Frequency Chart - is it ok?

[glennconti]

This was measured with a RS analog meter with corrections applied (80 db scale C-weighted Slow). Anything greater than +/- 10 db I didnt change the scale. This occurs at 10KHz and above and down in the 25 - 40 Hz range. The speakers are two H3's and a Sunfire True Sub.

Any comments would be sincerely appreciated.

[WMcD]

Hard to tell, but I believe it shows that all the drivers in HIII and the sub (wow) are working.

I looked at the Rives site and it shows their 1/3 octave sources on their "II" version. The x-axis looks to be set out out 1/3rd points.

IIRC, 1/3 octave noise is distinctly hissy. 1/3 octave warble tones sound like a Star Trek phasor. BTW.

The use of 1/3rd octave sources is a way of averaging out peaks and valleys in the measurement. It is not really averaging out what is measured (the speaker and the room) but rather what is fed to the speaker -- which amounts to pretty much the same thing.

Your graph looks ragged at first. But much of it fits in a plus or minus 3 dB window. I'd say that is not too bad.

The smoothing is supposed to remove (average out) the reflections from the room walls. But I think you might still be measuring the effects of floor, ceiling,and wall bounces.

Why don't you tell us more about where the speaker and microphone were located.

One technique for testing is to move the speaker outdoors and set it on a hard surface, like a driveway, away from buildings. The speaker box is placed upside down so the tweeter is near the ground. Then put the microphone about 10 feet away and cant the speaker front to aim at the microphone. Maybe more than you want to do.

It is difficult to convince people just how much the room reflections affect measurements. One time I used a single tone to a speaker (say 200 Hz). At some places in the room, the tone could not be heard at all. People have reported something similar with higher freqs (maybe 1000 Hz) and walking around the room with an RS meter. Meter readings (more obvious if you have a moving needle type) vary widely with movements of one foot.

WMcD

.

[glennconti]

There is a sofa drawn to the left; the microphone "M" on tripod is located near it. The speakers are located on the right wall labeled "H3" on either side of the entertainment unit. The sub is in the top right corner with a diagonal orientation (labeled "S"). The room is 15 x 15'. Each grid is one foot. Let me know if you need anything else, thanks.

[Quiet_Hollow]

Let me know if you need anything else

So this dimension (the one blue) is ~3 ft? The mic is four feet from the wall? What's the height of the ceiling? [8-|]

[glennconti]

Hi QH,

Yes, the blue dimension is 3 feet. The mic was four feet from the wall and the ceiling is 9 feet tall.

--Glenn

[glennconti]

This is the recomended sub location in the owner's manual. My top wall (horizontal) is an outside wall and the verticle wall in my house is a load bearing wall. The driver on the left as you face the sub is the active driver and the driver on the right is the passive driver.

[Quiet_Hollow]

As far as the chart being "ok", that's a matter or your personal tastes. Sub bass looks a little hot (you cut the graph off at 10 dB), but it's at the frequencies that need the most lift.

Using the link provided you can see:

1. Minor attenuation from the ceiling of the room at 9' above the sub.

2. Big cancellation from the wall behind the sofa affecting the mic. (try measuring closer or further from the wall and watch for this dip to coincide with the change in position)

3. Cancellation from the flank of the entertainment center and the wall...very likely affecting both the sub and the Heresy on that side of the room.

http://www.padrick.net/LiveSound/CancellationMode.htm

[glennconti]

Thanks for the input. I love the way my stereo sounds and it looks like the frequency response graph is not showing much of a problem with room acoustics. I did another frequency chart. This time I normalized the settings so the bass response was not getting clipped. Basically it showed, if you average out the peaks and valleys, that my subwoofer is set about 6 db "hotter" than the H3's. This gives me just about the right amount of bass to my taste. My bass tone control is set at 12:00 (as are my other tone controls) at the receiver and it's all good. Thanks again for looking at my chart and room layout. If anybody else wants to chime in feel free.

