Multiple Headphone Feeds (40) To Live Room?...

roddymacaudio · Post by **roddymacaudio** » Fri Jul 18, 2008 11:16 pm

Hi

(new to this forum thing so apologies for anything i should've done but haven't!)

I am about to take over an existing rehearsal/recording studio, it has a control room attached to a live room via a 24-way (+4 reaturns) XLR to XLR loom.

As the current live room is very small (165 sqr ft), i am planning to connect one of the existing rehearsal rooms which is much bigger (570 Sqr ft ) to the control room and use this in addition to the existing live space for recording.

I currently use a Soundcraft SOLO 32 console. This has 6 auxes, 5 of which are available during recording to use as headphone feeds. I am planning to upgrade to Sountracs Jade at some point in the future so want to wire with this in mind (it has 8 auxes).

My idea is to take my 8 auxes from my console when tracking & split them into 5 sets of eight. These would be then sent out to the live room where each performer would have his/her own little 8 channel submixer on a stand where they could build their own mix as they like.

My problem is that although i can competently carry out general studio wiring (connectors, cables & looms etc) i am not sure how to split these signals. I have searched around on the net for a device that would carry out this task but without much luck.

I would like to be able to input 8 line level signals (connector type can be anything - XLR/Jack/EDAC) into a unit and then take 5 identical sets out of the unit on EDAC connectors to looms which then terminate in probably jacks i think, dependant on what type of inputs the little mixes have.

Has anyone seen this type of thing in action or knows how i might implement it? Also as the desk is obviously going to be earthed at the mains in the control room am i likely to encounter any earth loop problems considering that each of the little mixers will also be powered & connected to the mains in the live room?

(that's 5 sets of mains connections in the live room going to one unit which is then earthed at the other end too - i must be mad!

)

Also, does anyone know if the splitter box will have to be active or passive?

Thanks for any help you can give me.

Roddy.

(Glasgow, Scotland)

Ro · Post by Ro » Mon Jul 21, 2008 6:05 pm

Hai there,

There's special pre-made outboard gear for that job. Headphone amps, line-level mixers/splitters etc.

Splitting lines just by cables, making parallel lines, ain't a wise thing. As you attach more headphones the signal will decrease. And using different impedance headphones will even create a bigger mess.

So using them premade devices (19" racks) you'll be a lot saver and it looks cool in your studio. Mind you, you can get away with budget stuff like Behringer, Phonic etc. Doesn't have to be expensive.

roddymacaudio · Post by **roddymacaudio** » Wed Jul 23, 2008 7:15 am

Hi Ro,

Thanks for the reply - i don't suppose you have any links to some of the gear you were talking about?

The most i can find is stereo in to 8 out. I need 8 in to 40 out if i can get it, and if possible on a tough connector like an EDAC or something similar.

If the BBC can do it when they are recording orchestras etc it must be possible...

If anyone out there can advise me on the theory of the splitting process - i can possibly get something custom made here in Scotland that will do the job...

Cheers.

Roddy.

AVare · Post by **AVare** » Wed Jul 23, 2008 9:31 am

An old design principle. Use a standard amplifier, like a Bryston 2B, and put ~200Ω resistor in series with each headphone's signal connector. The resistors act as isolators. If the headphones' impedances and or sensitivities vary, you will have level matching problems,

Andre

brianrcdd · Post by **brianrcdd** » Thu Jul 24, 2008 8:48 am

Yup, I agree with Andre. And if you choose the right resistors, you get both isolation and the ability to parallel them all and still end up with a proper load for your amp. consider the basic formula:

What this boils down to is 40 parallel resistors at 160 ohms each would be a 4 ohm load. A pair of 220 ohm resistors in each side of a headphone jack would get you the right isolation, and 40 of 'em in parallel would be well within a normal amplifier's output impedance. (No, I can't do the math in my head exactly, so you might want to double-check me

).

EK Sound · Post by **EK Sound** » Mon Aug 18, 2008 12:12 am

Hi Roddy,

http://aviom.com/Applications-1/Monitor-Mixing.cfm

The above link is an example of a really good expandable system that connects via standard unsheilded CAT5e cable. There are other systems from Furman and Hear Technologies that also work well. You could take your 8 Aux sends and feed them to 8 channels of the Aviom AN-16i, then use direct outs of specific channels on the SOLO to feed the last 8. The mixers can then be scattered about and linked with the CAT5. Looks expensive at first, untill you start adding up power amps, multi-core cable, splitters, etc etc etc.

Dave.

roddymacaudio wrote:Hi Ro,

Thanks for the reply - i don't suppose you have any links to some of the gear you were talking about?

The most i can find is stereo in to 8 out. I need 8 in to 40 out if i can get it, and if possible on a tough connector like an EDAC or something similar.

If the BBC can do it when they are recording orchestras etc it must be possible...

If anyone out there can advise me on the theory of the splitting process - i can possibly get something custom made here in Scotland that will do the job...

Cheers.

Roddy.

Post by **Aaronw** » Sat Sep 20, 2008 12:32 pm

I remember getting a demonstration on one of these a couple years ago from the sales rep when they came out. Looked like a pretty descent system and flexible.

My friend Brian is using the Furman one that uses cat5. His only complaint, is enough volume for some drummers. Other than that, he loves it. I helped wire it up. Just uses 2 cat5 cables for each unit.

dvdhawk · Post by **dvdhawk** » Wed Sep 24, 2008 12:26 am

I put a 16 x 18 Aviom system in at our church and I'm absolutely sold on putting a similar system in the studio building for which we just broke ground. Not only do the musicians have a headphone feed, but they have a personalized headphone mixer at their fingertips. Live I don't have to try to get 18 musicans to compromise on 2-3 wedge mixes anymore. Now each musician gets exactly the mix and volume they prefer in their ears. In the studio I expect it will save me quite a bit of the time spent tweaking their headphone mixes prior to tracking. It's simple enough to operate that, if they have any sense at all, a 45 second crash course before you start should be all they need. Yes, I know that's a big "if"

. And hopefully that's the last time you'll ever hear - "can I get a little more of me in the phones?"

As EK mentioned, at first glance it looks pricey, but when you consider how cheap unshielded Cat5 cable is, and all the things you won't need to buy, it will start to balance out the cost pretty quickly compared to starting from scratch. There's no expensive multipins or multipair cables. All you need is a mixer with sufficient Direct Outs, Subgroup Outs, Matrix Outs, or Aux Outs (which hopefully your exisiting console has) and the right Aviom front-end device. There's an XLR version and a TRS version. Then all you need is a handful of basic balanced patch cables and you're done. And there's no law that says one of the remote mixer units couldn't drive multiple headphones if properly split. (assuming all those connected would be happy with sharing that same mix).

We're using a 16 x 18 system at church, but they say there's theoretically no limit to the number of mixers you can use. Their specs claim less than a millisecond of latency through 500ft. of Cat5. They make a couple nice (but rather expensive) A-net distro hubs, or you can daisy chain the mixers together one to the next. I used 2 of their 8-way distros for the "power the mixer through the Cat5" convenience and less cable clutter on-stage.

Best of luck