A weighting or C weighting?
10-13-03, 11:42 PM
#1
DVD Talk Hero
Thread Starter
A weighting or C weighting?
I finally got an analog sound level meter at Radio Shack but no store I go to (Suncoast, Borders, K-Mart, Wal-Mart, etc.) carries Digital Video Essentials or Avia. Only Borders had one copy of DVE in store but they had no idea where they placed it. 
Anyhoo, I'm using my receiver's built in pink noise and a self made CD (for setting my subwoofer) to calibrate my system but am unsure wether to use A weighting or C weighting when using the sound level meter. The end result of using either weighting sounds fine to my ears when I use either to calibrate my main speakers (though I only used C weighting for setting my sub as I assume that is appropriate) but I wonder which is "correct". All I know is my centre and surround speakers have to be set 2dB higher when using A weighting than when I use C weighting.
My receiver is a JVC RX-DV3SL, BTW.
Which weighting should I be using?
Anyhoo, I'm using my receiver's built in pink noise and a self made CD (for setting my subwoofer) to calibrate my system but am unsure wether to use A weighting or C weighting when using the sound level meter. The end result of using either weighting sounds fine to my ears when I use either to calibrate my main speakers (though I only used C weighting for setting my sub as I assume that is appropriate) but I wonder which is "correct". All I know is my centre and surround speakers have to be set 2dB higher when using A weighting than when I use C weighting.
My receiver is a JVC RX-DV3SL, BTW.
Which weighting should I be using?
Last edited by RocShemp; 10-14-03 at 06:19 AM.
10-14-03, 08:48 AM
#2
DVD Talk Hero
Thread Starter
Anyone? I could really use some advice.
10-14-03, 08:57 AM
#4
DVD Talk Legend
I believe it's the C weighting, though I'd have to check when I get home to be sure. Video Essentials has specific instructions for how to use the Radio Shack analog sound level meter.
10-14-03, 09:04 AM
#5
DVD Talk Hero
Thread Starter
Originally posted by Josh Z
I believe it's the C weighting, though I'd have to check when I get home to be sure. Video Essentials has specific instructions for how to use the Radio Shack analog sound level meter.
I believe it's the C weighting, though I'd have to check when I get home to be sure. Video Essentials has specific instructions for how to use the Radio Shack analog sound level meter.
I know that the Video Essentials FAQ says the following:
Sound Level Meter Setup: In using the sound meter to set the levels from each audio channel Video Essentials says to use "C" weighting. I’ve read on the Internet that "A" weighting should be used. Which is correct? The audio noise test signals used in VE are pre-filtered so that C weighting on the meter should work just fine. If the noise on VE had been full bandwidth, the "A" weighting position would have been necessary. In the "A" position, the meter does the filtering that has already been done to the VE source signal.
A reference to this can be found in the menu system of the DVD of Video Essentials. At any point in the program, press the Title button to see the menu. You may have to look in the manual for the DVD player to find the location of the Title button. We understand that some players don’t clearly label this button. Once the title menu appears on screen, use the arrow pod to go to item 5, "Additional Information", then press Enter. A second menu will appear. Using the arrow pod, find your way down to the third item, Sound Level Meter Setup, then press Enter again. This will bring up a third menu screen, picturing the sound level meter. Follow the arrow pod instructions at the bottom right of the screen to continue navigation. Note that the Return or Enter button will take you up one level in the menu system.
We also took the time to ask Steve Thompson of Pacific Ocean Post to comment. After reading his thoughts on the subject, I’m beginning to believe the correct answer is that "It depends..." His reply in part:
"Theater alignment procedures published by a number of standards organizations define theater reference levels based on C-weighted SPL measurements in response to wide band pink noise. It is certainly correct to use this type of measurement. This is the method used for setting absolute levels in a playback environment. However, due to low-frequency effects of rooms, it is often useful to filter the low frequencies using A-weighting. The measurement is easier to read. In fact, professionally, we often use C-weighting to determine the absolute level in the room and then switch to A-weighting to check the relative level between channels. In the case of setting up a consumer listening environment, most test signals are band limited to the most critical listening frequencies. Also, most consumer environments concern themselves with attention to relative levels as opposed to absolute levels. It is therefore easier to use A-weighting and often results in more accurate channel balance."
