SPL Meter, calibrating two monitors, and subwoofer.

[delirium trigge]

I was about to buy an SPL meter, until I did research on the IOS meters for iPhone/iPad. Most of them got crap reviews from the professionals but there were two that were said were extremely close. Only about 1.5 off. That is acceptable to me. So, I bought the app recommended.

What was not disclosed in the articles I read, was would it help for me to use a high quality mic, such as the Rode i-XY condenser microphone into my iPhone 6 or just use the iPhone 6's microphone?

It seems to be working well, while allowing me to mix at 85db.

However, I still cannot figure out how to calibrate my monitors and sub. I have them sounding extremely good though. I have the monitors running through the sub, then out to the safari pro 40. Although, I hear some people run the monitor our to its own output, rather than plugging the monitors though them. What would be the advance to that?

I have found pink noise on Logic Pro X. The problem with that, is all of the videos show me how to turn the pink noise up to 85db and keep it there for good mixing purposes. That does not help me calibrate at all.

Since I figure my monitors stop at around 80hz, I then turn the cross over on the subwoofer to about 80hz. I do not have any boost going on the monitors as I do not need that on with the sub.

Any information?

 

[rob aylestone]

You seem to be a bit confused about what exactly you are calibrating? Most people cannot detect a 2dB change in level, so all those iPhone gizmos are really just guides. If you want to really do this properly, you need to separate two different processes. I assume you are trying to produce a flat response, to effectively 'remove' the cut or boost your room is applying to the sound at the mix position. To do this, you need an omni directional measurement mic - the Behringer one is rather popular for this, and you would use your studio system to record it's output, playing the pink noise from your monitors Looking at the recorded sound on a visual display will show you peaks and troughs - You will also see where your studio speakers start to fall off, not stop. It will be a steep or gentle roll off in volume. If you then do the same test using just the subs, you will see again a roll off, and you need to adjust the setup so that the two roll offs overlap, hopefully allowing the subs to take over at the appropriate frequency, with no hill or valley. You can drive them via a separate output, if you have one spare - which gives you a boost/cut feature on a fader, but in a studio it's probably best to run them as a chain so the balance tracks together. In a PA, it's nice to be able to push the bottom end on a fader for some songs, but in a studio, after your careful adjustment, being able to wreck it with a fader seems a bit of a risk.

Once you have your system balance sorted, all should be well. However, when you do this, you won't get a straight line frequency response when you play the pink noise. You will almost certainly have a mess, and bringing in some traps and absorbers will be pretty evident watching the display. You can tune the room, but playing with reflections, refractions, absorbers and other devices takes time and is quite frustrating. Other people will use a permanent graphic eq to adjust out the errors. I've never found this approach sounds right to me, but it can be handy for a room with a nasty spike in the response where the dimensions have conspired against you.

If the room does end up having a characteristic sound that is really not right - you can live with it, and your ears will adjust.

As for your desired volume setting, it depends so much on your music. If you have picked 85dB for a particular reason (maybe a level dictated by some outside authority for noise reasons) then if your preferred music type is drum and bass, it will feel rather quiet - if you record classical music, 85dB of trumpet can be quite piercing. Personally, I choose my own monitor level, and use a cheap meter to confirm what my ears tell me - that it isn't too loud. I don't like music ear shatteringly loud, but I do have trouble mixing at inappropriate levels. I like my levels to reflect reality, so a string quartet sounds best quieter than a rock band. I've not adjusted my monitor amp for years, and do find that I still need to use a desk control to go up down in mix level. I've tried going direct from the computer out to the monitor amp in the patchy, but the right meter reading on the output is usually too loud for my preferred mix volume. I just have it 'comfy' - and not harmful. That does me. Loads of people use science to set levels, but I just need it to be right.

I have no idea why you picked 85dB? Probably a level too quiet for me, I fear.

