XTZ Room Analyzer

jtwrace said:

... How does this differ from REW?

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REW is great software, and FREE. However, you still need a mic +/- calibration curves, and a USB soundcard. The XTZ Room Analyzer is a simple all-in-one-box solution. REW has more advanced features, but I only needed the basics.

Alan, congrats, this seems like a great tool.

Looking at your plot, you still have a couple of room modes, including a 60hz suck-out that's probably very position dependent.

It's important to take measurements at several locations around the main listening location (2'x6' rectangular pattern is my guideline for speakers with >6' between them), then average them to really see where the main modes are.

As for the contrast with REW, the all-in one box approach is very handy. And I do like the plots XTZ creates. Although REW waterfall plots can be stacked to see before-after or compare two measurement points, a handy feature for setup tuning.

Either way, being able to 'see' where the room modes are and what the results of room treatments and/or positioning might be is invaluable.

Jon, I'll definitely do more extensive measuring, from multiple room locations, in the weeks ahead.

Tom, consider this a BUMP of the proposal for a dedicated Room Acoustics section!

FYI, an updated version of the XTZ Room Analyzer software (Windows Vista compatible), is now available at their website. Unfortunately, I really haven't had time for further measurements of my system, but plan to do so next weekend. If anybody else is using this product, please post your opinions and/or measurements.

http://www.xtz.se/bilder/produktbilder/3d_waterfall_v2.jpg

Nice!
Really considering buying this kit and getting my geek on

urskog said:

http://www.xtz.se/bilder/produktbilder/3d_waterfall_v2.jpg

Nice!
Really considering buying this kit and getting my geek on

Click to expand...

Very cool looking plots.

If you really want to support your local economy, and get your geek on even more, check out the big brother versions of the software: http://www.wavecapture.com/

Personally, I'm lusting after the Room Capture app.

FYI, XTZ has just released the v2.0 Room Analyzer software (a FREE upgrade!). It appears to have added additional graphing capabilities, and (hopefully) addresses some of the reproducibility issues I found in the v.1.2 software. I just d/l this new version, but won't have a chance to use it for a couple weeks.

Is anybody else besides Stefan and myself using this?

Now that a few of us have the XTZ Room Analyzer, perhaps we can continue this thread sharing tips (and future measurement plots) as we together learn how best to use this tool (and others like it). Another forum member PM'd me today with specific questions about using XTZ, but I'll post my reply here, so we can have a public discussion.
Use the Y adaptor (I plug mine into my preamp, usually in Home Theater Bypass Mode mode) and measure both speakers simultaneously from the "sweet spot" (or multiple listening positions, if desired). You can also measure each speaker individually (nearfield best) if you want to compare their baseline frequency responses (which is how I discovered the woofers were out of phase in one of my Summits).
It's best to optimize speaker placement (and acoustic treatments, if any) first, then dial-in the bass controls for final tweaking. I use a furniture slider under my speakers, moving them no more than 1/2" at a time, and use listening tests plus measurements to chart my progress. Pay very close attention to exact distance from front wall, and amount of toe-in/tilt. It's a time consuming process. Jim Smith's book Get Better Sound is a superb reference.
I use the pink noise RTA to assess the full-range frequency response, not only the bass. However, it's particularly helpful in making final bass adjustments, while watching in realtime. If you have a particularly asymmetric setup, it might be useful to also measure each speaker individually (farfield, at sweet spot), just to see if one speaker requires particularly more bass adjustment than the other to yield the smoothest overall curve.
I was fortunate in having added some acoustic treatments (mainly bass traps) before even getting the XTZ analyzer, and had no bass nodes from day one. However, if you do, you need to revisit speaker placement (and acoustic treatments if possible), and try to treat them in that manner, before considering digital room correction options.

As for interpreting the color spectrograms, I'm still learning about that. Certainly less "ringing" is better. I'm fortunate in that I have a relatively "dead" room, without bass nodes, and minimal ringing, so I don't think that's much of an issue for me. However, I want to learn more about comb-filtering, and find out how those time-frequency response measurements can help me further tune my overall setup.

