1/8" (Macbook Pro) to Mixer (1/4" or XLR?)

[IamDeeBee]

Hi all,
I'm primarily a stage manager, but I do my best to be hands on, understand the equipment I'm working with and ask lots of questions. So I apologize in advance if I miss some basics or don't give enough info at first.

I'm currently working on a small show that is going to be touring regionally, and there isn't an audio engineer, so I've taken over (maybe over ambitiously so).

There isn't much in terms of sound (15 cues), but the sound is there. Were going to be using a Macbook Pro and running qlab (there are also projections which will be running from qlab as well).

I've been looking though old threads as best I can to get info on how to go from the computer to the boards at the various venues we're going to (they all have varrying levels of equipment). As helpful as reading some of the threads has been, I am unsure about the necessity of a DI?

From what I've read they seem
- to protect from power surges from phantom power that would come from the board and blow the soundcard or computer
- reduce interference that may be in the lines
- Convert lime level to mic level (This is still new territory for me, will be researching more later)
- offer a variety of connection into the boards (1/4" , XLR, RCA)

With all of that covered, if I'm running a short length from the computer to the board (Let's say 6 feet, maybe even 3 if it will make a world of difference) and I make sure phantom power is off on the board, then do I need a DI, or can I just get a 1/8" to 1/4" or 1/8" to XLR (Single or dual?) adapter and get by?

Thanks in advance

 

[josh88]

We've got one of these little guys because somebody picked one up at one point. ITs pretty handy for anything with an 1/8th out and given a long length of cable could be run almost anywhere.

http://www.musiciansfriend.com/pro-audio/rapco-horizon-ltiglblox-laptop-interface


Via tapatalk

 

[themuzicman]

Carrying both an 1/8" to 2x XLR and an 1/8" to 2x 1/4" TS is a good first step. I'd recommend a DI in line such as a Whirlwind PCDI or a Radial JPC just for safety because the bigger issue you will encounter is noise entering your system via your power cable with a PC. This can change theatre to theatre based on the power situation. You may never need it, but that one time you play your sounds and you hear noise you'll wish you had it.

You'll want 2x XLR if you want two QLab outputs (or stereo sends).

On your "mic level vs line level" point - to dumb it down, mic level is the level at which audio comes out of a microphone, and line level is the level at which audio comes out of a preamp or console. Mic level is usually around -60dBV - when measured it is in millivolts. Line Level is +4dBu and can be measured as a single digit voltage (1-3V). After this is speaker level which can be quite a high voltage, but is not part of the scope of your question. More than just convert the voltage of the signal, a DI box will convert the high-impedance of an unbalanced line level signal to a low impedance balanced mic level signal. The balanced versus unbalanced comes into play with the second point in your bullet point list of interference.

The final point you may list is entirely dependent on the DI box you get. More often then not a DI box won't output RCA - as that is usually going to be a line level unbalanced connector (by nature an RCA plug is unbalanced). Some (the PCDI and the JPC are the only two that readily come to mind) have RCA inputs however. More often than not you will see a standard 1/4" input and XLR output. Sometimes it'll have an XLR input too.

 

[Footer]

Just buy the PCDI (or one of the variants) and be done with it. First, you never know where they are going to set you up onstage or FOH. Second, you never know what your going to be interfacing with. A PCDI will work every time, no question. You don't have to worry about a house engineer doing something wrong OR running into a console with global phantom power. You also have to consider that many of the newer (and some older) digital desks don't have any unbalanced (1/4" or RCA) inputs. A PCDI and a 6' 3.5mm to 3.5mm cable is 135 bucks. Just do it and you won't have to worry about it.

 

[IamDeeBee]

Thank you everyone for the input!

Given the fact that we're going to be bouncing around to different venues, and you guys are right that we'll never be entirely sure of what we're walking into (the concept of a console of global phantom power hadn't even crossed my mind), I'm going to go for a DI. I'll likely go with the whirlwind so that we have the option of multiple connectors.

Thanks again everyone!

 

[avare]

I use a Peavey USB interface as first choice. It provides better sound than the internal DAs in computers. Second I use a Radial PCDI.

 

[65535]

I've personally used Presonus FireStudio and FireStudio Project, Focusrite Saffire Pro24, Motu Ultralite MK3, and HRT Music Streamer HD computer audio interfaces.

They all work fairly similarly, the Motu is probably the worst to deal with if you're new to the audio interface game as it's output routing doesn't include DAW outputs on it's software mixer where all the other devices have DAW outputs available to patch to outputs.

The Motu and the HRT just takes channels and output them in numerical order.

 

[TimmyP1955]

Best not to go directly from the 1/8" to the XLRs. If someone turns on the phantom power, the sound card on your MacBook might well be toast.

 

[65535]

This is the most basic device I could recommend for the job.
http://www.radialeng.com/r2011/jpc.php

Some cheaper PC-DI boxes just bind the two channels to a mono output which usually you want to avoid.

 

[avare]

This is the most basic device I could recommend for the job.
http://www.radialeng.com/r2011/jpc.php

Some cheaper PC-DI boxes just bind the two channels to a mono output which usually you want to avoid.

I found out that I can not edit my precious reply. The Radial JPC is the unit I was referring to in my previous post in this thread.