This is not a useful way to evaluate acoustic performance of a room. Why and how this works has been repeatedly explained by many. Though you may get an indication of the liveliness of a room by looking at RT60 numbers evaluated from the slope of the decay, and if you see numbers in 400-500ms range, that is way off (not enough absorbtion) for typical smaller rooms.So, a message to audio enthusiast is: if your Topt curve (under RT60 tab in REW) is relatively flat after 200Hz and sitting between 400 and 500ms - you're good.
This is not a useful way to evaluate acoustic performance of a room. Why and how this works has been repeatedly explained by many. Though you may get an indication of the liveliness of a room by looking at RT60 numbers evaluated from the slope of the decay, and if you see numbers in 400-500ms range, that is way off (not enough absorbtion) for typical smaller rooms.
The way i do measurements is as accurate as possible a hobbyist can provide,
While this would differ between homes, my own acoustically untreated open plan living room hovers around mid 300 ms. The bass, though fine, is quite lumpy and never even at any one spot anywhere. If I were more "enthusiastic" about putting in adequate acoustic room treatment, it would likely plunge that number closer down to ~200 ms or even possibly lower.
Well I’m yet to hear a constructive comment from you, so i think it’s hardly my attitude.I can easilly think of more than a few hobbyists on this forum that do measurements far better than you. But if you want to improve your measurement technique you should defintiely change your attitude, because as long as you think you're the best of the best you cannot possible learn and evolve.
Well I’m yet to hear a constructive comment from you, so i think it’s hardly my attitude.
So, acording to you it's constructive to claim that your measurements are "the best they can be" and that your magical curtains are siginificantly affecting the response down to 150Hz, but when you are told that physics teaches us that curtains can't do that which implies that your measurement technique needs improvement (and I suggested which!) - that is according to you a non-constructive comment?
Sure M8.. nothing wrong with your attitude.
If you choose to try to treat your room you will quickly learn that reducing decay time below 200Hz is far more complcaited and expensive than reducing it above 200Hz.
Not sure what the point of your platitude about room treatment below 200 Hz is all about…
It seems as if you think that the topt curve is not something anyone who’s a regular user of REW knows about — moreover, that just because it’s more reliable for the kind of smaller rooms we often measure that it’s somehow exempt from the same weakness of drawing generalized conclusions from rest of the other RTx curves. I’m pretty sure that’s no big revelation to Kvalsvoll as well.
Being helpful is one thing, but unnecessarily condescending to other members… esp. to the OP who has actually bothered with the effort of sharing these measurements to begin with?
While I won’t stop anyone from discussing whatever it is they want, it’s worth pointing out — something that should already be obvious from previous posts which you seem to continue to ignore — you’ve overstayed your welcome.
And this shows a similar result compared to OP. What it also shows, in the pictures, is the visual impact on the room, where you now really have to question whether living in a dark cave is worth the improvement..Running out of girlfriend patience after installing the curtains so don't have the time to do a whole lot of measurements today, but here's some preliminary ones;
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You still need to verify that the number for RT60 that has been calculated matches the slope of the decay profile, because this slope is not necessarily linear, it certainly will have a initial drop, and then some rooms actually does not have a linear slope by nature.Topt in REW has been optimised for small rooms. I suggest you familiarize yourself with the way how it works before commenting.
RT60 Calculation
The RT60 values are estimated by calculating the slope of the Schroeder curve, which is a plot of the energy (squared values) of the impulse response that is backwards integrated (summed starting from the end and moving backwards). The vertical axis of the plot is in dB. The different RT60 measures (e.g. T20, T30, REW's Topt) are derived by calculating the slope of a best fit line to the Schroeder curve over different ranges (detailed below). In a diffuse field the curve with the dB vertical scale is quite linear until it reaches the noise floor.
The start point for the classical T20 and T30 measures of RT60 is where the Schroeder curve has dropped 5 dB below its peak. That works well in the large spaces for which RT60 is most applicable, particularly if the source used for the measurement is omnidirectional. In domestically sized rooms using normal, directional loudspeakers as sources the initial drop of the Schroeder curve is quite sharp (the Early Decay Time is quite short) meaning the -5 dB point lies within the early decay region rather than the diffuse field region. That in turn means the T20 and T30 figures underestimate the RT60 time. Where the EDT is much shorter than the T30 RT60 figure REW's Topt RT60 calculation uses a start point based on the intersection of the EDT and T30 regression lines, to determine a point that lies within the diffuse field region. It then tests each possible end point in 1 dB steps and picks the one that gives a regression line with the best linear fit. That produces a more reliable RT60 figure.
The results are presented within octave or 1/3 octave bands, providing a view of how the rate at which sound decays changes with frequency. The lowest centre frequency for the RT60 plot is 50 Hz at 1/3 octave and 63 Hz at 1 octave, per ISO3382. For domestic listening rooms and recording studios with volumes of less than 50 cubic metres (1,800 cubic feet) the recommended RT60 value is 0.3 s. For larger rooms, up to 200 cubic metres (7,000 cubic feet) the recommendation is 0.4 to 0.6 s. In both cases the value should be fairly uniform across the frequency range, though it will typically tend to increase at lower frequencies.
Those are gorgeous speakers! Are they full DIY or did you enhance a complete pair of M2's?
Indeed, for all things meant to improve sound quality there is a price. I don't yet know if I can say there's a subjective gain as I didn't have time to listen much, but we all know that curtains are no substitute for broadband absorbers. Maybe especially true for the side reflections?And this shows a similar result compared to OP. What it also shows, in the pictures, is the visual impact on the room, where you now really have to question whether living in a dark cave is worth the improvement..
There is a point where the cost (visual/effort/price) becomes too large, compared to the improvements in sound. DSP is great, it can fix the tonality so you get a more neutral response with no need for more acoustic fixes, it is invisible. It will not be the same, it will not reduce decay times, but it may be a better compromise.
Thank you! These are full DIY speakers made of Baltic Birch and oiled for a nice look. I wish I could take credit, but these were not made by me. They were made as replicas of M2's with original components, similar dampening and internal bracing, but have since upgraded tweeter and experimented a little with stuffing.Those are gorgeous speakers! Are they full DIY or did you enhance a complete pair of M2's?