Straight Wire or Transformber Balanced splits?

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Straight Wire or Transformber Balanced splits?

Postby gigpiglet » Mon Nov 19, 2012 3:27 pm

topic sort of says it all..

when would a transformer balanced split be "necessary"?
does either sound "better"?

i see plenty of multicore systems (and wired them when i was working at revolver) that are just mults.. and i guess thats the same as a mult in a patch bay.
but then the pro systems seem to be transformer isolated (at least on one output)
given the cost difference, when/ why is it required and what is the argument one way or the other?

realise this may not be a right or wrong answer and will depend on the application, so keen to hear people thoughts and experience.
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Re: Straight Wire or Transformber Balanced splits?

Postby Chinagraf » Mon Nov 19, 2012 4:33 pm

As far as I can tell, the main reason is isolation, on a number of fronts.
- Ground isolation with earth lifts on the splitter side.
- FOH being isolated from the recording side.
- Impedance, as in having two pres going to the mic and loading it so the frequency response is out of spec.
- Phantom power - while a lot of pres could handle it, having the transformer split stops phantom coming back down the line into the other mic pre.
The other one is most FOH guys not letting you hook into the system without transformer splits. Which is fair enough.

I'm sure there is more on the technical side, and would love to hear it from those that know more.

Tranny splitters are expensive even to build yourself. There are cheaper ones that come in at a bit over $40 per channel, but they have some hf loss (-1.5dB from reports) so you need to convince the FOH guy to take the iso side which depends on his mood, as you then need to supply phantom. You can get decent trannies for around $30, but then when you add all the xlr's, switches and a box it gets pricey.
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Re: Straight Wire or Transformber Balanced splits?

Postby Enginearing » Thu Nov 22, 2012 3:43 pm

These days consoles don't have issues sharing a split with another console (IE Mons and FOH) so for standard gigs, Direct y-split is the norm, perhaps with one output ground liftable (usually FOH since Mons usually supplies phantom and requires pin 1)
Once a third preamp is involved it can be a bit greedy and rob the others of gain, so the third (and fourth etc) splits should be Iso'd.
Putting the OB on the far side of an iso'd output is the norm, that way they can gain up without affecting the others.
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Re: Straight Wire or Transformber Balanced splits?

Postby Chinagraf » Thu Nov 22, 2012 5:17 pm

Yeah, with monitors and foh in the same install people tend to use y-cords, but I don't know any foh guy that would let a recorder take mic splits without trannies. They will let you take direct outs from channels or groups but sometimes they are post eq etc although Midas and the like usually have a jumper that can be changed to make them either. The Digico and Presonus etc consoles are rendering a lot of this moot, as long as you are content with their conversion.
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Re: Straight Wire or Transformber Balanced splits?

Postby gigpiglet » Fri Nov 23, 2012 1:58 pm

so why would a FOH guy happily let a mons guy take a split without trannies.
but not a record guy.

bear in mind im all 3 depending on the tour

and i dont know the reason (hence the question)
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Re: Straight Wire or Transformber Balanced splits?

Postby Chinagraf » Fri Nov 23, 2012 3:44 pm

From what the foh guys I know say, it's because the foh and monitors are in their case part of the same system. They are powered off the same source, so it avoids ground issues, and if there is any problem like gain issues Ben mentioned they can control it and fix it or work around it well in advance. I kinda figure if a foh and monitor both have high enough impedance then it won't create loading problems on the mics, but once you add a third it is pushing it, espeacially if it is an older pre that is 600 ohms input? Things might also be different if you are feeding active wedges from a send on the foh desk instead of a monitor console so I guess it would depend on each individual setup as to how well y-cords would actually work. If you are doing everything, you could just suck it and see. I guess the thing with tranny splits is it avoids potentials issues. Nothing may go wrong with y-cords, but when things do, they go real wrong at least from what I've been told. I think some of it is just protective - If you are doing a big show, and know your setup works perfectly the way you set it up, are you going to let someone else come in and y-cord into your system despite you having no control over what gear they are using? As you are doing it all you could take yourself out for a few beers before the show so you will let you do what ever you want to yourself.

Maybe someone here can help out with parallel impedance calcuations - For 2 inputs it is Z1 x Z2 / Z1 + Z2, but for 3 do you just add another Z to each side of the equation?
Gareth are you planning on running another desk for monitors, or are you going to be feeding sends from foh for monitoring? That will determine the number of inputs each mic is feeding.

The only other thing I am a bit suss on is the phantom issue. What happens when it travels down a y-cord from one pre to the input of the other pre? Modern pres can probably handle it, but I take some old Neve's and V72's with me - would they get spanked around a little?
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Re: Straight Wire or Transformber Balanced splits?

