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.