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[Ron Roberts]

Hello,

Newbie here.... Can someone advise me on what is the best way to split mixing board main LEFT/RIGHT outputs?
I don't mean just a single Y splitter to split into two lines;  I mean split it multiple times to drive multiple power amps on each side of the stage and also to feed a recorder.  Right now I use two Whirlwind "Split 6" 1x6 splitters - but I am wondering if, after splitting it to 3, 4 or more outputs to various devices, is the signal weakening or is it straining the line-out electronics in the mixing board?

I realize there is probably advice on not using the main-outs to feed a recorder, but instead use separate AUX mixes for various reasons (e.g. to get a mix tailored for recording which may or may not be the live mix).  But in my case - due to lack of personnel resources and the time and isolation facility to create a separate recording mix - I just want the main mix that goes to FOH.

Is there a specialized line-level amplifier or appliance for this purpose?  Any help you can provide will be appreciated.

Ron Roberts
Fairfield, CT

[Erik Jerde]

From the whirlwind product notes:

Line level outputs can usually be split 6 times without noticeable loss of signal quality. The actual number of splits that can be accomplished depends on the level of the source signal and the impedances of the source and destinations in a particular application. It is not recommended that the SPLIT 6 be used to split a microphone level signal to more than two outputs. Attempting to do so may result in poor frequency response and reduced signal level. The SPLIT 6 may be used to split microphone level signals in most applications if this limit is observed.

If you find that it's working acceptably for you then just keep rocking it.  If your amps have through connections then that may be easier inside the same rack.  If you find your current situation isn't working for you then you need a distribution amplifier.  DAs usually have level controls so you can trim down signals as necessary too.  Something like the Rane DA216S might be what you're looking for if you want to move away from the Split-6.

[Ron Roberts]

From the whirlwind product notes:

Line level outputs can usually be split 6 times without noticeable loss of signal quality. The actual number of splits that can be accomplished depends on the level of the source signal and the impedances of the source and destinations in a particular application. It is not recommended that the SPLIT 6 be used to split a microphone level signal to more than two outputs. Attempting to do so may result in poor frequency response and reduced signal level. The SPLIT 6 may be used to split microphone level signals in most applications if this limit is observed.

If you find that it's working acceptably for you then just keep rocking it.  If your amps have through connections then that may be easier inside the same rack.  If you find your current situation isn't working for you then you need a distribution amplifier.  DAs usually have level controls so you can trim down signals as necessary too.  Something like the Rane DA216S might be what you're looking for if you want to move away from the Split-6.

Great info, thank you.  No, I don't split mic level or instrument level outputs.  Just mixer lineouts.
Most of the older vintage Crown and QSC power amps I use to not have throughput lineouts.  I wish they did, that would be much simpler.
When power amps *do* have throughput line outs are they boosted so that, theoretically, you can daisy-chain up to n number of power amps... where n can be... 6, 8, 10 or more power amps?
I think a DA is exactly what I'm looking for.  Thanks.

[Steve M Smith]

When power amps *do* have throughput line outs are they boosted so that, theoretically, you can daisy-chain up to n number of power amps... where n can be... 6, 8, 10 or more power amps?

No.  They are usually just linked directly.  It's standard practice to parallel connect a mixer (or crossover/processor) output to several power amps. 


Steve.

[Phillip Ivan Pietruschka]

No.  They are usually just linked directly.  It's standard practice to parallel connect a mixer (or crossover/processor) output to several power amps. 


Steve.

If it’s not practical or prudent to use passive splits including those built into amps, then you want a distribution amplifier. There are many out there.

[Matthew Knischewsky]

Hello,

Newbie here.... Can someone advise me on what is the best way to split mixing board main LEFT/RIGHT outputs?
I don't mean just a single Y splitter to split into two lines;  I mean split it multiple times to drive multiple power amps on each side of the stage and also to feed a recorder.  Right now I use two Whirlwind "Split 6" 1x6 splitters - but I am wondering if, after splitting it to 3, 4 or more outputs to various devices, is the signal weakening or is it straining the line-out electronics in the mixing board?

I realize there is probably advice on not using the main-outs to feed a recorder, but instead use separate AUX mixes for various reasons (e.g. to get a mix tailored for recording which may or may not be the live mix).  But in my case - due to lack of personnel resources and the time and isolation facility to create a separate recording mix - I just want the main mix that goes to FOH.

Is there a specialized line-level amplifier or appliance for this purpose?  Any help you can provide will be appreciated.

