Just grabbed this and used it for calibrating my monitor gains on the back. For any of you who aren't on the ball in that area I would highly recommend doing that!

Works great and displays to a decimal point which is handy. It's got a few other useful tools built in as well. Check it out:


App Store - JL Audio Tools

ps. Anyone with a real SPL meter feel like comparing for accuracy? I think it's good but a confirmation would be a nice bonus.

One notable detail is it will work better on the iphone 4 which has a better mic. The 3g mic is hindered by its roll off some.

Better than nothing but you'd need to upgrade/buy it to get A and C weighting, among other things. Without C weighting you're not really getting a useful audio db analysis tool.

How can you say it's not a useful tool without A or C weighting?

I sat in my mix position last night with a 1k test tone playing thru one speaker, iPhone placed in the speaker port with the display just barely visible to me, and I could see it change .1db when my arms were crossed vs hanging beside me. Like clockwork. That seems accurate enough to me to monitor volume changes. I wouldn't bet money on the readout being a true 75db but when comparing against itself it seems to be a useful reference. I got my monitors matched to .1 db accuracy with it and double checked the measurements.

A weighting is useless for music audio. It appears they made this app for music so its probably c weighting but they should tell you.

The problem is the mic on the iphone. I dont think you will get accurate spl using pink noise as the low end energy will not be measured.

I have not tested this product but I did test a similar product and it was off by about 10 db.

I have a 1356 sound level calibrator and a couple spl meters.

I will say that for quick and dirty usage you can figure out of say both your speakers are constant with each other. So devices from the iphone arent completely useless but I wouldnt completely calibrate my speaker system for actual work with something like this.

you should use pink noise for this.

Calibrate your dac with a 1 khz sine and a multimeter and then calibrate your speakers with pink noise at your reference. -20, -18, -14

My reason for sticking with a 1k on this was because it's a freq the iPhone mic should have no prob measuring plus it's directional. Anything with bass freqs in this case would be a bad idea I think. That would bring room interaction into effect a lot more than a 1k would. I was only after getting the gains on them matched to each other perfectly.

There's another free app by ultimate ears called UE which has choice of A and C weighting but no decimal point in the reading so it's harder to match as closely.

Well now that you have them calibrated regarding balance to each other if you pinker the left speaker only to a certain db and made a note of the monitor level all of ur productions would be essentially mixed at the same level. It may be interesting to see the difference in reading from sine to pink.

Well that was fun. Getting all fancy with the spl meters and figuring out how to most accurately measure them both without room interaction slanting it. Eventually I traced an outline on paper and taped it in place so I could measure each speaker in the identical spot. But you know what? I got them both matched dead on to .1db resolution of the JL audio app and dead on with both A & C weighting of the UE app.

Turns out it matches just as well as my old method of using the peak light on my monitor and a kick drum except that takes me about 30 secs to match dead on without any thought to room interference.

As for calibrating mix levels Jstorm.. I always have my reference. It's the peak light of my VXT 6's

Of course I do lots of stuff checking at all levels but It's part of the benefit of working on those for me as opposed to anything bigger or louder or involving subs. The only way to make them really rock is with a good production and mix. You're not getting help from 8" drivers or subs to compensate.

Anyways.. Both apps showed capability to give accurate reproducible measurement between different levels. I tried adjusting my output volume in 1 db increments and it followed it up and down. There's a setting in the JL though to adjust the calibration baseline so its' reference is true to real db level.

A lot of the apps these days actually give you the capability to calibrate, you need a reliable sound source but you can download a script to generate pink noise or you can do it with a calibrator if you have access to one.