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Author Topic: 2 Mixer question  (Read 3206 times)

Derek Harkins

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2 Mixer question
« on: October 10, 2007, 09:57:37 am »

I am getting ready to set up a new sound system tonight in my church.  I was wondering if anyone could give me some feedback if I am doing this correctly.  I will be Running a Peavey 32FX FOH mixer and using XLR Y splitters off of the snake at the FOH station.  The splitters will be on the first 16 channels so the signal can be shared from those sends to go to a broadcast board used for the TV Ministry.  I will not use any phantom power of either of the boards as I will purchase individual phantom power units to add to the mics that need them.  My thought behind this is that I do not want to fry either of the mixers because of  the phantom power being supplied from either one.  Does anyone see a prob in this setup or have any suggestions before I put this together tonight?
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Derek Harkins
Faith Christian Church
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Brad Weber

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Re: 2 Mixer question
« Reply #1 on: October 10, 2007, 12:07:43 pm »

For a single split it is usually possible to simply "Y" the mics and provide phantom power power from one of the consoles.  In many cases you can even supply phantom from both mixers with no problems.  However, some mixers do exhibit problems with phantom coming into their inputs, so what you are planning is a safer approach.

However, where is the TV mix and do you know that you will not have ground loop or noise problems if you "Y" a mic to both consoles?  The biggest potential problem with a physical "Y" is that it directly ties the two devices, so any noise picked up on a line affects both consoles and there is the potential for ground loops (pun intended).  Many times this ends up not being a problem, but if you are not sure about this you may want to consider using passive mic splitters with a transformer isolated output for the video mix.  Some passive mic splitters pass phantom power via the direct output while others allow for phantom powering via a power supply attached to the splitter.  Several manufacturers make 8 channel, 1 in x 2 or 3 out passive mic splitters, two of those units would serve your 16 mics.
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Brad Weber
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Derek Harkins

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Re: 2 Mixer question
« Reply #2 on: October 11, 2007, 12:33:32 pm »

Thanks Brad.  I did the install last night and I have to tune the system this evening.  I did not get any od noise from the FOH system but I will lok for buz when I set up the broadcast board and let you know what happens.

Thanks Again
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Derek Harkins
Faith Christian Church
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VT, USA
"The Frozen Chosen"

http://www.quietzonesd.info/images/quietzone%5B1%5D.jpg

David Sumrall

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Re: 2 Mixer question
« Reply #3 on: October 12, 2007, 02:26:19 pm »

Hey Derrick,

Let me tell you a quick story about one of our issues and the solution that worked for us.

When our Worship Center was built back in the early 80's a passive split via telephone punch block was installed.

Over the years the choir and orchestra was done in various forms with either FOH or broadcast taking care of the orch or choir submixes for both.

Eventually enough console was put in both places so each could do it's own mix.

When I came down here in 2003 I quickly noticed some issues on the choir sound and gain differences between events and services. The same mics, and settings, would have different gain and output etc.

It did not take long to realize that the difference was that we had less gain when the bcast consoles were up.

Digging a little deeper I found that there had been a history of  pre amp repairs for both choir submix consoles at FOH and Bcast.

Tracking down the culprit we found that many of the times both consoles were sending phantom. OUCH!

We then made it standar where only FOH did phantom for shared inputs, as it was used more of the time.

Once we straightened that out things were a little better, but there were still great differences for events with and without the bcast console up.

Doing some tests with all the consoles we found that there was definitely a loading issue with two desks on the same choir and orch inputs. We have a patch bay wired for 300 plus inputs and the cable runs are very long.

We had a couple Sescom IL19 Isolation transformers in stock and we tried putting them in line on the bcast end and bingo, problem solved.

So we bought enough for the choir and orch submixers in bcast to fix the issue.

We do have plans for a splitter upgrade eventually but in the meantime the iso transformers have done the trick.

I would suggest if you can find the money, to pick you up a good stock of the IL-19's, they are not bad in price at all and your inputs list is not so big for it to start costing you a lot.

Good luck!

David Sumrall
Technical Director/A1
First Baptist Orlando



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David Sumrall
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Gateway Church
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Derek Harkins

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Re: 2 Mixer question
« Reply #4 on: October 12, 2007, 03:40:19 pm »

David Sumrall wrote on Fri, 12 October 2007 14:26

Hey Derrick,

We had a couple Sescom IL19 Isolation transformers in stock and we tried putting them in line on the bcast end and bingo, problem solved.

So we bought enough for the choir and orch submixers in bcast to fix the issue.