Ron Roberts
Fairfield, CT

Hi Ron,

Balanced line level may be passively split many times before there's any problems with output drive level from the source, usually. The same impedance rules for speakers apply for line level in that each device has a rated impedance and we may calculate the impedance of the entire system to make sure it's not too low.

Generally, most professional balanced outputs are rated to drive 600 ohm loads. It's common to see balanced amplifier inputs rated at 20K ohms. You'll want to verify these specs for your own equipment. You mentioned "vintage QSC", not sure how vintage we are talking so I looked up Series Three, it's 20K ohms input impedance.

Using the formula for parallel impedance (resistance) we find out that 33 20k ohm loads in parallel is 606 ohms. So that's a lot of passive splits (essentially Y splits/cables) before the hypothetical 600 ohm minimum output impedance of the mixer is exceeded. Is this a good idea to do this many splits? Well, maybe not. My personal main reason why not to do this is for troubleshooting purposes. With a system of this size there's bound to be some troubleshooting required during set-up and it can be time consuming to power up and down the entire system to re-patch one cable. Also, there's the potential for one bad cable to take down a large system while in use, so I like to group things into zones or amplifier locations (whatever makes sense for the gig) so that if there is a cable problem it's easier to find without loosing everything that's fed from the main left or right. Usually I'm aiming for no more than a dozen amps connected to one output, but I also know there's a lot of drive available from that one output so it's a rule of thumb rather than a hard rule.

The device you're looking for is a "Distribution Amplifier". Often times I find myself using a DSP loudspeaker processor as a distribution amplifier in addition to it's processing abilities. Or, a digital mixing console/stage box having matrix busses and assignable outputs I'll use it as a distribution amplifier as well. It really depends on the gear at hand.

That's a lot of information to tell you "Don't worry about splitting to 3, 4 or more devices", but it's good to know a bit of theory behind why that's possible.

Matt

[Ivan Beaver]

A good guideline is to keep the total load (all other inputs paralleled) to 10x the output impedance of the driving unit.

So just do the math.

When the loads get to be less than 10x the driving source, you can start to experience a little bit of signal loss.  How much depends on the particular loads.

I would not load any output down to lower than its output impedance.  But that would be A LOT of devices, assuming a normal driving device.

[Andrew Broughton]

Professional mixers usually have around a 75ohm output impedance on their balanced outputs. Power amps are 20 - 25k input impedance typically.
So... 20,000 / 10 / 75 = 26.6 power amplifier inputs in parallel as a safe maximum.

[Peter Kowalczyk]

We discussed this concept as it applied to a similar-but-different application a while ago here:

https://forums.prosoundweb.com/index.php/topic,169944.msg1567131.html#msg1567131

As others have said, low-impedance outputs and high-impedance inputs allow us to drive a single output into many inputs in parallel with negligible signal level loss.

[Ron Roberts]

Hi Ron,

Balanced line level may be passively split many times before there's any problems with output drive level from the source, usually. The same impedance rules for speakers apply for line level in that each device has a rated impedance and we may calculate the impedance of the entire system to make sure it's not too low.

Generally, most professional balanced outputs are rated to drive 600 ohm loads. It's common to see balanced amplifier inputs rated at 20K ohms. You'll want to verify these specs for your own equipment. You mentioned "vintage QSC", not sure how vintage we are talking so I looked up Series Three, it's 20K ohms input impedance.

Using the formula for parallel impedance (resistance) we find out that 33 20k ohm loads in parallel is 606 ohms. So that's a lot of passive splits (essentially Y splits/cables) before the hypothetical 600 ohm minimum output impedance of the mixer is exceeded. Is this a good idea to do this many splits? Well, maybe not. My personal main reason why not to do this is for troubleshooting purposes. With a system of this size there's bound to be some troubleshooting required during set-up and it can be time consuming to power up and down the entire system to re-patch one cable. Also, there's the potential for one bad cable to take down a large system while in use, so I like to group things into zones or amplifier locations (whatever makes sense for the gig) so that if there is a cable problem it's easier to find without loosing everything that's fed from the main left or right. Usually I'm aiming for no more than a dozen amps connected to one output, but I also know there's a lot of drive available from that one output so it's a rule of thumb rather than a hard rule.

The device you're looking for is a "Distribution Amplifier". Often times I find myself using a DSP loudspeaker processor as a distribution amplifier in addition to it's processing abilities. Or, a digital mixing console/stage box having matrix busses and assignable outputs I'll use it as a distribution amplifier as well. It really depends on the gear at hand.

That's a lot of information to tell you "Don't worry about splitting to 3, 4 or more devices", but it's good to know a bit of theory behind why that's possible.

