Are they really worth the $150 price tag. Im aware that they only read to 130db but would it be useful to work out the loudest frequency and at comps just turn it up to full and you should have you peak spl.

CORRECT ME IF IM WRONG

I was thinking it might be easy to create an SPL meter. If anyone has a schematic, send it over...

I was looking at one of these and decided against it for 2 main reasons
- they only ready a max of 130dB so are only really useful for checking reasnonant frequencies (cause pretty much any SPL car will get above 130dB)
- they are only accurate to +/-3dB which means to succesive readings can be as much as 6dB different even in the same environment (which in my mind makes them pretty much useless).

I tend to agree.. they'd certainly be useful for testing, even if grossly in-accurate. Do some fiddling, play a low volume burp, do some more fiddling, play a low volume burp, compare.

I've been thinking of grabbing one of these just so I can mess about with box positions and see which way hits hardest, but its prolly a waste of money.
Cheaper to head to the nearest audio joint with an accurate meter and book an hour of test time for $20.

don't know where you are getting yours for 150 bucks from, but mine only cost i think 70-80 bucks from tandy's...

i have found my car's resonant freq, by playing a low volume burp (~120db), and this is the same freq it hits at on the real mic. so although it only reads at low volumes, it can still find your car's resonance, it was spot on with mine, and it's only off by +/- 1hz at the most...

ok well i have a friend at jaycar and have tested nearly everyhand held meter and i must say the hand held spl metre was a joke! it wouldnt even read above 110DB even the bloody boot (system was 141db at the time) it was a piece of **** and read my loudest frequency about 10 db away from what was the RF of the car and higest freq on another prob meter. 169 from jaycar dont bother your ears are much beter.

you have to flick the switch to fast reaction and weighting "c"... with weighting "a" my system doesn't even move it much... weighting "c" is accurate for spl burps...

Some of the best meters r hand held, IIRC the B&K can be had in hand held form and one of the hardest meters to hit on. but they do cost a bit

they r alright for freq testing and thats about it. as you want to do all other testing eg playing with ports, boxes, etc as close to full volume as possible.

im using a **** smith one - cost around $130.. was accurate to 1 Hz finding my RF, and i think its a pretty good investment for simple testing. obviously it isnt a substitute for proper testing, but its a good alternative!

another question regarding SPL measurement:

do you guys measure it in relation to the sensitivity of the human ear (less sensitive to bass/treble), or just in reference to "silence"

the best *cheap* hand held meter is the **** smith analog meter, it is only $70 or so and it is farily accurate (especially after the frequency response mod..) but of course only reads up to 124/6 dB so if you are hitting above 150dB, the results you get won't be that accurate.. but it is still a useful tool to see what helps and what doesn't help your SPL and get an approximate transfer function reading (at around 120 dB - it will differ a bit at 140-150+)

as rippedskin said, you have to set it on "c" weighting, as "a" weighting rolls off the low frequencys

Androo - the SPL meter part is the cheap bit, getting a mic that is accurate at high SPLs is the expensive bit..