SERIOUS HELP NEEDED; Setting Sub level (using Audio meter)

[rimisrandma]

I bought a Phonic Paa3 audio analyzer meter to help me set-up my monitors. I have 2 powered Event TR-6's monitors and an M-Audio powered BX10S Subwoofer. I have a Presonus FireStudio Mobile FW400 interface.

What I did was get a pink noise track and play it through iTunes. I set my iTunes output volume all the way up and let my interface be my master to my monitors. My M-Audio sub has an active cross-over that sucks out the lows and sends them to the sub and the mids and highs go to my left and right Event monitors. The sub has a defeat switch to take it out of the equation.

So I auditioned Events one at a time with the Pink noise, by defeating the sub and turning one on at a time. Both were about 73-75 db, it is hard to hold the meter and turn things on and off which is why the db moved around during the measurement.

Now with both Event monitors off and using pink noise, my sub was reading 50 to 60 db, something substantially lower. I do have my set-up in an untreated room and worse yet in a corner. So, I brought the sub up to about 74-75 db as well, and there is some pretty heavy boosting to get the same db measurement at the ear/sweet spot for monitoring, like 5db level boost on the sub. I did not have the output on my interface up the whole way either because it gave me some headroom later, things were pretty loud here, and I figured that matching level here was more of what I was after than db output at full output volume setting.

The biggest question here is, do you set the sub level to the same db as your monitors speakers? Each measured independently of course.

Another thing that sux about the M-Audio BX10s is that level will boost the lows as viewed on the meter, but changing the crossover also boosts and doesn't really move the lows up on the frequency spectrum. So, I usually have my crossover set at 80 or 85 hz and increasing the crossover above 100 etc....just seems to raise the mid hump like a level increase and not so much of a frequency shift to incorporate more bass above the 100 hz setting, which I kind of thought I would see.

 

[bouldersoundguy]

If I were you I would play a bunch of music I'm familiar with and set the sub to sound as right as possible with as many different songs as possible. Measuring speakers is a tricky business that takes a lot of skill and experience to get right. In particular, real time analysis is time blind and can mislead you. If you want to get into speaker measurement you'll need a reference mic, a 2x2 interface and some appropriate software.

 

[rimisrandma]

I have a meter.

 

[JimmyS1969]

dB meter is not what you would use to set up speakers. You are looking for a somewhat flat response in your room. This includes how the room affects the frequency response.

REW, and a suggested reference mic.

This will tell you what is actually happening in your room, but will also mislead you if your room is not treated.

Do what Boulder said, and just set the sub to sound good with music you are familiar with. Unless you plan to treat your room, you will have issues anyway. Just set it to where it sounds good, then leave it there until you see how your mixes translate. Not much less productive than playing with the level of a sub while mixing. Best to use it sparingly anyway.

 

[bouldersoundguy]

I have a meter.

Your meter can't tell the direct path of the sound from the reflected paths. You might get it to look right on the meter, but that has little to do with how accurate the response is or how it sounds. An RTA type measurement isn't going to do the trick for this.

The best way to align the sub to the tops with your meter, in my opinion, is to put it in SPL mode and send a sine wave through at your crossover frequency. Set the levels so it's the same level in the sub as in the tops when you play one or the other. When you put them both on it should be 3dB louder. If it's quieter instead of louder either the sub's polarity is inverted or there's some sort of room issue. If flipping the polarity (sometimes labelled "phase") doesn't fix it try moving the sub until you get a little boost. That should get them aligned at the crossover frequency. I would recommend something closer to 100Hz than 80Hz.

To get it more right you'll need a reference mic, an interface, a computer and analysis software.

 

[rimisrandma]

Your meter can't tell the direct path of the sound from the reflected paths. You might get it to look right on the meter, but that has little to do with how accurate the response is or how it sounds. An RTA type measurement isn't going to do the trick for this.

The best way to align the sub to the tops with your meter, in my opinion, is to put it in SPL mode and send a sine wave through at your crossover frequency. Set the levels so it's the same level in the sub as in the tops when you play one or the other. When you put them both on it should be 3dB louder. If it's quieter instead of louder either the sub's polarity is inverted or there's some sort of room issue. If flipping the polarity (sometimes labelled "phase") doesn't fix it try moving the sub until you get a little boost. That should get them aligned at the crossover frequency. I would recommend something closer to 100Hz than 80Hz.

To get it more right you'll need a reference mic, an interface, a computer and analysis software.

When trying to do this by ear, 80 hz seemed balanced or something, so I started there with your method. My one monitor was 3 db lower. My sub was WAY TO HIGH/LOUD. It's something like -20db (between -6 and -30db markings). One question that is left is with the phase switch, will it add 3db? When I press the 180 phase button, it adds 6db or cuts 3.