Matt

Thank you all ... a lot of good info.  Very much appreciated.  So I really don't require a DA, but out of curiosity and in the interest of erring on the side of caution, I started looking at the RANE DA216s and found it interesting that I couldn't find one with XLR ins/outs.  They have these "Phoenix" or "Euroblock" connectors - which I would have to get adaptors to go to XLR.  The other brands (ROLLS, Nady, Behringer, Whirlwind) have XLR ins/outs but only 8 outputs (4 per side).  Maybe I'm not looking in the right places, but I only found the RANE DA216s has 16 outputs.  Does anyone know of a 2x16 DA that has XLR ins/outs?

[Chris Hindle]

Thank you all ... a lot of good info.  Very much appreciated.  So I really don't require a DA, but out of curiosity and in the interest of erring on the side of caution, I started looking at the RANE DA216s and found it interesting that I couldn't find one with XLR ins/outs.  They have these "Phoenix" or "Euroblock" connectors - which I would have to get adaptors to go to XLR.  The other brands (ROLLS, Nady, Behringer, Whirlwind) have XLR ins/outs but only 8 outputs (4 per side).  Maybe I'm not looking in the right places, but I only found the RANE DA216s has 16 outputs.  Does anyone know of a 2x16 DA that has XLR ins/outs?

Euroblock and Phoenix connections are generally used in installs.
Think "Stadium without Danley" 
Chris.

[Steve Ferreira]

A Drawmer DA6 might work for you.

https://www.drawmer.com/products/signal-distribution/da6.php

[Erik Jerde]

Thank you all ... a lot of good info.  Very much appreciated.  So I really don't require a DA, but out of curiosity and in the interest of erring on the side of caution, I started looking at the RANE DA216s and found it interesting that I couldn't find one with XLR ins/outs.  They have these "Phoenix" or "Euroblock" connectors - which I would have to get adaptors to go to XLR.  The other brands (ROLLS, Nady, Behringer, Whirlwind) have XLR ins/outs but only 8 outputs (4 per side).  Maybe I'm not looking in the right places, but I only found the RANE DA216s has 16 outputs.  Does anyone know of a 2x16 DA that has XLR ins/outs?

I'd mount the DA in the rack with the equipment it's serving then use the phoenix direct to the amps.  For the inputs connectorize them on a rack panel.  Using input panels vs directly patching to the equipment is a cheap way to protect the equipment connectors from overuse/misuse. 

[brian maddox]

Euroblock and Phoenix connections are generally used in installs.
Think "Stadium without Danley" 
Chris.

this^^

Audio DAs are generally not necessary for most sound systems for all the reasons already discussed.  They ARE often used in permanent installs essentially as a way to balance different outputs as well as a way to "isolate" the different pieces of gear from each other; not so much in a grounding sense but more in a fault protections sense.  If you have all your amps essentially Y'ed together than a short ANYWHERE in the wiring shorts out ALL the inputs.  Using a DA helps guard against this situation.  In an install an audio DA is cheap insurance.  And most install gear does NOT use XLR connectors as they are large and expensive and harder to terminate than phoenix connectors.

[Frank Koenig]

To be clear, minimum load impedance for full output voltage swing (max current) and output impedance are not the same thing. A power amp may be able to drive a 4 Ohm load to full voltage but has an output impedance of  miliohms. Just keeping the terms straight.

[Benjamin Krumholz]

Hello,

Newbie here.... Can someone advise me on what is the best way to split mixing board main LEFT/RIGHT outputs?
I don't mean just a single Y splitter to split into two lines; 
Ron Roberts
Fairfield, CT

Two words... "Daisy Chain."  If the BIG boys do it why cant you...

We have chained "Hundreds " of amps together and its fine..

I have seen installations with the AES Digital lines Chained together for many, many amps.. and its fine..

Now granted we have started to use the Focusrite Rednet Systems to Create " DA" outputs for drive or press purposes... But often each one of those concurrent outputs drive dozens of amplifiers all chained together...

You are doing better then most with the Split 6.

[Tim McCulloch]

The OP's description gives me the mental picture of a bunch of 2 way loudspeakers piled up, driving by an equally impressive pile of 30 year old amplifiers.  I hope I'm wrong.

[Jean-Pierre Coetzee]

The OP's description gives me the mental picture of a bunch of 2 way loudspeakers piled up, driving by an equally impressive pile of 30 year old amplifiers.  I hope I'm wrong.

This ^^

I was hoping someone might be asking why he needs to do that. Want to enlighten us?

[Nathan Riddle]

I was thinking zoned (walled) distributed system? Hoping anyway

[ProSoundWeb Community]