Battle of the acoustic measurement packages: XTZ Room Analyzer vs Room EQ Wizard

Nyal Mellor

Industry Expert
Jul 14, 2010
590
4
330
SF Bay Area, CA, USA
Introduction

I was asked by Steve Williams to put together a comparison of XTZ Room Analyzer and Room EQ Wizard. This article attempts to outline the differences in an objective manner such that any prospective user has better knowledge of the advantages and disadvantages of each system. The software versions used were XTZ Room Analyzer 2.0 and Room EQ Wizard 4.11. I see that there is a new v.5 of Room EQ Wizard available in Beta with some interesting additional features. Once it is formally released I will update this comparison.

The two differentiators

In my mind there are two main angles that can be used to compare and contrast the vast number of acoustic measurement packages on the market:

  • Ease of use - how simple and straightforward is the product to use? Many acoustic measurement products were designed by engineers to solve an engineering measurement problems. They were not conceptualized and designed from the outset with the end user experience in mind and so tend to have old fashioned and clunky user interfaces.
  • Functionality - how many room measurement capabilities does the product offer? Whilst it might be tempting to go straight for a product that has all the 'bells and whistles' beware of the typical hit on the ease of use front. If you are new to room measurement then the learning curve is steep enough without you having to figure out how to use some complex and clunky software package.

Ease of Use

The reference procedure for establishing ease of use amongst consumer software is to setup user experience tests. These tests typically measure how long it takes real end users to complete tasks in the software. The end user's satisfaction / frustration level is also gauged through a survey. Since nobody to my knowledge has performed such a test on acoustic measurement software we'll need to find a different way to evaluate ease of use.

Two potential discriminating questions could be:

  • Are all the components required to measure a room included in one package? The rationale here being that without this the end user is left to work out the other things they need to acquire to successfully measure their room.
  • How many different features such as menus, dialog boxes, etc does the software have? The rationale here being that a functionally rich piece of software would be more difficult to use than a simple piece of software.

On both these fronts the XTZ Room Analyzer wins. Particularly since it is an all-in-one-box package of hardware and software. Room EQ Wizard is free but requires you to first identify and then purchase the soundcard, measurement microphone and cables that you need. Room EQ Wizard also has many more menus, options, dialog boxes and features than XTZ Room Analyzer which can be considered a proxy for difficulty of use. Take a look at these screenshots of the two producs:

Room EQ Wizard


XTZ Room Analyzer


Functionality

Functionality is a bit easier to compare. The table below shows whether each product offers a specified capability and the notes provide further clarification information.


Explanatory notes:

1. XTZ Room Analyzer's resolution is slightly limited at bass frequencies, with the maximum resolution being 6 display points per octave. REW can show measurements at higher resolutions.
2. The XTZ Room Analyzer allows averaging of three measurements from different positions in the room. When this is done it is still possible to view the time domain analysis. This is very useful in a home theater type situation where a single set of global parametric EQ filters is required to cover a large spatial area. Whilst frequency domain averaging is possible in Room EQ Wizard, time domain is not.
3. XTZ Room Analyzer is designed as an integrated hardware and software product. The software includes compensation for the included measurement microphone. Whilst Room EQ Wizard includes ability to load a compensation curve, the customer is then required to purchase a microphone with a frequency response included. Some of the popular models e.g. Behringer ECM8000 do not include the frequency response and must therefore be 'calibrated' at additional cost in order to use the compensation capability in the software.
4. XTZ Room Analzyer's automatic EQ mode tends to focus more on reducing the negative impact of room modes rather than optimizing for a completely flat frequency response. The after EQ decay time performance is shown. Room EQ Wizard's auto-EQ mode optimizes for frequency response and does not show you the after EQ decay time performance.
5. Both packages allow the user to manually set up EQ filters. In Room EQ Wizard this is done by specifying Q, dB gain/cut and Frequency in a parametric EQ filter table. XTZ Room Analyzer offers this table baed editing but in addition provides a more sophisticated graphical interface that allows an end user to drag a point on the frequency response to a desired new target. The Q, dB gain/cut and Frequency are then automatically generated by the software.
6. The XTZ Room Analyzer has an innovative 'stimulus EQ' mode that allows a new measurement to be taken that incorporates both automatic generated and manually created parametric EQ filters. The resulting frequency response and waterfall analysis show what the room response would be like if the proposed parametric EQ was added to the system.
7. XTZ Room Analyzer can, to my knowlege, only download EQ settings to their DSP enabled devices (they make a sub and sub amp that have DSP capability). Room EQ Wizard allows use with Behringer DSP devices and some older and no longer available Tag MacLaren devices. Obviously in either case the filters identified can be manually transferred over to any parametric EQ device easily enough.
8. XTZ Room Analyzer includes a measurement microphone, soundcard and cables within the package. Room EQ Wizard requires that the customer separately identifies and purchases these items.
9. Room EQ Wizard is a Java based application and can therefore be run on both Windows and OSX platforms.

