Splitting Balanced Feed In Live Environment

Hi,

A client of mine is a DJ / Producer with a large, roving setup. He uses a nice discrete EQ on the output of his master mixing console. The trouble is, the EQ only has one balanced o/p.

Ideally, he wants to split the EQ's output: one goes to the Main House rack, the other feeds his Monitors.

He wants an independent volume control for his Monitors, but the House feed doesn't need attenuating.  

As he already has a stack of gear, he wants something compact, simple, but high quality. As follows:

Bal I/P - Bal O/P (with level) + Second Bal O/P (without level, for house rack).

How would you do this? I guess the easiest option will be to have a Y-lead - one side goes straight to the House Rack, with the other going to a volume control + balanced buffer to feed his own Monitors.

As the EQ has plenty of drive, I guess we could use a passive option, with a Y-lead - one side direct to House Rack, other side goes to Balanced Passive Attenuator, feeding Monitor rack...

Hmmm... Has anyone got any ideas? Is there something on the market that can be had cheaply that won't colour the signal? I suggested a Presonus Central Station, but he says it's got too many bells and whistles for such a simple task.

Thanks in advance.

Justin

edit: He just emailed me this: http://www.tcelectronic.com/levelpilot.asp

I reckon a Y-lead, with one side to the House Rack, the other to Level Pilot - feeding House Amps.

edit - note EQ has transformer outs

Hi Justin,

Last week I knocked a quick design for a friend of mine to split his Motu output to the main monitors and the ghetto blaster.  I did the following;

Right channel

Balanced to unbalanced buffer. Then split to two volume pots.

One pot runs into unity gain, non inverting buffer. Unbalanced output goes to the ghetto blaster.

The other pot runs into unity gain, non inverting buffer. Output is Hot for balanced output to main monitor.
Hot output is inverted by another unity gain inverting buffer. Output is Cold for balanced output to main monitor.

All using 5532. I am writing from home just now and I don't have the facility to upload schematic, but I'll e-mail you tomorrow.

thermionic said:

Hi,

A client of mine is a DJ / Producer with a large, roving setup. He uses a nice discrete EQ on the output of his master mixing console. The trouble is, the EQ only has one balanced o/p.

Ideally, he wants to split the EQ's output: one goes to the Main House rack, the other feeds his Monitors.

Click to expand...

Ideally, he should be using a mixer with more than one stereo (I assume) output, one for the main feed and the other for his monitors. He will need a separate level control for the monitors. (Even if he doesn't realize he needs it.)

-a

Not sure where the Ugg Boots came into it...

Sahib - thanks for that - much appreciated, as always. To be honest, I'd prefer him to get the TC device I linked to, fed from a Y-lead. It's passive and won't need a PSU, which is desirable as he's already swamped with gear and leads.

Andy - his mixer has o/ps for Main and Stage etc. However, it doesn't have balanced inserts... Therefore, he's got the EQ on the end of the chain, with just a balanced XLR which needs to be sent the Main House Rack and the Stage Monitor Rack.

Thanks,
Justin

If he is sending to two balanced inputs a hard wire split should work.

JR

JohnRoberts said:

If he is sending to two balanced inputs a hard wire split should work.

JR

Click to expand...

Indeed. He needs an attenuator on one side for his feed (for Stage Rack), with the other feeding the House Rack. The EQ is t/former balanced.

The only thing that concerns me is that, in my experience, in the club world, I've seen XLRs feeding unbalanced / incorrectly terminated gear. The trouble with a y-split is that, if - for example - cold is shorted to ground where one of the feeds terminate, that unbalances the whole shebang... I now start to think of splitter transformers... and balanced attenuators being driven from them...what if?

What if the sky were to fall in? That would unbalance everything, right? I'm inclined to say that, for 49 quid (TC balanced attenuator in previous post) he should feed that off a y-lead. If he gets hum due to anomalies in venues, we tackle that when we come to it...

It is at this point someone chimes in (John / Cemal?) and tells me to build an active arrangement, because if one side gets improperly terminated, you don't upset the entire apple cart.

Thanks,
Justin

How about this:

http://www.jensen-transformers.com/datashts/mbc.pdf

A little more complicated than a Y split but pasive, you get an isolated line to FOH and a loop through for the monitors... Might want to look around for a higher headroom transformer (Lundahl LL1527Xl maybe?)...

An H pad with 4 precision resistors and a simple pot in the middle leg wired as a rheostat (variable resistance) will not imbalance a balanced split, and give you volume control.  Only negative is the kill will not be as good as straight fader, since it will be limited by matching of precision resistors and CMR of following stages. 

JR