[glennconti]

After seeing Artto's post:

http://community.klipsch.com/forums/t/162245.aspx

I am wondering if I am missing something? I don't want to pop the bucks ($330) for a Behringer DEQ2496 (plus it looks like it uses only balanced inputs and outputs - which I don't have) but I am wondering if I would hear any difference by using a 20 band (10 Left and 10 Right) equalizer? I can pick one up cheap on craigslist. I can get one for less than $50.00. I may just get it and experiment around with it today.

[artto]

After seeing Artto's post:

http://community.klipsch.com/forums/t/162245.aspx

I am wondering if I am missing something? I don't want to pop the bucks ($330) for a Behringer DEQ2496 (plus it looks like it uses only balanced inputs and outputs - which I don't have) but I am wondering if I would hear any difference by using a 20 band (10 Left and 10 Right) equalizer? I can pick one up cheap on craigslist. I can get one for less than $50.00. I may just get it and experiment around with it today.

The Behringer DEQ2496 can be had for less than $330. The first one I bought locally at Gand Music so I could easily take it back if I didn't like it ($299). The second one I bought new (open box) on Ebay for $200 w/free shipping. http://www.gand.com/

Personally, I don't think a 10 band graphic EQ which is going to give you the selectivity you need at low frequencies. At these low frequencies individual musical notes are only about 1Hz apart. The DEQ2496 has filters that go as sharp as 1/60 octave. And the time delay capability really helps make things sound more coherent. You can even adjust time delay by meters, feet and inches or milliseconds.

As far as the balanced connections go, you can use a cable that has regular RCA type connectors on one end and XLR on the other. I had some made in Mogami Neglex Quad 2534 in 3 foot lengths with Neutrik connectors, color coded from Upscale Music for $22.30 each. You can also get adaptors to do the same but I prefer as few breaks in the signal path as possible. And you may find that the adaptors are almost the same price as cables depending on the cable length you need.

http://www.upscalemusic.com/categories.php?cat=19

[glennconti]

Artto,

Thanks for the advice. I dont want to spend much for the experiment. So I got a used 62 band (31 left and 31 right) equalizer on ebay. A Samson E62 for $56 plus freight. This 1/3 octive setup corresponds to my Rives Audio test tone cd. The Sampson E62 also has 1/4" inputs and outputs so I got a bag of 10 1/4" male to RCA female adapters for another $8 on Amazon. This setup is nowhere near what you have but, as per your suggestion, it will be much better than the 10 band EQ I was originally considering. If the experiment goes well I may get a DEQ2496 and sell the Samson E62 for what I paid for it. Thanks again for your input. With this forum's help I don't feel like I'm gropping around in the dark as much.

[glennconti]

At these low frequencies individual musical notes are only about 1Hz apart.

After I get the Samsom E62 setup and a flat frequenct response for the 1/3 octaves, I am going to retest the frequency response with new higher resolution low frequency test tones.

This is a quote from Real Traps website which offers a free low frequency test tone cd:

"There are a lot of commercial test tone CDs available, but all of
the CDs we've seen suffer from the same fatal problem: The tones are spaced at either 1/3
or 1/6 octave intervals, which is far too coarse to assess the low frequency response in
rooms the size you'll find in most homes." This agrees with what Artto says.

"Therefore, we supply only low frequency sine waves, in 1 Hz
increments"

This will be interesting. However, they also don't recommend using correction factors for Radio Shack SPL Meters [*-)] So I am a little confused.

"Some test CDs "calibrate" the level of each tone to match
the known inaccuracies of the Radio Shack SPL meter, but we didn't do that for two
reasons. First, meter calibration offsets are not that useful because all Radio Shack
meters are not the same. More to the point, low frequencies are usually accurate enough
even with inexpensive microphones. We compared our Radio Shack SPL meter to our own
expensive AKG calibrated microphone, and they were within 1 dB of each other below 600 Hz.
The main point of these tones is to find the major peaks and nulls at low frequencies, and
any inexpensive meter is fine for that, calibrated or not."

