SPL calculation and Reference Levels
Greetings! I've been toying around with performing some calculations on my Polk 705's and seeing how close to reference levels for Home Theater I can push these speakers. I understand that the speakers have a 88dB sensitivity at 1 meter 1 watt. Assuming the main listening position is 12.5 feet, which translates to around 4dB loss per meter for dispertion according to most websites. Then we have a doubling of the power for each additional 3dB raise in volume.
Some questions below:
- When using a subwoofer how can one calculate the load removed from the avr /amp?
- How accurate is Audyssey XT32 for setting reference levels? Should I follow up with REW sending additional test tones?
- Movie content louder than -15dB, -10dB starts to sound a bit harsher especially on the high end. MultEQ is used to cut off the filters at 300hz to all speakers. Is this a sign of poor room acoustics? or distortion?
Gear:
Polk 705 LR crossover 80hz (Amp Outlaw 2200's (2) 200 Watt /channel)
Polk 706c Center crossover 80hz ( Amp Outlaw 2200 200 Watt/channel)
Polk Fxi A4 RS LS crossover 80hz (Denon X4400h 125 Watt/channel)
Rhytmik E15HP Subwoofer
Realistically I stay around -15dB or -10 dB max as reference is too loud. But how would I go about methodically testing the performance? I want to pick up a MiniDSP UMIK-1 and start playing with REW measurements. Any input would be appreciated.
Calculator used:
https://myhometheater.homestead.com/splcalculator.html
Some questions below:
- When using a subwoofer how can one calculate the load removed from the avr /amp?
- How accurate is Audyssey XT32 for setting reference levels? Should I follow up with REW sending additional test tones?
- Movie content louder than -15dB, -10dB starts to sound a bit harsher especially on the high end. MultEQ is used to cut off the filters at 300hz to all speakers. Is this a sign of poor room acoustics? or distortion?
Gear:
Polk 705 LR crossover 80hz (Amp Outlaw 2200's (2) 200 Watt /channel)
Polk 706c Center crossover 80hz ( Amp Outlaw 2200 200 Watt/channel)
Polk Fxi A4 RS LS crossover 80hz (Denon X4400h 125 Watt/channel)
Rhytmik E15HP Subwoofer
Realistically I stay around -15dB or -10 dB max as reference is too loud. But how would I go about methodically testing the performance? I want to pick up a MiniDSP UMIK-1 and start playing with REW measurements. Any input would be appreciated.
Calculator used:
https://myhometheater.homestead.com/splcalculator.html
Comments
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After you have run Audyssey XT32 what do the levels and corrections look like for each speaker?
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After you have run Audyssey XT32 what do the levels and corrections look like for each speaker?
This can vary with my mic placement. But the last run was below. I tend to bump my center up by +1 and lower my surrounds by -3. DynamicEQ seems to do weird things with the rears always being too loud.
L +2
R +2.5
C - 0.5
RS - 3.0
LS - 2.5
SUB: - 6.0
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You could by a meter or download an app.
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You could by a meter or download an app.
I've got this BAFX Advanced SPL Meter. I guess I'll send some signals through REW and measure:
https://www.amazon.com/gp/product/B00P1D84N6 -
Use your ears, there's nothing better.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I have heard "flat" before and it left me wanting.
Tom~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~ -
I've never cared for DynamicEQ. Were those numbers after to bumped the center and cut the surrounds. I wonder why Audyssey XT32 wants to cut 3db at 2k for all your speakers, must be some room issue.
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I don't understand why changing an individual speaker a few Dbs flattens out its frequency response. Did you have the other speakers playing at the same time and the microphone was averaging them in too? And if you had them all playing why does the sub not show anything over 500 Hz.
You should recheck the response at your listening location. Then play some white noise and toggle thru the speakers and make sure they are all playing at the same SPL. -
Why would any sub need to hit 500 Hz?
I think those old hand cranked victrolas hit 500 Hz. -
I've never cared for DynamicEQ. Were those numbers after to bumped the center and cut the surrounds. I wonder why Audyssey XT32 wants to cut 3db at 2k for all your speakers, must be some room issue.
That’s built in to their curve for all speakers. I can disable it with the app. Coined as the BBC dip. Info is below.
https://audyssey.zendesk.com/hc/en-us/articles/212347863-Midrange-Compensation
Post edited by pawelmwo on -
I don't understand why changing an individual speaker a few Dbs flattens out its frequency response. Did you have the other speakers playing at the same time and the microphone was averaging them in too? And if you had them all playing why does the sub not show anything over 500 Hz.
You should recheck the response at your listening location. Then play some white noise and toggle thru the speakers and make sure they are all playing at the same SPL.
Audyssey only corrects subwoofers to 250hz. Each speaker is measured individually. The after curves are just filter simulations. Not actual measured room response.
Post edited by pawelmwo on -
you don't need to run full speaker scans for each speaker with the Audyssey to get your speakers set up. Is there a mode where it just gives a single number for combined SPL in dBs? To set up your speakers all you need to do is play the white noise test tone, sit in your listening position, then toggle thru the speakers and make sure each speaker is playing at the same dB level. That is all you can do with the speaker setup AV controls. This can also be done with a free noisemeter app on your smartphone. Even if the apps are not as accurate getting the speaker to match up exactly to an arbitrary dB level is unimportant. The only thing that matters is they all play at the same level.
Later you can play with the tone controls to try and even out the response.
