Axiom Home Page Forums General Discussion Technical Questions Calibrating with Digital Meter

Hi All

First post. I searched for the answer to my question but couldn't find it. Sorry if it's been done and done.

1) I read that you need to adjust the RS analog meter results at various frequencies (add 2db at 30 Hz, etc.). I got the digital SPL meter from RS. Do I need to make the same adjustments?

2) I used my receiver to balance the levels driving each speaker individually. When I use warble tones to adjust the sub (crossover, volume, location, anything else?), should I be driving ALL speakers simultaneously?

3) (Is 2 the limit?) In adjusting the level of the sub, is better adjust from the receiver, the sub's volume control, or no difference?

Thanks.
And again, I'm sorry if (if?) these are tired questions.

-dale

System:
M22 mains
VP100
M3 surrounds
VTF-2 MK-2
Denon 2105
Denon 1910

1) As far as I know, YES! Here are the corrections. At any of the given frequencies, the reading on your meter is off by these amounts.

For example: At 40Hz, if your meter reads 75dB, you’re actually hearing 77.5dB. To achieve an actual output of 75db, turn the volume down until the meter reads 72.5dB. You’ll then be hearing 75dB.

At 5kHz, if your meter reads 75dB, you’re actually hearing 73db. To achieve an actual output of 75dB, turn the volume up until the meter reads 77db, You’ll then be hearing 75dB

2) I've never used warble tones, so I can't be any help here.

3) I don't believe it matters. Just be sure the sub is getting a strong enough signal from the receiver to cause it to turn on. Start with your receivers output set at 0. If that level is turning your sub on adequately, use the volume knob on the sub to balance your sub with the rest of the system when you calibrate. Then, should you want to turn the sub up or down, just because it's easier, use the receiver's menu.

If sometimes you sub doesn't turn on properly with the receiver's menu set at 0, increase it to +3dB, and turn the volume knob on the sub down to get it back in balance with the rest of the system.

I'm confused about how you are using the warble tones. Can you explain what exactly you are trying to do with the warble tones? Are you trying to chart frequency response?

Thanks for the all the info so far.

Re the warble tones: The Hsu manual suggests using a test disc with warble tones at several frequencies above and below the crossover, averaging above and below and adjusting sub level until both averages match. Hsu included a test disc with warble tones (randomly varied frequency over 1/3 octave) instead of pure test tones to avoid exciting narrow room resonances.

Cool. Sounds like you're on the right track to getting that sub dialed in. Just curious, which tone do you use as a reference?

Sorry for the delay Mike. First chance I've had since last night to reply. Hsu does suggest a reference frequency but I'm at work and manual is at home (what was I thinking!) so I'll have to get back to you.

However I still am not sure how I'm supposed to proceed. I had imagined playing the tones through all 5.1 channels and adjusting sub (or receiver output to sub) so low frequencies matched higher frequencies in terms of SPL. It's the fact that the receiver's setup routine matches channel output levels by driving each channel separately that made me think I should be doing it that way.

Thanks again.

-dale

Hello UCONN,
If you would like here is a link that will take alot of the work out of the process, plus it will provide you with a frequency response graph, so that it will be easier to see what you are working with. Once you click on the link, go to the "microsoft excell workbook" link and download it, you might also want to download some of the 1/6 octave sine waves also available in the manual.
And by the way, the manual is very informative if you ever decide to try the BFD, it is definetly something I would not want to live without.

Mace

Thanks so much. Cool stuff. Now I just need to finish all this grading so I can get back to what's important - fiddling with settings and setup!

-dale