Building an active isolated mic splitter?

[Unbound]

Hi there, I'm setting up a mobile recording rig, and I need some active isolated mic splitters (at least I think i do.) I was wondering if these would be tough to build either racked or in a box.
So if anyone knows how to build even a passive isolated splitter I would be interested!
I would like to have many channels, possibly racked, thanks!

Aaron Hyde
-Unbound Audio
"If my van doesn't start, is my studio still considered mobile?"

[Remoteness]

If you have technical ability to build your own active splitter, go for it. IMO, you maybe better off buying an active splitter from XTA, BSS, Klark Teknik, Whirlwind, et cetera, etc.

If you want to build a passive isolated splitter, there are threads with plenty of posts about it at the "Remote Possibilities" Forum.

Check it out...

You will not be disappointed.

[Tim Farrant]

Yes, an active mic splitter is essentially a mic preamp with not much gain, so it needs to be good to retain the best sonic's. You can buy transformers for mic splitting from various manufacturers, Sowter make some nice transformers for the job.

Cheers
Tim.

[Unbound]

My technical ability probably outweighs my bank account which is why I would be interested in trying my hand at these...I'm confused about the gain stage and what type of transformer should be used...I was interested in building one very similar to what I saw on the whirlwind webpage, they've got some pretty cool custom stuff- http://www.whirlwindusa.com/wnews.html or maybe something like the ones from wireworks?- http://www.wireworks.com/Microphone_...R-Splitter.htm

[Tim Farrant]

OK, go to the Sowter homepage, Sowter , and click on the PRO AUDIO button. Cruise down and you will find the 4079 type transformer, click on that. If you then scroll down, you will see the schematic and colour code.

To build your splitter, you need to wire the XLR-F (female) MIC INPUT connector to the primary (BLUE/RED - disregrad the GREEN centre tap). You will also need to parallel this to the first XLR-M (male) output, which we will call the DIRECT OUT.

The direct out is used to feed the console that will supply phantom power, usually the FOH console or maybe the recording console.

Then wire from the 2 secondaries (ORANGE/PINK and WHITE/GREY respectively) to another 2 additional XLR-M output connectors. These outputs are the isolated outputs used for sends to the other consoles in use at the gig.

Remember to keep things in phase, BLUE, ORANGE and WHITE are pin 2 HOT connections on the XLRs, RED, PINK and GREY are the pin 3 COLD connections.

Only connect pin1 between the MIC IN XLR-F and DIRECT OUT XLR-M. The other 2 isolated outputs should be OK without a pin 1 connection, however, some splitter boxes have a switch between the PIN1 of the output XLR and pin 1 of the input XLR, called GROUND on/off, but generally speaking, connecting all the console grounds together will only cause major earth loop problems.

I hope this makes sense to you. Obviously there is also a fair amount of metalwork involved getting it all mounted into a suitable steel box.

Good luck with it.
Tim

[Remoteness]

That's a very cool description on how to build a passive mic splitter.

There's a lot more to building an active one.

[DeadPoet]

thumbsup for this thread.

Buzz: these are passive splitters, right ? So no current needed (sorry to be a dummy).

Also: what would be the backdraws on using passive splitters vs active ones ? I think I saw Steve mention: put the preamps on stage, but my mind says: hey, those lines are balanced, so cable length shouldn't matter, or am I missing something here ??


Herwig

[mosfetmadness]

Cable Length always matters. With a balanced signal you are less susceptible to picking up interference but attenuation and filtering caused by cable parameters (capacitance, inductance, resistance) are always an issue.

[Remoteness]

Originally Posted by DeadPoet

thumbsup for this thread.

Buzz: these are passive splitters, right ? So no current needed (sorry to be a dummy).

Also: what would be the backdraws on using passive splitters vs active ones ? I think I saw Steve mention: put the preamps on stage, but my mind says: hey, those lines are balanced, so cable length shouldn't matter, or am I missing something here ??


Herwig

Yes, no AC or DC power is needed for ANY passive device.

Long line level runs is not the problem.
We have run over one thousand feet of cooper with no problems what so ever.
But, low level microphone lines are a different story.
Depending on who you ask, you should run them longer than 250 feet.
Some folks say, that's too long.

If you can hear the difference the answer should obvious.

Originally Posted by mosfetmadness

Cable Length always matters. With a balanced signal you are less susceptible to picking up interference but attenuation and filtering caused by cable parameters (capacitance, inductance, resistance) are always an issue.

So true -- but some folks cannot hear the difference.