"These go to eleven."

[MDS]

A stronger amp would give me the ability to listen to louder volumes without clipping and it'd fill a larger space without straining

That pretty much sums it up. If you have to have your amp/receiver near max volume to get the kind of SPL you want then it is working really hard and a more powerful amp is required.

You're in good company here Chris, we all like to discuss the theory and learn the 'truth' about this stuff. I've answered the 'reference level' type questions dozens of times and will continue to do so. The only question I don't answer is 'which receiver should I buy' because most people don't want to hear 'pick one - they're all similar'.

 

[annunaki]

I was under the impression that Dolby reference level was 85dB. Am I missing something here?

I believe that is the level at which the system should be calibrated with pink/white noise.

 

[ronnie 1.8]

If you use DVE or the receiver's test tones, you would calibrate so that the meter reads 75 dB because those tones are at -30 dB.

MDS, just came across this thread, and find it very helpful. You write that the receiver's test tones are at -30 db. Are the test tones of my Denon AVR3805 -30 db, as well? I don't recall seeing this published in Denon's user manual. I always feel rushed to leave the channel level menu, as the pink noise at that volume is most unpleasant! I see the Radio Shack units mentioned here and there in these forums. Do they seem to be good for this purpose?

 

[AVRat]

Yes, Denon’s tones are at -30dB. Unless you’re trying to calibrate your receiver so that 0dB is reference level, any volume level can be used to just balance the speaker levels. Yes, the RS SPL meters work well.

 

[ronnie 1.8]

Yes, Denon’s tones are at -30dB. Unless you’re trying to calibrate your receiver so that 0dB is reference level, any volume level can be used to just balance the speaker levels. Yes, the RS SPL meters work well.

I've ordered the Radio Shack SPL meter. I wish to set the channel levels for both my AVR and player. Do I simply adjust the level of each channel until it reads 75db (105dB minus 30dB)? Is the subwoofer level adjusted the same way? That seems more a personal preference? Also, does the AVIA Guide to Home Theater (1999) remain a good source to set my channel levels? Being out 7 years, I'm wondering if there is another preference? AVIA is $42 (Amazon), while Digital Video Essentials is $25 (Video Essentials.com). Again, I'm looking to setup my channel levels only. Many AVR's have built-in test tones (including my Denon AVR3805), but AVIA believes it best to use the test tones on their disc.

 

[mtrycrafts]

I've ordered the Radio Shack SPL meter. I wish to set the channel levels for both my AVR and player. Do I simply adjust the level of each channel until it reads 75db (105dB minus 30dB)? Is the subwoofer level adjusted the same way? That seems more a personal preference? Also, does the AVIA Guide to Home Theater (1999) remain a good source to set my channel levels? Being out 7 years, I'm wondering if there is another preference? AVIA is $42 (Amazon), while Digital Video Essentials is $25 (Video Essentials.com). Again, I'm looking to setup my channel levels only. Many AVR's have built-in test tones (including my Denon AVR3805), but AVIA believes it best to use the test tones on their disc.

Home components have their test tones at -30dB of full scale. Theaters set up at -20dB. That would be way too loud at home. A few test DVDs does have -20 dB FS test tones, others are at -30.

If you want your setup properly calibrated, you need to set the master volume control to 0, if your receiver offers positive values on the master volume control as some do, like Onkyo.

Then, you set each channel to 75dB spl on the RS meter. The sub, you add a few as the meter is not accurate in the low band.

 

[PENG]

Hi, MDS,

At this point the amp is still sending 1 watt of power. So to get back to 87 dB, I need the amp to add enough power to increase the SPL by 12 dB. It would work like this

1 w = 75 dB/4 m
2 w = 78 db/4 m
4 w = 81 db/4 m
8 w = 84 dB/4 m
16 w = 87 dB/4 m

Or thinking of it another way, for every 10 dB increase in SPL, I need an order of magnitude in power increase from the amp, assuming the same conditions:

1 w = 75 dB
10 w = 85 dB
100 w = 95 dB

On top of that, I can use the amp's volume scale to tell me approximately what percentage of the amp's power I'm using, depending where I am on the scale. Do I have all this right?

Chris

P.S. OK, feel free to hit me with your available rail voltage now.

I think your numbers (based on the inverse square law) apply only in free field, e.g. outdoor situation. In a room it behaves differently depending on the room's acoutical environment. In my room, the SPL does not drop that much as I walked away from the source.

 

[ronnie 1.8]

Unless you’re trying to calibrate your receiver so that 0dB is reference level, any volume level can be used to just balance the speaker levels.

What seems to be the difficulty w/ trying to calibrate a receiver so that 0dB is reference level? One suggestion immediately above by MTRYCRAFTS is to first set the AVR to 0dB, then set each channel to 75dB measured by the RS meter. Seems reasonable. Perhaps the RS unit is not accurate for this?

