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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Samuel Rees on April 26, 2012, 11:04:20 PM
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Preface - I know this has been discussed for years on this forum. I have been reading threads for about an hour. Someone turned what I thought I know about splits on its head the other day, and reading the archives only seems to confuse me more.
The question(s):
For small format FOH/MON configurations or IEM rack, is a hardwired snake (ex: EWI poorman's splitter) appropriate and/or safe? If yes, what are the downsides and risks? If no, is transformer isolated the only other option, and are there downsides to transformer isolated?
I previously believed that a transformer isolated split was essentially the only option, because passive splits could damage the secondary console by hitting it with phantom and that phantom from the secondary console could damage microphones. There would also be the non-damaging but annoying effects from gain changes console-console. I have never used a passive product for this reason.
Some people said things in the archives that seemed to confirm this for me. Others seemed to say the opposite, describing problems I didn't totally understand from trans-iso systems. Additionally, there are passive splits being sold all over the place - which confused me previously as I thought they were dangerous and and largely useless.
Can someone straighten me out? This is so simple I'm embarrassed I can't figure it out!
Thanks...
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Preface - I know this has been discussed for years on this forum. I have been reading threads for about an hour. Someone turned what I thought I know about splits on its head the other day, and reading the archives only seems to confuse me more.
The question(s):
For small format FOH/MON configurations or IEM rack, is a hardwired snake (ex: EWI poorman's splitter) appropriate and/or safe? If yes, what are the downsides and risks? If no, is transformer isolated the only other option, and are there downsides to transformer isolated?
I previously believed that a transformer isolated split was essentially the only option, because passive splits could damage the secondary console by hitting it with phantom and that phantom from the secondary console could damage microphones. There would also be the non-damaging but annoying effects from gain changes console-console. I have never used a passive product for this reason.
Some people said things in the archives that seemed to confirm this for me. Others seemed to say the opposite, describing problems I didn't totally understand from trans-iso systems. Additionally, there are passive splits being sold all over the place - which confused me previously as I thought they were dangerous and and largely useless.
Can someone straighten me out? This is so simple I'm embarrassed I can't figure it out!
Thanks...
okay, there are others who can go on and on about the technical aspects of this. i'm just gonna weigh in with my 20+ years in the trenches. take it FWIW..
by way of history, i started using passive splits with shared grounds. ewww. then we had nice custom built passive splits. then we had a 3-way jensen transformer split. i've used all 3 of these in quite literally hundreds of shows in all sorts of situations. here's what i found to be true.
passive splits can, possibly, maybe, in certain very specific situation, cause issues based on the fact that it's nothing more than a big y cable. however, out in the real world i have NEVER had a passive split damage anything, and I've had them hooked up wrong and double phantomed and wet with ribbon mics and all sorts of stupid things. i've occasionally had issues with ground loops, usually where there were unbalanced connections involved, either intentionally, or not. but i've never had them 'break' anything. and i can only think of a handful of times i wished i had the transformer split. as to there being issues with gain changes interacting across a passive split, i've never had that experience or even heard of it. if it happens, it's so minute a problem as to have escaped me entirely.
transformer splits give you a physical disconnect between the two destinations. and that's great. but they also introduce the 'sound' of the transformer, the potential of magnetic fields to induce hum in them, the inability to pass comm, and several other pesky issues. frankly, i've had far more times that i had the transformer split, and wished i didn't, than the other way around. and honestly, most of times that we used it, it was because it was spec'd and we were meeting the contract.
none of this even includes the cost factor. my 2 cents is, if you need a splitter, get a good, well-built passive one with pin1 lifts on every channel. you may have the rare occasion where you'll wish you had transformers. but you're gonna be hard pressed to find yourself in a situation where this will ruin your day.
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Thanks Brian, I really appreciate the boots on the ground info. The fact that they sell passive splits like the ones from EWI in large amounts was contradictory to my understanding that they were largely a bad idea. I've spent most of my short career working for venues with isolated splits I never gave a second thought. I wonder know if some of them were even hardwired and I assumed they were isolated.
Quick clarification on the below:
by way of history, i started using passive splits with shared grounds. ewww. then we had nice custom built passive splits. then we had a 3-way jensen transformer split. i've used all 3 of these in quite literally hundreds of shows in all sorts of situations. here's what i found to be true.
..........................
my 2 cents is, if you need a splitter, get a good, well-built passive one with pin1 lifts on every channel. you may have the rare occasion where you'll wish you had transformers. but you're gonna be hard pressed to find yourself in a situation where this will ruin your day.