I'm hoping JonFo will get the XTZ Analyzer, and really teach us all how to best use it! BTW, Kal Rubinson of S'phile has mentioned it a few times in his Music in the Round column, and says he'll comment on the new v.2 software shortly. Also, the British audio mag HIFICRITIC is slated to review the XTZ Room Analyzer in it's next issue...
http://www.hificritic.com/upcoming/default.aspx

Thanks for addressing my questions! I agree that the more information we can all provide each other, the more effective we can be!

I've started using it and taking measurements. The tool is a remarkable bargain! Also, I just received the Better Sound book ... what a wealth of information! Jim's really done a great service to the audio community!

Here's a great article from Kal that helps explain how interpret and use the results of the analyzer: http://www.stereophile.com/musicintheround/1108mitr/index.html

Yes, that's helpful, as is the downloadable product manual available at the XTZ website... http://www.xtz.se/produkt.php?allmant=true&produkt=41&eng=true

However, the software seems capable of MUCH more than XTZ, or Kal, has ever covered. For instance, what's the purpose for the anechoic, ambient, and raw options in the full-spectrum measurements, and which resolutions (e.g. 2, 3, or 6 ppo) are best when interpreting bass level measurements. I've kept everything at their default settings for now.

Of note, the XTZ software is actually a trimmed down version of the (also Swedish) Room-Capture or Live-Capture products found here... http://www.wavecapture.com I haven't time to read the literature available there, but some of it looks helpful.

Also, one VERY important caveat I forgot to mention above, is that the mic is VERY directional for the higher freq measurements. It's critical to always point the mic towards the speakers, rather than upward towards the ceiling, while measuring (this is in contrast to the Audyssey mic that shipped with my Denon receiver).

Hah! I just realized that XTZ has updated the user manual for the new v.2 software! It looks a LOT more useful than the rudimentary pamphlet that shipped with v.1 Definitely gotta read this new version!

Would have totally missed that! My new XTZ which arrived last week still had the old manual. Good catch!

After fixing my out-of-phase Summit woofers (see thread... http://www.martinloganowners.com/forum/showthread.php?t=9648) I have been using XTZ to re-tweak their positioning/setup. At this point, I'm quite happy with how they measure and sound. XTZ finds no measurable bass nodes, and minimal reverb time (at 50 ms time threshold) on waterfall plots. There is still a trough and peak from ~50-125Hz that I can't get rid of, but will wait until I get the Summit X legs before trying to address it. Moving the speakers out another 6-12" from the wall would probably help, but I don't think that will be feasible. Frankly, I don't think it's particularly audible anyways. I've posted all three of the standard XTZ Room Analyzer plots here for comments/comparisons.

Sleepysurf,

I am so envious of your results! That looks pretty flat to me. And you don't have a lot of delayed energy to muck things up! However, I'm just starting to use trapping in corners and experimenting with absorption.

My plot still has a lot of red and yellow, centered around the 40hz region. Did you have a systematic approach to dialing down all that excess energy?

One think I did find listening was that absorption behind the speakers made them somewhat lifeless. It was better to keep pulling them out from the back wall until the rear-wave delay stopped smearing the high end. I think diffusion or better yet absorption/diffusion combined might be the ticket I'm looking for.

Currently I'm experimenting with panels from RealTraps and GIK to see overall which work better for me in my setup. Also, I'm thinking of the BAD panel from RPG which combines absorption and diffusion in one panel. However, I'm open to many things as I've also experimented by placing plants behind the speakers. These seem to help too. Nothing permanent yet, still experimenting.

Lots of trial and error. I'm counting on the XTZ to guide me and confirm what I hear.

Hi Alan, looking good.

One observation is that it seems you are measuring at a low (54dB) avg level. this is not enough to energize the low-freq. room modes.

