound Check" which has a forum where you can ask questions. There are some helpful guys over there but, in my opinion, it's better to do as much research as you can using the web and then ask at CSC if you get stuck on some points. There is a lot of good information there, but not always - if you know what I mean.

So, praise the Lord, Amen? And I wish you all the best!

[David Kulka]

Originally Posted by aussie_techie

huh? its done all the time and works fine in most settings.

to the OP, the best solution without spending money on quality transformers or active splits is just to spend time to work out the best way to run things and to clean up your foh/monitor areas.

oh and read up on how transformers and any other devices you arnt familiar with work so you know what to ask for when/if you revisit the issue.

I guess I'll just have to respectfully disagree. I haven't seen this done and would not recommend it. I guess it might work ok in some situations, sometimes, but my main concerns would be ground noise, the possibility of oscillation or instability caused by 2 mic pre's being wired in parallel, possibility of frequency response issues caused by impedance mismatch, and the really nasty possibility that someone might accidentally hit the phantom power switch on one board, which could easily blow out the mic pre on the other one.

[aussie_techie]

Originally Posted by David Kulka

I guess I'll just have to respectfully disagree. I haven't seen this done and would not recommend it. I guess it might work ok in some situations, sometimes, but my main concerns would be ground noise, the possibility of oscillation or instability caused by 2 mic pre's being wired in parallel, possibility of frequency response issues caused by impedance mismatch, and the really nasty possibility that someone might accidentally hit the phantom power switch on one board, which could easily blow out the mic pre on the other one.

go to your local bar thats big enough to have a monitor desk and you will see it done. i know its not the best option in theory but how can you comment on it beyond that if you have never done it?

when you do your own power distro and everything is running off the same outlet/generator with the same earth then you rarely have a problem that can be fixed by simply lifting the ground on one side. (apart from the fact that power is never great coming from a diesel generator anyway) any modern mic output transformers that is worth its weight is designed to work with a wide range of loads, does anyone ever think about the loading on a mic the rest of the time? how about every time you engage a pad? passive splits don't solve the impedance mismatch issue either, only active splits can.

ive just had another weekend of running vocal splits on the same foh, the change in sound due to loading is interesting to observe but its subjective and certainly not a life changing thing.

while its certainly not desirable you wont destroy any thing by running phantom into it if everything has been designed to accept phantom anyway, any any modern gear apart of those that explicitly state DC input will be. have you ever thought about how phantom can break down a transformer?

I know its not the best solution in theory but Y-Splits are used all the time because they are simple cheap and they work, if you don't believe that then go out into the real world and see it for your self.

[sissybum]

Thanks all for your help. We do use a lot of mics with band and singers and so-on. I am thinking I just need to install a transformer for each mic input. VITALIS that was a great explantion thank you. And David you are right on track with Y-splits, we use them now and until we get some extra cash, well you know they work now so it must be good. I am just trying to build a better system and clean up the back room so-to-speak

[Audioconsultant]

Originally Posted by Vitalis

Well, first of all, you have to understand why a transformer is needed in the first place and then your questions will become clear to you. The transformer actually performs a number of functions - all of which you absolutely need. One function is to isolate one output from another. The way you have it now, the mic is being expected to drive both inputs - which it was not designed to do. Both FOH and monitor boards are drawing current from the mic which causes it's voltage to drop to a lower level than if it was only driving one console. Therefore, both mic pres will have to be turned up further than they would normally need to be, causing noise.

Most mics are rated to drive a load of no less than 1000 ohms, and it is true that this can be a problem when one mic drives more than one console input. If the mic is rated to drive 1000 ohms then as long as the console inputs are over 2000 ohms each you are OK. If the console inputs are less than 2000 ohms each, the mic performance could be degraded.

HOWEVER, the use of a transformer splitter in stead of a simple Y cable split in no way changes this.

Originally Posted by Vitalis

Second, because both consoles are now connected in parallel across the mic, the total impedance the mic sees is only half of what it needs to see in order to deliver it's specified frequency response. In other words, because there is now a greater load on the mic, it's high frequency responce will start to roll off at an earlier frequency than it should, causing the sound to be dull.