So David you are saying all I need to do to keep the gain is add the IL19's to each one of the 16 inputs on the broadcast board?
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Derek Harkins
Faith Christian Church
Assemby of God
VT, USA
"The Frozen Chosen"

http://www.quietzonesd.info/images/quietzone%5B1%5D.jpg

David Sumrall

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Re: 2 Mixer question
« Reply #5 on: October 16, 2007, 01:02:14 am »

Hey Derek,

You may not have the same issue.

But yes I would offer that as a solution for those that don't have, can't afford, or will not have a true isolated split installed anytime soon.

Good Luck!

David
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David Sumrall
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Karl P(eterson)

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Re: 2 Mixer question
« Reply #6 on: October 16, 2007, 10:41:45 am »

These days with remote pre-amps and digital consoles, I find passive splits more and more compelling.

While I truly appreciate iso'ed splits when we are driving very long copper runs to separate systems sitting on there own "power islands" these days when we are looking at stage splits with all of 30 feet of tail on them to go in two or three remote preamp racks I find the need for a completely iso'ed system becoming more and more unnecessary.

David,

In your guys console search have you guys looked at the Studer Vista 8?

Grainger just bought 3 (FOH,Mons,Broadcast) with the associated infrastructure and seem to think they are the best thing since sliced bread. Up to 1000 inputs by 700 outputs (or something crazy like that) as well.

Karl P

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Brad Weber

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Re: 2 Mixer question
« Reply #7 on: October 16, 2007, 01:36:12 pm »

A little off topic, but some of the comments provided bring up the fact that accommodating future mix and split provisions is something to consider in any system design.  I've seen many systems where adding mic splits, whether active, iso or passive, was greatly compromised by the fact that little or no related provisions had been provided in the initial system installation.  Mics often get wired directly to the FOH console inputs with no provisions for inserting a split of any type, greatly increasing the cost and complexity involved in adding a split at a later time.  Too often, adding even a simple two-way passive split ends up entailing new wiring, splices, etc.

If you have any thoughts of potentially incorporating additional mixes and splits, then consider addressing it in the initial system design.  This may be as simple as running all the mics to a common large junction box in a handy location with cable loops in the box or providing additional rack space and cable length in the racks where the mics do run in order to allow later wiring in splitters.  This may be some additional cost upfront, but can avoid all sorts of headaches and problems later on.
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Brad Weber
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Derek Harkins

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Re: 2 Mixer question
« Reply #8 on: October 16, 2007, 03:46:36 pm »

Well the 2 boards are installed and I have not had a loss of gain on either board as of yet.  All I have left is a anaoying buzz from my sub ehrn it is plugged in.  I think that this is a grounding issue as the buzz volume done not go up or down when ajustments are made.
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Derek Harkins
Faith Christian Church
Assemby of God
VT, USA
"The Frozen Chosen"

http://www.quietzonesd.info/images/quietzone%5B1%5D.jpg

David Sumrall

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Re: 2 Mixer question
« Reply #9 on: October 16, 2007, 07:00:03 pm »

Hey Karl,

Good Question.

Yep, I have looked at the Vista 8 as an option. Once on the Harmon road show and again at Info com or NSCA. I have talked to Studer but I have not had great follow up.

Midas and Yamaha have both responded well. Midas has added side cars to the XL8 and software to have a multiple console systems, but I have not seen that in action yet. We have a tentative demo coming for a couple weeks soon but the dates have not been locked down yet.

It will be interesting to see what the next line of Yamaha large digital desks has in store, whenever that is.

I do like the surface on the V8 and the vistonics controllers. And I love the concept and the modularity  and customization of it.

I'm waiting to see what the Cadac does too.

I finally have a rough time line on our end and right now I am not in a hurry. It is happening but not tomorrow. I want to explore all the options until I have to move on it. Technology and digital consoles is an exciting thing to watch right now.
I think we are going to see some even better things in the next little bit.

I'll have to catch up with the Grainger guys and check it out.

Sorry if this was off topic:O)

Take Care.

David

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David Sumrall
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Arnold B. Krueger

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Re: 2 Mixer question
« Reply #10 on: October 25, 2007, 07:01:19 am »

Karl P(eterson) wrote on Tue, 16 October 2007 15:41

These days with remote pre-amps and digital consoles, I find passive splits more and more compelling.