Can you clarify the "passive splits with shared grounds" to "nice custom built passive splits" spectrum? I assume the EWI Poorman's Splitter would be the former. What would be the latter? Do you just mean generally better quality or some technical difference (like a pin1 lift switches?)
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Look at it this way; if a console is capable of producing phantom power, applying phantom power externally is not going to damage it.
You can also look at it this way; If a mixer input can be damaged by external application of phantom power, it deserved to die anyway <g>
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You can also look at it this way; If a mixer input can be damaged by external application of phantom power, it deserved to die anyway <g>
Yeah. My sentiments too! :)
I think Brian is correct, that a "passive" split with ground lifts will work in almost all situations, at least that has been my experience over 20+ years. That's particularly true, if you have control over the complete system, both consoles, and power distribution to them. And the chances are even better that it will work now, rather than 20 years ago, because "pin 1 problems" are better understood by the manufacturers, and console grounding schemes are better.
However, if you don't have control over the complete system, or the setup is not always the same, transformers can be a show saver. Part of my day job involves looking after a remote recording truck, and we learned fairly early on that the only way to get clean recordings in certain situations was to have transformer isolation. And I can't remember a single instance in over 20 years of using transformer splitters, that there was a hum problem that couldn't be solved with the ground lift switches. There have been problems with bent or broken multipins, but that was operator error, not poor design.
It's true that you have to plan carefully how to run com and condenser mics that may only be going to the recording console (audience mics), if transformers are involved. Splitter transformers are also optimized for mic level signals, and may introduce distortion if line level with significant low end is run through them. Sometimes the only practical way to do that is to run another snake, but that's just the cost of doing business.
Also keep in mind that adding splits is effectively the same thing as adding cable capacitance to each microphone. The load on each mic is also doubled once another console is added. Most splitter transformers are 1:1, so electrically they behave pretty much the same as a hard wired split. The Whirlwind 3-way transformers, and perhaps others, have a 3 dB voltage loss on each of the two secondaries. That reduces the impedance and capacitive loading effect, at the cost of some signal level on those outputs.
Maybe I should also add that technically, hard wired and transformer splits are both "passive". A real active split is another step up, although it adds even more complications, besides the greatly increased cost. The ones I've seen had options for transformer isolation on at least some of the outputs, so a split can be active and transformer isolated at the same time. Like an active DI, the active split is useful when you need to drive long lines, because the microphones don't see all that extra capacitance.
The last remote I worked on had an interesting combination of technologies. There was a passive 3-way split on stage. One split went to the analog inputs of the M7 on stage, another went to the Yamaha stage boxes, and then CAT6 to the FOH M7, and the third split went to our SSL stage box, and then fibre to the truck. Other than one suspect channel in the split, which the PA company had already found before we got there, it all went together flawlessly, and worked on the first try.
GTD
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Can you clarify the "passive splits with shared grounds" to "nice custom built passive splits" spectrum? I assume the EWI Poorman's Splitter would be the former. What would be the latter? Do you just mean generally better quality or some technical difference (like a pin1 lift switches?)
actually, by 'passive split with common ground' i was referring to the splitters i used when i first got into the business in the early 90s. the company i worked for had these splitters they had made ten years prior that used a 27 pair and a 19 pair snake together to get 46 channels. ALL the shields were tied together and went through one big switch on the split output. this was NOT ideal to say the least and i think you'd be hard pressed to find anyone doing this now. after a few years of suffering through that system, we had built for us a modern style 56 channel 3-way splitter with pin1 lifts on all channels independently. while pin1 lifting the whole thing was a bit tedious [switching all 56 switches] it was world's more reliable. a few years later we got a 3-way jensen transformer split based on the same design as our non-transformer one. so those are the 3 different configurations i was referring to.
geoff makes some excellent points. transformers can absolutely save you when you can't control all the variables. and the drawbacks can be dealt with if you understand what they are. and he is absolutely correct in saying that all these options are actually 'passive' splits. i've had the privilege on rare occasion to use true active splitters [BSS units as i recall] and it really was a treat. they have their own issues as well, cost perhaps being number one on the hit parade, but in the right circumstance they are wonderful things to have...
my bottom line is still that in 99.8 percent of cases you're gonna get totally satisfactory results out of a good ol' fashioned non-transformer split with individual pin1 lifts. and if i was doing PA work, and i was spending my money, that's what i'd buy...
