Originally Posted by moleman74
My problem is exactly as you describe but I can not figure out how to read the reverb measurements. I do not have a laptop that I can connect so I am stuck with osd. I have uploaded som pic.from measurements without EQ maybe you can see something from them.
I have turned trim level down from 0db to -2db since that was the only thing that I could see related to volume.
I have a sclx85
OK. Might me more complicated than I thought. For discussion, I included one of my reverb plots. Don't worry about the PC software. I have never used it either. It's not very convenient to pull this big receiver out of the cabinet to connect a cable to the back.
I don't know how technical you are, so I may describe things you already know. Not trying to offend anyone. I certainly don't know everything, just enough to be dangerous. The plot shows sound magnitude as a function of time. No system is infinitely fast, so the plots will always start at some lower magnitude and increase with time. Ideally each trace would quickly rise to it's steady state value and stay there for the rest of the time plotted. Each colored trace represents a different frequency. Ideally, the magnitude should be the same at all frequencies.
In my plot, most of the traces rise reasonably quickly and reach nearly the same level by 30-40ms. The 16kHz trace settles to a slightly lower level than the other frequencies. This data is for my center channel which is mounted over the TV slightly above head level. The listening position is slightly off axis, causing a little roll off at the highest frequencies. The interesting trace is at 63Hz. At this frequency, the amplitude rises more slowly and overshoots the traces for all other frequencies by a significant amount. If there were a measurement at 30Hz, it would be even worse. As I mentioned in a previous post, 30Hz is my worst frequency due to a standing wave along the long dimension of the room.
Looking at the 63Hz trace on my plot, you can see what's going on with MCACC. If I measure at 80ms, MCACC will think my system is much more efficient at 63Hz than at higher frequencies. As a result, the calibration will attenuate the lower frequencies (our original weak bass problem. If, on the other hand, I were to measure at 20ms, MCACC would think my system is much less efficient at 63Hz than at higher frequencies. The calibration would turn up the lower frequencies, resulting in overpowering bass. At about 40ms, my 63Hz trace is about equal in amplitude to the other frequencies. I know from manual measurements that my center channel has flat response across this frequency range. Therefore, I conclude that the 30-50ms window captures the best representation of my system in my non-ideal listening room with reverberation. It's not an exact science, but this logic gets you pretty close to what you want.
I don't think I see a 63Hz plot in your data. I assume your speakers to not produce these frequencies. Your data shows similar behavior to mine at 125Hz. Looking at your center channel, it takes about 80ms for your 125Hz trace to reach the steady state. The 250Hz and 500Hz also show some behavior below 40ms. In your data, there is no overshoot, so I assume MCACC will need to boost these lower frequencies a few dB in the calibration. Same as me, for longer notes, that will cause your amplitude at 125, 250, 500Hz to be slightly higher than at higher frequencies. That's the compromise. For your center channel, I think I would still use 30-50ms window.
I am a little more concerned about your right and left channels. Both of these show low 125Hz levels. The level is low for all time captured. This does not look like a reverberation issue. This looks like the left and right may be smaller than the other channels and not able to easily produce 125Hz. MCACC will try to boost the L/R channels by 4-5dB at 125Hz, significantly increasing power and excursion on these channels. If this is correct, you may want to pick a higher crossover frequency and avoid damage. I don't know how high the crossover selection goes.
Based on your data and my experience with MCACC so far, I would say calibrate using the 30-50ms window. Listen and see how over-pronounced the bass sounds. If it is too much, go into manual EQ and lower the 125Hz band 2dB or so. Repeat until you find the balance.