To window out reflections requires an impulse response, so a sweep measurement. The width depends on the time to the reflection(s) to be removed, which in turn depends on how far you can place the speaker from all surfaces (including floor and ceiling). Best measuring suspended outside for an approximation to anechoic when suitably windowed.
Hi ... sorry if this has been asked elsewhere, I've been searching and can't find it. How can I use REW to set the speaker distances on my surround pre-amp and also to make sure the polarity of my center speaker is right? I did the loopback calibration, and measured group delay (see attached graphs of left speaker and center). Not sure if this is close enough?
OK, I didn't have loopback as a timing reference enabled in the analysis section, so did that and looped back the 2nd channel (btw - any way to verify that the loopback is actually working? When I run soundcard calibration it always uses the measurement channel).
Now looking at the IRs for center and left speakers (with loopback reference timing enabled), here's what I get. Not a clear peak ... and it seems to start around zero for the left speaker, but quite negative delay for the center ... not sure what to do with that?
If you use the % FS scale the peaks will be easier to see. The centre measurement looks like there are two speakers playing as there are two peaks of the same level. When using loopback as a timing reference it would be very strange to have negative timings assuming outputs and inputs are on the same soundcard - difficult to see how a signal through the speaker could arrive earlier than a direct wired connection at the soundcard. Perhaps you should explain exactly how you have things wired up, preferably by starting a thread just for this since it doesn't really have any to do with the REW V5 tips.
Hi shnee(I know you by another name lol). By "good enough", do mean flat enough? I've never known the phase information to be terribly useful, but the freq graph looks really nice to me. Curious, why you're measuring in 7ch stereo. I would think that could add combing, or other phase issues that would be irrelevant during actual listening. I would also prefer a house curve over flat.
Haha, I think I know you from the other forum too. Thanks to REW, I have collected numerous graphs for my several setups including the two channel ones. I thought the HT setup was good enough based on the freq response graphs, so I have been too lazy to do try any manual adjustments after Audyssey. So yes, to me good enough means flat enough, though I do understand the waterfall graphs should be looked at too to see that decay times are not a problem. That may change because I have just been told by TheWarrior that I should pay attention to the phase graphs as well. That's something I never thought would make much difference in a real room playing real music, 99% movies in that room too and that's why I focused on getting the flattest response for 7 channel. I used 7 CH stereo for taking measurements only.
I thought maybe someone like JohnM or other resident experts here wouldn't mind enlightening me on whether the phase graphs indicate something of significance. I always assumed Audyssey had to do the balancing act, such that something could be made worse but the overall results would be better. All I can see from my REW graphs is that it has improved the frequency response from 10-110 Hz, a touch worse between 115-200 hz and didn't do much above 200 Hz. I don't know if it made the phase and decay times audibly better or worse as I am not 100% sure that I interpret the graphs correctly.
I'm sure John, Wayne,(not john Wayne lol), or jtalden will pop in sooner or later and give a more expert opinion. As far as ringing goes, my understanding is once you get driver control to a certain level, i.e: quality subwoofers, bass traps are the way to handle that. It does look like 35 and 55hz(ish) are the worst for ringing, but I am not very well versed on waterfalls so... sure the guys will give you plenty of help. I kinda just wanted to not let your post sit. I think you'd be good here. I'll see you over there. Lol
I was just thinking (scary...) it might be useful to be able to adjust sub integration in real time. What I mean is to have the mic at the listening position, your computer running REW near the sub, send 10-250hz pink noise through the appropriate channel(s) covering the speakers you are trying...
I have used REW over many years, but not for the last 6-8 years.
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I'm somewhat new to the program. Can someone double check my work and give me suggestions on how this plots out.
If i were to tweak it, what should I change?
TC Sounds Neo Axis 12" (RED)
TC Sounds 3000 12" (GREEN)
IAS Prototypes 12" (BLUE)
Passive Radiator modeled is 4 FT^3 and 15" TC...
I was measuring yesterday (blue), turned everything off, started again today (red) and I have stage little “impulse response looking” glitches along my spl measurements, I didn’t change any settings or move speakers or mic, they should look the same (apart from the slight gain difference)...