On the functionality side it looks like a tie - whilst Room EQ Wizard does have a few more measurement capabilities (spectrum analyzer, signal generator, energy time curve analyzer) it lacks some of the innovative and sophisticated features that the XTZ Room Analyzer has for dialing in room equalization like the 'measure with EQ' and 'three position spatial averaging allowing viewing of time decay'.
 

The Smokester

Well-Known Member
Jun 7, 2010
347
1
925
N. California
Nyal,
Very nice writeup. I am a rank beginner so can I ask a couple of dumb questions?

1. What is different in the capability between the "XTZ Room Analyzer allows averaging of three measurements from different positions in the room" and the averaging (tab) capability of REW which allows averaging of multiple responses?

2. I am a beginner, but to me, the impulse response is very useful and apparently XTZ does not produce this analysis. Anyway, the impulse response allows me to identify, and hopefully selectively remediate, sources of reflections by measuring the time-of-flight. Maybe this is more useful to me because I am stuck in a living room and have more clutter than a dedicated listening room. Impulse measurements allow me to present "evidence" to my wife when negotiating modifications to our living room and so are not to be dismissed lightly.

Also, by narrowly time-gating the impulse windows, I believe that some aspects of the speaker response can be estimated thus allowing that source of uncertainty to be reduced.

So, is there a way to get at these issues (reflections and speaker response) with XTZ?
 

audioguy

WBF Founding Member
Apr 20, 2010
2,794
73
1,635
Near Atlanta, GA but not too near!
I just sold my XTZ package and will continue to use the PITA REW. For me the only real value of XTZ was ease of use and repeatability. XTZ lacked way too much functionality to be of any real use for my purposes. RT60 analysis was too limited. No easy way to easily compare curves. I could go on. If your only interest is the ability to move your sub around and find the optimum spot for the flattest FR, XTZ might work.

Having said that, the frustration caused by having to go thru all of the "krap" with REW may cause you to pull out your hair. I have also used ETF and it is also not quite plug and play either.

Mark Seaton posted on another forum that he saw a measurement package at CEDIA. "At CEDIA I had a moment to look over what looks to be a great little measurement system from Parts Express. It will have some limits, but it is a calibrated plug and measure (USB) system with most of the important capabilities. They are hopeful it will show up before the end of November, and at $349 I expect it will definitely see so" Sound a bit like XTZ !
 

FrantzM

Member Sponsor & WBF Founding Member
Apr 20, 2010
6,455
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405
Nice job, Nyal. I think you nailed it.

As for the Parts-Express OmniMic System, I expect to have one in about 2 weeks.

Kal

+ 1 .

Also agree with Audioguy on REW. Once one's past the steep learning curve, it is a very powerful and useful tool. One that goes beyond simple subwoofer placement. Now I am also interested in that Parts Exxpress tool.. Availability? Final Price?
 

Nyal Mellor

Industry Expert
Jul 14, 2010
590
4
330
SF Bay Area, CA, USA
Nyal,
Very nice writeup. I am a rank beginner so can I ask a couple of dumb questions?

1. What is different in the capability between the "XTZ Room Analyzer allows averaging of three measurements from different positions in the room" and the averaging (tab) capability of REW which allows averaging of multiple responses?

2. I am a beginner, but to me, the impulse response is very useful and apparently XTZ does not produce this analysis. Anyway, the impulse response allows me to identify, and hopefully selectively remediate, sources of reflections by measuring the time-of-flight. Maybe this is more useful to me because I am stuck in a living room and have more clutter than a dedicated listening room. Impulse measurements allow me to present "evidence" to my wife when negotiating modifications to our living room and so are not to be dismissed lightly.

Also, by narrowly time-gating the impulse windows, I believe that some aspects of the speaker response can be estimated thus allowing that source of uncertainty to be reduced.

So, is there a way to get at these issues (reflections and speaker response) with XTZ?

