Question regarding sound calibration with SPL meter

[Kain]

Previously, I had calibrated my system to 85 db when the volume control was at 0 db. The settings came out as follows:

Left main: -7, center: -6, right main: -8, both surrounds: -7

Today, someone accidently unpluged my A/V receiver and I had to recalibrate everything because it was reset. I did the same procedure of 85 db when the volume control was at 0 db. Settings came out as follows:

Left main: -6, center: -5, right main: -8, both surrounds: -5

I didn't change anything in the system or the SPL meter (which is the Radio Shack's meter). So my question is how come the settings came out different? Is this normal?

[michael hurd]

Moving the meter even a few inches from it's previous position will affect the readings. So as long as the meter was not moved during the setup, you should be good to go, as the channel levels should be balanced good enough. There are other factors that may affect the readings as well, reflections from objects can also play a role in the readings.

[TheSoundBroker]

When calibrating, your center channel level, not your volume control, should always be set as the reference (zero) at 85 db. Your volume should be adjusted so that the center reads 85 DB at zero level. All other speakers should key off the center channel. In that case your settings should have been...Center 0, Left -1, Right -2, Surrounds -1. As pointed out before, chances are, your meter was put in a slightly different place. It helps to use a mic stand with your meter to get consistent heights and no noise or movement from holding the meter. This is also why you should take multiple calibration readings and average them (room acoustics can play a big part).

[IndyKlipschFan]

Soundbrokers advice is very good and dead on! "When calibrating, your center channel level, not your volume control, should always be set as the reference (zero) at 85 db. Your volume should be adjusted so that the center reads 85 DB at zero level. All other speakers should key off the center channel."

Very good points too. I was also taught to start at the center channel. And to use a tri pod or mic stand as well.

I should re draw my room out now that it is finished.

[IndyKlipschFan]

The front lay out now. Finished.

[JetJockey]

Indy, that room brings a tear to my eye, gorgeous!

Chris

[JetJockey]

Is this method used with a disc such as DVE or the AVR internal pink noise? I always used the internal and set it at 75db as the ref volume always goes to 0db when you select test tone. Supposedly this avr is THX certified. I tried setting levels with DVE at 85db at ref of 0db but it wouldn't even go that high! Must be me.

Chris

[IndyKlipschFan]

Here it is without the scrims too up front.

[IndyKlipschFan]

FYI, the Upper sections are for 2 extra TV's... Gotta love NCAA Tourney time.. hahahahahaha Also these TV's double for karaoke, so the audience can see the words the singer is singing to sing along too.

I am especially proud of how it all came together and it is done. The speakers are hidden behind the scrims... and it is a clean look when the lights are dimmed! I now have insulation around all of the speakers in every cranny and that helped a lot as well. Glad you like it as well. I took a lot of ideas off of this board from others, read a lot of books , websites, and used some personal preferences too.

Roger

[InVeNtOr]

indyklipschfan, quick question about the screen, it says 106" is that diagonal or across? (i assume it is diagonal, but i would like to know for sure) where did you get it?

[IndyKlipschFan]

52" H x 92" W

Your correct, it is 106" on the diagonal measurement of the screen size in HDTV Format. 16 x 9

I could of gone up to 110" - 120" But found it would be too big to capture what was on the full screen with your eyes from my seating position. That would be like sitting in the front of your local movie theater. And 106" is still a BIG screen! (BTW, bigger is NOT 100% of the time better.. Wow factor yes.. But eye fatigue too.) You also have to figure out throw distance for your projector at that size as well for mounting it on your ceiling. The frame has 3" all around it in felt.. I highly suggest this too, even if you frame the felt yourself for you do it yourselfers.

I got it through Rick Goren at Technology Interiors. 317 574 9500. Indianapolis, IN.

Tell him I sent you, he will give you a fair price I am sure. He is a Da Lite dealer.

http://www.da-lite.com/products/product.php?cID=20&pID=234 For more info.

Always look on the avs forum, Klipsch BB, and your dealer for sugestions. A propper screen to match with your projector will make HUGE strides in the performance wow factor too! Do NOT skimp on the screen! A few extra bucks spent here is well worth it!

