Can you summarize one last time how we did this?
Manual “SPL/IR” SW+Main timing alignment method:
[An alternative method to the “SPL/RTA” SW+main timing alignment method.]
Setup steps:
> Mic at LP.
> Choose to use either the FL or FR to establish the timing alignment with the SW. We chose the FR.
> Measure and record the physical distances from the LP of both the SW and FR. Set one of them to 5 m in the AVR and the other to the difference in physical distance. Example: SW measures about 2.8 m and the FR about 3.2 m. So we could add 1.8 m to both values and enter SW = 4.6 m and FR = 5.0 m in the AVR. We will adjust the one that is set to 5 m. In this example that is the FR.
> Previously entered EQ settings can be either left on or turned off.
> Activate Loopback feature in REW.
> Set REW preferences to use 1/3 or 1/6 smoothing.
> Use only full range sweep measurements (15 – 20k Hz) for all measurements.
> Choose the AVR distance increments to be used for the trial and error process. I recommend about 0.5 m.
Process:
[Trial and error method. (See post 140 for a calculation method.)]
> Sweep measure SW, FR, SW+FR
> View IR locations of the SW and FR initial peaks. [If the initial distances are entered properly the initial rise of the FR and SW IR peaks should fall within 1 or 2 ms of each other. This is good enough for the starting point of this process.]
> Be sure to label the distance setting on each measurement
> View the overlay SPL graph for the SW, FR and SW+FR. Identify the XO freq range as the range between where either the SW or the FR SPL falls more than maybe 20 or 25 dB from the average SPL in the area adjoining that range.
> Increment the FR distance and measure both FR and SW+FR.
> View the overlay SPL graph for each SW+FR measurement. Look to identify a setting that is nearest to the initial starting setting of 5 m that provides the highest SPL through the XO range. [I like to leave the “SW” and “FR at 5.00 m” traces visible also as I review the SW+FR increments because that better shows the SPL fill in the XO range of the traces. A good alignment will have the SPL+FR trace fall as high as possible over the SW or FR trace at all points in the XO range.]
> After we find that good alignment we can then optionally fine tune that setting by using smaller distance increments. The difference in distance between the SW and FR is the magic number we need to later set the distances in the AVR.
> The setting with the initial rise of SW and FR IRs falling closest to each other is the alignment that provides the closest phase match of the SW and FR throughout the entire XO range.
> Once we find this first solution we can predict the approximate location of alternate solutions. Another solution will fall the distance of one WL (wavelength) greater and another one WL less.
[For example if we find that a solution with the FR at 4.85 m and the XO is at 80 Hz then another solution will be found with the FR near 4.85 + 4.30 = 9.05 m and also one at 4.85 – 4.3 =
0.55 m (4.3 m being the approx. WL of 80 Hz).]
If we invert the polarity of the SW, we can expect to find solutions at about 1/2 WL more and 1/2 WL less.
> We are only interested in 3 of the alignments the one that places the initial IR rise of the SW and FR closest to the same time and the ones 1/2 WL above and 12 WL below that. We can go find those alignments and fine tune them if we want. [The distance offsets are only estimates as the actual phase timing may not actually be right at 80 Hz XO freq as was the case here for Sanders setup. To maximize the SPL fill-in in this case the alignment target was nearer 65 Hz than 80 Hz. The offsets distances are thus impacted according, WL distance for 65 Hz is about 5.16 m]
> We should also confirm that this solution works well for the FL speaker as well.
[I would think it would in most cases, but with my very asymmetrical room setup I decided to use a compromised solution falling between the best solutions found for the FR and for the FL.]
> We now use any FR and SW distance values in the AVR that retains the offset distance between them. We just need to select values that will provide enough room to allow us to set the CC, SL and SR distances to the values needed. Those that match the same IR arrival time as the FR IR.
One thing though: Auddysey measured totally different distance settings (Auddysey corresponds with tape measuring, eg. my surround speakers are @2.80m physical distance and audyssey measured 2.85m). Is audyssey THAT bad?
Most comments I see indicate that Audyssey does very well in aligning the SW to Mains. I have not seen measurements (other than my own experiments) that do a good job of comparing the Audyssey results to a well aligned manual setup. My own experience with Audyssey timing is not good, but I have mostly tested it with non-standard setups. If I set my DCX filters to simulate the standard main speaker roll off rates at about 80 Hz then Audyssey did in fact find a good XO setting and good timing. It still boosted my SWs excessively (about +9 dB at 20 Hz; their lower limit). Maybe like many automated setup systems (for any type of system) as long as the expected conditions are found the setup will be acceptable?? Speaker designs and room responses vary so much it is probably difficult to get it right in all cases.
Your 0.05 m difference for the surrounds is insignificant. The initial timing of your FR was much worse however. I think that is what started the initial concern.
I speculate that, had you just reversed the polarity on the SW (or all the main speakers) then Audyssey may well have gotten it right. I say that because your initial alignment was close to correct if the polarity of the SW was switched. The IRs were aligned well, but it was about 160 deg out of phase alignment leaving a big dip in your SPL response.
SPL I can see but phase is a thing I would still like to learn too how to see this. Can t one just say that the phase is correct because the SPL has the least dips in the CO range?
Yes.
why don t we check the SPL and phase of the SW+CC, SW+SR and SW+SL? Escpecially the center speaker does a lot during a movie.
I think that in movies the CC is primarily a dialog channel and there is little if any bass in it? You can test this with the REW RTA if you like. Maybe someone else here already knows. Even if it does contain bass would you decide to prioritize the timing for the CC at the expense of the FL and FR?
Your particular speakers are designed to properly to go together in an HT setup. The CC and surround designs are both complimentary to the FL/FR so that the phase timing would be expect to be very similar. I did indeed check this out and, as expected, the phase timing of all 5 speakers is similar so no worries.
what was a reduced GD again?
I was referring to adjusting the timing such that the GD (Group Delay) of the mid bass (maybe 40 – 65 Hz) would be minimized with the tradeoff being that the phase tracking at the extremes of the XO range is somewhat less than ideal. The phase and GD near the XO will still be the same however.
just checked my AVR. 9.41m (4.25+5.16) is possible with my AVR.
maybe the subwoofer distance @9.41m is good to go
Yes, that works fine.
My AVR lets me EQ all speakers (not the subwoofer though, but that s the Behringer for right?)
Shall I try to EQ all speakers (FR, FL, CC, SR and SL) so they all have a good SPL response? My AVR lets me do per speaker:
-20 to +6 (0 default) for 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz and 16000Hz. And if I EQ them all (separate), are there 'rules' to keep in mind? I remember from my Velodyne SMS-1 subwoofer eq I had a few years ago that increasing (+) was an abslote no-go and that only a few minor decreases (-) at some peaks was recommended. How will that be with my AVR?
I’ll let someone else help you with EQ questions. You might want look through the sticky threads and do some general searches on the topic. There is lots of EQ related info available including regarding the boost vs cut situation. You should be able to easily find info on these kinds of basic questions and read through them before you get started.
will adjusting EQ in my AVR affect delays (timings) that we fine-tuned?
Not significantly.