A reference to this can be found in the menu system of the DVD of Video Essentials. At any point in the program, press the Title button to see the menu. You may have to look in the manual for the DVD player to find the location of the Title button. We understand that some players don’t clearly label this button. Once the title menu appears on screen, use the arrow pod to go to item 5, "Additional Information", then press Enter. A second menu will appear. Using the arrow pod, find your way down to the third item, Sound Level Meter Setup, then press Enter again. This will bring up a third menu screen, picturing the sound level meter. Follow the arrow pod instructions at the bottom right of the screen to continue navigation. Note that the Return or Enter button will take you up one level in the menu system.
We also took the time to ask Steve Thompson of Pacific Ocean Post to comment. After reading his thoughts on the subject, I’m beginning to believe the correct answer is that "It depends..." His reply in part:
"Theater alignment procedures published by a number of standards organizations define theater reference levels based on C-weighted SPL measurements in response to wide band pink noise. It is certainly correct to use this type of measurement. This is the method used for setting absolute levels in a playback environment. However, due to low-frequency effects of rooms, it is often useful to filter the low frequencies using A-weighting. The measurement is easier to read. In fact, professionally, we often use C-weighting to determine the absolute level in the room and then switch to A-weighting to check the relative level between channels. In the case of setting up a consumer listening environment, most test signals are band limited to the most critical listening frequencies. Also, most consumer environments concern themselves with attention to relative levels as opposed to absolute levels. It is therefore easier to use A-weighting and often results in more accurate channel balance."
But I'm using the pink noise generated by my receiver to set the levels of my front and surround speakers so I'm unsure which weighting I should have used.
Anyhoo, thanks again and I eagerly await when you can respond again.
10-14-03, 09:39 AM
#6
DVD Talk Legend
In reading that explanation I believe that unless you are setting up a "highly specialized" theater, "C" weighting should do just fine.
I don't even want to begin to get into room acoustics, standing waves, room treatements, sound absorption materials, null spots, eq curves etc.
Always remember, trust your ears, whether it's speakers, cable or setup procedures.
Good luck!
I don't even want to begin to get into room acoustics, standing waves, room treatements, sound absorption materials, null spots, eq curves etc.
Always remember, trust your ears, whether it's speakers, cable or setup procedures.
Good luck!
10-14-03, 01:11 PM
#7
I see you have a sub. Are your five channels essentially identical speakers? If so, C would be OK. If not, I think I would use A.
First what are A and C? C is essentially flat, down a few dB at 20Hz and 20Khz, it covers the total audio range. If your five speakers are essentially identical, and bass is produced by a separate subwoofer, C would be ideal.
However, your ear doesn't hear equally well at all levels. It doesn't hear bass or high frequency sounds very well at low volume levels. A-weighting mimics this rolloff to approximate how you hear sounds at low volume levels. That isn't the reason for recommending A though. The ear directionalizes sound mostly through the midranges. Bass can't be directionalized at all (that's why subs work) and very high frequency doesn't directionalize well either. A-weighting rolls those off and ephasizes the mid-range. The five speakers are mostly to give a good experience in terms of correctly localizing or directionalizing the sound wave. I would say put most of your focus on those frequency bands which dominate the ear's ability to directionalize sound, and take what happens at very low or very high frequency. A isn't the ideal weighting for that purpose, but it is the better of A and C. (Probably, D weighting is, but you don't have that choice)
This is especially important if speakers are unequal. My mains are also used for music, have 15" woofers and I don't have sub. My center and surrounds have 5 1/4" woofers. Bass has to be separately set by directing to mains and I don't want frequency differences at a hundred Hz or so affecting my channel balance.
If you use A for balancing the five channel sound, you have to do something else, probably using C weighting, to check that bass response is balanced with the five channel sound, whether the bass comed from a sub or two mains.