Roger

[Islander]

Previously, I had calibrated my system to 85 db when the volume control was at 0 db. The settings came out as follows:

Left main: -7, center: -6, right main: -8, both surrounds: -7

This seems like an unusual concept. Why not just set the center channel at 0, turn the volume up to 85dB, then match the rest of the speakers to the center as needed? Did you want to strictly limit your maximum volume, or did you interpret "calibrate your system at 85dB" as "calibrate your system to 85dB"? Putting needless extra limiting on your speakers doesn't improve the sound.

[Kain]

Previously, I had calibrated my system to 85 db when the volume control was at 0 db. The settings came out as follows:

Left main: -7, center: -6, right main: -8, both surrounds: -7

This seems like an unusual concept. Why not just set the center channel at 0, turn the volume up to 85dB, then match the rest of the speakers to the center as needed? Did you want to strictly limit your maximum volume, or did you interpret "calibrate your system at 85dB" as "calibrate your system to 85dB"? Putting needless extra limiting on your speakers doesn't improve the sound.

Wouldn't that yield the same calibration result as my method? I stuck in AVIA, turned the volume nob to 0, and adjusted each speaker till it read 85 db on the meter. Is this wrong or something?

[Islander]

Not necessarily wrong, just different. If you set your center channel to 0, then turn up the volume of the center channel to 85dB and set the rest of the speakers to match, you will have much more volume available, since all the speakers will be set within a few dB of 0, not at -6 or -7 or so. This may also improve the available headroom for musical peaks (someone correct me if I'm wrong on that one). As well, although this may be more true in theory than practice, it's considered better to have as little in the signal path as possible, so if your front and center speakers are set at 0 or close to it, the sound may be a little cleaner, since it's not being "modified" by going through a volume control.

In a way, it's as if you're setting the cruise control on your car while driving with the parking brake on.

How high does the volume go on your amplifier? Does it go very far past 0, to +10 for example? With a typical setup, 0 on the volume is very loud, producing over 100dB. It was simpler in the past, with volume knobs that went from 0 to 10. If you turned it up past 7, you'd risk clipping the amp, so it was sometimes suggested that if you needed to turn it up past 7 (or 5, for the really conservative types) you need a more powerful amplifier.

[Kain]

Not necessarily wrong, just different. If you set your center channel to 0, then turn up the volume of the center channel to 85dB and set the rest of the speakers to match, you will have much more volume available, since all the speakers will be set within a few dB of 0, not at -6 or -7 or so. This may also improve the available headroom for musical peaks (someone correct me if I'm wrong on that one). As well, although this may be more true in theory than practice, it's considered better to have as little in the signal path as possible, so if your front and center speakers are set at 0 or close to it, the sound may be a little cleaner, since it's not being "modified" by going through a volume control.

In a way, it's as if you're setting the cruise control on your car while driving with the parking brake on.

How high does the volume go on your amplifier? Does it go very far past 0, to +10 for example? With a typical setup, 0 on the volume is very loud, producing over 100dB. It was simpler in the past, with volume knobs that went from 0 to 10. If you turned it up past 7, you'd risk clipping the amp, so it was sometimes suggested that if you needed to turn it up past 7 (or 5, for the really conservative types) you need a more powerful amplifier.

So, you are saying that I should set the center channel to 0 db, insert AVIA, bring out the Radio Shack meter, and adjust the volume nob till it reads 85 db for the center channel, leave the volume control in the same position, and adjust the rest of the speakers till they all read 85 db?

BTW, my A/V receiver goes up to +18.

[Islander]

Exactly! Try that and see how it sounds to you.

[Arky]

yep

[DrWho]

While you're at it, you should maintain stereo symmetry on the settings as well. For example, set your L and R mains both to -2dB or both to -1dB. If there is a volume mismatch, then it is better corrected by moving the speakers around.

[Arky]

While you're at it, you should maintain stereo symmetry on the settings as well. For example, set your L and R mains both to -2dB or both to -1dB. If there is a volume mismatch, then it is better corrected by moving the speakers around.

For 2 channel do you speak?

[DrWho]

For surround sound do I speak....like the rear left speaker should be the same as the rear right speaker. Of course, this will require that both are equidistant from the listening position, but that has other advantages of its own.