I'd suggest using a 65 to 70dB reference to find the worst offenders.

Also, finding room modes requires looking at 200 to 300ms time-windows to spot the resonances.

Looking at the plots, it seems you do have a room induced issue at 50-something hz (which is echoed by the harmonic at 100+Hz). some additional bass trapping could help (but it will take the big guns, 6" thick traps).

Changing the placement might shift the peak-trough relationships, but the only way to minimize them is through room treatments or EQ.

But overall, pretty good.

DC-Audiophile said:

...My plot still has a lot of red and yellow, centered around the 40hz region. Did you have a systematic approach to dialing down all that excess energy?

One think I did find listening was that absorption behind the speakers made them somewhat lifeless. It was better to keep pulling them out from the back wall until the rear-wave delay stopped smearing the high end. I think diffusion or better yet absorption/diffusion combined might be the ticket I'm looking for.

Currently I'm experimenting with panels from RealTraps and GIK to see overall which work better for me in my setup. Also, I'm thinking of the BAD panel from RPG which combines absorption and diffusion in one panel. However, I'm open to many things as I've also experimented by placing plants behind the speakers. These seem to help too. Nothing permanent yet, still experimenting.

Lots of trial and error. I'm counting on the XTZ to guide me and confirm what I hear.

Click to expand...

It takes a lot of trial and error to find out what works best in your room. IMHO, the first step to taming your 40 Hz energy is to add as much bass-trapping as possible. I was limited by WAF, but was able to place a single GIK Pillar Bass Trap in a corner, and a GIK Table Trap along a side-wall, plus 2' x 2' x 2" absorption panels at the bottom third of my "acoustic bookshelves," for additional bass trapping. I agree fully with your observation that too much absorption behind the speakers can suck the life out of the music. My upper bookshelves (randomly stocked with books and CD's) yield a mixed absorption/diffusion effect, which I think sounds better (though others may disagree). I previously used silk trees as diffusors, but the bookshelves work just as well. Moving the speakers as far out as possible really helps tighten things up. XTZ will illustrate how even a little change in speaker positioning, toe-in, or rake angle, can have huge impact on the overall room-speaker frequency response (and soundstage/imaging). Surprisingly, I've found the positioning of my flat-screen HDTV, with or without an absorptive covering, has had a relatively minimal effect on the XTZ measurements. I think that's because I am using a fair bit of speaker toe-in, such that the (minimal) lateral dispersion from the ESL panels doesn't reflect off the screen. YMMV.

Please post some XTZ plots, so we can watch your progress!

JonFo said:

Hi Alan, looking good.

One observation is that it seems you are measuring at a low (54dB) avg level. this is not enough to energize the low-freq. room modes.

I'd suggest using a 65 to 70dB reference to find the worst offenders.

Also, finding room modes requires looking at 200 to 300ms time-windows to spot the resonances.

Looking at the plots, it seems you do have a room induced issue at 50-something hz (which is echoed by the harmonic at 100+Hz). some additional bass trapping could help (but it will take the big guns, 6" thick traps).

Changing the placement might shift the peak-trough relationships, but the only way to minimize them is through room treatments or EQ.

But overall, pretty good.

Click to expand...

Jon, good observations! The XTZ software has adjustable outputs and a "level meter," and I tried to keep the peaks out of the "red" zone. However, I can change it to the 80 dB scale, and try cranking it up a bit more. I can also use the 6 PPO (points per octave) intead of the 3 PPO option for higher-res measurements. I'll try that with my next go-round. I would prefer more bass trapping as well, but will have to settle on pulling the speakers out a bit more to try and tame those remaining peaks.

Didn't you once contemplate getting this XTZ product?

sleepysurf said:

...
Didn't you once contemplate getting this XTZ product?

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I want their Room-Capture program, but it's $1,000. Plus, I'm hyper busy these days.

Maybe in a year or two I'll come back to acoustics-in-depth <sigh>