Postby rob » Fri Nov 23, 2012 6:40 pm

ok, its friday afternoon so forgive me if I get something wrong here.....

lets break this situation down:

one mic to two or more preamps.
Issues:
grounding: if there is a ground loop between the preamps, you'll get hum. Solution ... lift the ground on all but one preamp. Now you are thinking you need a transformer involved to do this. But no, you can lift the ground on a Y cord. But you ever seen a Y split cable with a ground lift switch? Sidecutters or soldering iron will do it but do you have time for this before the band hits the stage? Star earth all equipment... good practice anyhow and if the two preamps (consoles) are plugged into the same outlet... it should be fine.

phantom: whichever preamp is providing phantom needs to keep the ground intact. So two preamps connected via Y split? What happens! Most preamps when phantom is turned off connect the far end of the 6K8 feed resistors to ground. So one preampnhas phantom on, one has it off. Now the mic sees the phantom voltage divided in half ... sort of ... it depends on the current draw of the mic... so every mic requires a separate analysis of the situation. Does it matter? Often no ... many mics will work fine off a lower phantom voltage .. but not all (U87) . So it becomes an uncertain situation... suck it at soundcheck and start the armwrestle between the recording tech and the FOH guy as to whether those condensors on overheads sound right or not. Transformer splits fix this uncertainty.

impedance: the impedance that the mic sees will be 1/ ( 1/Z1 + 1/Z2 + etc etc ). For two modern pres with a typical input Z of 2K, the mic will see 1K. Does this matter? Depends on the mic, by and large no. If a modern transformerless condensor nothing, dynamic, say 57 , a bees tit difference, an old RCA ribbon, a bit darker. Three pres and all this gets slightly accentuated. Toss in old old valve preamp with a 200R input Z and this will now dominate the loading on the mics and the result will .... depend on the mic. Now ... Transformers don't alleviate this issue. A transformer reflects through the impedance of the load (preamp). It gets a tad more complex due to things such as winding resistance but to a first approximation, transformer or Y cord ... the impedance issues don't change.

class dismissed...
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Re: Straight Wire or Transformber Balanced splits?

Postby gigpiglet » Sat Nov 24, 2012 11:51 am

thanks for the details rob

to clarify - i wasnt really talking about doing anything "dodgy" with y cables

im talking about split racks (by big manufacturers)
that come in transformer balanced versions and not
there are still ground lift switches
and JANDS racks for instance that are just multipins with no transformer
or coda splits that have BOTH options on them and so on

both seem to happen all the time
my query was which is better/ why and how the "standard" came about that FOH and MONS are direct but record is transformer iso.
thought there may have been history/ rules for that being the case

but doesnt seem to be
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Re: Straight Wire or Transformber Balanced splits?

Postby rob » Sat Nov 24, 2012 12:02 pm

there are no rules in audio ...

I'm not familiar specifically with the products you mention. Never the less I think the information in my post paints the general picture and would apply to these products.
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Re: Straight Wire or Transformber Balanced splits?

Postby Ben M » Sun Nov 25, 2012 4:32 pm

I've gotta confess I've been eyeing off this splitter for the past bunch of weeks. Me wanty :x

http://www.ebay.com.au/itm/360477716463 ... 742wt_1332
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Re: Straight Wire or Transformber Balanced splits?

Postby Chinagraf » Sun Nov 25, 2012 5:43 pm

Can you imagine the postage on that thing?
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Re: Straight Wire or Transformber Balanced splits?

Postby Ben M » Sun Nov 25, 2012 9:27 pm

Chinagraf wrote:Can you imagine the postage on that thing?

Andy I must confess again that I contacted the seller a couple of weeks ago about that.
Postage is really not too bad. Plus he's open to an offer.
All those Sowters are transforming me.
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Re: Straight Wire or Transformber Balanced splits?

Postby Enginearing » Mon Nov 26, 2012 12:53 pm

gigpiglet wrote:so why would a FOH guy happily let a mons guy take a split without trannies.
but not a record guy.


gigpiglet wrote:
im talking about split racks (by big manufacturers)
that come in transformer balanced versions and not
there are still ground lift switches
and JANDS racks for instance that are just multipins with no transformer
or coda splits that have BOTH options on them and so on

both seem to happen all the time
my query was which is better/ why and how the "standard" came about that FOH and MONS are direct but record is transformer iso.
thought there may have been history/ rules for that being the case

but doesnt seem to be


Doing it this way means that neither OB or Live production are affected by each other. You can patch and repatch on the other side of the iso and nothing will translate back into the house.

Chances are the monitor guy is...
A: supplying phantom power.
B: in direct communication with the FoH guy (MUTE BASS DI!)
C: not going to make huge gain changes after line check.

If the gig is being run on a JANDS split rack and you require a third output for OB, your multipins will be feeding a set of transformer plates.

Doing it this way keeps the OB guy self sufficient, out of the way and in a quieter environment (much easier to hear what's going on with your capture if you're not sitting in front of the PA). It also means he isn't affected by FOH gain changes or fader moves as he would be if trying to hang a record off the FoH console.

There are no rules but there are standards and systems, based on years of experience by the people who develop them.
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Re: Straight Wire or Transformber Balanced splits?

