Room Response - comments, please! - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 25 Old 04-06-13, 07:56 AM Thread Starter
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Room Response - comments, please!

Hi Folks,

I am re-visiting some REW room response plots I did a while ago and would appreciate any comments.

Please take a look at the attached plot. This is a stereo pair of Fostex FE167E full-range drivers each supplemented with an HiVi TN28 supertweeter. The response was measured using the Behringer ECM8000 microphone, which was located in the listener position. The room is 5.5m (L) x 3.5m (W) x 2.5m (H). The plot shows the LH channel (purple), RH channel (blue) and the averaged response (green). One-third octave smoothing has been used.

Despite the use of the TN28 supertweeters, HF roll-off is apparent beyond 3.5kHz. It is 3dB down at 6kHz and almost 8dB at 10kHz. I am also curious about the dip between 100Hz and 700Hz reaching a trough at 200Hz.

Would anyone care to shed light on these observations?

Thanks in advance.

JPC
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post #2 of 25 Old 04-06-13, 08:55 AM
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Re: Room Response - comments, please!

Is there a calibration curve in use for the mic? The HF rolloff looks like what one might find from the mic's natural response.
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post #3 of 25 Old 04-06-13, 09:28 AM
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Re: Room Response - comments, please!

My understanding is that gentle falloff is natural. If you were to have a flat even line that stays even with the rest in those frequencies your ears would hurt particularly at higher volumes.

Home theater:
Onkyo 805, Yamaha YDP2006EQ, Samson Servo 600 amp
3 EV Sentry 500 monitors across the front, 4 Mission 762i's Surrounds, SVS PB13U sub, Panasonic BDT220, Harmony 1100, Nintendo WiiU
Panasonic PT-AE8000 on a 120" 2,35:1 fixed screen

Living room system:
Sherwood/Newcastle R972, Mission 765's, SVS SBS02's, A/D/S MS3u sub, Yamaha YDG2030EQ
Yamaha KX-393 Tape deck, CDC 805 CD changer, Panasonic BD60, Sony turntable PS-T20
Panasonic TC-P50ST60, HD-PVR & WDTV Live, Harmony 900

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post #4 of 25 Old 04-06-13, 09:48 AM Thread Starter
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Re: Room Response - comments, please!

Quote:
AudiocRaver wrote: View Post
Is there a calibration curve in use for the mic? The HF rolloff looks like what one might find from the mic's natural response.
Hi AudiocRaver,

Thanks for your reply.

Yes, I used the calibration file that is available on this site.

Perhaps tonyvdb is correct? It just seems like a significant loss in HF but I'm really not sure. What kind of response is to be expected in the listening position? And what about that 200Hz trough?

JPC
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post #5 of 25 Old 04-06-13, 09:54 AM Thread Starter
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Re: Room Response - comments, please!

Quote:
tonyvdb wrote: View Post
My understanding is that gentle falloff is natural. If you were to have a flat even line that stays even with the rest in those frequencies your ears would hurt particularly at higher volumes.
Hi tonyvdb,

Thanks for the reply.

Your point that "gentle falloff is natural" makes sense but is this a case of gentle falloff? As I said above, the response is 3dB down at 6kHz and almost 8dB at 10kHz. That seems a lot. Presumably, it would be different with headphones in that the HF would be at much the same level as the rest of the response?

JPC

Last edited by jaypeecee; 04-06-13 at 10:00 AM. Reason: Clarification.
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post #6 of 25 Old 04-06-13, 09:57 AM
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Re: Room Response - comments, please!

It seems a little bit much however even my EV 500 studio monitors exhibit the same roll off above 10k using the same mic your using. They are flat 35-18,000Hz

Home theater:
Onkyo 805, Yamaha YDP2006EQ, Samson Servo 600 amp
3 EV Sentry 500 monitors across the front, 4 Mission 762i's Surrounds, SVS PB13U sub, Panasonic BDT220, Harmony 1100, Nintendo WiiU
Panasonic PT-AE8000 on a 120" 2,35:1 fixed screen

Living room system:
Sherwood/Newcastle R972, Mission 765's, SVS SBS02's, A/D/S MS3u sub, Yamaha YDG2030EQ
Yamaha KX-393 Tape deck, CDC 805 CD changer, Panasonic BD60, Sony turntable PS-T20
Panasonic TC-P50ST60, HD-PVR & WDTV Live, Harmony 900

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post #7 of 25 Old 04-06-13, 10:13 AM Thread Starter
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Re: Room Response - comments, please!

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tonyvdb wrote: View Post
It seems a little bit much however even my EV 500 studio monitors exhibit the same roll off above 10k using the same mic your using. They are flat 35-18,000Hz
Hi tonyvdb,

Thanks again.

When you say "They are flat 35-18,000Hz", is that in the listening position? If so, then what I'm seeing with my setup is very different. At 18kHz, the response is 16dB down at the listening position with my setup.

JPC
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post #8 of 25 Old 04-06-13, 10:20 AM
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Re: Room Response - comments, please!

Sorry, I meant to say the Specifications on the speakers are flat. My measured response with the sub is below.

Home theater:
Onkyo 805, Yamaha YDP2006EQ, Samson Servo 600 amp
3 EV Sentry 500 monitors across the front, 4 Mission 762i's Surrounds, SVS PB13U sub, Panasonic BDT220, Harmony 1100, Nintendo WiiU
Panasonic PT-AE8000 on a 120" 2,35:1 fixed screen

Living room system:
Sherwood/Newcastle R972, Mission 765's, SVS SBS02's, A/D/S MS3u sub, Yamaha YDG2030EQ
Yamaha KX-393 Tape deck, CDC 805 CD changer, Panasonic BD60, Sony turntable PS-T20
Panasonic TC-P50ST60, HD-PVR & WDTV Live, Harmony 900

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post #9 of 25 Old 04-06-13, 10:50 AM
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Re: Room Response - comments, please!


Quote:
jaypeecee wrote: View Post
Yes, I used the calibration file that is available on this site.
Our calibration file is generic; you can’t be absolutely certain that your measured response is accurate without a custom calibration file. Mic orientation can make a difference too, whether or not you measured with it pointing at the speaker.

Regards,
Wayne



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post #10 of 25 Old 04-06-13, 12:33 PM
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Re: Room Response - comments, please!

As Wayne P. says, using the generic cal file could easily leave you with that amount of error.

As far as how flat you want it to be, it depends on your room. In a fairly live typical home theater or music listening room, the high-frequency buildup due to reflections will indeed seem harsh with a flat response. The rolloff you see is not too far from some suggested "target curves" for rooms like that, the intent being to help tame that harshness. A studio control room or mixing room, with well-damped acoustics, is generally tuned for flat response and it seems "just right" because of those acoustics.
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