I bought a
sound pressure level meter (SPLM) to measure and correct the frequency response of my dedicated listening room back in the day.
http://www.tnt-audio.com/clinica/spl-meter_e.html
It's a very useful tool that you can use to simply and quickly measure dB readings using two different weighting methods.
If all you are interested in is an objective measurement of your sound pressure level ("loudness" or "volume"), in dB, it's as simple as: point, shoot, and write down the instrument reading for each cabinet.
I use a tripod to position the microphone element at the same distance from the loudspeaker driver, and the same distance from the floor when measuring a bass cabinet (for hi-fi, I position the microphone on axis with the center of each loudspeaker when calculating the relative sensitivity of each driver for comparison purposes). Measurements will be comparable IF you take environmental conditions into account; for example, the measurements wouldn't be comparable if "Cabinet A" were measured while sitting in the corner of a wooden stage, and "Cabinet B" were measured outdoors, sitting on the lawn.
The obsessive among us have been known to measure SPL by frequency, first for the listening room, and then for the bass cabinet. After taking both sets of measurements, you can overlay the two graphs to identify possible environmental explanations for anomolies. (When I was setting up my listening room, my source was the best recording of acoustic piano I could find: if I could make it sound like there was a Bosendorfer grand in my listening room, the fidelity would be perfectly acceptable to me
)
Make note of the gain, tone, and equalization settings on each rig you're testing, and use the same bass (same strings, volume, and tone settings) for each test if you can. I test using at least three different amplifier attenuation settings because frequency balance can shift dramatically as a function of volume.
Be kind to your ears: when you're performing tests with SPL greater than around 80dB, wear hearing protection.
You may be surprised when you graph the decline in
SPL as the distance from the loudspeaker increases; if you test by frequency, you'll notice that the bass frequencies will have different
SPL readings, depending on where you take the measurements.
If you want to go whole hog, like I did when I was setting up my listening room, you can use a graphic equalizer to take
SPL readings at each frequency and plot the results of your bass cabinet and listening room. I use a
pink noise generator to provide a consistent reference for all room measurements (mine is built into my graphic equalizer).
If you find this exercise valuable, you'll probably also find it illuminating take third-octave measurements at different locations throughout a venue and see how significantly directionality increases with frequency, and how standing waves effect perception of bass frequencies.
If nothing else, it can be a fun learning experience; refining your awareness of relative SPL by frequency can be a genuine force multiplier in a bassist's arsenal of useful skills.
Sorry for such a long post.
simpy1 said:
Hey guys - thanks for all the replies.
Well my band doesn't play that loud, we play funk/soul music and usually it's quiet enough not to have to wear earplugs. We don't mic up the drums.
I saw a guy in the weekend playing with my same Trace amp thru a 1x15 at a party, and his volume was on 3. And this was the loudest (unmic'd) band I've ever heard! The bass sound was massive.
Funnily enough the EA sounds WAY louder than the SWR at the same volume level. Also funnily enough my TE is definitely louder than the power amp!
I'm thinking my problem could be that my bass really doesn't put out much low end (also not a very hot signal), so I end up EQ-ing in to compensate. The volume thing shouldn't matter, I just set the input gain to what it should be. The EQ thing I guess will make a big difference. But I don't add any 30 or 60 Hz, only freqs higher than that.
Also as a side note - I had my Trace amp serviced because I remember playing a gig ages ago and my volume on 3/10 was huge. I got asked to turn down (this is thru the Goliath Jr and a 1x15). The servicing did nothing for the volume difference, so maybe I'm just imagining that it's getting quieter!
I have never had any trouble getting the volume I need for any small to medium venues. If the venue is bigger than that, there should be PA support. BTW, I'm only using my TE 215 and a Bright Box. They aren't the most efficient cabs out there and still no volume problems.
