Axiom Home Page Forums General Discussion Technical Questions Calibrating Speakers

I posted this on another forum but I think my question got lost in the thread so I'm reposting. Does calibrating speaker levels at 75db at different levels on your master volume control impact how "loud" you can go. In other words, if you calibrate with the master volume at 40 vs. 50 (arbitrary settings) and you can go up to say 80 on the master volume, do you have more headroom or volume using 40 as the reference level? Logically it seems that you would because you would have more volume runout left on the control at 40 than you would at 50. Does this make any sense? or am I just confused?

Logically what you are saying makes sense, when you calibrate using test tones the receivers master volume should be turned way down, then each speaker would be moved up in db to reach the desired level.
If the master volume is turned way up during the tones each speakers volume level would have to be reduced to hit the desired db. Thus leaving you less headroom to raise the volume. That is at least my take on it.

The correct way to do a calibration is to have a reference speaker. In this example lets say the left main is the reference speaker, this speaker should be at 0db trim, but should be at 75db on the SPL meter. To do this, you need to use the main volume to get your left speaker to 75db.

Once your reference speaker is done, proceed to do the other speakers, matching your reference speaker using the trims for each speaker (not the master volume like you did with the reference speaker).

Does this make sense?

Makes sense to me, how does that affect using the auto calibration, should all speakers be cleared to 0 trim before beginning the auto calibration process or will the receiver do that?

I think the auto calibration does this automatically. I have found that the left speaker is usually the reference speaker, even with auto calibrations. The Mic uses the master volume to get the left speaker to 75db, it then proceeds to get all the other speakers to 75db using the individual trim for each speaker. Of course I have no proof that the auto programs do this, it would make the most sense.

Hut, I don't think that works for all receivers. I suppose if your using a CD test tone maybe. When I use my Denon's built in test tones, you can't do it this old fashioned way I don't believe.

Michael,
Makes sense to me. The lower the volume control is at 75db, the more headroom there is or should be.

I don't think that's the case at all, cgolf. A system calibrated such that all speakers are playing at 75dB loudness when the master volume is at, say -25dB, will use the same amount of power as the system calibrated to 75dB with the master at, say -18dB. The trim settings make up the difference. Whether you like to set your master low and boost the trims or set your master high and cut the trims is a matter of preference. The amount of headroom is determined by the efficiency of the speaker. A more efficient design will be able to take advantage of the headroom better than a less efficient type.

OK. I'm just trying to understand the dynamics behind this. So if we take your case & calibrate at both levels, and then raise the master volume to say 0, should the SPL level be the same for both initial calibrations? If yes, then I guess I'm confused somewhere.

I understand what Peter is saying, but if you crank the master volume all the way during test tones and reduce the speaker trim to get you down to 75db, it would seem to me the only way to raise the speaker volume levels above 75db would be to individually adjust the trim on each speaker rather than using the master volume control since it was already calibrated to be maxed at 75db.

HomeDad, I hear what you're saying, but is it even possible to trim a speaker down far enough from a maximum master volume setting, which I assume would be pushing 100dB in many cases?

Good point, maybe when I recalibrate everything and hook up my amp again next weekend for comparison I'll give that a shot also.

OK. I'm just trying to understand the dynamics behind this. So if we take your case & calibrate at 2 different levels (-10 & -20), and then raise the master volume to say 0, should the SPL level be the same for both initial calibrations? If yes, then I guess I'm confused somewhere.

No, I don't think so.

Well, yes, that does make sense put that way. In reality, you're still starting out at the same levels, just either trimmed or not trimmed.

Thanks, Hutz. I get it now.

My Denon doesn't care what the master volume is set to during calibration.

Hut that is incorrect, at least on Denons. On the Denons if I put it at -80dB's and then kick off the test tones, the Denon ignores the volume setting and uses the preloaded setup levels built into the algorithms.

Now that I've thought about it a minute I realize I'm still confused or missing something. 2 receivers exactly the same. Set one receiver at -20 on the volume / 75dB and a second receiver at -10 on the volume / 75dB. Move them both to 0 so 20 bumps up on the first and 10 bumps up on the second. How can they both now be at the same level?

Hutz is right. My main point, though, was that your amps will be using a specific number of watts to drive your speakers to 75dB (using test signals) -- regardless of the master volume or trim settings. So there will always be a set amount of headroom above that. Remember that volume adjustment is not linear (e.g. the scale does not map linearly to the number of watts being used).

Last question of confusion then. Is it possible to run out of volume before running out of headroom? If you had calibrated at 75dB very high up the volume knob...

To do that, you'd probably have to put in -12dB settings on all the speakers. If the volume knob actually is in dB, you couldn't get all that high on it--you're limited by the fact you can only go to -12dB.

I think I'm beginning to understand all of this. I'll find out tonight when I get home. Of course the other factor that hasn't even been mentioned are the distance settings that could also impact and affect the calibration if not correct.

Distance settings would not effect db output, it only effects the delay of output.

May I add that this thread is giving me a headache?

Thank You.....

Well, I tried it and my Denon does not appear to care about the master volume.

1. I set the master volume to -70dB. I manually engaged the test tone out of my left speaker and the SPL meter read 74 dB.

2. I then came out of "setup", I set the master volume to 0dB, went back into "setup", manually engaged the test tone out of my left speaker and the SPL meter read 74dB.

The way I look at it, the channel trim sets the relative level between the speakers. So it doesn't have to care about the master volume. The master volume simply raises the level on all speakers equally.

Mojo,

how high can your trim go for each speaker? My yamaha cuts off at +10 max

It goes from +12 to -12.

Hey, mine only goes to 11!

Charles, the bottom line is that you can't gain any advantage in remaining power capacity("headroom")by calibrating at a lower number on the volume control. The master volume control and the individual channel trim controls allow more or less voltage from the player, etc. to reach the amplifying section and then be amplified, but the relative settings can't change the maximum power capability which is designed into the amplifier.

I use internal test tones for setting up the Audyssey EQ curves, then pop in the Avia disk and set up my speakers. I like -15 to equa. 85 db. At that level my mains are both at Zero, and my center is – 4. Surrounds are a little to the positive.

…..not really sure why I felt compelled to post that.