Room Correction Systems?

Below is an edited repost of a description of my experience with digital room correction systems. My comparison of the Tact unit is a year old and I don't know if they have made software upgrades which may have addressed some of the short comings. To summarize a long post, if your primary source is digital and you listen to late romatic classical music, I think that a DSP is a valuable addition on top of a high end system that is already excellent. While it can correct for gross defects in rooms and speakers I believe that this use is self defeating as far as sonic realism is concerned. It does nothing for high end vinyl so you must use other approaches to room treatment if you use high end vinyl as a source./

I recently hired an audio engineer for two days (costs less than high end cable) who had the MLSSA speaker measurement equipment along with all the impulse, spectral decay, modal, FFT, etc analysis equipment. I experimented with speaker placement, room treatments and both the Tact and Sigtech signal processors over those two days. I then listened to both DSP units for a week. Since I have Dunlavy V speakers I have the exact anechoic frequency/time response curves of the actual speakers for comparison to my in room measurements and don’t need to worry that my speakers are not impulse coherent. Using the impulse response measurements it is easy to see the room effects. From FFT you also see the modal response. The secret to good room treatment is to smooth the frequency response while damping the first and most of the second reflections while leaving the direct sound and later reflections to provide air. Sound travels at about 1 foot per millisecond. Reflections under 5-7 ms are perceived as colorations. Over 30 ms the perception is of ambiance, reverberation or echo. The best DSP units use algorithms that are designed with the psychoacoustice s in mind as well as with variable amounts correction with respect to frequency. The best are amazing. I first used the RPG Room Optimizer software to get some ideas of my options for speaker placement and modal analysis. I moved the speakers and listening area around my dedicated room both listening and measuring (modal and impulse) until I got what was the best untreated response and sound. The RPG software (within its level detail) was roughly similar to the actual measurements and I recommend it highly since it recommend where to put the passive treatments. I used the Sigtech with basic ASC/RPG room treatments and without. The Sigtech without any passive treatments corrected (and sounded) significantly better than the basic passive treatments alone, particularly in the 20-80Hz range. Adding, the passive treatments at first reflection points with bass traps and using the Sigtech improved the sound only a little more. The Sigtech provides the most impact on large scale complex orchestral/choral/opera recordings. Especially on those with heavy bass (Mahler, Wagner, Stravinsky) the improvement is amazing. On simpler ensembles like rock and jazz the bass articulation and detail is noticeably improved but not a lot more than with large ASC bass traps and passive treatment. However, my room is pretty good to begin with. The Tact unit based both on measurements and listing is not as good as the Sigtech and I would not recommend it for a two channel very high end system. The Tact unit added noticable digital glare in bypass mode which I did not hear with the Sigtech. It also was not as accurate in its correction as measured by using the MLSSA measurements after using its own measurement/correction software. I think it would be fine for most home theatre applications. I listen primarily complex classical, heavy metal, opera and art techno. I bought the Sigtech and couldn’t live without it. My wife and our two female friends who participated in the evaluation tried to convince Sigtech to leave the loaner unit with us until our unit could be manufactured. Your Mileage May Vary.

I posted a review last week of the Tact RCS 2.0 under the thread "Tact RCS" in this forum. Bottom line: Tact RCS 2.0 costs $3K, Sigtech is pushing $10 K. Tact is a DIY project, Sigtech comes with Real Engineers. Tact RCS 2.0 gives a very noticeable improvement. I didn't listen to the Sigtech. The Absolute Sound is scheduled to render a verdict on Tact RCS 2.0 vs Sigtech in the December 2000 issue.

Pls1, If you don't mind my asking, how much did it cost for the engineer for 2 days. It seems like you did the entire setup the right way. Very interesting!

The engineer is $100 per hour. It took about 10 hours. The Sigtech configuration cost me about $6K which is roughly 10% of the total cost of my system.