How to make a mic lead splitter box

[walding]

HI all

I'm in experimental mode at the moment and what I want to do is wire a box so I can plug a mic into it and run 2 mic leads out the other into 2 different pre's at the same time for ABing or recording both at once.

In effect it's like a Y cable only a balanced mic version.

I plan to make a hard box device like a A B pedal to do this.

Now my question is can I simply just wire it by duplicating the ins to both outs (cannons of course) or is there something else I may have to wire into it ie; resisters?

I hope this makes sense as I'm not up on this technical stuff :D

Much thanks in advance for any advice

Mark

[TimS]

Not sure how if you are interested, but there is a really nice splitter box writeup in the latest AT - made by Ivor Drawmer..
Gives lots of options too..
Might be worth checking it out.
Tim..

[chris p]

Hi walding

Most splitter boxes have an input that is directly wired to a direct out, but the second (and multiple) out that is isolated from them using a transformer.

Jensen make some especially for this purpose, eg

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

but pretty much any 1:1 low-Z (eg 600 ohm) transformer would do the trick.

Of course, the tranny can be replaced by some active electronics, such as an opamp buffer at unity gain, if you are happy to introduce power into the equation.

[walding]

Much thanks guys for your insight.

Could you direct me to a site that has a schematic.

The drawmer looks nice but expensive and I only want one channel.

[mfdu]

the PDF that chrisP kindly linked to have a schematic for a 1 in / 2 out splitter box. couldn't be easier!

[walding]

Thanks :D

[TimS]

Mark,
I knew it was a little left of field (the Drawmer), but thought you might like to check it out..
Tim..

[walding]

The drawmer looks like a fine piece of kit and would be awesome for live recordings although you'd need at least 3 of them.

Strange though it only has 6 inputs and not 8.

[chris p]

Walding

I should add that if you are using phantom power with the transformer design, it must come in along the direct line. Phantom on the isolated line will do diddly squat.

[walding]

WHOA

This is starting to get more complex than I thought :(

I hadn't factored in phantom power Mmmmmmm

Might have to get somebody to build it for me.

Recommendations for melbourne?

[chris p]

I'm sorry, I didn't mean to scare you.

There is nothing extra you need to build for phantom power, its still the schematic as above. Its just that a transformer (usually) blocks phantom power.

So taking that schematic, with a MIC IN, a DIrect OUT and an ISOlated OUT, if the MIC needs phantom power, you need to switch it on at the DI line. The MIC will then work just fine. It can be on or off on the ISO line, doesn't matter. But the mic won't get actually get phantom power unless it comes via that DI line.

To make this, you need 1 x XLR(F), 2 x XLR(M), 1 x transformer, 1 x box and hookup wire. That's all it is.

[mfdu]

[ paging Barney Loveland ]

i could do it for you easy, but Barney is your man if you actually want it done right.

but you'd be able to do it yourself. have another look at the schematic in the PDF (above).
the direct path passes phantom with no tricks or jiggery pokery. the trannie isolated path don't pass no stinkin phantom.
theres no power supply to burn - it's totally passive. get yourself a wee jiffy box, two XLR out, one KLR in and the trannie.

if you do it yourself, you'll be so darn proud. of yourself.

c.mfdu

EDIT (chrisP - simultaneous posting. mmmmmm gotta love it!)

[rob]

just try a straight Y split like you outlined in your original post. It'll cost you only a couple old XLRs and in 90% of situations it will work fine.
You will be double loading the mic, but depending on the mic it will make either no difference or a subtle difference, possibly even a good difference!
Ensure the two preamps you are using are plugged into the same power board or preferably are two channels from one unit. Only turn phantom on with one channel, not both, if the mic requires phantom.

The transformer idea is an ideal way of doing it but is mainly done to provide a galvanically isolated split so as to avoid earth loops between ( say ) a FOH and a monitor console. In a more controlled studio situation this may not be necessary.

Rob

[Barney Loveland]

I guess you'd have to try it and see if loads it down in a bad way. I can build you a box, but then again a transformer will impart some sort of sonic imprint too. Harbuch have a suitable trannie or you could go all out with a Sowter/Cinemag etc. It would also be able to have three outputs, one direct and two others but you'd also need a simple regulated 48V supply for this type of box. Try it and let us know if it works with a y split.