TACT RCS 2.0 Users Group

For any DSP room correction system:

For 5: Remeasure only when things that impact the time behavior or gross frequency behaviours of your system change. That includes new speakers, new pieces of furniture, moving your speakers, moving your furniture, or moving your listening position.

For 4: the answer should be to take a true time domain measurement after each curve fit to see that you actually achieved your desired response but that is the limitation discussed above.

Drubin,

Let me address a few of the questions you raised based on my experience to date with the Tact:

Your questions 1 & 2;
First, as to the Tact supplied target curves - my experience was to throw all of them away except the Near Field (NF) curve. Also, ignore the placement of the speakers that Tact recommends and go with the formula that George Cardas recommends.

Then, using the NF curve, and ideally a NF listening position (measure the distance between your speakers and move your listening position out from the face of the speakers that distance) and begin to make very small incremental changes of just 1/2 db in the frequency areas you feel need modification.

A lot of trial and error is what worked for me. Actually, the target curve I ended up with that sounds the best took very little modification from the NF default curve, but the changes were effective.

Question 3;
I have not found any tricks to the measurement process. I place the mic exactly where the center of my head will be positioned while listening, then have my computer and myself on the floor behind the listening chair.
I have experimented with sitting in the listening position and quickly swinging the mic from where my left ear is to where my right ear is during the measurement cycle, but I did not like the results I got.

Question 4;
Next step to get more out of the system is, IMHO, to have all of us push Tact to release the enhanced software that they said they would in the last issue of Absolute Sound under the Manf. Comments area on the article Robert Green wrote reviewing the Tact with the Sigtech. That plus support for running the software on a laptop in 600x480 res would be nice.

Question 5;
Actually, I have found I do remeasure after changing any element in the system. Now, bare in mind, I'm the Poster Child for the Anil Retentive of North America, but I can see in the measurement graph and hear a difference. In my experience it is worth the extra effort.

I have recently been testing different digital cables and analog interconnects and found it necessary to remeasure and reload the target curves to get the best sound from my system.

In closing, I would like to suggest that each of us begin pushing Tact to satisfy some of the user needs that this thread has brought to light. Collectively we have a lot more clout than any one of us does alone.

One additional suggestion which is a substitute for indpendent measurement. Get a good Mercury Living Presence CD that was recorded in Mono. A stereo recording played in mono won't work because you do't know the actual left right time response. I recommend the Dorati recording of Tchaikovsky's Swan Lake with the Minneapolis Symphony. It doesn't matter if you don't like classical this is a test record. Listen to the last 15 minutes with your eyes closed. If your curves succesfully correct for the room and speaker anomolies, the image should be rock solid between the speakers. If the instruments wander depending on what is playing or how many other instruments are playing, you should check your speaker placement and remeasure. This should work with just about any reasonable target frequency response curve.

I would also recommend that people looking to understand the response of their room try ETF 5.x. Look at http://www.etfacoustic.com/. It is some times simpler (and cheaper) to correct the response this way.

Question 1: I found the TactG1 best suited my taste in terms of the provided target curves. I have a PSB Stratus Gold-i speakers (full range). Other curves would work better for speakers with a more restricted LF response.

Question 2: TactG1 was a good starting place, but what I'm running now is a hybrid of TactG1 and TactF1 (I spliced the HF portion of TactF1 in place of the highend of TactG1), and I tweaked the midrange (500 -1500 Hz) up a bit, with a max rise of about 1 dB at 1 kHz for a bit more presence, and boosted the upper bass / low midrange a a skoche for a tad more warmth and bass oomph. I find the Tact curves just a little too dry (I add ed 0 dB boost at 250 Hz rising to about 2 dB boost at 100 Hz, then smoothly sloping to match target curve at around 50 Hz). I'd be happy to e-mail my target curve to anyone who's interested.

Question 3: Get the house as quiet as possible. I wait until everyone's gone to bed (although St. Bernards snoring in the mudroom carry a long way), turn off the central heat, and wait 'til the refrigerator stops running. Turn up the preamp volume to a LOUD listening level, and use a lot of averaging (I use 20 averages, but 100 would be better -- an effective SNR increase of 7 dB in the measurement).

Question 4: tweak and listen. An experiment I'd like to do is to program a Fletcher-Munson equal loudness curve as a target curve. See, for example,
http://www.sfu.ca/sca/Manuals/ZAAPf/e/equal_loud_cont.html The curve describes the relative power level needed for a sound at any frequency to sound as loud as a
reference tone at 1 kHz. In effective, it's an equalization curve for the "typical" human ear. It shows that at moderate levels (say 80 dB SPL at 1 kHz) significant
boost and buck (a few dB to over 10 dB) of various frequencies is needed for those frequencies to sound as loud as the reference 1 kHz tone. So even though the target
curve is decidely unflat, using this target should result in a systems that SOUNDS flat. By the way, see the Stereophile archives for J. Gordon Holt's article on why "Flat is Bad" (or similar such title).

Question 4, cont'd -- I'm also suspicious that the Tact inverts polarity (am running in DD mode)... I found that with the Tact in the signal chain, my systems sounds a bit more open if I switch on polarity inversion in my preamp (this effect passed the "honey, do you hear this?" A/B blind test). I suppose what I ought to do next time I calibrate is turn polarity inversion on, calibrate, and then turn polarity inversion off and run the system that way as a matter of course.

Question 5: I remeasure every time the room configuration changes. I've found that once I've calibrated the room, even relatively small changes are audible degradations
in sound quality -- a large pile of books on the coffee table for example changes things noticeably. I've changes some components ranging from cables to preamps and not
recalibrated. If these components do not have flat frequency response, then any sonic impact they provide will be (or should be) washed out the next time I recalibrate.