Recent content by Keith_W

ASR DIY microphone calibration.

Please understand what I am trying to tell you: RT60 is meaningless at low frequencies in small room acoustics. The reasons are: 1. There are no reverberant fields, there are room modes. Even at high frequencies, reverberant fields may or may not exist. There are specular reflections. Toole...

You should be able to answer your own questions by reading that eBook. Re: the ETC peaks, read the section on ETC to see what they mean, determine whether they are a problem, and how to work out what is causing the peak. As for your other measurements, here is something rather interesting...

I don't have a lot of time right now, but i'll answer this question first. The answer is: measurement artefact from an improperly centred microphone. This is the proof: This is a comparison of the vector sum of L+R ("before treatment") in purple, and the actual measurement in red. We can see...

One glance at your RT60 chart and it is easy to see that you have WAY OVERTREATED your room, look at that - the RT60 at high frequencies is 150ms or less. At times it's less than 20ms. It would sound close to an anechoic chamber. And if you are not used to those numbers, it should be about 200ms...

That ETC looks excellent, I don't think you have much to complain about. If you want a better idea what your bass is doing, use the spectro and waterfall. The spectro needs to be "normalized to peak at each frequency" to give you an idea of bass decay. The waterfall should be extended to...

Please think a bit about what the Clarity measurement is. It has nothing to do with subjective clarity. I think it is the most useless measurement, and I can't think of any application for it. How REW calculates clarity C50: the first 50ms of the impulse is expressed as a % of total energy...

Correct, I align all the drivers on the left speaker to the left tweeter. That makes sense to me :) A 4th order LR can be either linphase or minphase. If you are using linphase, then the 90deg phase rotation per order does not exist. All symmetrical filters of whatever order will sum...

Here are a few points about driver time alignment. 1. The acoustic centre of the driver depends on the driver, where the XO point is (because of frequency dependent group delay), any phase rotation introduced by the XO or the driver, and lastly its physical offset on the baffle. Contrary to...

You could do this: 15 sec should be enough time for you to run to a new location and set up your tripod.

Ahhh. Well it would appear that spike is at 126Hz and not 160Hz. This is what it looks like in RT60 decay. To be honest it looks like a room mode to me. I am not sure what it is about its appearance that suggests that it is a physical resonance, i.e. something rattling. Could someone...

These are all your L+R RT60 measurements. I do not see a "weird spike at 160Hz". In any case, the RT60 should be interpreted with caution below the transition frequency. What you are looking at is not necessarily decay, it might be a room mode. And if you haven't taken the measurement...

As for your subjective impression, i'm not surprised. Take a look at how your measurements compare to the Harman target:

Your subwoofer measurement does not have a timing reference. No matter, I was able to infer how much the subwoofer was delayed by lining up the impulses in the step response. This is how I did it: These are four step responses overlaid over each other - through the Wiim and through the...

I wouldn't say that a 2ms subwoofer delay at say 50-80Hz is audible. The threshold of audibility for group delay at bass frequencies has not been well studied, about the best study we have is by Liski, Makivirta, Valimaki et all which used headphones and test signals found that the threshold...