Originally Posted by Steffo
So I bought a T758 V3 and replaced my HK AVR460.
After following the steps of setting up and going through the Dirac room measurements twice, the result is a bit wierd.
Bass is extreemely low compared to before, but in 5.1 mode I get a pretty decent "in the movie" feeling. I might be able to tweak the bass by working with the filters, so I'll leave that open.
When running only the front speakers however, the previously fantastic stereo image (I have a pair of Kii Three as fronts) is completely ruined. Smeared, close to the left speaker, and all clarity of all frequencys are ruined. I deleated all data and redid all the measurements and filters and tried again, but the result is the same.
All speakers distances and volume levels were correct and tuned in before starting the measurements.
So two questions again:
1, Any ideas of what might be wrong? The Kii Three have their own DSP magic done to correct for positioning and room. Can it be that this is the problem? If so I must be able to exclude them from the filtering.
2, Is there any way to exclude the two front speakers from being affected by Dirac and still have them connected on the pre outs? I mean, can I remove the filters from the two front speakers before exporting the Dirac filters to the NAD 758?
I reported the same issue in stereo mode a few pages back, and I have an open request with NAD... I suggest you report the issue as well.
After detailing the precision of my measurements and describing the problem, their solution- so far- is to tell me to follow the guide and center the first measurement. Not at all helpful. So I sent them the following:
"Thank you... I have been using the guide you attached, and that is definitely not the problem.
Please re-read my first post and then carefully read my post below. ..
Bottom line, Dirac is never able to match the calculated impulse response to the measured center listening position, NO MATTER WHERE THE CENTER POSITION IS MEASURED. The "listening center" that is calculated by Dirac is always ~4" to the left of where the mic was actually located for the first position measurement (caps for emphasis... not because I'm angry 😁)
I have verified that the microphone is absolutely centered both acoustically (using omnimic impulse response and measured stereo frequency response summing) and via a laser distance measuring device with every single run. I can say with certainty that my first measuring position is not the problem.
I can perfectly center the mic as validated above, do a single position calibration (never moving the microphone through setup, calibration, and testing) and the following will happen:
With Dirac calibration turned off, the test sweeps in Omni mic (impulse and frequency response summing) show a unified arrival time, and the image is centered between the speakers. Turning on the Dirac calibration (made in the EXACT same mic position) results in the center image moving to the left, and the impulse response of the left speaker now arriving AFTER the right speaker with Dirac turned on. The frequency response no longer sums in stereo, which confirms the problem.
If I move the Omnimic microphone ~4" to the left, the impulse response is once again in sync between the left and right speakers, and the frequency response shows proper stereo summing. Listening with a 4" offset to Left creates a center image that is now straight ahead (though offset by 4 inches between the speakers).
This problem is so predictable that I used my laser measuring tool and Omni mic to deliberately position the Dirac mic the same ~4" offset to right for the first run, and got proper summing in the Real center position between the speakers.
It is predictable and repeatable whether I do this with one measured position or all 9. I've completed multiple factory resets on the receiver, removed and redownloaded Dirac on my PC, and completed nearly a dozen calibrations with new measurements... all with the exact same problem.
I am happy to provide you with photos/video and screen shots if that would be helpful."
I’ll let you know what they come back with...