Beginner SPL meter questions

[Mark B123]

I've been reading about SPL meters and I have some questions that have been hard to answer by searching online. I read this article Crafting Loud Mixes That Sound Great and the part about SPL meters was helpful but I'd like to know

does the meter have to be at a certain place in the room?

With the RadioShack analog model off the market is this the best budget model?
Galaxy Audio CM-130 Check Mate SPL Meter

Do I need one of these to get the most out of a home studio setup and how does using software such as http://www.roomeqwizard.com/ with a condenser mic and an audio interface compare to using a real SPL meter?

I searched for sites with beginner information about this topic but I couldn't find anything that seemed trustworthy.

[Jim Lockhart]

Some short answers:

The SPL usually varies from point to point in a room, so you will probably want to measure it at all locations of interest.

The Galaxy CM-130 is a good unit and likely the best budget model. If you have an iPhone or iPad, you can use the low-cost SPL meter application from Studio Six Digital (www.studiosixdigital.com).

You can use the SPL meter function of Room EQ Wizard, but will need to buy or borrow a calibrated SPL meter to calibrate Room EQ Wizard for your microphone, preamp, output amplifier, and speakers.

It is not necessary to have SPL readings in order to measure your room response with Room EQ Wizard and then use traps, absorbers, and EQ to tune your room.

[Hugh Robjohns]

I read this article Crafting Loud Mixes That Sound Great and the part about SPL meters was helpful but I'd like to know

does the meter have to be at a certain place in the room?

I think Paul was making the point that our sensitivity to high and low frequencies varies (relative to mid frequencies), with the flattest notional response being at an SPL of 83dB...

However, if you try to listen to tracks at an average level of 83dB SPL in a typical small home studio you'll go deaf very quickly. It's a completely unrealistic working level unless you are in a very large control room.

As it happens, I've just written a feature for the mag about setting up calibrated monitor levels, and the use of SPL meters in that process etc, so it might be worth holding fire for a month or two until that gets published as I'm sure it will answer all your questions.

Regarding the SPL meter itself, I'm not a fan of simple meters with digital displays because they are almost impossible to read in any meaningful way. The reason is the audio levels are not static (unless you're using sine wave tones, which I really wouldn't recommend for acoustic testing!) and the digits often scroll around in a very distracting way!

I would recommend an SPL meter with a VU display instead, which allows your eyes to average the movement making it far easier to perceive the nominal level. For simple monitor calibration work, I use a cheap and cheerful meter like THIS FROM AMAZON.COM.

In either case, for this kind of work you need the meter to have a slow averaging mode, and C weighting option.

H

[Martin Walker]

For simple monitor calibration work, I use a cheap and cheerful meter like THIS FROM AMAZON.COM.

Yep, I've got one of those as well, although mine originally came from Tandy - very handy!

Martin

[Hugh Robjohns]

Yep, I've got one of those as well, although mine originally came from Tandy - very handy!

Mine came from a shop at the bottom of Tottenham Court Road in London, because Tandy no longer existed!! But it is available from Amazon on both sides of the Pond, and comparing it with pink noise against a decent Class-II calibrated Sound Level Meter it was remarkably accurate.

H

[Ron Snijders]

This thread should've existed before I bought a cheap Made in China SPL meter! Mine has that digital display Hugh mentioned as being terrible
Ah well, I got it to get a general idea of what the '45dB(A)' a central heating unit produces these days actually sounds like... I'll get a different one when stuff gets more critical

[Skerrick]

just a tip,
i learnt at uni recently (i just started studying a degree in audio engineering, so im still a hectic noob) that 85 db/SPL is the 'perfect' mixing volume,
engineers and such apparently often say that you can mix at this volume for hours without risking hearing damage and ear fatigue, but again, in regards to positioning the db/SPL meter, im really not sure..

we're about to start some coursework thats all about measuring the db/SPL of various objects and sound sources and such, with the main goal to be an introduction to training our ears properly..
im bookmarking this thread as i'll almost definitely have some questions for you regarding some more in depth analysis of the topic, should you guys be willing to help of course

[Hugh Robjohns]

i learnt at uni recently (i just started studying a degree in audio engineering, so im still a hectic noob) that 85 db/SPL is the 'perfect' mixing volume

It's not. That's a gross over-simplification and is only valid in a very specific set of circumstances which makes it completely impractical (and even dangerous) in typical small home project studios.

You university lecturer is probably basing that statement (if that's what he/she really said) on the notion that 85dB SPL is the approximate level at which the Fletcher-Munson curves indicate that the ear's perceived frequency response is most linear. And that's quite a different thing...

...engineers and such apparently often say that you can mix at this volume for hours without risking hearing damage and ear fatigue

In Europe, exposure to a long term average level of 85dB LAeq for 8 hours requires the use of ear plugs! Thankfully, music rarely maintains a steady average level anything like that high... The important point here is that you have to be very careful about the terminology and nomenclature you use. Peaks of 85dB SPL is a very different condition to average levels of 85dB SPL, and different again to exposure of 85dB LAeq... The devil is in the detail and can be the difference between appearing in court or not!

... but again, in regards to positioning the db/SPL meter, im really not sure..

You're talking about the sound level to which the listener is exposed, so the SPL meter goes where the ears would normally be.

we're about to start some coursework thats all about measuring the db/SPL of various objects...

You might want to get in the habit of using a capital B for dB then.

H

[chris...]

However, if you try to listen to tracks at an average level of 83dB SPL in a typical small home studio you'll go deaf very quickly. It's a completely unrealistic working level unless you are in a very large control room.

As I understand it, that's a figure measured at the listening position. So it seems counter-intuitive that the size of control room makes significant difference (given the same level at listening position in small versus large room).

Just wondering if any obvious explanation. I think this has been mentioned before, but I don't remember any clear conclusion being reached.

[Hugh Robjohns]

As I understand it, that's a figure measured at the listening position. So it seems counter-intuitive that the size of control room makes significant difference (given the same level at listening position in small versus large room).

It's to do with the balance of direct and reflected sound, and the way that influences your perception of loudness, rather than the sheer sound pressure level itself.

H

[chris...]

Interesting - thanks.

[Mark B123]

As it happens, I've just written a feature for the mag about setting up calibrated monitor levels, and the use of SPL meters in that process etc, so it might be worth holding fire for a month or two until that gets published as I'm sure it will answer all your questions.

Hey Hugh

Is this the article that you were talking about?
http://www.soundonsound.com/sos/may14/a ... toring.htm

[Hugh Robjohns]

Yep

[Zukan]

Great article Hugh. Shall share it.