With remote preamps and digital consoles and digital snakes, it seems like it is getting to be the time to move the split point back past the mic preamp output to the digital converter. The new relatively inexpensive high quality converters with 130 dB dynamic range mean that there's really no longer any need for preamp gain to be adjusted to match the needs of the console. The remaining need to adjust preamp gain relates to the source.

Quote:


While I truly appreciate iso'ed splits when we are driving very long copper runs to separate systems sitting on there own "power islands" these days when we are looking at stage splits with all of 30 feet of tail on them to go in two or three remote preamp racks I find the need for a completely iso'ed system becoming more and more unnecessary.


There should be racks of preamps on stage whose gain is only adjusted to adapt to the source. They  should feed a mulitplexer that delivers the output of every source to as many consoles as is needed, via a digital link.

Quote:


In your guys console search have you guys looked at the Studer Vista 8?


I saw a 1 hour demo of it at a regional church tech exhibition. My first impression is that it is a gorgeous user interface attached to pretty much the same collection of digital functions that are part of even the most inexpensive digital consoles.

Oh, there are neat refinements, but here's my favorite question -How many souls are we going to save with that added bell or whistle? How many lives are we going to change, even inside the sound booth?

I admit it, I'm a bit of a minimalist when it comes to console UIs. I happily mix on an 02R96 which seems to be somewhat legendary for its lack of ease-of-use in the user interface department.

Quote:


Grainger just bought 3 (FOH,Mons,Broadcast) with the associated infrastructure and seem to think they are the best thing since sliced bread. Up to 1000 inputs by 700 outputs (or something crazy like that) as well.


Grainger has a very impressive ministry and very impressive infrastructure. The other day I was talking to our youth guy for the 70-11th time about *venuizing* our youth room with its first designed, integrated and installed sound, video, and lighting. I said to him "If Grainger did this, they'd do it first class and it would cost them $50,000. If we bought really good hardware and did it ourself it would cost us $20,000. If we cut every corner and still got something that was reasonably robust and worked well enough and installed it ourselves, it would still cost us $4,000."  He's still agonizing over spending the $4,000, it seems.

<another letter from Buried Talent Community Church ;-)>

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Brad Weber

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Re: 2 Mixer question
« Reply #11 on: October 25, 2007, 08:30:59 am »

Arnold B. Krueger wrote on Thu, 25 October 2007 07:01

Karl P(eterson) wrote on Tue, 16 October 2007 15:41

These days with remote pre-amps and digital consoles, I find passive splits more and more compelling.


With remote preamps and digital consoles and digital snakes, it seems like it is getting to be the time to move the split point back past the mic preamp output to the digital converter. The new relatively inexpensive high quality converters with 130 dB dynamic range mean that there's really no longer any need for preamp gain to be adjusted to match the needs of the console. The remaining need to adjust preamp gain relates to the source.

Quote:


While I truly appreciate iso'ed splits when we are driving very long copper runs to separate systems sitting on there own "power islands" these days when we are looking at stage splits with all of 30 feet of tail on them to go in two or three remote preamp racks I find the need for a completely iso'ed system becoming more and more unnecessary.


There should be racks of preamps on stage whose gain is only adjusted to adapt to the source. They  should feed a mulitplexer that delivers the output of every source to as many consoles as is needed, via a digital link.

That's a nice theory, but it doesn't work in practice.  Assuming that all mixes would always want exactly the same gain settings and changes just isn't realistic.

Think of the situation where the FOH is given control of the preamps.  Maybe something is a little down in level and the monitor mixer caught it first and turned up their channel gain to compensate.  Now the FOH mixer sees it and turns up the preamp gain, sending the monitors into feedback.  Now imagine this in the one project I had where the Owner wanted the recording studio in another part of the building to have control of the preamps on stage.  And saying that you preset the preamp gain and leave it is the same as saying you never have to adjust the trim after sound check, which is not a situation I've encountered too often.  And then you still have differences in inputs between consoles, imagine if the console with +24dBu input capability is adjusting the preamp gain for a console that has a +18dBu max for the inputs.
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Arnold B. Krueger

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Re: 2 Mixer question
« Reply #12 on: October 25, 2007, 08:54:31 am »

[quote title=Brad Weber wrote on Thu, 25 October 2007 13:30]
Arnold B. Krueger wrote on Thu, 25 October 2007 07:01


There should be racks of preamps on stage whose gain is only adjusted to adapt to the source. They  should feed a mulitplexer that delivers the output of every source to as many consoles as is needed, via a digital link.


Quote:


That's a nice theory, but it doesn't work in practice.  Assuming that all mixes would always want exactly the same gain settings and changes just isn't realistic.


