Recording acoustic guitar redux.

October 4, 2010 8:31 PM

I've just been trying to record some acoustic guitar using a crossed coincident pair of condensers. Overall the sound is really good, and better than the (already good) results I got with the B1. But I have a couple of questions.

1. What's a good distance for the pair from the guitar? I'm in the 12-18" range at the moment. Closer and I get a lot of boom, farther and it's a bit distant. Is that the ballpark?

2. Where should the pair be in relation to the soundhole. Basically if you drew a line perpendicular from the guitar, mine are right opposite the soundhole, mostly because that way one mic is pointing at the neck and the other just behind the bridge. Again, is that basically the right idea?

3. The tricky question. How on earth do I record to a click without the spill of the click from the phones spilling into the mics? When I've done this before it's been to drums or something similar, but in this case I need to play to a click and a click alone. But my AKG 240s cans spill way too much of the click, and if I don't use the click, my timing is all over the place. Any tips or tricks?

4. I tried a different method, miking the neck and soundboard separately with the mics about 27" apart and 6" from the instrument. This resulted in a big stereo separation but the L and R channels seemed very disconnected. Is there any trick for making them less so?

Thanks in advance.
posted by unSane (9 comments total) 1 user marked this as a favorite

1. If your mic or preamp has a bass roll-off, try using it to minimize the boom. The distance you described sounds about right. When you pull them off of the guitar and they sound distant, what you are probably hearing are the secondary reflections coming in from the room. Try hanging a large heavy blanket over a horizontal mic boom and placing it behind the mics to minimize this echo. The reflexion filter that I recommended in a previous thread is good for this as well.

2. This is different for every guitar but as a rule of thumb, I point one where the neck joins the body and then maybe move it a bit towards the sound hole. I point the other starting towards the space between the sound hole and bridge and move it towards the large end of the guitar. Sometimes it sounds good when the mic is pointed between the bridge and the large end of the body with the connector end of the mic bending away from the guitar at a 45°-ish angle.

3. AKG 240s are semi-open headphones and are kinda known for bleeding into the mics. Try looking for specifically closed headphones. I have the Sennheiser EH 150 and they work with very little bleed through. Other than that, try experimenting with a different sound for the click that you don't necessarily need to crank up in order to hear.

4. The rule of thumb is to generally have your mics the same distance away from the sound source in order to minimize phase problems. With acoustic instruments this is a bit easier said than done because the entire body of the instrument resonates differently at different places. Use the 3:1 rule to find the best sounding set up and tweak to taste. Because the mics are in different positions, they are just going to pick up different parts of the sounds, period. This can be minimized by using the 3:1 rule, but one trick to use during mixing to help achieve a unified sound is to compress the loudest or most dynamic signal and then compress the other as well but to use compressor's side-chain input and feed it the signal of the louder track. That way they are compressed the same amount with the same settings. Or use a stereo compressor which pretty much achieves the same effect. Another tip is to actually not pan them hard left and right but maybe one at 1 o'clock and the other at 3 or 4. Experiment to find out what works.

If you have a buddy that plays well, have him or her play while you wear headphones and experiment with different mic positions. That way you don't have to concentrate on the playing. If you have more than one guitar, try it with all of them so you can find the sweet spots on each instrument. If you have a mic with multiple pick up patterns, try them out and see what happens.

Another strange effect you can achieve by using the phasing to your advantage is to put one mic on the guitar and hang another with the cable over a mic stand like a pendulum. While you are recording, have someone else lightly push on the cable near the boom so that the mic swings towards and away from the guitar. Voila! Instant phaser. This works with any sound source but sounds really cool on guitar amps for solos.
posted by chillmost at 10:58 AM on October 5, 2010

Also, pursuant to point 4: When mixing the 2 signals, try rolling off more bass on the signal that has a brighter tone, generally the one that was pointed at the neck.
posted by chillmost at 11:00 AM on October 5, 2010

Thanks, Chillmost. That is all most helpful. I found a good balance point between boominess and distance in the end, and switched to an old and very cheap pair of AKG K55 phones which are fully closed and killed the click spill completely. (Incidentally, although they feel like complete crap, the K55s actually sound really good, way better than I expected). The 240s fooled me because they look closed but aren't.

I fiddled around but in the end stuck with the crossed pair set-up. It sounds really, really good. The other set-up I described has a massive stereo spread but the two sides sound so different both in terms of frequency and, I guess, phase, that it's quite strange to listen to. The mics are at the same distance from the instrument so the fundamental phase is probably the same but the higher harmonics are all in and out of phase and it almost sounds like two guitars playing in two different rooms. It could work really well in a mix but exposed it sounds weird.
posted by unSane at 6:21 PM on October 5, 2010

For what it's worth, unless it's almost a solo guitar performance, I wouldn't record in stereo. Just a single LDC 2 or 3 feet away, aimed roughly where the neck hits the body, sometimes a touch toward the soundhole. (Although I do use the XY setup when I want a stereo guitar, a little closer, aimed at the same spot; that is, the invisible line between the mics pointed there.)
posted by uncleozzy at 6:55 AM on October 6, 2010

It's a song which has a big jangly acoustic part which is basically solo in a couple of verses. I wanted it to be really full but didn't want to muddy it up by double tracking it or using chorus. I think the stereo works really well for it, actually - surprised me.
posted by unSane at 9:49 AM on October 6, 2010

You are using the coincident mic technique, no? It is designed to avoid phase cancellation by the mics being right next to one another. Make sure they are very close together and have them close to your source. I'd lower the trim on the channels. I'd put them facing where uncleozzy suggests, where the neck joins the body. I usually do it only six or so inches from the body. But it is ok to put them close together. With the "XY" or "Coincident" technique, you are going to put them much closer together than you usually would.

I'd google coincident mic technique.

I can check some of my sources when I return home tomorrow.
posted by Ironmouth at 11:02 PM on October 11, 2010

It just occured to me that one could use in earbud style headphones walkman / ipod style phoens to avoid spill with Click tracks - has anyone ever tried that?
posted by mary8nne at 5:48 AM on October 12, 2010

I'm stuck using in ear headphones at the moment and there is definitely some spillover. It's not noticeable on the finished track but it depends on how sparse your songs are.
posted by minifigs at 10:07 AM on October 12, 2010

Update: I stuck with the XY/ crossed coincident pair method and used a pair of closed cans. It was hard not to get a good sound with this! I had the mics about 12-18 inches away from the guitar with one pointing at the bridge more or less and the other at the fretboard. The positioning was not critical and the two resulting tracks gave a lot of tonal options. Here's the track... the acoustic guitar is panned slightly but still very much in stereo.
posted by unSane at 8:41 PM on October 26, 2010

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