1) The three average capability offered by XTZ allows you to measure the room in three positions. It then calculates an average from which you can see performance in both the frequency (e.g. frequency response) and time (e.g. waterfall) domains. Room EQ Wizard (and all the other software products I have used) do not allow you to average multiple measurements whilst preserving the time domain information. Once you average in Room EQ Wizard then you can't see the time domain performance of the room. I don't know what the writers of the software (Wavecapture AS) do with the maths to make this work but it is useful to see how the average low frequency performance of a room.

2) Yes, XTZ does not offer impulse or the much easier to understand energy time curve (ETC). However from experience I can say that even with an ETC you still have to identify the surface that is causing the reflection by turning the time figure into a length figure. In 90% of cases you can quickly see where the strong early reflections would be by looking at the first reflection points in the room (i.e. the side walls, wall behind the listening position, ceiling and floor). So whilst ETC is nice to have you can get by without it.

XTZ does offer a way to gate the measurement on the 'Full Range' tab. Unfortunately it is not infinitely adjustable and only offers 3 choices for gating (4ms, 8ms and ungated).
 

audioblazer

Member Sponsor
May 13, 2010
765
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Nyal, I m not sure whether it's appropriate to ask you some questions abt some of the functions in full range tab in this thread. However would appreciate if you could answer.
Just got the XTZ analyzer and whether I use the full range tab, I noticed there are 3 graphs once I tap the measurement button ie anechoic , ambient and raw? Which is the actual full range graph? Raw? Thanks
 

Nordenstam

New Member
Aug 18, 2010
37
0
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nordenmaster.no
2) Yes, XTZ does not offer impulse or the much easier to understand energy time curve (ETC). However from experience I can say that even with an ETC you still have to identify the surface that is causing the reflection by turning the time figure into a length figure. In 90% of cases you can quickly see where the strong early reflections would be by looking at the first reflection points in the room (i.e. the side walls, wall behind the listening position, ceiling and floor). So whilst ETC is nice to have you can get by without it.

I will offer a different viewpoint.

The arrival time differences can be translated to equal lengths, yes. This only works for simple reflections, typically the ones that bounce on one surface. For more complex paths between speakers and sweetspot, such approaches fall short without complex geometrical modelling.

ETC's can be used to identify any and all reflections. By blocking the possible arrival directions to the microphone with an absorptive patch, the general direction will be found. Try absorber at righ, at left, above and below. One of the directions is bound to correspond to the arrival direction of the reflection. By moving the absorber further away from the mic, one will eventually end up identifying the exact point of origin for any reflection. If a loopback connection is used for referenece, it's also possible to move the microphone to get the general idea of where the reflections is comming from. As explained here: http://www.synaudcon.com/site/articles/how-to-determine-a-reflections-direction-without-polar-etc/

First reflections are not the only early reflections. There are typically many early reflections that have bounced on more than one surface.

When the general area of the reflection have been identified, treatment can commence. This typically involves some sort absorptive device. The effectiveness of the device can be considerably better if it's placed precicely where it's needed most. This seldom corresponds directly to the geometric reflection point as seen in mirrors. Amongst other effects, the absorber itself will change the path of the sound. By moving the absorber around a bit in the general area, the ETC graph will tell where the most effective place for the absorber is. It will also be obvious if the absorber is reaching the desired goal of attenuation in dB. Many times, the angle of the absorber have to be quite specific to attain maximum attenuation.

This will also help avoid a much overlooked factor in room treatment; the tendency for sound to reflect at grazing angles. Many absorbers are too dense to let the sound inside at high angles. This leads to a specular reflection where the end user expects absorption. The ability of ETC graphs to quantify the level of a particular reflection in deciBel helps avoid this subtle effect that can lead to sonic nightmares.
 

Nyal Mellor

Industry Expert
Jul 14, 2010
590
4
330
SF Bay Area, CA, USA
Nyal, I m not sure whether it's appropriate to ask you some questions abt some of the functions in full range tab in this thread. However would appreciate if you could answer.
Just got the XTZ analyzer and whether I use the full range tab, I noticed there are 3 graphs once I tap the measurement button ie anechoic , ambient and raw? Which is the actual full range graph? Raw? Thanks

Hi Audioblazer

Sorry I've been on vacation!