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geoff makes some excellent points. transformers can absolutely save you when you can't control all the variables. and the drawbacks can be dealt with if you understand what they are.
my bottom line is still that in 99.8 percent of cases you're gonna get totally satisfactory results out of a good ol' fashioned non-transformer split with individual pin1 lifts. and if i was doing PA work, and i was spending my money, that's what i'd buy...
+1
and for any pesky problems, buy a few in-line iso transormers to keep on hand.
Cheers,
Hammer
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Look at it this way; if a console is capable of producing phantom power, applying phantom power externally is not going to damage it.
You can also look at it this way; If a mixer input can be damaged by external application of phantom power, it deserved to die anyway <g>
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Good in theory, but I have seen it fail in practice. Phantom power in a hardwired split should not damage a properly design, professional live sound console, but I once encountered issues with a direct coupled split to a broadcast console that resulted in all the splits carrying phantom from the house mixer causing the correpsonding channels to fail on the broadcast mixer.
I'd also think twice about hardiwred splits if you are feeding something like a broadcast or production truck running off different power such as their own generator. That's a situation where the transformer isolation may be warranted.
For a more technical discussion on microphone splitters try http://www.audiosystemsgroup.com/Mic_Splitters.pdf (http://www.audiosystemsgroup.com/Mic_Splitters.pdf) and http://www.audiosystemsgroup.com/AESPaperSplittersASGWeb.pdf (http://www.audiosystemsgroup.com/AESPaperSplittersASGWeb.pdf).
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Any recommendations on where to get a decent priced splitter for a band that's looking to carry their own monitor console? Ground lifts would definitely be nice. Though, I've always seen phantom supplied by FOH as the arrangement when I've used a splitter. Would it be enough to hard lift pin 1 on the feed to the monitor console off something like the EWI poor man's splitters?
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George you took the words right out of my mouth just there. EWI's snakes, which have seemed to be the budget favorite in the past, don't appear to have ground switches on any of their models. Any recs?
My app is all rock&roll use. Splitting from house console to my SiC or an LS9.
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Any recommendations on where to get a decent priced splitter for a band that's looking to carry their own monitor console? Ground lifts would definitely be nice.
Well, it depends on the size of the monitor console. A number of models have built-in splits - you wire the stage inputs directly to the monitor board and then patch the split outputs into the FOH snake head or FOH mixer, if you keep monitor world up that way because you're the only sound person.
The APB ProRack Monitor (http://apbdynasonics.com/Images/prorack/1016_back_highRes.jpg) has this, as does the A&H MixWiz 12M (http://www.allen-heath.com/uk/Products/pages/ProductDetails.aspx?catId=MixWizard3Series&ProductId=MixWizard312M&SubCatId=).
You don't necessarily have to go for a standalone splitter snake, either…you could make up your own rack of splitters (passive, active, etc.) and do it that way (http://whirlwindusa.com/catalog/snakes-splitters-and-multiwiring-systems/splitters/spc84). Or, you can use existing snakes and just buy the splitter box (http://whirlwindusa.com/catalog/snakes-splitters-and-multiwiring-systems/splitters/sb-series-multichannel-passive-mic-splitters).
Though, I've always seen phantom supplied by FOH as the arrangement when I've used a splitter. Would it be enough to hard lift pin 1 on the feed to the monitor console off something like the EWI poor man's splitters?
You can always create your own wiring harness/snake fanout with pin 1 lifted…all it takes is some time and a little bit of work.
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Personally I'm using either an Si Compact 24 or an LS9 all the time, but I realize this has moved on to more than just advice for me which is totally cool. I was hoping this would become a great thread to find in the archive.
Any products out there on the market like that? A budget friendly split with lifts?
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+1
and for any pesky problems, buy a few in-line iso transormers to keep on hand.
Cheers,
Hammer
+2
Am I allowed to agree with someone who's agreeing with me? :-)
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Quote from: Charlie Zureki on Today at 10:40:34
+1
and for any pesky problems, buy a few in-line iso transormers to keep on hand.
Cheers,
Hammer
+2
Am I allowed to agree with someone who's agreeing with me? :-)
I've wondered about this. Is it sufficient to just transformer isolate only a few channels? My gut tells me you have to isolate them all, or there will still be a ground loop between the consoles, but maybe not.