I notice the article under Audioholics left-nav "Set-Up Your System", then "Setting Speaker Levels & Distance in a Surround Sound System" advises to use the test tone generated by one's receiver/preamp, while AVIA suggests using the test signals on their discs, as they claim pink noise...

"...don't have the same [recommended shape] spectral distribution and consequently result in different speaker level settings. Another reason to use AVIA DVD's test signals rather than built-in tones is that doing so checks your entire playback chain from source to speakers. Setting your system to play back AVIA's test signals correctly compensates for variances caused by your playback equipment."

Why doesn't the above Audioholics article address setting one's receiver so that 0dB is reference level? Is it simply not too important? I can easily see how I listen to my system based on my personal comfort, not the volume indicated by my AVR, so perhaps it's not relevant.

My other question, what is the proper way to level my channels - by using my AVR's test tones, or by using an external source, such as the AVIA disc?

 

[AVRat]

What seems to be the difficulty w/ trying to calibrate a receiver so that 0dB is reference level? One suggestion immediately above by MTRYCRAFTS is to first set the AVR to 0dB, then set each channel to 75dB measured by the RS meter. Seems reasonable. Perhaps the RS unit is not accurate for this?

The problem would present itself if the room is too big for the capability of the ampage. IOW, if the room is too big, the channel levels are pushed higher to reach reference level, thereby overtaxing the amps. IIRC, your room is smaller so this shouldn’t be an issue with the 3805 & PSBs.

I notice the article under Audioholics left-nav "Set-Up Your System", then "Setting Speaker Levels & Distance in a Surround Sound System" advises to use the test tone generated by one's receiver/preamp, while AVIA suggests using the test signals on their discs, as they claim pink noise...

"... Another reason to use AVIA DVD's test signals rather than built-in tones is that doing so checks your entire playback chain from source to speakers. Setting your system to play back AVIA's test signals correctly compensates for variances caused by your playback equipment."

This is more or less a double-check for your system. But, for the most part, unless you can set settings for each input it’s irrelevant.

Why doesn't the above Audioholics article address setting one's receiver so that 0dB is reference level? Is it simply not too important? I can easily see how I listen to my system based on my personal comfort, not the volume indicated by my AVR, so perhaps it's not relevant.

I don’t know, but like you, most people don’t listen at reference levels, most of the time I don’t.

My other question, what is the proper way to level my channels - by using my AVR's test tones, or by using an external source, such as the AVIA disc?

In your case the AVR's test tones will work fine for the audio, but these calibration discs can also help you adjust the picture quality of your display. That’s all I use DVE for.

Perhaps, others will chime in with additional input or correct anything I may misstate.

 

[mtrycrafts]

What seems to be the difficulty w/ trying to calibrate a receiver so that 0dB is reference level? One suggestion immediately above by MTRYCRAFTS is to first set the AVR to 0dB, then set each channel to 75dB measured by the RS meter. Seems reasonable. Perhaps the RS unit is not accurate for this?

I notice the article under Audioholics left-nav "Set-Up Your System", then "Setting Speaker Levels & Distance in a Surround Sound System" advises to use the test tone generated by one's receiver/preamp, while AVIA suggests using the test signals on their discs, as they claim pink noise...

"...don't have the same [recommended shape] spectral distribution and consequently result in different speaker level settings. Another reason to use AVIA DVD's test signals rather than built-in tones is that doing so checks your entire playback chain from source to speakers. Setting your system to play back AVIA's test signals correctly compensates for variances caused by your playback equipment."

Why doesn't the above Audioholics article address setting one's receiver so that 0dB is reference level? Is it simply not too important? I can easily see how I listen to my system based on my personal comfort, not the volume indicated by my AVR, so perhaps it's not relevant.

My other question, what is the proper way to level my channels - by using my AVR's test tones, or by using an external source, such as the AVIA disc?

I used that 0 dB for reference levels as I have experience with THX rated receivers at friends. When one starts the calibration procedure, the master volume control goes to 0 automatically.
Using a test CD, you'd be blindly accept that their test tones are actually at the right level and all channels are equal. Maybe, next time there, I'll play with both methods and even check the spectral content of the test DVD compared to internal tones.

 

[PENG]

I used that 0 dB for reference levels as I have experience with THX rated receivers at friends. When one starts the calibration procedure, the master volume control goes to 0 automatically.
Using a test CD, you'd be blindly accept that their test tones are actually at the right level and all channels are equal. Maybe, next time there, I'll play with both methods and even check the spectral content of the test DVD compared to internal tones.

I played with both methods a few times, and the results were similar.

 

[ronnie 1.8]

I used that 0 dB for reference levels as I have experience with THX rated receivers at friends. When one starts the calibration procedure, the master volume control goes to 0 automatically.
Using a test CD, you'd be blindly accept that their test tones are actually at the right level and all channels are equal. Maybe, next time there, I'll play with both methods and even check the spectral content of the test DVD compared to internal tones.