First what are A and C? C is essentially flat, down a few dB at 20Hz and 20Khz, it covers the total audio range. If your five speakers are essentially identical, and bass is produced by a separate subwoofer, C would be ideal.
However, your ear doesn't hear equally well at all levels. It doesn't hear bass or high frequency sounds very well at low volume levels. A-weighting mimics this rolloff to approximate how you hear sounds at low volume levels. That isn't the reason for recommending A though. The ear directionalizes sound mostly through the midranges. Bass can't be directionalized at all (that's why subs work) and very high frequency doesn't directionalize well either. A-weighting rolls those off and ephasizes the mid-range. The five speakers are mostly to give a good experience in terms of correctly localizing or directionalizing the sound wave. I would say put most of your focus on those frequency bands which dominate the ear's ability to directionalize sound, and take what happens at very low or very high frequency. A isn't the ideal weighting for that purpose, but it is the better of A and C. (Probably, D weighting is, but you don't have that choice)
This is especially important if speakers are unequal. My mains are also used for music, have 15" woofers and I don't have sub. My center and surrounds have 5 1/4" woofers. Bass has to be separately set by directing to mains and I don't want frequency differences at a hundred Hz or so affecting my channel balance.
If you use A for balancing the five channel sound, you have to do something else, probably using C weighting, to check that bass response is balanced with the five channel sound, whether the bass comed from a sub or two mains.
10-14-03, 02:41 PM
#8
DVD Talk Hero
Thread Starter
OldDude,
My centre speaker is a 75 watt 2-way DCM speaker (I forget which particular model) that has served me well for quite few years. My front left and front right speakers are a pair of 3-way Aiwa speakers (the largest cone is just over 4 inches in diameter) that came with my old Aiwa mini theatre. The woofers of my centre are about the same size as the midrange cones of my 3-way speakers. My surrounds are a pair of Sony SS-V335 mini satellite speakers. Are they close enough to use C weighting or do you believe that A weighting would be more appropriate? My main worry is that A weighting requires that my speakers would be set 2dB higher than C weighting does and I worry about wether or not I'm driving my speakers too loud.
As for setting the sub with the sound level meter, is the following the correct course of action?
Since the mini speakers are my weakest of my main five I set my receiver's crossover (my sub - a Sony Sony SA-WMS335 does not have a crossover) to 150Hz (what was reccomended for the mini satelights), set my receiver to two channel mode and my two front speakers to large. With the sound level meter set to C weighting, I measured a 100Hz tone reproduced my my two front speakers. Then I set the speakers to small and, using the same 100Hz tone, I adjusted the volume knob of my sub until the sound level meter measured the same volume as when I set my speakers to large and selected "no subwoofer".
Advice? Reccomendations? Warnings? Corrections?
My centre speaker is a 75 watt 2-way DCM speaker (I forget which particular model) that has served me well for quite few years. My front left and front right speakers are a pair of 3-way Aiwa speakers (the largest cone is just over 4 inches in diameter) that came with my old Aiwa mini theatre. The woofers of my centre are about the same size as the midrange cones of my 3-way speakers. My surrounds are a pair of Sony SS-V335 mini satellite speakers. Are they close enough to use C weighting or do you believe that A weighting would be more appropriate? My main worry is that A weighting requires that my speakers would be set 2dB higher than C weighting does and I worry about wether or not I'm driving my speakers too loud.
As for setting the sub with the sound level meter, is the following the correct course of action?
Since the mini speakers are my weakest of my main five I set my receiver's crossover (my sub - a Sony Sony SA-WMS335 does not have a crossover) to 150Hz (what was reccomended for the mini satelights), set my receiver to two channel mode and my two front speakers to large. With the sound level meter set to C weighting, I measured a 100Hz tone reproduced my my two front speakers. Then I set the speakers to small and, using the same 100Hz tone, I adjusted the volume knob of my sub until the sound level meter measured the same volume as when I set my speakers to large and selected "no subwoofer".
Advice? Reccomendations? Warnings? Corrections?
10-14-03, 03:54 PM
#9
With a "mixed bag" of speakers, I would use A-weighting and settle for getting the mid-range right. That's where you will be most sensitive to any difference between channels.