GTD
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I've wondered about this. Is it sufficient to just transformer isolate only a few channels? My gut tells me you have to isolate them all, or there will still be a ground loop between the consoles, but maybe not.
GTD
Properly designed consoles shrug off ground loops....
JR
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I've wondered about this. Is it sufficient to just transformer isolate only a few channels? My gut tells me you have to isolate them all, or there will still be a ground loop between the consoles, but maybe not.
GTD
Hello Geoff et al...
It may be sufficient to use a transformer to isolate a channel or a few,or not necessary at all.
It depends where, how and what exactly a Tech may be doing. For example: If you're powering the Foh Console at the same source as the Mon Console, you, more than likely would not need to isolate between the Consoles. But, if you were perhaps running an Audio input(s) to the Foh from a Video World's deck, or an audio return to Video World, you may need isolation as chances are now you'd have a big loop between all three pieces of gear (or maybe more) at different locations.
There are other scenarios too... possibly running a matrix output to another room's system, Video truck inputs/outputs, Or outputs to a Protools Op or other Audio Recordist, or even a pressbox.
Some years ago before all of the fancy, off the shelf gizmos we have today, I had built my own "multi box" which sometimes needed transformer Isolation . The box had a standard stereo headphone output and a stereo input (from the console headphone jack) and another input from clearcom, for the Mic and earset. There was an XLR input for a Microphone.
I used this rig instead of having to switch from headphones to the clearcom headsets. It had a built in "ducker" with adjustment too.
Sometimes it is only one channel out of a few dozen that gives us problems, sometimes it's all of them.
Hammer
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Sounds like a hardwired split with ground switches and a few inline-iso transformers on hand would be sufficient for a small format PA FOH/monitor split or IEM rack split.
Besides building your own - what products like this are on the market?
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Properly designed consoles shrug off ground loops....
JR
Do I hear an amen brother John. Some times the world at large tends to over engineer a simple solution which in the end is just fine if you're willing to spend the money on something you rarely need.
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Any recommendations on where to get a decent priced splitter for a band that's looking to carry their own monitor console? Ground lifts would definitely be nice. Though, I've always seen phantom supplied by FOH as the arrangement when I've used a splitter. Would it be enough to hard lift pin 1 on the feed to the monitor console off something like the EWI poor man's splitters?
If you have soldering skills and some spare time, it's not very expensive to add a pro split to an existing snake. I have a relatively standard Whirlwind 24x8 Medusa 100' snake I need to add a split to. I got a 40' snake from Whirlwind that had the proper fan-out for the monitor desk side and a blunt end on the other. WW sent me all the ground lift switches with guards, strain relief with Kellems, and even precut shrink for splices into the stage box XLRs. A day of some drilling and soldering give me a good quality split with minimal cost. I paid around $300 for all the parts.
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Maybe I should also add that technically, hard wired and transformer splits are both "passive". A real active split is another step up, although it adds even more complications, besides the greatly increased cost. The ones I've seen had options for transformer isolation on at least some of the outputs, so a split can be active and transformer isolated at the same time. GTD
I'd like to add to Geoff's note about correct terminology.
Audio is confusing enough without employing incorrect terms which imply conditions that do not exist within the context of, or are not relevant to, the discussion.
A hardwire split is passive.
A transformer isolated split is passive.
An active splitter consists of a microphone preamp for each channel with (typically) electronically buffered outputs (splits) and (as someone else noted) optional transformer-isolated splits.
Active requires a power source.
You can apply the above to direct boxes:
A hardwire split is passive.
A transformer isolated direct box is passive.
An active direct box consists of a preamp with a low impedance balanced output, plus the loop-through (parallel) jack. Optionally there may be a transformer on the output.
Like an active DI, the active split is useful when you need to drive long lines, because the microphones don't see all that extra capacitance.
The primary reason an active split may be useful or deemed to be better is that the output is line level and this reduces the potential for ill effects when driving long lines.
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Understood. Any non-DIY options out there that won't break the bank? EWI Splits don't have lift switches, how big of a deal breaker is that?
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Any recommendations on where to get a decent priced splitter for a band that's looking to carry their own monitor console? Ground lifts would definitely be nice.
Here's an example of a simple splitter I built a few years ago. It was made for someone who does location recording, but the idea is the same for bands carrying their own monitor console. Whirlwind and Radial, as well as other manufacturers seem receptive to custom work like this. You just have to spec exactly how you want it built for them. I think it's important in a situation like this to cause the least grief possible for the host PA company. With this setup, the end of the snake with the single XLRs stays plugged into the monitor console, and the end with the doubled connectors gets inserted between the stage mic cables and the main snake inputs. You simple pick off which channels you need in the monitors, and insert the double end XLRs.