With an 80 hz sine wave. L and R were referenced at 75db each solo. Sub solo was set at crossover 80 hz and set to 75db. Turn everything on, 81db one way with the sub's phase switch and 78db in the the phase switch's other position.

 

[rimisrandma]

Your meter can't tell the direct path of the sound from the reflected paths. You might get it to look right on the meter, but that has little to do with how accurate the response is or how it sounds. An RTA type measurement isn't going to do the trick for this.

The best way to align the sub to the tops with your meter, in my opinion, is to put it in SPL mode and send a sine wave through at your crossover frequency. Set the levels so it's the same level in the sub as in the tops when you play one or the other. When you put them both on it should be 3dB louder. If it's quieter instead of louder either the sub's polarity is inverted or there's some sort of room issue. If flipping the polarity (sometimes labelled "phase") doesn't fix it try moving the sub until you get a little boost. That should get them aligned at the crossover frequency. I would recommend something closer to 100Hz than 80Hz.

To get it more right you'll need a reference mic, an interface, a computer and analysis software.

When trying to do this by ear, 80 hz seemed balanced or something, so I started there with your method. My one monitor was 3 db lower. My sub was WAY TO HIGH/LOUD. It's something like -20db (between -6 and -30db markings). One question that is left is with the phase switch, will it add 3db? When I press the 180 phase button, it adds 6db or cuts 3.

With an 80 hz sine wave. L and R were referenced at 75db each solo. Sub solo was set at crossover 80 hz and set to 75db. Turn everything on, 81db one way with the sub's phase switch and 78db in the the phase switch's other position.

Anyone?

 

[bouldersoundguy]

I can set my sub's polarity using my ears. I put my head halfway between the sub and the nearest main with the left ear toward the main and the right toward the sub. When the polarity was wrong it sounded more diffuse. When it was right it sounded centered and solid. I generally just set the level to sound right with various commercial recordings in spite of the fact I could get the reference mic out and measure it. Doing it by ear is close enough and a lot quicker than measuring.

 

[rimisrandma]

I can set my sub's polarity using my ears. I put my head halfway between the sub and the nearest main with the left ear toward the main and the right toward the sub. When the polarity was wrong it sounded more diffuse. When it was right it sounded centered and solid. I generally just set the level to sound right with various commercial recordings in spite of the fact I could get the reference mic out and measure it. Doing it by ear is close enough and a lot quicker than measuring.

PUZZLED, but this may just be off thinking...............

Did everything. L, R, and sub are all about 75 db.
Will everything solo be about 75 db and then when all three speakers are back on (L&R with sub), will I get about 82 db?

Because solo, everything is 75 db, have 2 speakers on, I get about 78 db, and all 3 on, I get about 81 or 82 db?

I was thinking that I would get 75 db with L&R's on OR sub, and 78 with all 3 on?

 

[rimisrandma]

PUZZLED, but this may just be off thinking...............

Did everything. L, R, and sub are all about 75 db.
Will everything solo be about 75 db and then when all three speakers are back on (L&R with sub), will I get about 82 db?

Because solo, everything is 75 db, have 2 speakers on, I get about 78 db, and all 3 on, I get about 81 or 82 db?

I was thinking that I would get 75 db with L&R's on OR sub, and 78 with all 3 on?

kind of important bump

 

[sjjohnston]

One thing to consider (going back to the original question);

If the crossover is at 80 dB, and your signal runs from 20 Hz to 20 kHz:

There are 2 octaves in the subs and about 8 octaves in the main monitors.

That would be about consistent with your original measurements if it's flat. Of course, there's a fair amount of "play" here: is your dB meter accurate across that frequency range by design (not weighted); even if it is by design, is it accurate in practice; overlap in the crossover; room effects, as already mentioned; etc.

 

[sjjohnston]

My post immediately above was written with no idea what a Phonic Paa3 is. Since posting it, I Googled it and looked quickly at the description. From the first post, I was assuming it was just an SPL meter, but it's not. It looks like it has a 1/3-octave graphic analysis display built right into it. It also has a pink noise generator built right in. Now I'm confused how you're using it. Unless I'm looking at the wrong product description (or it doesn't do what it claims to be able to do), look at the bar graph display, not the SPL meter.

And, of course, at the end of the day, it matters more what everything sounds like.

 

[bouldersoundguy]

The thing about the meter is that the room effects will be impossible to filter out. You can measure at two places a few feet apart and get drastically different numbers. The only way you can start to separate the speaker system response from the room effects is with a transfer function type measurement, something that takes skill to perform and interpret. Short of that ignore the meter and do it by ear.

That said, about 3dB of gain from adding similar signals (right and left speakers) imperfectly in a room is about right. Another 3dB from adding the sub doesn't seem out of line, especially if the OP is using a pure tone at the crossover frequency.