G'day Farrs!
I don't remember what country you're in, but an XLR splitter is very common, can be found at just about any music store in the US. I think I may have a couple laying around my home actually. If the DVT option doesn't work out, let me know and I'll see about sending you a splitter. And yes, they are VERY handy.
Lemme know if I can help out.
D

I have several A.R.T. SplitCOM - Mic Splitter/Combiner's that have worked well for me. There are many, many others just as good.

DJ,
placed a call with DVT, see what they come up with.

Daryl, tried local music houses, not as common as I'd have thought.
Sure, heaps of DI boxes, not the same thing!

What I want is a unit that bridges balanced audio lines, that means hard wired in to out connections with HiZ tap to another feed that's balanced LoZ. Why am I so pedantic. Well if I was the guy responsible for the sound in the venue I'd sure insist on nothing less. That way what I do cannot mess with his sound.

Seems Samson might have something, Rolls have the MS20c which is pretty close to what I'm looking for, those guys seem to make all the usefull widgets. Only concern would be the quality of the transformers and how much load it's placing on the passthru connection.

Bob.

Looks good, wonder how well it handles line levels say +10dB?

I know I'm being picky but a lot of transformers designed for mic levels saturate at line levels.

Bob.

Here is a page: nullmodem.com/audio. There are some links to suppliers towards the bottom.

Tor

After lots of searching and a few phone calls I think I'll roll my own, time permitting.
Core of the unit will be two Jensen JT-10K61-1M transformers.
The primary impedance of 10K means it can bridge the direct in/out without loading the line outputs in the mixer.
The 600 ohm secondary is ideal for feeding whatever I want the tap to feed, loss of 13dB but that's OK. Only issue is those Jensen transformers are expensive.

Bob,

A simple XLR splitter can be constructed as follows:

The Y adapter must route the + side (pin one an RCA, tip one a phone plug, #2 on an XLR) of the source to the + of both inputs, and the - side if there is one (#3 on an XLR) to the - of a balanced input. Keep pin one isolated from the shell on an XLR to eliminate the potential for a ground loop hum from Phantom Power if used. In a proper phantom circuit, equal positive voltages on pins 2 and 3 return through pin 1. If you disconnect pin 1, the only voltage left would be whatever difference there is between 2 and 3... and there shouldn't be any. It should only be disconnected on one of the male ends, not both male ends. You should connect the shield to XLR body on the pin-1-lifted side. Use shrink tubing so the cable shield is totally insulated there.

Galaxy Audio makes some . I am not sure if they carry them in Australia. I think you can buy Samson boxes there though.

John

After lots of searching and a few phone calls I think I'll roll my own...

Bob, if you go to the Jensen site, specifically the Schematics section, you'll find all kinds of wiring diagrams to do almost anything you want/need to do with their product.

Mike

Farss,
I use a Rapco press splitter, we have two.
One is 2 in/8 out, the other is 8 in, 24 out. Works really well with ground lifts, etc. No power, no batts, unless on the larger one, we want LEDs to let us know what inputs are being used. Generally tho, I just look at the box to get the same information.
Whirlwind, Rapco, Horizon, Rane, Mackie, all make both active and passive boxes.
Whirlwind boxes
HTH

In addition to Spot's recommendations, I forgot that I had recently picked up an for press conferences around the college. I got the BM-AV model as it more than met my needs.
Single line level audio source feeds 12 XLR and 4 -1/8” mini phone audio outputs with balanced isolation and a single 1V p-p video input feeds 6 video outputs. As I recall, price was around $1,700 Cdn.
Sorry but I don't see a distributor outside of the USA :-(

Mike

edit: corrected price

The design is very simple.
Decades ago I used to make many of these kinds of things, I used to work for Muzak ( I've done my penance OK) and dealing with properly matched audio lines etc, etc was part of the task when you sent music down phone lines, or a feed from a mic through miles of unshielded twisted pair, through a telephone exchange, through a few more miles of twisted pair and got something useful out the other end. And had the whole thing not even hiccup when you stuck a 2KV isolation tester on it.

There's quite a few manufacturers of this kind of gear that I've found but mostly it's for radio applications, big rack mount units, not something you'd throw in the kit bag.

The transformers for building these boxes were pretty common back then but ICs are way cheaper. I get the willies when I look at the schematics of most audio gear today, balanced outputs that aren't, playing very loose with specs and I've been caught out. On one gig I got a feed from an early model Behringer mixer. I have no idea what was going on but I needed 20dB of balanced attenuators to get it to a point where my kit didn't go nuts, I just could not turn the level down on my recorders, damn wierd whatever it was.

I have a real issue with "feeds from the desk", on another gig we got a nice clean feed from the desk, but it wasn't the house mix, it was the foldback mix and the MC wasn't getting foldback, great. You let others stuff up your job and you learn real fast, trust nothing.

And then there's the desks with lifted earths floating at who knows what voltage. Some venues are absolutely great, all the audio gear on technical power with clean grounds and others are just a mess.

Thankfully there's still companies like Jensen making the bits that old buggers like me need.

Bob.

John,
looked at the Samsons but all I see are mic level splitters, most likely they'll saturate at line level, heaps of stuff for mic / instrument splits around (although a lot of it isn't balanced), line level splitters really do need to be able to handle well over +4dBU, +20 gives you a good margin. Good insulation and shielding is also important.
I used to use I think Trimax transformers, things were around 2"x2"x4", hematically sealed, uMetal cases, cost a bomb but they worked beautifully.
All Old School stuff I know but yet to see anything that makes it obsolete.

Bob.

Bob,
If you are set on building a transformer coupled splitter here is a schematic you may want to look at. Mouser is a very good and reasonably priced supplier of electronic parts and they sell in Australia. Here is the transformer shown in the schematic.

John

John,
that schematic is a disaster waiting to happen, no one should use such a thing, at least not for what I'm doing.

Remember I'm inserting my box into the house feed, do you see the problem, batteries go flat, no house feed and it's not balanced although that bits easy enough to fix.

My design is so simple I can decribe it in words.

One XLR female, one XLR male.

Pin 1 to pin 1
Pin 2 to pin 2
Pin 3 to pin 3

Nothing but solid wire inserted into the house feed!

Add another male XLR to the box, that's for my feed / split.


Primary side of transformer goes accross pins 2 & 3 of house feed.
Secondary side goes to pins 2& 3 of male XLR to feed my gear. Pin one of male XLR goes to nowhere. ES shield of transformer goes to pin 1 of house circuit.

Primary of transformer Z > 10K, secondary Z = 600 ohms.

No active bits, no way to screw up house feed. No ground interconnects either.

My feed ends up about 16 dB lower than house feed, this I can live with.

Bob.