Probably best in general to direct queries to my email address or phone number which can be found on my website in the Contact Us section that way you will get a quicker response :)

Anechoic, Ambient and Raw refer to the gating time used by the Room Analyzer. Basically Anechoic cuts off the impulse response after a short period of time (the time it takes for the sound to travel from speaker to microphone and a few milliseconds after) to try to give a view into the what the speaker's response is compared to that caused by placing the speakers within the room (what is shown on the Raw measurement). Generally for acoustic measurement you will use the Raw measurement since that equates to what your ears hear...

Hope that answers your question!
 

Nyal Mellor

Industry Expert
Jul 14, 2010
590
4
330
SF Bay Area, CA, USA
I will offer a different viewpoint.

The arrival time differences can be translated to equal lengths, yes. This only works for simple reflections, typically the ones that bounce on one surface. For more complex paths between speakers and sweetspot, such approaches fall short without complex geometrical modelling.

ETC's can be used to identify any and all reflections. By blocking the possible arrival directions to the microphone with an absorptive patch, the general direction will be found. Try absorber at righ, at left, above and below. One of the directions is bound to correspond to the arrival direction of the reflection. By moving the absorber further away from the mic, one will eventually end up identifying the exact point of origin for any reflection. If a loopback connection is used for referenece, it's also possible to move the microphone to get the general idea of where the reflections is comming from. As explained here: http://www.synaudcon.com/site/articles/how-to-determine-a-reflections-direction-without-polar-etc/

First reflections are not the only early reflections. There are typically many early reflections that have bounced on more than one surface.

When the general area of the reflection have been identified, treatment can commence. This typically involves some sort absorptive device. The effectiveness of the device can be considerably better if it's placed precicely where it's needed most. This seldom corresponds directly to the geometric reflection point as seen in mirrors. Amongst other effects, the absorber itself will change the path of the sound. By moving the absorber around a bit in the general area, the ETC graph will tell where the most effective place for the absorber is. It will also be obvious if the absorber is reaching the desired goal of attenuation in dB. Many times, the angle of the absorber have to be quite specific to attain maximum attenuation.

This will also help avoid a much overlooked factor in room treatment; the tendency for sound to reflect at grazing angles. Many absorbers are too dense to let the sound inside at high angles. This leads to a specular reflection where the end user expects absorption. The ability of ETC graphs to quantify the level of a particular reflection in deciBel helps avoid this subtle effect that can lead to sonic nightmares.

All very true, thanks for the additional insight. Just one thing I might add - due to the way in which sound pressure level drops with distance generally speaking one needs only worry about the first reflection. However, as Nordenstam points out, in some cases the layout of your room and speaker location may cause some high level reflections from strange places. In these instances the method Nordenstam outlines works a treat.
 

audioblazer

Member Sponsor
May 13, 2010
765
204
1,605
Malaysia
Nyal, thanks for the clarification. I have been using the raw measurement for room & speaker interaction . Anyway the XtZ is so easy to use. It certainly make positioning the speaker or listening position or both easier. I was able to adjust my listening position to get a flatter bass response and frequency response . It's a no brainer measurement tool for some of us with cones more expensive than XTZ. However I wish that the manual could have been more details and include concise explanation on how to interprete the graphs
 

Nyal Mellor

Industry Expert
Jul 14, 2010
590
4
330
SF Bay Area, CA, USA
Nyal, thanks for the clarification. I have been using the raw measurement for room & speaker interaction . Anyway the XtZ is so easy to use. It certainly make positioning the speaker or listening position or both easier. I was able to adjust my listening position to get a flatter bass response and frequency response . It's a no brainer measurement tool for some of us with cones more expensive than XTZ. However I wish that the manual could have been more details and include concise explanation on how to interprete the graphs

I definitely agree on the manual and more explanations needed on how to interpret the graphs. I am planning on creating some videos and further text and diagrams on each what each measurement is, what acoustical distortion is associated with it, the target for the measurement from a best practice perspective and the different methods to improve the measurement. In that way I hope I can make acoustical measurement and improvement more 'consumable' for the end user.
 

cjf

Well-Known Member
Nov 19, 2012
452
101
948
Resurrecting this thread back from the dead.

Has anyone tried the PartsExpress product mentioned above and if so, would you be so kind to report on its capabilities? I would also be interested in hearing how it compares to the REW and XTZ products if possible. Any glaring shortcomings of the PartsExpress offering?

Thanks
 

Kal Rubinson

Well-Known Member
May 4, 2010
2,360
697
1,700
NYC
www.stereophile.com

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