SPL Meter & Me (1 Viewer)

[AbelM]

Ok, so I have a question about this. I have Cast Away, so should I use this disc or not to calibrate my speakers? Also when I use Cast Away, do I need an SPL Meter to do this? Or does it do it by it self?
Please help soon, and THANX!!

 

[Brian Bunge]

Abel,

I personally would use the test tones in your receiver first. Then use some sort of disc for verification. If there's a big discrepancy then I'd stick with the receiver's test tones.

Brian

 

[RobY]

I'm with Mark on this. Educate me, please.

 

[Charles L.]

I beleive it was 2 db off. I set it to 75 db by my test tones and later checked it with VE and got 77db or something like that. Its been too long ago. My third test was sine waves from MCM Electronics. It looks like my opinion on VE's test tones are in the minority here.

 

[ColinM]

But if each channel is the same level, balanced that is, what's the harm?

I'm skeptical about the TT generator in my HK, so I use VE.

I think this may be the most analyzed part of HT.....

 

[Brian Johnson]

Well. I seem to have a hot little thread going here. I went out & bought VE last night. I may sound like the minority here but I think my reciever test tones were correct(well close enough for me) and the video test patterns were nearly useless(my tv options/setting menu blocks out 1/2 of the screen.) So i think media play is getting this one back. I dont think it was worth the 25 bucks I paid. Am I missing something on the disc. I was expecting more than just test tones in the audio dept. Sure there were some neat demonstrations, but hardly worth its weight. And as I mentioned before the video was difficult to deal with.

Like I said, am I missing something?

EDIT:

I am failing to see the problem with a test tones calibration tone to be the incorrect loudness. If all of your speakers are balanced together, then what is the problem? Can someone explain this to me?

Can some explain this also, great question mark, almost missed it)

 

[ColinM]

No, that's about it.

I hope they take it back for you...

 

[Brian Johnson]

Me Too

 

[Vin]

I am failing to see the problem with a test tones calibration tone to be the incorrect loudness. If all of your speakers are balanced together, then what is the problem? Can someone explain this to me?

Any type of calibration is only as good as the standard it's being calibrated against. In other words, using the SPL meter will allow you to adjust the outputs for each channel/speaker until it reads 75dB on the meter but if the tones being produced, by your receiver for example, aren't all at the same loudness you won't get accurate reproduction from your DVDs that were recorded at a specific loudness according to DD standards, i.e., 105dB peaks from all 5 main channels and 115dB peaks from the LFE channel...also known as Reference Level.
So, using the SPL meter and a known standard like Video Essentials (or Optimode from Fight Club) with tones recorded at 75dB for each channel, you'll be sure each speaker is indeed calibrated to the same output level after having adjusted the output from your receiver for each channel accordingly (against that known standard of 75db for each channel) and you'll also know exactly where reference level is provided you made note of where your master volume control was set prior to calibration.
Vin

 

[ColinM]

Jimmy has speaker set 'X' calibrated at 70db on the meter all around.

Bobby has the same set, calibrated at 80db on the meter all around.

Each using the same source chain all the way down to the software.

Both ok?

- CM

 

[Vin]

Jimmy has speaker set 'X' calibrated at 70db on the meter all around. Bobby has the same set, calibrated at 80db on the meter all around. Each using the same source chain all the way down to the software. Both ok?

If they both used that known standard that produced test tones at 75dB for each channel both systems would be balanced but Jimmy's system will play back 5dB below reference level when his master volume control is set where it was set during calibration.
Bobby's system will play back 5dB above reference level when his master volume control is set where it was set during calibration.
In order for Jimmy to play back at the same volume (dB level) as Bobby, he would have to adjust his master volume control 10dB higher than Bobby's.
If Jimmy wanted to playback at reference level he would have to adjust his master volume control 5dB higher than he had it during calibration, Bobby would have to adjust his 5dB lower than he had it during calibration.
I would advise both Jimmy and Bobby to calibrate to 75 dB on the meter when using 75dB test tones from a known standard....it'll make it a whole lot easier to remember exactly where reference level is.
Vin

 

[Rick Radford]

I have both VE and Avia and have calibrated with both. I found ~2 dB difference between the 2 reference discs.
Sometime back, Guy Kuo (of Avia fame) explained to me why that difference exists.. and it made sense.. but I do NOT remember what he told me!
IAC, 2 dB diff between your receiver's test tones and a reference DVD may not be unusual and may not violate any standards. One reason you may find a difference between calibration with the receiver's test tones vs the DVD is because the DVD signal is coming from the player via the associated interconnects, etc. while the receiver's test tones are internally generated.
One of the reasons to calibrate is so that you can listen at a volume based on a known reference standard. You may not like to listen at reference level and may prefer 10-15 dB under ref. I like to use 10 dB under ref (when I can get away with it!) and at night we frequently use 15 to 25 dB under ref.
There was a lengthy thread on HTF sometime back that got into calibration using built-in test tones on the receiver vs a calibration DVD like Avia or VE. I think the thread started out dealing with reference level. Best I recall, there was a camp on both sides and no consensus as to which was correct.
Here's the thread.