I'm sorry that I didn't express myself well. The idea is that the preamps and converters have enough dynamic range that their gain need only adjusted to suit the source. IOW mic preamps for a dynamic mic and a condensor mic would be initally be set up with different gains because the output of the mics can vary so much, but once the mic preamp's is set its gain would not be changed as we so commonly do now.

Quote:


Think of the situation where the FOH is given control of the preamps.  Maybe something is a little down in level and the monitor mixer caught it first and turned up their channel gain to compensate.


No doubt the scenario you described Brad, where people keep on tweeking the mic preamp gain after everybody has already done their own local settings and optimizations, raises a lot of valid concerns.

I'm used to my digital mixer where there is a channel gain control in addition to the usual preamp gain control. I do most of my channel gain changes with the digital channel gain control, so there I have no need to change preamp gains "a little".  

I rarely change mic preamp gains after setting up the source,  because the mic preamp gain controls all over the place (some onboard, some in 8 offboard mic preamps, and some in ADA8000s). They are not just in my console.

Furthermore, no preamp gain settings can be saved in a scene on my console. None! So, unless I carefully stabilize them, I can easily create something like your scenario, where pulling up a scene that used to work, now goes into feedback.

Sharing resources requires discipline. Moving a mic can change things a lot for the operators of different consoles, and that is hard to avoid. So, we're already struggling with discipline issues, even if we don't share mic preamp gain settings.



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Andy Peters

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Re: 2 Mixer question
« Reply #13 on: October 25, 2007, 03:48:06 pm »

Arnold B. Krueger wrote on Thu, 25 October 2007 05:54

I'm sorry that I didn't express myself well. The idea is that the preamps and converters have enough dynamic range that their gain need only adjusted to suit the source. IOW mic preamps for a dynamic mic and a condensor mic would be initally be set up with different gains because the output of the mics can vary so much, but once the mic preamp's is set its gain would not be changed as we so commonly do now.


You set the gain based on whether the mic is a dynamic vs a condenser?

How about setting the gain based on the SPL of the source?

Question: would the gain of an AKG C414 inside a kick drum be the same as the gain of that mic in front of choir?

-a
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Arnold B. Krueger

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Re: 2 Mixer question
« Reply #14 on: October 25, 2007, 04:37:51 pm »

[quote title=Andy Peters wrote on Thu, 25 October 2007 20:48]
Arnold B. Krueger wrote on Thu, 25 October 2007 05:54

I'm sorry that I didn't express myself well. The idea is that the preamps and converters have enough dynamic range that their gain need only adjusted to suit the source. IOW mic preamps for a dynamic mic and a condensor mic would be initally be set up with different gains because the output of the mics can vary so much, but once the mic preamp's is set its gain would not be changed as we so commonly do now.


Quote:


You set the gain based on whether the mic is a dynamic vs a condenser?



I'm sorry that I didn't express myself well. My point that all other things being equal...

Quote:


How about setting the gain based on the SPL of the source?



How about setting the preamp gain based primarily on the:

SPL of the source
Postion and orientation of the microphone
Sensitivity of the microphone

Quote:


Question: would the gain of an AKG C414 inside a kick drum be the same as the gain of that mic in front of choir?



All other things being equal, yes. Just stiking a mic in front of a choir or inside a kick drum doesn't change its sensitivity.

Wink


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Karl P(eterson)

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Re: 2 Mixer question
« Reply #15 on: October 25, 2007, 09:07:21 pm »

Again, I agree with you in principal, but reality doesn't play out.

In reality I have multiple bands with dozens of members and just as many different events. 20 different video clips coming from who knows where, halve a dozen potential operators, a keyboard that for some reason is just _blasting_ me and an acoustic G that just can't seem to get loud enough today.

I realize that there are a lot of applications where the cost effectiveness of shared pres and the convenience of a digital split are great things - but the window of their usefulness is very small.

Go with split pres - while you may regret you didn't - you will never regret that you did.

Karl P
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Christopher Buehring

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Re: 2 Mixer question
« Reply #16 on: October 26, 2007, 01:39:00 pm »

Arnold B. Krueger wrote on Thu, 25 October 2007 15:37


How about setting the preamp gain based primarily on the:

SPL of the source
Postion and orientation of the microphone
Sensitivity of the microphone




Translated: Set the preamp gain according to the strength of the signal coming into it.
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Re: 2 Mixer question
« Reply #16 on: October 26, 2007, 01:39:00 pm »


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