Posts Tagged 'guitar'

Mic’ing Guitar Amps

First, identify the location of the speakers in the cabinet. Don’t assume that the speaker location is symmetrical (some are, some aren’t.) You may have to look inside the back of the cabinet if you can’t see through the front grillcloth.

You may need to look at the back of the cabinet or shine a flashlight through the grillcloth to locate the position of the drivers inside the cabinet.

Next, aim for the center of the paper cone, and about 1-2” from the grillcloth. This is the general starting place for all setups. Adjustments will be made from this baseline, based on the sound desired and/or to fix problems.

WHICH MIC? There are quite a few choices these days. The baseline microphone for guitar amps is the Shure SM57. It will almost always work.

Shure SM-57

Working from the 57 as a baseline, there are some other choices such as the Beta 57, Audix i5, and the Sennheiser e609. The Audix i5 has a more pronounced proximity effect, which might give you more low end if close-mic’d. The Sennheiser e609 goes the other way, offering a less pronounced proximity effect if the amp is pretty bass-heavy already. Beyond that, you have the more exotic and expensive choices of large diaphragm condensers and ribbon mics.

New options: The Shure Beta 57, Audix i5, and Sennheiser e609.

TONE TIPS: There are two ways to get more low frequency response. (1) move the microphone closer to the grillcloth and take advantage of proximity effect, or (2) move the microphone more to the outside of the paper cone area. These tips also work in reverse for more brightness. You can also try angling the mic to see if the off-axis response might work to your favor. It’s always better to try moving the mic rather than reaching for EQ though. Moving the mic a couple inches might dramatically change the sound, and still leave you some EQ options.

A pedalboard help's today's guitarists achieve a wide variety of sounds.

PHILOSOPHY: We always start from the assumption that the musician knows their gear, knows what sound they are trying to achieve, and has adjusted their pedals, tone knobs, and gain structure to produce the sound they want. So the primary goal here is to faithfully reproduce the sound that is coming out of the amplifier. Match tone first. Then improve if it needs it. Don’t just hang out in the booth during rehearsal. See what it sounds like coming out of the amp so you know what it should sound like coming out of the house.

WHAT IF THE TONE STILL STINKS? Sometimes, especially with newer players who do not know their gear very well, you have the situation where the sound coming out of the amp is just not good. If, regardless of mic choice, mic placement, and tone adjustments in the booth, the electric guitar sound is still unusable in your opinion, then it is time to talk to the stage. The first thing to do is to confer with the Music Director, Road Mgr, or Band Leader. DO NOT APPROACH THE MUSICIAN DIRECTLY UNLESS YOU HAVE A GOOD PERSONAL FRIENDSHIP WITH THEM. Calmly explain the problem. Let the Music Director, Band Leader, or Road Manager make the call.

WHAT ABOUT VOLUME? If the stage volume is out of control, the first thing to determine with a player’s rig is if they are using the speaker cabinet as a monitor or as a tone-generator. For example, if they use a Line 6 Pod or other tone modeling device to achieve their sound, then the amp could just be used as a simple monitor, and lowering the volume will make everyone happy. However, if they are using the tubes in the amp to achieve the desired tone, then it may be a tough sell asking them to lower the volume. If that’s the situation, then you have to look at (1) changing the direction of the amp, (2) changing the location of the amp, (3) changing to a smaller amp, (4) utilizing one of the many “power attenuator” type devices on the market (such as the THD Hot Plate) to lower the cabinet volume, or (5) building an iso-box for the amp.

A look inside an iso box at Buckhead Church.

BONUS: How to build a isolation box to eliminate stage volume. (source: Buckhead Church’s production people.)


My “Bass Player’s Compression Dilemma”

I am a bass player. I play a passive bass (one where the pickups do not require a battery inside the guitar). I love the tone of them – I love the low maintenance aspect of not having to wonder if I accidentally left the guitar plugged in and my battery might be drained.

But I’m not a rich man. I do not own a Lakland, or other high-end bass. My 5-string Yamaha cost me about $450 new several years ago. As such, the low B-string is a little “flabby” sounding – it doesn’t have a real strong fundamental tone down there. In order to correct that issue, I’ve been able to use compression. Compression is generally needed on all bass guitars because the volume tends to jump up and down a lot depending on the note, the fret position and the pickup selection. But with a rather inexpensive 5-string bass with a flabby B string, good compression is an absolutely CRITICAL part of my signal chain. [Here’s a quick video of my playing with the bass so you can hear what it sounds like with compression on the front end]

But now comes the dilemma – part 1: Do I totally depend on the sound guy of whatever venue I’m playing to instinctively know I have Flabby B Syndrome and assume he has the gear and knowledge to fix it? I’m not a fan of that option. How do I know he isn’t using too much or too little compression and completely desroying my dynamic control? No – I’d much rather have control of the compression on stage with me so I can set it correctly, monitor what it is doing, and can actually hear the results live.

Now for the dilemma – part 2: 99% of all stomp-box type compressors STINK for bass. They are noisy. They pump and breathe (an audible, non-pleasing compression side effect). How about the other 1% of them that are decent? They’re EXPENSIVE! Like $185 expensive. No thank you. If I’m going to pay that much for a compressor, then it had better be recording studio grade, baby. Come to think of it – that’s what I’m really looking for anyway – a studio-grade compressor for my bass rig.

So here comes dilemma – part 3: Studio-grade compressors are made for Line Level usage. As in +4 dBm (1.23 volts). These compressors want to see that hot of a signal coming into them. But wait! Instruments – especially passive ones – don’t put out even CLOSE to that amount of signal. Another issue is that of pickup loading. If the bass pickups do not sense the correct high-impedance load connected to them, then they will not output at their maximum capability and will lose some frequency response and level. So directly connecting my bass right into a studio-grade compressor is not really a viable option. There would also be the problem of monitoring. How would I connect my amp? The output of the compressor would be line level – and my amp’s input will be expecting instrument level! ARGH!

But here’s where I found the magic answer. An older dbx 163x compressor was EXACTLY what I was looking for. It has some unique features that fit my purpose wonderfully. First, it has two different inputs – a front and a rear. The rear input is line level and works like most high quality compressor inputs do. But the front input is High Impedance – SPECIFICALLY MADE for instrument level. The unit actually has a little preamp built into this input, so it even loads my pickups correctly! As for output, it has a very easy to adjust output level – so I can send out instrument level to an amp or direct box!

They don’t make these any more, but you can still find them on eBay and such. I was able to purchase two of them for $80! I now have exactly what I was looking for – studio grade compression with on stage control – and it wasn’t expensive!


Audio Training for Live Sound. All content ©2010 Jeremy Carter Consulting.

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