With a dynamic mic loaded to too low an impedance the response can change. With a condenser mic you are more likely to have reduced maximum level when the load impedance is too low.

HOWEVER, the use of a transformer splitter in stead of a simple Y cable split in no way changes this.

Originally Posted by Vitalis

Third, because the mic has to drive two inputs, it can only drive half of the cable length that it normally could. This also causes high frequency loss.

If the total cable length driven (going to both inputs) is no more than 300' don't worry about this. If it is over 300' you would be best off using a low capacitance "digital rated" mic cable.

HOWEVER, the use of a transformer splitter in stead of a simple Y cable split in no way changes this.

Originally Posted by Vitalis

Fourth, again because the mic is driving two inputs, any change in input parameters of one console will influence the other console as well. If for example, one console is providing phantom power to the mic, this can effect the other console's input, or, if one console has noise or RF on it's input, this will carry over to the other console.

Most mics can stand getting phantom power from two sources, without acting up.

This is the first thing you have mentioned where a transformer based splitter has an actual advantage.

Originally Posted by Vitalis

I'll bet you that if you listen to a mic on an instrument and then disconnect the "Y" feeding the monitor board, that the sound will greatly improve.

Only if the loading on the mic is too great - which a transformer splitter would not help.

Originally Posted by Vitalis

At any rate, the transformer split will solve all of the above mentioned problems by, first of all, allowing the mic to see the correct load impedance, which is usually around 1 kilo Ohm per leg. If you "Y" it, it will only see 500 Ohms per leg. It will also provide the necessary isolation between consoles to prevent loading and to prevent ground loops.

Most consoles have input impedances between 1500 and 3000 ohms. If the consoles have input impedances of less than 2000 ohms they should not be used with any common passive split system, transformer isolated or not.

Mics don't have a "correct load impedance" only a minimum load impedance for proper operation.

Originally Posted by Vitalis

What you need here is NOT a splitter transformer because a splitter has one input and two output taps - you don't want your FOH signal going through the transformer. So, all you need is just a single, balanced in/balanced out transformer per stage box input. The way to connect it is simply to tap off the plus and minus "legs" of the mic input on the stage box and feed that tap to the monitor board. In other words, your mics will all feed straight through to your FOH console and the monitor board inputs will be fed from the transformer outputs. The two issues you need to pay attention to are that the transformers have a high enough input impedance, say about 10k Ohms, so as not to load down the mic at the split point. These transformers also should have an output impedance of around 150 to 200 Ohms so that the monitor console will see it's correct source impedance. Sescom transformers are inexpensive and are certainly good enough to feed a monitor board. Don't buy Jensens because you will never actually need all the specs that they deliver.

Cheap transformer are cheap transformers and cause all the typical cheap transformer problems such as strange frequency response and distortion. If I could not afford Jensen transformers on a project I would strongly consider not using transformers at all, and doing a simple Y split.

Originally Posted by Vitalis

I realize that it takes a good amount of technical understanding to grasp what I have said here, but I believe that as a sound tech, you absolutely have to understand this stuff. There is a website called "Church Sound Check" which has a forum where you can ask questions. There are some helpful guys over there but, in my opinion, it's better to do as much research as you can using the web and then ask at CSC if you get stuck on some points. There is a lot of good information there, but not always - if you know what I mean.

On CSC we do our best to make it a myth free zone. All are welcome. If you think something there is in error, please post a reply. Anyone can make a mistake.

[ripple_fx1]

Another option, less abhorent than the Y's, but not even close to the ideal xfrmr splits is the use of direct outs - provided the console with the best preamps has them balanced (I'm guessing your consoles aren't sitting side by side), pre-fader, pre-mute, and pre-eq...
Silent Way's recording tricks-The Direct Out Database
Good luck - there's gotta be a boatload of used splitters available now as production companies migrate to the fiber snakes, eh? Call up Showco and the others.
Cheers! JR