D.I. Box

Uncle Neil

I've got a question about DI boxes. I'm playing my first solo show in a couple weeks and I'm trying to get my equipment in line (I've previously only ever played at open mic nights). Do I need a DI box for my acoustic or can I just plug straight into the mixer? I'm also planning on miking my amp for my electric guitar... I just run the mic straight to the mixer as well, correct?

Any help would be greatly appreciated, I just want to make sure I get this right!

mccreadyisgod

I'd recommend using a DI box to get the input impedance correct, but it won't blow anything up or sound glaringly wrong if you don't. If the mixer has 1/4" line inputs, then you can just plug straight in. The only problem would be if the mixer is more than 10 feet from where you're playing, as a 1/4" instrument cable can't pass signal more than 15'-20' before signal degradation (and you need room to move around a little). If the mixer is at the back of the room, you'll need a DI.

As for mic'ing an amp, yes, you run the mic from in front of the amp's speaker into the mixer. If at all possible, make sure the mic points into the speaker, rather than just draping it on the front of the amp. There are a couple mics designed to drape (Sennheiser MD 409, e609, e906) but most are designed to point into the source (Shure SM 57 et al). So having a short mic stand would be great, if possible.

Are you providing and running the PA for your own show, or does the venue have a sound system and a sound guy?

Uncle Neil

Thanks for the info. It's my own PA and I'm setting it up myself. I'm going to try to enlist the help of one of my buddies who is an audio technician. I 95% know what I'm doing, I just want his expertise to help out, especially if there are any problems. I've got a Shure SM57 for miking my amp, and yes I have a small stand for it as well. I believe the best place to position it is 4" to the side of the center of the woofer in the amp, and about 6" from the grill (those figures come from memory, I'll look it up again before I actually do it).

Does the presence of a DI correct any signal degredation in the guitar cable? If I run my line into a DI, and then there's 30' from the DI to the mixer, is that a problem, or does the DI keep the signal strong? I don't think it will be a problem in this application, because the mixer is likely to be about 10' from me, I'm just curious.

Thanks again.

mccreadyisgod

RE: mic position on an amp... there are a lot of different techniques for mic'ing a guitar amp, so I'm not going to say anything is absolute. But I can tell you that, for a live show, putting the mic pretty much right against the grill pointing into the speaker is the best method. I usually place the mic off-center, about halfway between the center of the cone and the edge of the cone, pointed slightly toward center. But play around with it. For recording, you might pull back a little bit, but live, you want to put the mic right up there.

As for the DI and cable length, if you use a DI then you shouldn't have any problems. The DI takes your 1/4" Hi-Z unbalanced cable from your guitar and converts it into an XLR Lo-Z balanced cable. A balanced signal with low impedance (lo-z) can travel for about a quarter-mile before losing signal strength, so you're good (the term "XLR" stands for Xtra-Long-Run). So, as long as the cables and DI are working, then you're in business.