 

[ColinM]

I crank the VE test tone through the left channel, trim at 0db, to 75db on the meter.
Then I adjust up or down as the tone goes around on each channel.
Winds up like this -
L) 0db
R) -1db
C) -4db
SL) -3db
SR) -3db
Sub) Flat from 20hz to 75 or so, after correction, set to +3db.
They all (except the sub) wind up within .5db of each other.
End of story, enjoy the movie.
If I am missing something, I don't need it.

 

[Mark Fitzsimmons]

Hmmm, I may be failing to understand still.

Reference is 110db right? Does this mean that if I have my reciever set to -10db and I play the tones from Avia, it will come out of my speakers at 75db? However, when I play a DVD on my system with my reciever set to -10db it will play at 110db?

So the importance of knowing how loud your test tones play is only to know where referance is, right?

 

[AbelM]

SO are you saying that Fight Club and Cast Away have the best Optimode? If so, and after you use your own receivers test tones, should I use this Optimode off of Cast Away? Do I need an SPL meter or not fo rthis job??

 

[BruceD]

Actually the whole point of using a known calibrated test tone, like VE's 75dB, is precisely to set the entire HT speaker volume to a known reference standard. Typically these test tones (like VE) are -30dB less (quieter) than full "Reference Volume".
This means if I play the movie at a volume setting of Zero "0" (typically referred to as "Reference Volume") I will be receiving 105dB SPL levels at my seat from the main speakers (75dB test tone + 30dB) and 115dB at my seat from the LFE bass (75dB test tone + 30dB + 10dB).
This means I'm listening to what the director intended me to hear exactly the way he intended me to hear it, although I actually may prefer to listen at a lower volume like -10dB or more on my receiver's volume control.
If you use the test tones and SPL meter to calibrate the speaker's SPL output to something other than 75dB (like 60dB or 80dB), you won't have a common reference point to compare with other people's impressions. Will it actually alter the soundscape, I don't really know, but . . .
Our ears don't have a linear response to all frequencies, that means when we lower the overall volume we lose more volume in the lower bass frequencies than in the higher frequencies.

 

[Kevin C Brown]

Yeah, yeah!
If I don't care what the reference is, and just make sure that all my speakers match at *some* sound level pt, should be OK, right?
And, in actuality, usually ends up to be middle 70's-ish anyway!

 

[Rick Radford]

Just a minor input on this:

This means if I play the movie at a volume setting of Zero "0" (typically referred to as "Reference Volume") I will be receiving 105dB SPL levels at my seat from the main speakers (75dB test tone + 30dB) and 115dB at my seat from the LFE bass (75dB test tone + 30dB + 10dB)

That should read peaks of 105/115 dB... not continuous SPLs that high. Also note that YOUR ref level as calibrated in your HT may not be at 0 (relative). In my case, I did like Colin and set the MV to 0 and then adjusted (trimmed) the speakers to 75dB with VE (and I used -10 MV and also set 75dB with Avia.. that way, MV=0 equalled Avia at 85 dB). I found Avia/85 dB a bit loud for my tastes while calibrating. Be advised that some will take exception to my method of using simple arithmetic to lower the SPLs while calibrating with Avia.. and perhaps rightly so. But I'm happy with it.
If using the receiver's test tones, I believe that THX receivers automatically set the MV to 0 and use 75 dB for calibration levels. I don't know about non-THX receivers.
I keep meaning to take my geek meter.. er, I mean SPL meter to the theater with me to see how close to ref they actually run. But we seldom go and I have yet to remember!
It can be confusing trying to understand ref level and how the calibration discs work being recorded at -20 and -30 dBFS. But once you see it, it makes sense.

 

[Mark Fitzsimmons]

I have the Terminator 2 DVD which has the TXH Optimode test tones, it says on screen they are 75db, but is this right? Should I use these to calibrate my speakers or just use the test tones on the receiver?

 

[BruceD]

Thanks for clarifying that for me Rick.

I get writing and my head gets ahead of my fingers.