Direct Audio Capture options?

September 20, 2007 9:07 AM

I need to ensure that I can record, via line-in or other direct method, audio at conferences...how?

I'm going to be recording audio for podcast at a number of upcoming conferences, and would like to get past the "microphone in the room" method and move to directly capturing the sound from the mic that the speaker is using.

In the past, I've used a Blue Snowball USB mic connected to my Macbook to capture the audio. It does a good job, but nothing beats direct capture for clarity. The problem is that I have no way of predicting what sort of setup the conference rooms will have...they will almost always be in hotels, and I'm assuming that most will use microphones on a podium that feed into speakers set up around the room.

Should I assume that most of these microphones are XLR mics, and that they are feeding directly into powered speakers? If so, can I use some cables to go:

mic cord>recorder in > recorder out > speakers?

Or do I need a mini-mixer to do that?

Current tools available: macbook, mini-mixer. Will probably need to buy cables/adapters...what sort? Will it significantly hurt my signal if I use adapters to go from 1/4 inch mono jacks to stereo miniplug? The reverse? What about XLR to 1/4 inch?

I'm a technical guy, but this audio stuff is driving me nuts.

Help me, oh audio gurus of mefi!

posted by griffey to media & arts (6 comments total)

In a setup like you describe, the signal from the mic is probably going to be going into a mixer/amp of some sort that powers the speakers. It would be very unusual if this powered mixer didn't have a monitor out or aux line out that you could grab the audio from. In this case all you'd need is some standard connectors and adapters (1/4" mono to 1/8" mono, 2 x 1/4" mono to 1/8" stereo, 1/8" stereo to 1/8" stereo, etc.) to plug in and record direct.

Will it significantly hurt my signal if I use adapters to go from 1/4 inch mono jacks to stereo miniplug? The reverse?

No, but it's possible you could end up with just sound on the left channel, for instance, and something like that can be easily fixed on the computer later.

What about XLR to 1/4 inch?

This can be a little trickier, as there are hi-z and lo-z xlr connections. I think it's unlikely, though, that you'd need to convert betweent the two.
posted by erikgrande at 9:23 AM on September 20, 2007

if you want to go the more professional route so that you don't have to worry about what the venue has you're going to want to split the signal between the mic and the pa. there are several different levels from something similar to a y-cable for headphones (not so hot an idea) to mic splitter boxes that are transparent for the venue and isolated you from their equipment for a clean mic signal. you can see a bunch at musician's friend

getting it into your mac is an entirely different issue, your blow snowball combined a mic, preamp and d/a conversion all into one device to avoid the ugliness of using the preamp and d/a chip that your mac has onboard. you'll probably want to get at least some sort of external audio interface with a preamp. a bunch more at musician's friend
posted by noloveforned at 9:28 AM on September 20, 2007

to save money on the second bit, if your mini-mixer has xlr inputs, i'd use that as a pre-amp and send that to the line-in on your mac. not the best quality but should work.

you also might consider keeping a room mic going, especially if there's any q/a portion. use your mini-mixer to pan one all the way to the left and the other all the way to the right and you can then mix them together after the facy.
posted by noloveforned at 9:50 AM on September 20, 2007

er, fact.
posted by noloveforned at 9:50 AM on September 20, 2007

I don't think you can make any assumptions about how these places are wired - there's a million different audio companies out there wiring up convention rooms, and I've seen everything from a mic right into powered speakers to a super-overkill system with touchscreens and 16 input boards.

That said, you definitely can use a mic-splitter to go between the output of the mic and wherever the mic cable goes, assuming that it isn't hard-wired. And that they're not using a wireless lavaliere, with a receiver you can't get to. And that there's not some union guy/facilities guy there that will get angry at you for unplugging the cable and putting your own equipment into his signal chain. This would be a legitimate problem in a place like Pittsburgh, where EVERYTHING is union.

So, if you can get to the audio, and there's nobody breathing down your neck, I'd set it up as the following -

1. Mono mic splitter between inserted in the signal chain.

2. I'd avoid a mixer completely and just use a USB audio input device, and use Peak to record. Or hell, there's some even cheaper audio recording programs that are more reliable than Audacity.

3. That'd cover most of it, but you can definitely try the room mic + panning hard left/right. I personally think that'd end up being futile - the reason you're doing this is because you don't like the sound of the room mic.
posted by god hates math at 10:21 AM on September 20, 2007

Organisers usually have a long list of requests that they agree with the venue (whether it's just number of seats, or more complex arrangements about lights, mics, lecterns and so on). Have you thought of asking them to include an audio feed in their list?

That's what I do whenever anyone asks me to do this. It's just too risky to think that I can guarantee a recording without knowing the details of the system otherwise. Besides which, the person who deals with the system regularly will know more about it than you.

I usually do this, ring the venue to speak to the tech person a few days beforehand, and then turn up with an iPod video with belkin recording adapter (48khz recording, much less hassle/room for picking up internal interference than my PC laptop).
posted by unless I'm very much mistaken at 2:17 AM on September 21, 2007