Ha! I never knew the AVR would go to 0dB when running test tones. After reading this, I tested and confirmed. Thanks for that information! So I test and trim as necessary each channel to 75dB. My installer did set my AVR's and player's channel levels upon installation last Nov, but I've since changed players, so will need to measure/adjust when I receive my RS SPL meter. I'll also measure the AVR's channels to see if they've changed as the speakers went from new to broken-in.

 

[ronnie 1.8]

What seems to be the difficulty w/ trying to calibrate a receiver so that 0dB is reference level? One suggestion immediately above by MTRYCRAFTS is to first set the AVR to 0dB, then set each channel to 75dB measured by the RS meter. Seems reasonable. Perhaps the RS unit is not accurate for this?

The problem would present itself if the room is too big for the capability of the ampage. IOW, if the room is too big, the channel levels are pushed higher to reach reference level, thereby overtaxing the amps. IIRC, your room is smaller so this shouldn’t be an issue with the 3805 & PSBs.

You are right, my room is 196 sq ft, and very bizarre in shape. It has 11 sides, and I'm only using about 60% of the room for my system, though I do have some room treatment in the other 40%.

 

[mtrycrafts]

Perhaps, others will chime in with additional input or correct anything I may misstate.

The problem would present itself if the room is too big for the capability of the ampage. IOW, if the room is too big, the channel levels are pushed higher to reach reference level, thereby overtaxing the amps. IIRC, your room is smaller so this shouldn’t be an issue with the 3805 & PSBs.

Not sure that was also you input above or not.

If the room is so large and listening levels are such that the speakers and power available is insufficient, where you level match the speakers is really immaterial.
If you reduce the master volume control, then you have to make that up by increasing the trim pots to reach the 75 dB spl. If you don't use 75 but a lower number as you decrease the master volume, you will still increase the master volume to hear it with program and will over tax the amp, if that was an issue in the beginning.

 

[ronnie 1.8]

The problem would present itself if the room is too big for the capability of the ampage. IOW, if the room is too big, the channel levels are pushed higher to reach reference level, thereby overtaxing the amps. IIRC, your room is smaller so this shouldn’t be an issue with the 3805 & PSBs.

Not sure that was also your input above or not.

If the room is so large and listening levels are such that the speakers and power available is insufficient, where you level match the speakers is really immaterial.

If you reduce the master volume control, then you have to make that up by increasing the trim pots to reach the 75 dB spl. If you don't use 75 but a lower number as you decrease the master volume, you will still increase the master volume to hear it with program and will over tax the amp, if that was an issue in the beginning.

I originally asked, "What seems to be the difficulty w/ trying to calibrate a receiver so that 0dB is reference level? One suggestion immediately above by MTRYCRAFTS is to first set the AVR to 0dB, then set each channel to 75dB measured by the RS meter. Seems reasonable. Perhaps the RS unit is not accurate for this?"

and then AVRat responded with "The problem would present itself if the room is too big for the capability of the ampage. IOW, if the room is too big, the channel levels are pushed higher to reach reference level, thereby overtaxing the amps. IIRC, your room is smaller so this shouldn’t be an issue with the 3805 & PSBs."

AVRat is correct, I believe, in that my PSBs can more than fill my 196 sq ft room, with plenty to spare. Using my AVRs test tones, I should easily be able to adjust my trim to measure each speaker at 75dB. Just waiting for my SPL meter to arrive. I mainly want to ensure my channels are level.

 

[mtrycrafts]

I played with both methods a few times, and the results were similar.

Good to hear. Some tests DVDs are very accurate. One I use on occasion for full range pink noise is withing .2dB spelled out in the instructions, no guessing about accuracy.

If you have Avia, I think that may use a -20dBFS where as others use -30. I found when comparing, there were not a 10dB difference on the meter but around 7.

 

[mtrycrafts]

I'll also measure the AVR's channels to see if they've changed as the speakers went from new to broken-in.

Waste of time. If you do see a difference, then one has to question the accuracy of the two time delayed measurements. Don't forget the spl meter differences, etc.
There is a paper here on the home page about speaker break in with plots. You can barely see the divergence in the plot, and, at the frequency where it does, the JND is well above the differences.

 

[ronnie 1.8]

Waste of time. If you do see a difference, then one has to question the accuracy of the two time delayed measurements. Don't forget the spl meter differences, etc.
There is a paper here on the home page about speaker break in with plots. You can barely see the divergence in the plot, and, at the frequency where it does, the JND is well above the differences.

This comment fits with what I experienced. At the AVR, I changed the dB level from not at all on a couple channels, 0.5dB on maybe 2 channels, and 1dB on the other 2. The changes I made will probably not be noticed by my ears, but I did make a few minor changes, and it's nice to know that my levels are balanced and at reference.

The channel level changes I made at the DVD player were similar. They are balanced and at reference level. Relatively speaking, I'm sure. The Radio Shack SPL meter isn't something Widescreen Review would be using for their holosonic reference theatre.