Should I correct for the C-weighted drop off or not? Any comments would be appreciated. Thanks.

[artto]

There is a free audio test CD, Bink Audio. Also NCH Tone Generator. They have a free trial period and has the actual individual musical notes as sine wave test tones ($59).

You should use the "C" weighting on an SPL meter, no compensation needed, thats the flatter response of the two (A or C). I don't use calibration files for the Radio Shack SPL meter because there is too much variation in their product. Most "omni" directional microphones produce a pretty flat response curve, it's the nature of the beast. It really boils down to how accurate you want to get and how much you want to know in how much detail (resolution).

Behringer and Dayton Audio makes an inexpensive omni microphone. With the Dayton you can download the actual calibration file for the specific mic you purchased using its serial number. The file can be read by any number of Room EQ software applications (it's just a basic text file) and automatically correct for deviations in the response of your specific mic. In most of these programs you can also take it one step further and calibrate the sound card too. But below 20Hz pretty much everything seems to get a little dicey and has to be taken with a grain of salt.

1/3 octave is IMHO pretty much useless for subwoofers. The frequencies I show SPL levels for on my charts are the actual musical tones and as you can see they are about 1Hz apart, 12 notes to an octave.

[glennconti]

Reviews

the absolute sound

February 2003

If
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combinations are free of annoying peaks and dips--especially peaks,
those infuriating one-note booms. [...]



But with BEHRINGER, you can always make it work out, and most systems need help in this area. [...]



I believe that every audiophile who does not own a digital EQ device
ought to think seriously about buying the BEHRINGER just as an
experiment. [...]

Looks like it's time to test my room frequency response in the lower frequencies and, if needed, save my money for a Behringer experiment.

[Quiet_Hollow]

The DEQ 2496 is very handy device...especially when you buy the ECM8000 microphone to go with it. The RTA function is very quick to setup...

However, after a year or so of using manual EQ, I stepped up to subwoofer Auto EQ and time alignment in the form of a AS-EQ1 and haven't looked back since.

The AS-EQ1 is no longer available...but a similar product, the Antimode 8033 might just be the ticket for your sub. Very quick results. To do what it does in a matter of minutes can take hours of measuring, data analysis, and tweaking otherwise.

[artto]

The AS-EQ1 is no longer available...but a similar product, the Antimode 8033 might just be the ticket for your sub. Very quick results. To do what it does in a matter of minutes can take hours of measuring, data analysis, and tweaking otherwise.

Tom, have you used this device yet?

(big price difference too) EDIT: well, not as big as I thought ~ was looking at the stereo version.

EDIT: Just for the record, I have a BIG problem with products that claim things like " ANTI-MODE 8033 technology eliminates the acoustic resonances of the
room by correcting both the amplitude and the phase of the disturbing
frequencies"

That phrase in particular, to me, demonstrates that the manufacturer/design/engineer of the product has no idea what they are talking about to the degree that they apparently do not even know or understand what a room mode is. Now, perhaps, admittedly, I'm the one who is stupid. If so, someone please explain it to me! (and you don't even have to be nice about it) []

I'll begin with a retort before anyone starts to explain anything. They don't build (even) large concert halls with integrated bass traps six stories tall for nothing. (do the math ~ six stories defined generally speaking = 10' to 12' or more per story. 6x10' = 60'. 19Hz= aprox. 60' ~ a full wavelength of near or at the lowest fundamental frequency produced in music, typically pipe organ)

The problem with these "automatic" devices is that I'm stuck relying on a "secret" algorithm from some unknown person to provide a solution to a problem for which they have no knowledge or definition of, and from I can tell don't even understand the concept in its most simple and general terms.