Postby gigpiglet » Wed Nov 28, 2012 3:15 am

thanks ben

totally appreciate there are some common practices.. but there actually doesnt appear to be a standard.

my comment on JANDS was that (as far as i am aware - though im willing to be corrected) their patch plates are ALL direct outs (no iso) as opposed to coda or some of the other "newer" systems that have one (or two) of the outputs iso'ed


PS: re the split rack on ebay.... seems really expensive, and only a 2 way split, and all XLR (no multis) i imagine you could do a lot better/ smaller/ more efficient with something that coda make, or whirlwind or the like (and get 3 way in the process) no pun intended... ;-)
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Re: Straight Wire or Transformber Balanced splits?

Postby Enginearing » Wed Nov 28, 2012 9:01 am

Yep, the Jands are multi-pin out, but on a record gig, the multis will hit a transformer plate, which is where OB will pick up their XLR feeds. Other splits are also three way and have no iso output, but will require OB to bring isos or active splits etc.

By keeping the transformer in a separate plate further downstream, it means there is redundancy in the system. For example if the monitor output is damaged or has issues, it can be bumped to the third output with no issues since it is a direct Y. By building the TX into the split, you lock out the possibility of using that output for a spare, since it won't pass phantom etc.
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Re: Straight Wire or Transformber Balanced splits?

Postby gigpiglet » Sun Dec 02, 2012 12:46 pm

awesome - thanks for that bit of info ben
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Re: Straight Wire or Transformber Balanced splits?

Postby gigpiglet » Mon Feb 11, 2013 1:08 am

just stumbled across this while doing something else

not particularly new or different info... but still relevant and from some guys in the know.

http://www.gearslutz.com/board/remote-p ... nyway.html
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Re: Straight Wire or Transformber Balanced splits?

Postby Alastair Reynolds » Tue Feb 12, 2013 8:33 pm

Harbuch transformers do some nice passive Mic splitters, I have an 8 way one with 2 transformer and one direct out for each channel and ground lift on each output. It would be easy enough to make one on a big XLR plate and Harbuch will discount on bulk transformer purchase. Quality is on par with sowter and they're localhttp://www.harbuch.com.au.Peter did a custom pickup head for an Ampex 440 capstan for me last year,tiny transformer with wire thinner than a hair and 20,000 turns.Perfect results and only about $50 .Off the shelf transformers in standard con figs are very competitive.
there's my 2c worth and you're supporting a local Australian manufacturer
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Re: Straight Wire or Transformber Balanced splits?

Postby Gian » Wed Feb 13, 2013 9:34 am

I have dealt many times with Peter at Harbuch and he is very helpful. Have bought many transformers from him - mostly custom designed.
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Re: Straight Wire or Transformber Balanced splits?

Postby Damien » Fri Feb 15, 2013 9:47 pm

i love this stuff... heres my take. remember in a live and studio guy, ive toured lots and done lots of ob's JJJ live at the wireless and live recordings etc.. ive been all these people below.

from the PA company's thinking
in a normal show the "system" it prepped or put together from a single source as in one company usually owns the whole pa FOH, MONS, cables core/splits set. it goes in and up every day and "works".
when you add anything they will blame whoever "added" the stuff.. its your bla bla bla thats causing the issue. it wanst like that last night without you and your toys..(you will later find the real issue, or maybe not).

from the OB people. the cores stuffed, noise everywhere, you need ISO's/transformers, they start de earthing bla, bla BANG..

both sides blame the other. its usually power earth from different locations causing the "noise", and a few bad cables as no one had enough leads to do a 3 way patch and everyone has used their last cables from the bottom of the packer that are sus anyway.

now im not taking into account the load with a third console/system connected and some gear really freaks out.

in the 90's i did lots of JJJ live at the wireless shows as i had old yamaha consoles with transformer balancing on the ins and outs for both the FOH and MON consoles. i had simple passive splits and used 2 of them for a 3 way split (foh, mons and radio.) we were the only pa campany thay wanted to use as the radio feed was clean with our system and other pa companies with newer "Better" gear had lots of issues.. their consoles were not transformer on in 's and outs.

today we have "much better" equipment and most live consoles are NOT transformer balanced.. so theres no isolation. everything talks to each other and at least 1 of not all 3 systems will be digital without any master clock, but with analogue interconnects (the multicore).

so again most PA companies will blame the third split (even if they provide it, its your stuff hanging off our split thats causing the issue, its you not us, it was fine last night, bla bla bla..)

what to do. you will be blamed no matter what.
most PA companies already have all the splits they need (1 for FOH, 1 for MONS) and they are now usually straignt, no trsansformers, no earth lift (some older cores had the ability to lift all the earth from at least 1 side with 1 switch).
you need to provide 2 x splits and if you want to be safe make 1 straight and the other transformer isolated. the best way is to take the inputs out of the main core (if they will let you, i bet they will all be sacred) and you give them back the STRAIGHT split. so mics into your core, your straight split to their core, you them use the transformer iso split for recording. you cant effect them and they are effectively connected as normal..

if they say no, take the monitor split (their tails) into your core, you take the transformer end and give the mon system the passive/straight split.

or just use a straight passive split ;).

BTW these things are quite good and inexpensive if you dont want to make one yourself.they do use DB25's which some people love, some hate. ive used them and a system i use regularly with digital consoles uses them

http://www.violetaudio.com/index.php?op ... view&id=25
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