Sierra 2 - Understanding REW Results

[Agd]

Hi all,
Getting my sierra 2's dialed in (they already sound phenomenal, but pursuit of perfection and all) and wondered if the community had thoughts on my graphs.

My first question, there is natural rolloff from about 7k onward which I haven't seen in other REW charts or my factory calibration results pages. Is this a placement issue? I'm sitting about 14 feet away, they are about 14' apart, and they are toed in about 10 degrees.

My second question, slight dip at 2.5k, should I ignore this? Crossover interaction I'm assuming?

Last question, I still need to sweep for the optimal crossover, but do my graphs point towards one that may work the best?

I've currently settled on LR bypass with audyssey, dynamic eq on (+15db offset), and my subwoofer is a single rythmik L12 placed under the front L channel. S2's are using included felt feet + a dab of museum putty, sitting on floating shelves that are mounted with isolating rubber dampeners.

Any thoughts or input are greatly appreciated!

173317341732

[mikesiskav]

It may have something to do with your room. The easy way to check is to take measurements closer to the speaker, say 5ft away or maybe even 3ft with the mic halfway between the woofer and the tweeter. That reduces the effect of the room. What type of mic are you using?

[Agd]

Yea can definitely do that, I don't think it's an issue with the speaker as they came with a measurement chart, but that could at least highlight if it's early reflections or room reflections or placement? It's a umik-1

[Agd]

I held the mic about three feet away centered between the tweeter and woofer, here are smoothed and an unsmoothed graphs. I'm assuming that doesn't look right? Sidewall cancellation as they are both up next to a wall on the shelf?

It does seem to have improved the treble drop off, but not sure how to correct it for my listening position.

Forgive my ignorance with reading these, this room and these speaker locations have been my only real baseline.

[Beave]

Can you post a pic of your room and the speaker locations?

REW frequency response measurements are good for subwoofer placement and EQ, and for bass response peaks, nulls, and subsequent ringing in the bass range. Above that, they don't necessarily tell you much about sound quality.

[davef]

Hi all,
Getting my sierra 2's dialed in (they already sound phenomenal, but pursuit of perfection and all) and wondered if the community had thoughts on my graphs.

My first question, there is natural rolloff from about 7k onward which I haven't seen in other REW charts or my factory calibration results pages. Is this a placement issue? I'm sitting about 14 feet away, they are about 14' apart, and they are toed in about 10 degrees.

My second question, slight dip at 2.5k, should I ignore this? Crossover interaction I'm assuming?

Last question, I still need to sweep for the optimal crossover, but do my graphs point towards one that may work the best?

I've currently settled on LR bypass with audyssey, dynamic eq on (+15db offset), and my subwoofer is a single rythmik L12 placed under the front L channel. S2's are using included felt feet + a dab of museum putty, sitting on floating shelves that are mounted with isolating rubber dampeners.

Any thoughts or input are greatly appreciated!

173317341732

These measurements look good. There are many reasons why you could be seeing a mild high frequency rolloff.

Are these measurements made with Audyssey EQ turned on? If yes, what target curve for Audyssey are you using?

Accurately measuring such extreme high frequencies is tricky. These wavelengths are very short -- a 20kHz wavelength is only slightly larger than a 1/2 inch. 7kHz is just under 2 inches. This means the microphone must be perfectly lined up on-axis with the tweeter (both vertically and horizontally), which at a 14 foot mic distance would be quite difficult to achieve.

Is your microphone properly calibrated above 8kHz?

What objects are located between the speakers and mic?

Did you use a tripod to hold the microphone?

Did you measure with the speaker grilles on or off?

Without the right equipment and knowledge, measuring the frequency response of a speaker is tricky. REW is a reasonable hobbyist's tool for measuring room acoustics. What you are seeing in these measurements is the response of the speaker combined with your room acoustics at the location you placed your microphone, and in this regard, your measurements look excellent.

You can go crazy with this stuff, just sit back and enjoy the speakers.

[davef]

I held the mic about three feet away centered between the tweeter and woofer, here are smoothed and an unsmoothed graphs.

You physically held the microphone? If so, you can't do that...

[Agd]

To Dave, this is super helpful, thank you for the input! It's reassuring to know that it's normal, I guess my fear is that I was missing out on "better" because of a compromised room that my umik mic showed in response graphs.

I used the UMIK calibration and set it on it's tripod on my listening position (couch), grills on but nothing else in the way. Measured pure direct so no audyssey on the first chart without sub, then LR bypass on the one with sub (so no correction on LR)

The clean bill of health is the reassurance I need to sit back and enjoy, so thanks again!!

