Cornwall, room response figures.

[Klipschguy]

Okay, Using a test CD and an SPL meter, I've compiled a list of in room response numbers for my Cornwalls and the Cornwalls with an M&K Volkswoofer sub (Cornwalls run full range with sub, so they share in the bass reponsibilities).

My room is 20' X 30' with cathedral ceiling. Cornwalls are toed-in in the corners of short wall. Sub is on a long wall about four feet down from a rear corner. Measurements were made from my listening spot, which is beteeen the speakers, slightly to the left, and about 2/3 of the way back in the room.

Reference level= 76dB @ 1000Hz

20Hz= 70dB..........without sub= 60dB

25Hz= 74dB..........without sub= 62dB

31.5Hz= 75dB........without sub= 66dB

40Hz= 78dB..........without sub= 71dB

50Hz= 84dB..........without sub= 78dB

63Hz= 85dB..........without sub= 86dB

80Hz= 82dB..........without sub= 83dB

100Hz= 81dB.........without sub= 81dB

125Hz= 83dB.........without sub= 83dB

160Hz= 83dB.........without sub= 83dB

200Hz= 78dB.........without sub= 77dB

250Hz= 78dB

250Hz= 78dB

315Hz= 73dB

400Hz= 76dB

500Hz= 77dB

630Hz= 76dB

800Hz= 73dB

1000Hz= 76dB (reference level)

1250Hz= 75dB

1600Hz= 75dB

2000Hz= 75dB

2500Hz= 75dB

3150Hz= 78dB

4000Hz= 76dB

5000Hz= 82dB

6300Hz= 86dB

8000Hz= 87dB

10,000Hz= 82dB

12,500Hz= 77dB

16,000Hz= 66dB

20,000Hz= 61dB

I'm no expert, but it looks like I'm getting most of the audible spectrum here. To my ears, the last two fequencies were basically inaudible, so I'm not so sure a roll off here makes a bunch of difference to my ears. 20Hz was also almost inaudable to my ears - although the deeeeep 20Hz "rumble" helped my identify and correct a nasty window rattle. My room is mostly tile, so it may account for the boost in the 6000Hz to 8000Hz range? Other observations: 1) there is basically no notch at the 600Hz crossover point, 2) Cornwalls, in room without the sub, were only 5dB down at 40Hz - which is right in line with the Klipsch specs (contrarily, they are 10dB down at 16,000Hz - maybe I should test them without the grills?).

I understand you want you room response to be basically flat, but I'm no expert on "in room response curves." Any insights into these numbers? Subjectively, the system sounds good.

Thanks,

Andy

[Colin]

great, thanks, looks relatively flat, what model do you have? My own measurements show the bass bounce higher, about 100 Hz, but I have the same 6-8 KHz bounce, but so do the other speakers that I have measured in the same room ...

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Colin's Music System Cornwall 1s & Klipsch subs; lights out & tubes glowing!

[Klipschguy]

The speakers are bone stock 1977 Klipsch Cornwall I's with the type B balancing network. Drivers: K77 alnico tweeters, K55-V alnico mids, K33B woofers.

Andy

[Kevin S]

If you used the analog Radio Shack SPL meter, did you account for it's rolloff in the bass frequencies and above 10khz when you made you measurements? SVS has the adjustments needed on their web site. Also, keeping your Cornwalls in the corner, but moving them out several inches to a foot may reduce your bass bump at 50 & 63hz a couple of db. Also, if you are going to run the Cornwalls full range, I would recommend that you cross the sub over at no higher than 40 hz if possible, also to help minimize the 50hz bump. I have found that a bump of more than 3 or 4db at 50hz and 63hz initially gives the impression of great bass, but ultimately is where "boominess" resides and will actually hide bass detail above and below those frequencies.

Your high end response is certainly affected if you have a mostly tile room, but I have found that when trying to measure high frequencies in my room, very slight movements, especially up and down, will cause the measurements to vary greatly, so I don't spend the time trying to smooth them the way I work on the bass.

I hope this helps.