Contrary to what they say, you don't need to set your speakers to produce "reference level" (+85 dB, with a specified signal) you just need to set them all the same. Using A-weighting, you are cutting off measurement of some frequencies, and it would be fine if your speakers are 2 dB below reference.
If you really want reference level, set one to reference level with C-weighting, then go back to A-weighting, note the reading, and set all the others to be the same reading. Because A-weighting cuts off some frequencies, it should give a lowering reading that C-weighting for the same sound. With pink noise, that could be calculated, but it is a ton of calculation. Just follow above suggestion. Note if you use A-weighting, you do need to separately balance bass level in sub.
The old Avia DVD makes note of this and points out 75 dB at reference level may be more appropriate to a home environment. That's what I set.
Oops: Missed the sub question. If you have a separate sub, I don't think any of the speaker settings should be set to large. I think you want the bass from your subs. Set crossovers based on what you think the speakers can support, natively, and let the sub carry from there. My 15" are "large" and take all the bass with no sub, center and and surrounds are "small" but I'd have to check their cutoff. If I had two more amplifier channels, I would bi-amp mains and drive the woofers separately as subs, but "large fronts" works OK too.
Contrary to what they say, you don't need to set your speakers to produce "reference level" (+85 dB, with a specified signal) you just need to set them all the same. Using A-weighting, you are cutting off measurement of some frequencies, and it would be fine if your speakers are 2 dB below reference.
If you really want reference level, set one to reference level with C-weighting, then go back to A-weighting, note the reading, and set all the others to be the same reading. Because A-weighting cuts off some frequencies, it should give a lowering reading that C-weighting for the same sound. With pink noise, that could be calculated, but it is a ton of calculation. Just follow above suggestion. Note if you use A-weighting, you do need to separately balance bass level in sub.
The old Avia DVD makes note of this and points out 75 dB at reference level may be more appropriate to a home environment. That's what I set.
Oops: Missed the sub question. If you have a separate sub, I don't think any of the speaker settings should be set to large. I think you want the bass from your subs. Set crossovers based on what you think the speakers can support, natively, and let the sub carry from there. My 15" are "large" and take all the bass with no sub, center and and surrounds are "small" but I'd have to check their cutoff. If I had two more amplifier channels, I would bi-amp mains and drive the woofers separately as subs, but "large fronts" works OK too.
Last edited by OldDude; 10-14-03 at 04:12 PM.
10-14-03, 04:11 PM
#10
Just wanted to add, the built-in calibration source and procedure differs a lot between receivers. Mine was pain in the ass to use. I have old Avia DVD, but it or Video Essentials is worth getting. You can probably find online. Obviously, while you wait for it to come, you want to do best calibration you can using built in source in your receiver. But just regard it as temporary, and adjust again when you get your reference DVD. Any friends have either of the references? You only need to buy for a few hours or a day, to adjust TV, HT receiver, etc.
10-15-03, 12:24 PM
#11
DVD Talk Legend
Just to build on what OldDude mentions in his first post, I will note that although I used the sound level meter to begin my calibrations, I actually found the Video Essentials "Walk Around the Room in Voice" sequence to be much more helpful in setting the relative speaker levels, and wound up punching up my surround speaker volumes a bit over what the sound level meter says is technically accurate.
As OldDude says, your ear doesn't hear equally well at all levels. Setting the speakers strictly by the sound level meter, I could almost never hear any surround activity unless it was a particularly loud and direct effect. Adjusting to compensate so that the walk-around voice sounds even from all speakers lead to better overall results.
As OldDude says, your ear doesn't hear equally well at all levels. Setting the speakers strictly by the sound level meter, I could almost never hear any surround activity unless it was a particularly loud and direct effect. Adjusting to compensate so that the walk-around voice sounds even from all speakers lead to better overall results.
10-15-03, 03:47 PM
#12
DVD Talk Hero
Thread Starter
Thank you both very much for the advice you have offered me. For now, I've done as OldDude said I should but will keep in mind you advice, JoshZ, for whenever I may actually be able to find a copy of Digital Video Essentials.