[Agd]

Can you post a pic of your room and the speaker locations?

REW frequency response measurements are good for subwoofer placement and EQ, and for bass response peaks, nulls, and subsequent ringing in the bass range. Above that, they don't necessarily tell you much about sound quality.

Good to know, and welcome any recommendations about potential improvements. I needed to move the sub to the front as it was pressurizing one side of my head when in the back corner.

Currently upgrading decor, so it's a bit mismatched, but with new decor I'll try and add acoustic treatments.

[davef]

To Dave, this is super helpful, thank you for the input! It's reassuring to know that it's normal, I guess my fear is that I was missing out on "better" because of a compromised room that my umik mic showed in response graphs.

I used the UMIK calibration and set it on it's tripod on my listening position (couch), grills on but nothing else in the way. Measured pure direct so no audyssey on the first chart without sub, then LR bypass on the one with sub (so no correction on LR)

The clean bill of health is the reassurance I need to sit back and enjoy, so thanks again!!

You are very welcome!

Also, when taking speaker response measurements, I do recommend removing the speaker grilles. However, when setting up Audyssey or for any auto-eq, if you plan on keeping the grilles on when using the system, the grilles should be kept on for setup procedures.

[Beave]

Consider re-thinking the current placement that is so close to the sidewalls.

You might be better off with one speaker in the corner on a little stand on top of the subwoofer, and the other speaker on the right top of the piece of furniture that holds your receiver. Or put *both* speakers on that piece of furniture, with one on the left edge and one on the right. They'll be too close together, but that's probably better than now - too far apart and too close to the sidewalls.

If you must leave them where they are now, then toe them in considerably, pointing toward the center of the room. And then consider getting a center channel speaker, which is a must if movie/TV watching is involved and your L/R speakers are so far apart.

[mikesiskav]

The speakers are definitely going to have issues being so close to the side walls. If you could somehow get them moved away from the walls it would be better. That being said, the nearfield measurements show less roll-off in the high frequencies so I don't see any issue with the speakers themselves.

[Agd]

I tried a more aggressive toe in (say 25 degrees?) to get the face of the speaker further away from the sidewall and it produced a more 'present' treble. Not fatiguing, just more pronounced. My initial amount of toe in was preferred for it's balance. I'm going to split the difference and see if I can find a happy medium, or just go back to how it was.

Going back to Dave's point, it all sounds great so I may be worrying about it on principle more than practical need. And it is intriguing that I can fine tune my treble response to my taste without falling back on eq, so some experimenting to be done there.

Regarding addition of a center channel, the center image with just the LR is nothing short of amazing. Defies physics that I can sit anywhere on my 4 seat couch and still have a pinpoint image center of the room. I'm not in any rush to purchase a center as I feel I'd be trading off AVR watts and more difficult EQ just for the ability to raise or lower the voices against background. If the image is already anchored to the screen is there anything else to gain?

[Bruce Watson]

I tried a more aggressive toe in (say 25 degrees?) to get the face of the speaker further away from the sidewall and it produced a more 'present' treble.

Getting your speakers off the walls isn't so much about frequency response as it is about the timing of reflections. So-called "rapid reflections" smear the stereo image among other artifacts. And the fact that your setup is so susceptible to toe-in is an indicator of this due to the heavy amount of side wall reflections you're current speaker placement creates.

I'm not saying it's bad. If you like the results, it's by definition good. But understanding what's going on can only help you obtain the results you want.


Regarding addition of a center channel, the center image with just the LR is nothing short of amazing. Defies physics that I can sit anywhere on my 4 seat couch and still have a pinpoint image center of the room. ... If the image is already anchored to the screen is there anything else to gain?

I used to think this too. Used to watch movies with just my two stereo speakers forming a "phantom center" like you are doing. Did this for years. Was perfectly happy.

Until... I tried a Sierra S2 center. Holy Cats! What a vast improvement! Made placement of dialog much more solid and centered with the video image (and stopped what little wander it had in the stereo image also). Increased intelligibility of the dialog quite a bit, especially low volume level dialog like whispers. Unloading the L/R pair of the dialog made the music and effects cleaner (similar but different to how adding a sub unloads the L/R of the heavy lifting and therefore cleans up the L/R sound). And most important of all, had my wife asking why I hadn't done this sooner. :cool:

Of course, YMMV. But I'm not going back to a phantom center. Instead I'm looking to upgrade from my current S2 center to the Horizon center.