Axiom Home Page Forums General Discussion Technical Questions SPL Calibration Procedure

I've read the majority of post regarding SPL calibration, but I'm still somewhat confused as to how to set the AVR to 75db. Is this set with the main volume control when beginning the test tone program of the AVR(HK435)?

Yes, I would use the main volume control to start the procedure.

Yes, listen to RAT. Start out with the front right or left,(your choice), set it to 75db using the Main Volume control. Then balance all the other speakers to 75db using the trim/level function.

I'm not familiar with the volume control of the HKs. My Onkyo's volume control says -82 when at it's lowest point, and + 18 at it's highest point. This is a "relative" scale and the "0" point is considered "reference" level. that's where I set my receiver's master volume when I begin calibrating. If the HK has a similar volume display, set it to "0".

Other receivers have "0" as it's lowest volume point, and the scale goes up numerically to whatever is it's highest point (most often "100"). This is an "absolute" scale. In that case, as Richeydog says, run a test tone through the left or right front channel with the setting for the same front channel speaker in the receiver's speaker setup menu set to "0". Then, turn up the receiver's master volume until your meter reads 75dB. That is where you leave the master volume when calibrating the rest of your speakers.

Now, run test tones through the other speakers, and adjust them to 75dB using the settings in the receiver's speaker setup menu. Do not change the receiver's master volume. That master volume setting will be your "reference" level.

NOTE 1: Some receivers test tones are meant to be set to 85dB. See your HK manual to see what it says.

NOTE 2: Very few of us listen to music or watch movies with the volume all the way up to reference level. Don't feel you're doing something wrong if you listen considerably lower than your reference level.

John, welcome. Your 435 has an excellent auto-calibration system which you should use at least initially. Follow the instructions in the manual for using EzSet, and you don't have to worry about setting the volume control. You may want to manually set all speakers small with most likely an 80Hz crossover, but first see what the 435 comes up with. You can also make small level adjustments later to suit your taste, of course.

Jack, my HK 635's lowest volume level is -80 and the highest volume level is +8 although I didn't find anything in the manual regarding a reference level for calibrating I don't believe I'd set the HK to "0"...that's a whole heap of volume on the 635. I don't know if I've ever had mine turned up that much.

The test tones for the HK are meant to be set at 75db.

The HK's manual can be a pain to decipher at times.

Guys, calibrating to the "0," or reference level, mark doesn't mean that one listens with the volume level set at that mark. As far as I know, calibrating to the "0" mark, by having "0" equal 75dB, merely provides a means of referencing your volume to a standard (dat's why it's called "reference" level ).

If you have two guys who have calibrated their receivers to the "0" mark, and the both say they listened to a disc at -20dB, you know they both listened at the same volume (20dB lower than the reference volume). If I calibrate to the "0" mark and you don't, then my -20dB mark and your -20dB mark are two different volumes, and yours isn't actually -20 dB from reference.

That is not to say that you can't set your reference point at whatever mark on the volume dial you wish. But if you don't use the "0" mark, the receiver's volume dial is inaccurate, and you can't equate your receiver's volume setting to anyone else's, excepting those who've calibrated to the exact same setting.

By the way, I listen, most often, between -27 and -16 dB from reference, depending on the source material and how loud I want the material to be. I have never listened at reference level (though I've come close, once or twice ), and few people I know have.

Jack are you saying that we should set and calibrate to the 75db (SPL) level to coincide with the "0" setting on the dial? In other words Sean and I would actually be turning down the internal speaker outputs of our 635s to set a reference level of 75db whenever the volume dial is set to the "0" position?

Or something like that.

Also, other than Sean and I being able to compare different db levels to volume levels on our 635s what would be the reason for doing this and wouldn't room and environment conditions come into play?

I want to emphasize that I'm not saying you "should" do as I do. I'm just trying to explain what I do, and why I do it.

I don't know where you set your HK master volume to when calibrating or what settings you end up with in the receiver's speaker setup menu. But, if you currently calibrate at a master volume setting lower than "0," should you now opt to calibrate at "0," the settings in your receiver's speaker setup menu will indeed go down from where they are now.

When calibrating, I set my Onkyo's master volume to "0." Then, I play the test tones from my receiver, and adjust the settings in the receiver's speaker setup menu until the meter reads 75dB for each speaker. I end up with:

FL: -1
Center: - +2 (bumped a few dB)
FR: -1
SR: +2
SL: +2
Sub: -1 (this setting is actually bumped 5 dB for movies. If necessary, I back it off for music)

So with the master volume at "0," my settings in the speaker setup menu need to be tweaked only a few dB either way to achieve 75dB. I have no HK experience so I cannot say if your results would be the same. No speaker of mine is farther than 9 feet from the meter. If your distances are greater, your settings in the receiver's speaker setup menu may need to be higher to achieve 75dB with the master volume at set at "0", depending on your amplifier power.

When I use DVE, I end up with virtually the same settings to achieve 75dB (Avia users should be calibrating to 85dB)

You got it. The only advantage, I'm aware of, to doing what I do is that you are calibrated to a universal reference. No matter where you set your master volume when calibrating, if you calibrate properly, your results will be the same. But, your master volume will not reflect the actual level at which you are listening.

Lets say you like to listen to both music and movies at 20dB below reference level. If you set your master level to -10 and calibrate to 75dB at that point, your ears will still steer you to listening at 20dB below reference, but your volume level will read -30dB, rather than the accurate -20dB.

Room and environment conditions certainly come into play when you are calibrating, as does amplifier power. But, even though my room and amplifier capacity may be different from yours, once calibrated, room and amplifier conditions remain constant at all volumes. That's the whole point of calibrating to a universal "reference" setting. Obviously if you make drastic changes to your room, recalibrating would be prudent.