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Sound level meter usage

abarson

abarson

Nov 6, 2003
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Santa Cruz
#1
A local band I recently saw did their sound check, and part of it was using a sound level meter for each amplified instrument. I have to admit that their overall sound was very balanced, with no-one drowning out everyone else. Seemed like a good method.

1. Are there any guidelines to this method?
2. Do you use a different target dB level, depending on the venue and crowd?
3. Are the Radio Shack meters good enough, or is there something else (affordable) that will do the job?
 
#3
SPL and dB meters do a lot of the guess work, but tone and eq effects how the mix sits. As a tool to know you have an even playing field is a good place to start, but knowing where and what to add is what makes a good soundman great.

Use your ears on the volume of space. Distortion is mainly what you are listening for, shooting for max headroom (not pushing the PA to its limits, and having room to turn up). If you do not have the speakers to push the air, eq and more power is a poor way to overcome that. To directly answer your question the meter will tell you once you have bodies in the room how much sound is being absorbed and the difference of volume(cubic air space) in the venue for a listener to be comfortable with the volume (dB) with the band playing.
 
#4
Haven't used one of those meters in a long time. Generally, my current band listens and mixes to itself very well. However, I was not always so fortunate. One band I was in employed a db meter, and the singer/songwriter/guitarist--who cranked a Fender Twin louder than anyone should EVER be permitted to--nick named the device...

The Accuser!

I still get a chuckle out of that after all these years...
 
#5
I don't think (IMO) that there's any need to use a meter to balance instrument in a mix - frequency has more of an influence than volume in a mix. Your ears will tell you if a mix sounds right or if the mix is too loud.

That said, I have started using an RTA app on my ipad to identify room nodes. Paired with a decent parametric eq in my Zoom MS-60b and a 31 band eq on the PA, this works wonders for honing in on low frequency feedback/rumble and taming rogue boomy notes. If you've ever had one note leap out of your bass amp at certain problematic venues, you'll know exactly what I mean.
 
#6
Also frequencies are heard differently by the human ears - check out Fletcher-Munson curves - so the same sound pressure does not equate the same perceived loudness. Human ears more sensitive to mid-range than low freq.
 
#7
It may have nothing to do with the actual loudness - it may be that have determined a specific level that works, and are setting to that level.

Also - most instruments fall well within the middle range of the Fletcher-Munson curves and will be weighed roughly equally.
 
#8
Hapa,
I get your comments, but maybe I needed to add a bit more detail. This was in a bar situation where the only sources going to the PA are the vocal mics. All the rest of the band's sound is emmanating from the onstage amps. No DI, and no micing of amps. There's not much for a soundman to do in this situation (or is that an erroneous assumption?).

ga_edwards,
Good point about the RTA app. Thanks!
 
#9
ahhh, I see.

In that situation, a meter is more a sign of not knowing what you are doing... I mean that like someone using a cnc machine to make fence posts. Not wrong but not right.

In that situation ideally the amps would be as close to each other as possible. The PA adjusted at sound check then again with a full house. It has already been said but tone and eq of the amps will play a lot more with the room than reading spl/ dB. (flame on) tube amps create tone that is perceived by the human ear as deeper/thicker...read up on even and odd order harmonics ;) that being said a 50w guitar tube amp may read 95dB but be sonicly blasting everyone in the face next to a bass guitar amp at 98dB.

Then the natural acoustics of the room: Positive and negative harmonic distortion, phasing issue, resonance(s), the stage it self, distance behind the speakers in relation in front, room shape, the walls: type of surface, diffusion, absorption. etc. this is what acousticians train engineers to be aware of. Most guys just use their ears and over time figure out the most effective way to overcome obstacles.
 
#13
Dang right. that is too darn loud.

BTW The apps for iPhone, etc. are VERY accurate. I compare mine to some very expensive lab gear all the time as I do acoustic consulting. They are usually within +/- 1 dB. The manufacturing tolerances of the tiny condenser mics used in good phones are amazingly tight! I use several iOS apps for sound and noise measurement, and can tell you that iPhone measurements will stand up in court if they are done properly.
 
#14
Hi.

If You didn't see a constant measurement fixture in use, I have a hunch that using the meter had nothing to do with the balance or balancing of the instruments, but was done to keep the SPL of each amp/cab below a certain level.

Whether that level was set by the band members, by the bar owner, or by someone else, that's obviously not known.

Mis-using a spl-meter either accidently or intentionally can probably be only rivaled by mis-using heat imaging camera.
Or airborne particle counter.
Or micro-manometer.
Or...

All accurate enough, yet measurement method dependent instruments can be used to serve the goals of the one holding the meter. Or the party responsible of paying for the measurement ;).

I know, I do that kinds of measurements for living :).

Regards
Sam
 

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