Best way of expanding number of XLR inputs?
 

Hello everyone,
Now that Pro Tools 7.4.2 is out, I'll be purchasing a 003 Factory Rackmount within the next few weeks. Everything about the 003 looks great, the only thing I need is more XLR inputs. What is the best way to add more? Ideally I'd like to expand to 12-16 total, including the 4 that are already on the 003. I've heard one way to do this is to buy a preamp and connect it to the 003 with ADAT lightpipe. Is this the usual route? What do you suggest?

Re: Best way of expanding number of XLR inputs?
 

Yep, that's the usual route. Check out Presonus Digimax, Focusrite Octopre, M-Audio Octane, Behringer AD8000 (if you're on a budget).

By the by, "XLR inputs" can be mic level or line level. To accept a micprophone signal, a microphone "preamp" (which is essentially a microphone amplifier) has a mic level input. The preamp then performs the amplification necessary to make a microphone's signal strong enough to record, and outputs the signal as line level.

XLR cables are typically balanced, meaning that the cable is actually 3 cables in one: a positive, negative, and ground. The positive and negative cables are wrapped around each other, and the ground cable surrounds (shields) the two. This is why there are 3 pins on an XLR connector.

The positive and negative cables actually carry identical signals, except that they are 180 degrees out of phase. In this way, any noise in the positive cable is cancelled by the out-of-phase noise in the negative cable.

Usually, 1/4 inch (TRS) inputs are line level, but TRS cables can be balance or unbalanced (the cable only carries positive and ground). Unbalanced cables are fine for short distances, but over long runs the signal can degrade and is susceptible to noise and interference. 15 feet is usually the maximum.

Re: Best way of expanding number of XLR inputs?
 

Also, check out the new Presonus D8 as it is less money than Digimax. The big diffeence is the D8 is lightpipe out ONLY so it will not work as a firewire interface directly to the computer for non-protools stuff. It is perfect for expanding the 003 and SHOULD sound better than the Behringer ADA8000. TRS cables are balanced. Unbalanced quarter inch (i.e. GUITAR CABLES) are unbalanced. Balanced TRS cables have the same noise characteristics as balanced mic cables using XLR connectors. The noise cancelling function is usually referred to as CCMR or common mode rejection. If you plug a guitar cable into a TRS jack, you will defeat the balanced feature but it usually works fine as long as cable length is kept under 18'.(shorter the better)

Re: Best way of expanding number of XLR inputs?
 

Awesome! Thanks so much!

Is there a difference in sound between the 8 XLR inputs on the preamp and the 4 on the 003? Will the quality match or will it be noticeably worse?

Re: Best way of expanding number of XLR inputs?
 

the studio at our school has a digidesign 002, and when we need more mic inputs, we use an M-audio octane preamp with optical connection to the 002. I can tell you that the Octane sounds very good, in fact the pre's in the Octane are better than the 002's.We almost always run vocal mics into the Octane because it has less noise,is more transparent, and what coloration it does add is desirable. Also, the AKG 414s and our Neumann mic are just about always run through the Octane, and it sounds fantastic recording acoustic instruments like piano or violin. I have not had the pleasure of using an 003, but I think you woulld be happy using an 003 with an Octane, based on my experience with the 002.Hope that helps.

Re: Best way of expanding number of XLR inputs?
 

I'm using a Presonus Digimax FS - sounds great, sets up easy, perfect!

Re: Best way of expanding number of XLR inputs?
 

I found the preamps in the Audient 008 to be far cleaner than any of the Presonus stuff. Just get the ADAT/Lightpipe version and you've instantly added 8 high quality XLR mic pres.