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Dale M
05-10-2004, 03:33 PM
Hi.
I borrowed and SPL meter from work today and am about to calibrate my HT
I know somewhere here I was reading all about how to do it but thought Id ask instead of searching for a week to find the article.
So here's my plan of how to do this, please correct me if Im wrong..
First I set the receiver volume to-15 then get the test tone doing its thing and from the sitting position I then adjust the db level of each speaker until I get all of them as close as possible to each other according to the SPL.. Is that right?? should I use the A or C weighting on the meter?if for example the front left needs to come down 3dbs should I move it down or the others up? , is keeping them all as close to zero a good thing?, or if 1 speaker needs to come way down is it better to move all the others up?
Im finding this kinda tricky as the test tone moves from 1 speaker to the the next pretty fast.
Thanks
Dale M

Dale M
05-10-2004, 03:45 PM
Hi Again
on my first attempt at this it appears Both my back speakers need to come down,, the back left down to -7 the back right to - 6,, is that ok or should I move the fronts up a few dbs and try to stay closer to the center by bringing the front level up??

cam
05-10-2004, 04:26 PM
Hi Again
on my first attempt at this it appears Both my back speakers need to come down,, the back left down to -7 the back right to - 6,, is that ok or should I move the fronts up a few dbs and try to stay closer to the center by bringing the front level up??
If your amp volume goes from -60db to +18db set it at 0db. Set your spl on fast and C wieghting and from your listening position set each speaker to + or - so it reads 75db. Do not change your master volume away from 0db. When you are done you could have some speakers in the + and some in the - , it doesn't matter what they are set at aslong as they are all reading 75db at your listening position. 0db is now your reference. If your master volume goes from neg. whatever to 0 being full volume then you pick -20 or-25 on your master volume, set each speaker individually from there. In this case just remember what your reference is. Your sub should be about 4 db higher, maybe more or less depending on your preference.

Woochifer
05-10-2004, 04:27 PM
In general, you should use the C weighting and the fast setting on the SPL meter. What you should do first is establish a reference level with the two main speakers. It doesn't have to do with the volume position on the receiver, but with the actual output volume (although so long as you're consistent, it doesn't really matter). I typically use a reference level of 75 db, which is close to my normal listening volume, while others recommend going to 80 or 85 db as the reference level.

First thing to do is make sure that the L-R balance between the two main speakers is correct. Once you have those two channels equal, THEN you set the subwoofer, center, and surround speakers and adjust those levels until all channels are equal. The levels on those channels are designed to vary, whereas it's common for the L/R mains to not have a separate level adjustment available. That's why it's more practical to use the L/R speaker levels as the reference, rather than the center speaker.

Another thing to consider, the bass frequencies measure and sound a little differently than the higher frequencies because 1) human hearing is less sensitive in the lower frequencies; and 2) the RS SPL meter is less sensitive once you go below about 60 Hz. Because of this, a lot of people on this board recommend that you set the subwoofer level about 4 to 8 db higher than the mains (keep in mind that if your room acoustics create big bass peaks, then you will need to correct those problems before boosting the subwoofer level, otherwise the bass will sound way too boomy).

Also, I would suggest that you calibrate your system to the test tones on a calibration DVD like Avia, Digital Video Essentials, or the less expensive Sound & Vision Home Theater Setup disc. This is because the wideband test tones generated by most receivers include a lot of the bass range, and in rooms with acoustical issues, this can give you erroneous readings. The test tones on those calibration discs are narrow band and more accurate for what will actually play through your speakers.

Lastly, if you have a camera tripod, mount the SPL meter on it and angle it at about 45 degrees pointing towards the center (you should try and hold it that way even without a tripod). This ensures that the meter will consistently measure from the same height (which should be right at ear level), and that sound waves bouncing off your body don't give you erroneous readings. The tripod just gives you an added level of consistency and accuracy.

Woochifer
05-10-2004, 04:36 PM
If your amp volume goes from -60db to +18db set it at 0db. Set your spl on fast and C wieghting and from your listening position set each speaker to + or - so it reads 75db. Do not change your master volume away from 0db. When you are done you could have some speakers in the + and some in the - , it doesn't matter what they are set at aslong as they are all reading 75db at your listening position. 0db is now your reference. If your master volume goes from neg. whatever to 0 being full volume then you pick -20 or-25 on your master volume, set each speaker individually from there. In this case just remember what your reference is. Your sub should be about 4 db higher, maybe more or less depending on your preference.

That SPL level for a specific master volume level can vary considerably from model to model, and from speaker to speaker, and from source to source. The key is not to recommend a specific volume position, but a consistent output level, whether that be 75 db or 85 db or whatever. I know that if my receiver were set to 0 on the volume position, the actual measured SPL would be well over 100 db, and even at -20 db, it would still be somewhere close to 90 db, and that's just with one particular calibration DVD. With the internal test tone generator, the playback levels are even higher. Also, consider the variation in speaker efficiencies out there. A volume position that causes my speakers to output around 75 db, might sustain a level of 90+db with some Klipsch or Avantgarde models.

Dale M
05-10-2004, 05:30 PM
Hi
I tryed out this SPL and heres what I get,, I dont have a test tone dvd so I am only going by the test tones that my HK225 puts out..I set the master volume to -12,,that where I normally listen to it,,,the receiver has no test tons for the sub, I sit about 12 feet back from the tv and main speakers, the center is on top the tv and the left surround is about 8 feet the the left of the listening position(sp)l and straight in line and the right surround is also 8 feet to the right but it had to go back about 3 feet behind . heres what I got
sound like it could be close?
front left +1
center 0
front right +1
surround right -3
surround left -6
I will listen to the beginning of swat to see if I hear a difference,, have always used this dvd
when changing anything,,
Thanks Guys:)

Dale M

cam
05-10-2004, 06:45 PM
That SPL level for a specific master volume level can vary considerably from model to model, and from speaker to speaker, and from source to source. The key is not to recommend a specific volume position, but a consistent output level, whether that be 75 db or 85 db or whatever. I know that if my receiver were set to 0 on the volume position, the actual measured SPL would be well over 100 db, and even at -20 db, it would still be somewhere close to 90 db, and that's just with one particular calibration DVD. With the internal test tone generator, the playback levels are even higher. Also, consider the variation in speaker efficiencies out there. A volume position that causes my speakers to output around 75 db, might sustain a level of 90+db with some Klipsch or Avantgarde models.
That is what I was told in the past and was under the impression that if my master volume is set at 0 and all my speakers were adjusted independently to all read 75db from my listening level then 0 on my master volume was my reference point. Most of my movies I listen at -5db under reference.

Sir Terrence the Terrible
05-11-2004, 10:16 AM
That is what I was told in the past and was under the impression that if my master volume is set at 0 and all my speakers were adjusted independently to all read 75db from my listening level then 0 on my master volume was my reference point. Most of my movies I listen at -5db under reference.

Man you guys watch your movies loud. If I even tried to listen to my system at a reference level of anywhere near 75db, the bass would cause my guts to fall out and my head to explode!

Using my IVE 333 PDA do everything meter, I measured a overall peak SPL of 112db(75db reference) from my system while playing the Superbit version of Air Force One(Dts). It was very clean and powerful, but I would never do this again. I am sure my neighbors hate me