Sorry, but I need a lot more information about this company and its products and its people. Right now it just looks like another "black box" to me. Might as well just get some of these: http://www.musicdirect.com/p-7267-marigo-3mm-green-tuning-dots-set-12.aspx or this: http://www.musicdirect.com/p-7504-shakti-hallograph-room-optimizer-pr.aspx or this: http://www.musicdirect.com/p-7157-golden-sound-dh-acoustic-disc-set-of-12.aspx or this: http://www.musicdirect.com/p-4665-finite-elemente-the-resonator-ea.aspx

[glennconti]

Here is more info:

http://www.hometheatershack.com/forums/bfd-electronic-equalization-devices/11699-testing-dspeaker-anti-mode-8033-a.html

EDIT: I must say being a little over my head in this area the simplicity of the anti-mode 8033 is appealing. I will figure out the Behringer if necessary but the appeal of the 8033 is that it's a piece of cake to set up.

[artto]

Here is more info:

http://www.hometheatershack.com/forums/bfd-electronic-equalization-devices/11699-testing-dspeaker-anti-mode-8033-a.html

EDIT: I must say being a little over my head in this area the simplicity of the anti-mode 8033 is appealing. I will figure out the Behringer if necessary but the appeal of the 8033 is that it's a piece of cake to set up.

Glenn, believe me when I say there is no such thing as an anti-mode acoustical correction device ~ unless its capable of physically changing the size and proportions of the room. Anyone who claims otherwise does not fully comprehend the problem. The best these devices can do is move the "problem" to a different location or reduce its effect to some extent at the desired location and even that is within certain limitations. They cannot for instance eliminate a cancellation in one location without moving it somewhere else. Even the common "bass trap" can do better than that! Whatever, whenever it can make something "better" in one location it will certainly make things worse in another place.

More specifically, if the manufacturer of this product had said something like "room compensation", I would have no argument. But when they says it "corrects" and refers to "room modes", that immediately tells me that they are either deliberately lying, misleading prospective customers in order to sell their product, or they simply don't understand the problem. If they don't understand the problem, how are they to provide a solution?

And as far as hometheatershack goes, I know a lot people like that Forum, but from what I've seen, IMHO there's a lot of "the blind leading the blind" over there.

[glennconti]

Artto, we know you have gotten good results with the Behringer DEQ 2496. Quiet Hollow, from his post, makes it seem that the DEQ 2496 with RTA mic is not too hard to set up. I found a DEQ 2496 on ebay with RTA mic and free shipping in lightly used condition for $200. The DEQ can do a lot more things that the 8033 cannot such as EQ the mid and high freqencies too.

The anti-mode 8033 for what I need is $495 and is black mystery box (I spoke to one of their sales people about the resolution of the unit and he didn't know other than it has 24 filters). Also I think I am going to have problems cableing it up to my Marantz. In the anti-mode's favor it was reviewed at hometheatershack by the author of REW so he should know alot about equalizers. However I think the marketing at anti-mode is disingenuous or has too much hubris. It was like the marketers didn't talk to the engineers enough or something. To Quiet Hollow's point I think auto EQ is theoretically possible and he is having good results with his (discontinued) SVS auto EQ device.

Well I pulled the trigger on the Behringer DEQ 2496 for $200. It should be here in about a week. I found a video on youtube which walks you through the subwoofer/DEQ 2496 setup procedure. So that will help. the whole video was only about 5 minutes long. Not too bad. Lots of buttons to push though (not just two like the anti-mode 8033.

Thanks Artto and Quiet Hollow for your input. Anything else I should know, please clue me in.

[artto]

Ask the seller for the date code and version of firmware on the DEQ2496. The firmware should be V2.5. The date code should be within the last few years. (date code example: 1005 = year 2010, month May). This will assure that you are buying one of the more recent units. I haven't been able to find exactly when Behringer made the changes in production but I do know that they now use different processors and that the older processors are not compatible with the newer firmware and vice versa. Also forget the video. The guy doing it has it all wrong. Follow Behringer's instructions. You can download the manual.