December 2012

Audiolics Anonymous Chapter 157
XTZ Room Analyzer II Pro
This system is a steal as a measurement microphone and a great way to improve your system and room's sound!
Article By Bill Gaw

  Welcome to my pre-Christmas article. In past years this month's column has centered on budget priced gifts that either you could hint for or actually treat yourself to without the family thinking that you're crazy. This time I'm going to discuss a component that, while not cheap, is reasonably priced and at the same time should elevate your system's sound to higher levels with minimal work and expense.

Before that though, I'd like to discuss a web site that you'll have to be careful with High Def Tape Transfers. While their name suggest that they are getting their files from master tapes and selling very high definition files up to 24-bit/384kHz., many of them are being transcribed from vinyl. While this may be of some value to the younger audiophile who cannot find the vinyl at the local used record store, there are two problems. First, whether the original recording is coming from vinyl or tape is spelled out with very small print, and easily missed. Second, there is considerable vinyl hiss on some of them. I don't mean scratches, but the inherent continuous noise that is improved upon by the best phono systems. While they are otherwise using audiophile grade components to produce the files, I find the naming of their site less than honest. "High Definition Transfers" would be more accurate. Caveat emptor!

XTZ Room Analyzer II Pro
I purchased this speaker and room analyzing and correction system from XTZ Sound, , about six months ago. I forgot to write the article as I was ecstatic with the results and went on to review other products with the improved sound. My bad! At that time, about 20 minutes was spent setting my home theater computer up with its software, and about two hours correcting all 7 speaker systems plus 8 subwoofers in my media room. Most of that time was consumed learning how to work the software, after which each speaker took about 15 minutes to correct its response to what was not quite flat, but what I consider to be optimal sound that I hear in a concert hall.

How do I know that it was improved? Not by rapid double blind testing of the speaker's obviously, which would entail having to change all of the values back and forth on the crossover and computer's digital correction, but by having kept all of the speakers' sound field values on my Smyth Realizer A8 headphone unit, and switching rapidly back and forth between the two to see which was correct in my estimation. The Smyth Realizer allows this because of it uncanny ability to reproduce almost perfectly a system's soundfield through appropriate high end  headphones.

My system has seven speakers, each with three sets of horns and drivers plus a subwoofer controlled by 4 way active crossovers that allow me to change crossover frequencies, slopes, relative driver distances, and relative volumes, plus the use of digital correction through my home theater computer or Classé CT-SSP pre-pro to do fine corrections of room and speaker frequency-produced anomalies. Thus, compared to most available speakers that have built-in passive crossovers that are tuned for the ears of the developer, my system can be tuned any way I want. What do I mean?

There are several possible ways to set up a speaker's output. First is for flat frequency response from 20 Hz to 20 kHz or more. Thus you'll hear exactly what is on the source. Unhappily there are few sources that hold what the average listener hears at a concert venue because the microphones are in a different position from the listener, have different pickup characteristics, and there is a sound engineer between you and the source manipulating the data.

Second is to set it up to obtain the sound heard in a concert hall. The further one sits back, the less direct high frequency information and more ambiance information is available. Thus, on some recordings one can reproduce a concert hall effect but obviously not on all, depending on again on the mic'ing and manipulation of the music by the sound engineer.

Third would be the way the speaker builder hears sound and fourth would be how the listener prefers his sound. Obviously with most speakers, the third type in the past has been the most frequent as most listeners wouldn't be able or willing to open their speakers and play around with the passive crossover, and the available digital and analog methods of adjustment weren't very good.

Tweakers, on the other hand, could play around with the crossover values, and with active crossovers and the newest digital signal processors, manipulate the speakers to what they considered the "absolute sound." For this discussion, it doesn't really matter which method one prefers, as the XTZ unit allows one to set up the speaker and room output in any manner.

I know, for some of you out there the ultimate system is the one with the least manipulation of the signal to obtain exactly what the recording engineer wanted you to hear. But remember, what they produce is theirs and possibly the musician's subjective feeling of what should be on the recording reproduced through usually less than audiophile standard equipment. One need only listen to golden era Columbia verses RCA verses London or Deutsch Gramophone recordings to understand what I mean. Each had it "home sound" with each recording engineer adding his artistic impression of what one should hear. This has been carried over, and to some extent been worsened by modern engineers with their increasing ways of manipulating the sound.

Also, some of you out there have pre-pros that have some sort of auto digital speaker and room correction, such as the Tact, Trinov and Anthem. My previous Onkyo Integra had the Audyssey system, but each time I tried it, the system came up with different frequency responses that were never quite correct to my ears. My new pre-pro, the Classé CT-SSP unit, has the ability to digitally correct the speaker and room response, but no way of measuring it. With the XTZ unit one can objectively watch and adjust the sound to perfectly match what you wish to accomplish. Of course this can be seriously overdone by the listener with less than perfect ears, but I don't expect any of my readers to have this affliction.

The system is delivered in a double packed thick cardboard box with all components housed in a light aluminum case. Inside the case is a +/- 1 dB measurement microphone with a long XLR cord, table-top stand,  a long cord with XLR connector on one end and stereo mini phono jack on the other and a control box. The software is downloaded from the XTZ web site.

One puts the microphone at the exact position of the center of your head's listening position, set the computer sound card to input to the box and output a signal to your preamp or pre-pro. The software is then set up to do real time analyzing of your speaker and room frequency response and produce graphs of this, 2d/3d waterfall room reverb time, and FFT measurements.

The box and software will send one of several different types of signals through the speaker depending on what you are measuring, and produce a graph of the type of measurement you are doing on the computer screen. First, graphs of the room modes at the listening position are plotted. One can then correct the peaks by adjusting the crossover values, volumes of the various drivers, and the valleys by use of room correction devices such as tube traps. Then, fine adjustments of the speaker frequency outputs by digital or analog signal correction are performed, and finally the room reverberation times can be adjusted with appropriate sound absorption materials.

For instance when measuring frequency response of the speaker a frequency sweep will be performed and the reproduction of the sweep with the speaker and room response for that place in your room will be produced. One can then adjust the crossover and/or digital signal processing on the computer to get the speaker to whatever one wishes.

Because of the long length of the cables, I was able to actually sit right next to my active crossovers throughout the room and do immediate adjustments of the measurements to get what I consider to be optimal reproduction. I prefer a tilted but internally flat curve with about a 3 dB decreasing output from bass to treble. Interestingly, my two main speakers at the beginning of the measurements almost met these criteria. Where the XTZ helped me tremendously was the ability to match the center and surround speakers' outputs to the main speakers, something that I've had trouble with in the past, and to get rid of a room mode at my listening position in the 800 Hz range.

I've used several other systems in the past to do room and speaker correction and none of them match this unit's speed, ease of use and quality of the final product. A big plus is that you purchase directly from them with a three week no questions asked return policy. At $330 plus shipping, the system is a steal as a measurement microphone alone can cost several times that. As a way to improve your system and room's sound it's a no-brainer.

Happy Holidays!