Nathan, regarding the Overlap setting: try using 25%. Long ago I asked Jamie (or maybe it was Arthur) about this and for each set of FFT windows that are captured, Smaart will interpolate another set of overlapping FFTs that it can use to refine your measurements. If you set it 25%, Smaart will start the 'virtual' FFTs at the 25% mark of the first 'real' FFT and then overlap each boundary by 25% going forward (Maybe the 'virtual' FFT starts at the 75%, mark; I'm not positive to be honest). When you choose 0% or 99%, you are essentially getting the same measurements as the originals because the interpolated FFTs start / end essentially where the originals do. I think I asked about using 50% or 33% as the boundary markers, and IIRC, the answer was that it didn't significantly increase the precision for the amount of time added. You should definitely check with RA about that though; I have been known to be mistaken more than just occasionally.
Hi Nathan, I've been doing bunch of impulse response measurements last few days to get some RT60 data, the one piece of data that I was struggling to hit with pseudorandom noise was trying to get Lr1 to Lr2 to be a minimum of -20db. It was in a fairly big space without a dodec, a makeshift array to excite the room as much as possible but I found it really hard to get -20db. The Level reverberant 1 to Lr2 data according to the manual is supposedly a good way to check you've got a decent measurement. Thanks for the information here, although I tried most things to get above the noise floor I feel maybe I might have misunderstood some of the theory behind improving S/N with FFT and averaging. Had no problems with Pink Sweeps mind..
Hey Chris, I haven't done much of that kind of research, but definitely go with the sweeps for that. I only started looking at alternatives to save time and lower the signal in the room.
Hey Ganesh, I think you'll be able to answer this question for yourself pretty easily. Take an IR with pink noise, then repeat with a sweep, and compare. Let us know what you discover. :)
![5 ideas to improve Main+Sub phase alignment with Smaart® [GSwSST35]](/img/1.gif)
Nathan, regarding the Overlap setting: try using 25%. Long ago I asked Jamie (or maybe it was Arthur) about this and for each set of FFT windows that are captured, Smaart will interpolate another set of overlapping FFTs that it can use to refine your measurements. If you set it 25%, Smaart will start the 'virtual' FFTs at the 25% mark of the first 'real' FFT and then overlap each boundary by 25% going forward (Maybe the 'virtual' FFT starts at the 75%, mark; I'm not positive to be honest). When you choose 0% or 99%, you are essentially getting the same measurements as the originals because the interpolated FFTs start / end essentially where the originals do. I think I asked about using 50% or 33% as the boundary markers, and IIRC, the answer was that it didn't significantly increase the precision for the amount of time added. You should definitely check with RA about that though; I have been known to be mistaken more than just occasionally.
Great tip. Thanks!
Hi Nathan, I've been doing bunch of impulse response measurements last few days to get some RT60 data, the one piece of data that I was struggling to hit with pseudorandom noise was trying to get Lr1 to Lr2 to be a minimum of -20db. It was in a fairly big space without a dodec, a makeshift array to excite the room as much as possible but I found it really hard to get -20db. The Level reverberant 1 to Lr2 data according to the manual is supposedly a good way to check you've got a decent measurement. Thanks for the information here, although I tried most things to get above the noise floor I feel maybe I might have misunderstood some of the theory behind improving S/N with FFT and averaging. Had no problems with Pink Sweeps mind..
Hey Chris, I haven't done much of that kind of research, but definitely go with the sweeps for that. I only started looking at alternatives to save time and lower the signal in the room.
How Impulse response of subwoofer using sine sweep and pink noise differ. In smaart subwoofer impulse response using pink noise is difficult for me.
Hey Ganesh, I think you'll be able to answer this question for yourself pretty easily. Take an IR with pink noise, then repeat with a sweep, and compare. Let us know what you discover. :)