 

[bouldersoundguy]

I set my sub level by ear, both at home and with my PA. On a bigger PA system with more setup time I might get the measurement mic out and run some sweeps, but at home it's easiest to do it by ear. I just place my head between the sub and one main, set an approximate level, set the polarity (sounds centered rather than diffuse when correct). Then I put on a variety of music and walk around the room while listening. Of course in a control room it's the sweet spot that you need to check most.

Be sure to experiment with placement.

I'd set your crossover frequency somewhat above the main speakers' LF cutoff. 100Hz is probably about right.

 

[bouldersoundguy]

I have the monitors running through the sub, then out to the safari pro 40.

For clarity it helps to describe connections in order of signal flow. So that would be out from the Safari through the sub to the monitors.

Although, I hear some people run the monitor our to its own output, rather than plugging the monitors though them. What would be the advance to that?

Unless you're doing live sound or mixing for surround sound just keep it all on one output. You could get a separate crossover/digital speaker processor to use instead of going through the sub, but that's a bit advanced and probably not necessary.

 

[miroslav]

You seem to be a bit confused about what exactly you are calibrating?

Yeah...I think he is.

I have no idea why you picked 85dB? Probably a level too quiet for me, I fear.

Well...in the end you'll settle on what's comfortable for you, but 85dB SPL is sorta the outer limit for extended mixing purposes. It's actually more like 80dB SPL...that would be the best comfort zone for both good volume and 8-hour sessions.

I have one of them big knob Level Pilot thingys...it's just a volume control for the monitors that's wired into my PB.
It comes unmarked from TC Electronics...but I calibrated using my Radio Shack analog SPL meter, set for C-weighted, and marked the Level Pilot so that it has 70/75/80/85/90 dB SPL has marks on it, that way I can always set it to the same spot.
It's quite interesting how some days 80dB SPL sounds quite loud, and it's often like that when I first start a session...then after a couple of hours it seems rather low.

OP...

That's really the whole point of calibrating, and knowing what level you're listening at, other wise you will have level-creep..and after a few hours you want 90 dB SPL.

I usually stay at 80 dB SPL...but will turn up to 85 and even 90 for short periods.
I rarely go lower than 80, as I find it too soft for anything usable, but occasionally I like to check at the lower settings to see if anything is revealed...because the boomy stuff will stick out at the lower levels.

Oh...you don't need Pink Noise to set the level...just use any music CD. Sometyhign that doesn't have huge dynamics makes it easier to set the level.
Pink noise is used more for checking the frequency response of your room...but sure, you can use it also for setting level.

 

[bouldersoundguy]

I would use the built in mic on the iPhone rather than an external mic to set basic listening volume. It's probably what the app is expecting.

 

[Lionzeye]

I have one of them big knob Level Pilot thingys...it's just a volume control for the monitors that's wired into my PB.
It comes unmarked from TC Electronics...but I calibrated using my Radio Shack analog SPL meter, set for C-weighted, and marked the Level Pilot so that it has 70/75/80/85/90 dB SPL has marks on it, that way I can always set it to the same spot.
It's quite interesting how some days 80dB SPL sounds quite loud, and it's often like that when I first start a session...then after a couple of hours it seems rather low.

This is basically what I did, I tested the left speaker (w iphone app and pink noise @ 85dB), Then the right speaker, BUT, I also made sure that my main monitor Gain control knob was pointed 90 degrees straight up so I know on my main monitor controller 85 dB is Straight up!

I do have a question for everyone and I hope not hijack dillirium tregge's thread...

... Mixing Handbook by Owenson states to test left and right speaker, BUT also to put the sub at 79dB...

...HOW in the world do you get a meter to read sub frequencies??

 

[bouldersoundguy]

...HOW in the world do you get a meter to read sub frequencies??

If your SPL meter has A-weighted and C-weighted settings use the C-weighted.

 

[Lionzeye]

If your SPL meter has A-weighted and C-weighted settings use the C-weighted.

Thanks again BSG!!