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L/C/R: Klipsch Heresy II

Surround: Klipsch RS-3

Subwoofers: 2 HSU-VTF-2

Pre/Pro/Tuner: McIntosh MX-132

AMP: McIntosh MC-7205

DVD: McIntosh MVP-831

CD Transport: Pioneer PD-F908 100 Disc Changer

Turntable: Denon DP-72L

Cassette: Nakamichi BX-1

T.V. : Mitsubishi 55905

SAT/HDTV: RCA DTC-100

Surge Protector: Monster Power HTS-5000

[JohnA]

That looks like superb in-room response to me! I'd look at some rugs or wall tapestry to help with the 8k bump, it it is still there after you correct for the instrument error.

John

[mike stehr]

http://www.gti.net/wallin/audio/rsmeter/33-2050/33-2050.html

Mod your meter!

[Klipschguy]

Thanks for the input guys,

My meter is the digital one. The cool mods Mike provided with the web listing show an analog metered instrument. Are the mods the same? I do like tinkering with my soldering iron (I like the smell of rosin core solder in the morning, it.....).

I going to experiment with speaker and sub placement a little bit to see how it affects the numbers. I'll post 'em.

Warm regards,

Andy

[mike stehr]

http://www.gti.net/wallin/audio/rsmeter/33-2055/33-2055.html

Mods for the Digital meter.

THANX!

[Klipschguy]

Thanks Mike! Just what I was looking for.

Andy

[Klewless]

Klipschguy,

You are right on about not hearing the last two bands! The reason is that you did not have them loud enough. Look up the dope on fletcher mundson curves (My spelling may not be up to par here) which relate loudness and our ability to hear them at different frequencies. Our ears are sensitive to the middle of the audio frequency band only.

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John P

St Paul, MN

[mobile homeless]

Andy,

I just wanted to let you know that I found this post/thread excellent. Glad you went through the trouble of posting this. We have nearly the same Cornwalls (mine are 77 Designer Series made without the grill) and I will be looking to this for comparison purposes. Good Work!

kh

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Phono Linn LP-12 Vahalla / Linn Basic Plus / Sumiko Blue Point

CD Player Rega Planet

Preamp Cary Audio SLP-70 w/Phono Modified

Amplifier Welborne Labs 2A3 Moondog Monoblocks

Cable DIYCable Superlative / Twisted Cross Connect

Speaker 1977 Klipsch Cornwall I w/Alnico & Type B Crossover

system one online / alternate components / Asylum Listing f>s>

[Klipschguy]

Thanks for the thoughts, responses and analysis! When I set out to test my system, I wanted to see what my ears were hearing at my listening spot at my typical moderate listening levels using said meter. I also wanted to give people here on this bulletin board an idea of what they can expect from a pair of Cornwalls in a given application.

My system has been set up purely by ear so it sounded the best to my ears. I'm NOT saying it can't be improved upon, but it is quite interesting to see on paper what my ears are telling me "hey, this sounds good."

I am also unsure about the full ramifications of these numbers. Data is data, analysis is quite another. I was/am hoping to get some enlightenment as to the significance of the data from some of you whom understand room acoustics.

Also, I am aware of the hearing response curves and needed loudness compensation at low levels (by the way, tone controls are always defeated on my system). One observation: similar hearing curves are used by sound engineers (they have human hearing) when they mix and equalize recording and should be reflected in the recordings at some reasonable listening level. I doubt they tweak the recordings at 120dB nor 50dB.

My hope is to understand these numbers better so I can use my meter and test tones to get the most out of my system. As understanding is gained, more numbers will follow.

Warm, happy regards,

Andy

This message has been edited by Klipschguy on 01-30-2002 at 12:25 PM

[tidmack]

Fellas,

maybe someone can help me out. . .how exactly are these results read? I know the basics about db's and their log relation to wattage. I guess my question is: what do these results mean? I too own cornwalls and la scala's and I think it'd be fun to someday do a side by side, comparing each speaker's qualities. Thanks guys

Jeff

[dougdrake2]

Andy - What CD did you use to create your test tones?

Doug

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My System

[Klipschguy]

Hi Doug,

I used the Stereophile Test CD's #1 and #3. It's a set of three CD's which were obtained from Parts Express for about $30 (for all three). CD #1 has only the bass 1/3 octave warble tones at -20dB including a 1KHz reference tone. CD #3 has bass, midrange, and treble decades which are successive 1/3 octave warble tones - also recorded at -20dB. There is a bunch of other good stuff on these CD's too. GREAT fun on a lazy Saturday afternoon.

