Ramblings
August / September 2007

  Preview: ETF Acoustic RPIusD room measurement software (www.etfacoustic.com)

The ETF 5 measurement system has been instrumental in many of my TSS reviews on speakers and electronic equalizers. A reasonable starting point to use this inexpensive software package is as your computer’s internal sound card and the microphone in a Radio Shack sound level meter. Better results, like the ones I present in TSS, are obtained with an external sound card and calibration microphone.

ETF Acoustics has recently introduced RPlusD, which is designed for analysis of combined room and speaker response characteristics.. The GUI is much improved over ETF 5. For example, the frequency band can be specified on the x-axis between any two arbitrary values and the log graph is spaced on decades of 1 regardless of the start and end frequencies. Thus, the subbars are incremented by a factor of one until the next decade is reached at which point the sub bars will increment by a factor of 10 higher. Setting amplitude limits on the graph is also easer as is the selection of gate times and smoothing filter for the frequency-domain graphs. Similarly, time-domain displacements are easier to manipulate with the new GUI.

ETF Acoustics has modified the test signal so that both the maximum length sequence noise-like signal and the frequency chirp work in tandem to maximize the signal-to-room-noise value. Display of the signal-to-noise ratio has been much improved so you can check where measurements are valid.

Up to 32 multiple measurements can be displayed together in the frequency or time domain with the RPlusD software, a distinct improvement from the single-profile plot function of ETF 5. With RPlusD you then just press the average button to see the average measurement. Displaying multiple measurements on the same graph and generating averages was a multi-step process in ETF 5.

 

Consider This Application Of The New Software

The microphone is placed at various locations in the listening area. By examining the individual curves and the averages, you can identify room modes as well as the loudspeaker’s response (above about 300Hz). The frequency-domain measurements can serve as a useful guide for to for positioning the speakers for optimal bass response smoothness. If you are using a subwoofer, you can view the response effects of moving the subwoofer and! or the satellite speaker in the crossover region. Likewise, you can examine the impact of changing the crossover frequency should your AV receiver give you the option to change it.

Studying the effect of a low-frequency absorption panel on room response is a recent exercise of mine for which the new software proved helpful. In the next issue, I will review one such product (the MondoTrap) manufactured by Realtraps (www.realtraps.com).

RPJusD also lets you see the effect of an electronic room EQ system on room response. I have been using RP1usD extensively in my review of the Audyssey Sound Equalizer scheduled for the next issue.

In the time domain, you can identify the arrival of the direct sound and the reflections of the signal off the walls, floor, and ceiling. The correct placement of mid and high frequency passive absorption panels can be easily confirmed using RPlusD. As in the ETF 5 software, room reflection can be viewed as energy time curves that allow the user to see individual frequency bands where the reflections are occurring. If the reflections occur only at high frequencies, a thinner, less expensive, passive absorber can be used.

The software has a number of advanced features for the adjustment of parametric and graphic electronic equalization systems. Extensive documentation on the product is on the ETF acoustic web site.

 

Sangean HD Tuner

I promised a review of the Sangean HD tuner that I previewed in the last issue but a newer model HDT-1X which I do not have in hand yet has features including the ability to lock the unit in analog reception mode when the HD signal is weak and the availability of an SPDJF output allowing for direct digital connection to an AV receiver. This is the unit I will test.

 

Trinnov Processor Becomes Affordable

Sherwood has announced that they will be using the Trinnov processor in a top of the line receiver to be introduced latter this year. The price has not been announced. More details will be provided by Sherwood in September at the CEDIA EXPO.

 

At CES

The following was on a poster attached to the wall of the exhibit room of a manufacturer cables, switches, repeaters, etc.

“For maximum performance and profits connect HD customers with <our> latest accessories.

At the Sony press event Joshua Bell played live and I had a good 4th row seat. It was good to see that Sony still believes classical music is an important part of the audio business. At another Hi End press event, a recording of Joshua Bell was used. The marketing person explained that his equipment was so good that you could hear Bell when he moved his violin around as he performed. Strange but I heard no such effect during his live performance.

 

Coming attractions

Electronics including the Audyssey Sound Equalizer, Parasound Z phono, Rotel RQ-970 phono preamp, and Realtraps passive bass attenuators. Speakers including the Ohm Walsh 200-S3, NHT Classic Four Home Theater System, KEF Reference, and SVS.

-DAR