You still have to decide what to do with the shields on one of the outputs. For this example, I think I connected all the grounds, since the owner might want to use it as a non-split snake in some applications. For one that would always be used with a monitor console, I'd just leave the shields disconnected at the monitor console end. The cables will all get their ground from the house system (which is presumably already working), and the monitor console gets its ground from the AC plug. As much as I'd like to think that pin 1 has been solved as JR noted, I think it will take a few more years before the offenders are all banished to garage practice systems. ;D
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My $0.02
I have an EWI poor mans split. Never had a problem using it with consoles made in the past 20+ years.
I used to have 24ch of transformer split. It weighs a lot and uses up lots of rack space unless you have a custom unit made.
An IEM rack I made for a band with 4 transmitters and 16ch with mixer weighed 250lb.
Sent from my iPhone using Tapatalk
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Understood. Any non-DIY options out there that won't break the bank? EWI Splits don't have lift switches, how big of a deal breaker is that?
I don't think it is a deal breaker at all.
The odds are if you need a ground lift, it is going to be for one particular channel because of something that is on that channel. In that case I really don't want the ground lift at the stage box, I want it where I have better control, i.e. either at FOH or Monitor land or at the equipment itself.
Anywhere you decide you need one, a handful of barrel type (I use the ones from Audiopile) take care of the need.
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I don't think it is a deal breaker at all.
The odds are if you need a ground lift, it is going to be for one particular channel because of something that is on that channel. In that case I really don't want the ground lift at the stage box, I want it where I have better control, i.e. either at FOH or Monitor land or at the equipment itself.
Anywhere you decide you need one, a handful of barrel type (I use the ones from Audiopile) take care of the need.
Makes sense. Actually, would it make sense to open the box up and just cut all the grounds for the secondary leg and label it as such? That way Phantom would always be from FOH/Primary leg and grounding would always be from FOH power?
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Makes sense. Actually, would it make sense to open the box up and just cut all the grounds for the secondary leg and label it as such? That way Phantom would always be from FOH/Primary leg and grounding would always be from FOH power?
Unnecessary.
I've been following this thread and have a couple of observations -
I've been a "isolated split" guy for a long, long time and was very reluctant to accept "wye" splitters. Remember that I'm an old, crusty guy that lent the brass key to Ben Franklin for his little kite/lightning experiment... and back in the day we had lots of gear that had "pin 1 issues" designed into them, no standard for electrical powering of FOH (get it where you can, usually), and often had to interface with artist-provided gear of unknown status. Transformer isolated splits without grounds were the primary way to keep ground loops out of inputs.
Fast forward to more recent times and sound company practices have improved regarding power to FOH, most gear no longer exhibit pin 1 issues and most artist-provided equipment is of more current vintage.
About 10 years ago I reluctantly approved purchase of wye splitters and we have not had any ground loop experiences that could not be dealt with by pin 1 lifts... and if lifting pin 1 doesn't solve the problem, chances are a transformer won't, either.
Impedance changes brought about by varying the input gain on consoles will pass through the transformer. The only way to not have that happen is with a true active split as described by Tom Young, and such splits are very, very expensive and usually unnecessary unless you must interface with the "outside world" like recording or broadcast trucks.
Get a poor man's splitter or just make up a bunch of XLR wye cords. Carry a half-dozen pin 1 lifts (that will go mostly unused).
It is not necessary to over think this.
Have fun, good luck.
Tim Mc
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Makes sense. Actually, would it make sense to open the box up and just cut all the grounds for the secondary leg and label it as such? That way Phantom would always be from FOH/Primary leg and grounding would always be from FOH power?
That's what I was thinking of doing. Except I think I'd open the connectors for the monitor side and snip them there. Then again, it'd be a lot easier to do it at one time in the stage box, as long as you keep the lines straight. Mix them up and you might have to do a bunch of re-soldering.
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Makes sense. Actually, would it make sense to open the box up and just cut all the grounds for the secondary leg and label it as such? That way Phantom would always be from FOH/Primary leg and grounding would always be from FOH power?
I think you should buy a poor mans splitter without ground lifts. Do not cut pit 1. Use phantom from both consoles. Don't worry about it.
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Thanks everyone. This is something I really needed to get into my head.