Regards,

Andy

[Mike Lindsey]

Andy,

I used the Stereophile #3 CD as well. I put the Denon in Direct mode, volume to -13 to calibrate 1k hz to 76 db. This chart also includes the adjustments to the SPL meter (inside the parenthesis), as well as the use of my SVS subwoofer. Here are my results:

___20hz-80db (7.5db)

___25hz-81db (5db)

___31hz-81db (3db)

___40hz-82db (2.5db)

___50hz-78db (1.5db) This is about where my Chorus's rolloff

___63hz-76db (1.5db)

___80hz-79db (1.5db) Fixed x-over in Denon to subwoofer

__100hz-81db (2db)

__125hz-80db (.5db)

__160hz-76db

__200hz-75db

__250hz-76db

__315hz-78db

__400hz-76db

__500hz-75db

__630hz-78db 650 is the mid x-over on the Chorus's

__800hz-77db

_1000hz-76db

_1250hz-78db

_1600hz-79db

_2000hz-79db

_2500hz-77db

_3150hz-76db

_4000hz-79db

_5000hz-81db

_6300hz-81db (2db)

_8000hz-80db (3db) 7k is the tweeter x-over on the Chorus's

10000hz-78db (4.4db)

12500hz-77db (6.2db)

16000hz-75db (8.5db)

20000hz-73db (12.2db)

Mike

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My Music Systems

This message has been edited by Mike Lindsey on 02-01-2002 at 10:21 AM

[Klipschguy]

Mike,

VERY, VERY nice response! How big is your room? I didn't adjust for the meter with my posted numbers. Is your meter the digital or analog Radio Shack model? With your corrections, my system is at +1.5dB @20Hz, +3dB @25Hz, +2dB @ 31.5Hz (I think I need to turn my sub down a little). The high frequency responses are also much flatter with the corrections. I will make the meter corrections with my next set of numbers. WOW, with the corrections, my Cornwalls are only 8.5dB down at 20Hz. Great stuff.

Andy

[Mike Lindsey]

Andy,

My room is 17' x 15' x 10'. I only have 3 walls and it opens to the kitchen on the other side. My whole house has 10' ceilings and the Family room has berber carpeting. I am attaching a shot of it.

I used the analog adjustments from the SVS website...

Mike

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My Music Systems

[WMcD]

Tidmack asks how to interpret the FM curves. They really are a magnificent piece of research. Also called "equal loudness" curves. Let me suggest you print the curves and follow along.

My understanding is that the survey has been made by other experimenters with pretty much the same results. Also, the results are avereged (sp) with some listeners departing from the norm.

Let's first look at the test methodology and hard data.

A listener is given a reference tone at 1000 hz at 30 dB. (Find that curve in the collection.) It is a soft level almost like background music. Note that the labels on the curves correspond to the left data axis.

Then the subject is given a tone at 4000 hz and asked to adjust the level (electrical volume control) so that it sounds equal in perceived volume. The level is about 25 dB on the curve. Ha, for the equal perceived level the physical sound pressure measured by the machine is 5 dB less! The ear is 5 dB more sensitive at 4000 Hz.

Now the listener is given the same 1000 Hz tone as a reference at 30 dB and the frequency is changed to 50 Hz, which is a bass frequency. The subject adjusts the electrical volume control until the 50 Hz tone sounds equal in level to the 1000 Hz tone. It is about 72 dB as measured by the machine. The ear is 72 - 30 dB = 42 dB less sensitive.

The ear can't hear bass frequencies equally well unless they're boosted by 42 dB. That is more than 10,000 times more electrical power.

There is a similar problem when the frequency is moved up to 10,000 Hz, which is high treble. We see on the same curve that the level has to be boosted to 40 dB to sound equally as loud as the 1000 Hz tone. That is a 10 dB increase. The ear is 10 dB less sensitive at that frequency.

We find very different results looking at the 90 dB curve. This is "loud" music. Again start at 1000 Hz. Shifting to 4000 Hz shows almost the same increase in sensitivity. And at 10,000 Hz we find the same relative decrease in sensitivity. It takes 100 dB to sound as loud. Same 10 dB.

However, follow the 90 dB curve into the bass region. I.e. start at 1000 Hz and go left. It is just about flat.

Just about now, you're starting to think that the ear is a good or bad microphone depending on the the overall level. At least that is what I think.

I turn the print out paper upside down and reverse it and hold it up to the computer screen for back light. We now see the frequency response of our ear's microphone. Look at the bottom three curves (in this view) for 90, 100, and 110 dB levels. The bass response is good.

On the other hand, look at the upper curves which are low levels down (here up in the view) to 0 dB. Our ears have poor low frequency response when the music is quiet.

What conclusions can we reach to make things better for listening?

The 90 dB level is a pretty good reference. This, or 100 dB curve, is flat for bass. Also, looking at the curves, we don't have a problem with the treble higher in frequency than 1000 Hz. The curves track each other down in level.

The bass is the problem.

Suppose we want to hear flat bass referenced to the 30 dB 1000 Hz tone. Essentially, "I want to hear the bass when the overall volume is turned down low because the kids are in bed."

At 200 Hz, (on that curve) we need about 15 dB of boost, at 100 Hz we need 25 dB of boost. At 50 Hz we need 30 dB of boost.

But if you pick another curve, the amounts are different by some amount.

The "loudness" switch follows compensation for one curves, and we can't know which.

There is another implication. If you listen to any speaker at a high level, and the same speaker at a low level, you're going to hear decreased bass in the second instance. Also, do a side by side comparison of different speakers, the one at the lower level might well sound deficent in bass.

Ergo, it says something about speaker testing by ear. If the volume is turned up, bass will sound better. It has to. But it is our ears. That is what the FM curve tells us.

Overall, the curves describe what we hear. Turn down the volume control and all we hear is the midrange and treble.

Regards,

Gil

[HornEd]

Thanks, Gil, for another well reasoned explanation that any Klipsch juror should take to heart. Too few people seem to realize how much energy and structure it takes to crank out quality bass... as your figures indicate, you have to double the capacity of your sub for each 6dB of improvement!

Your opinion of my latest center channel tweak would be most appreciated. Now all of my primary speakers are KLF-30's. The latest edition is the center speaker with its new "horizontal" motor board. The new board has the 12" woofers on either side of the stacked horn tweeter and exponential horn.

My reasoning was that 5.1 (and above) movies pump upwards of 75% of the sound to the center speaker... which to my mind makes it THE main speaker. So by what acoustic reason should it be a lesser speaker than the Right and Left Fronts? Sure I understand the space and aesthetic objections... but are there any sound objections from your point of view.

Frankly, Gil, the reason I ask is that I respect your opinion... and my six KLF-30's create a very "live" concert like realism... and the converted center has turned out to be much better than expected. Also the timbre matching obviates all that Doppler effect when there is a wide sound pan. The difference is as dramatic as when all the Legends were set to "SMALL" and the Twin SVS Ultras wired fired up.

I had a whole lot of concerns before I turned the center on... which completely disappeared. Speech is more intelligible than with the KLF-C7 as the sound has a more detailed and revealing character. An extra bonus is that my rig is more "musical" than ever. I just followed listening to the Eagles dts "Hell Freezes Over" with the nearly two hours of the Smithsonian's dts DVD honoring the 300th anniversary of the invention of the piano (one of the best eclectic piano centered DVD's I have ever heard).

I picked the KLF-30's for their bright character to counter the age of my 94 year-old mother's ears. Speakers more highly rated by audiophiles (like I first installed) may be smoother and more accurate but mother's ears (and mine too for that matter) are no longer acute enough to enjoy the audiophile fare.

I have been somewhat out of it for a few months... but was glad to see you still rendering service to those of us who want to know... but can't find it in the Enquirer. HornEd

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"Where Klipsch Legends Cavort Six Ways!"

FOREGROUND SOUND STAGE:

KLF 30's: Left Main, Center Main, Right Main

SB-2's: L & R Front Effects on 5' sand filled columns

BACKGROUND SOUND STAGE:

KLF 30's: Left Surround, Rear Effects, Right Surround

LARGE MOUTH BASS:

Twin SVS CS-Ultra subs, Samson Megawatt Amp

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and such... Tweakin' On!

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