Ron’s New System
- Thread starter Ron Resnick
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We don't talk about it enough, but the utility of WBF as a globally crowdsourced source of audio information is incredible.
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By golly, I think Rune and Anthony did a darn good job!
Interestingly, the iPhone app suggested that my speaker positioning from a couple of nights ago achieved a smoother response than I saw on it yesterday, but I am beginning to think that a lot of the iPhone FFT screenshots I have posted over the last several days have been spurious.
Even without an external microphone, this iPad app seems more accurate.
I suspect the Magnapan 86 db Sensitivity rating is somewhat optimistic..... Best guess it's probably lower.... around 80 to 82 db.
Sensitivity of planars is usually a misleading characteristic, as they are not point sources and due to their size it is very hard to measure correctly. Most time manufacturers just quote an "equivalent sensitivity" number obtained by comparison with a known box speaker in a particular room.
As planar speakers sound intensity does not follow the inverse square law it very hard to make guesses considering about the needed power.
I was in a hurry before. Here is some info on windowing an RTA signal from the REW Manual
The FFT resolution is also affected by the Window setting. Rectangular windows give the best frequency resolution but are only suitable when the signal being analysed is periodic within the FFT length or if a periodic noise signal is being measured. The Rectangular window should always be used with the REW periodic noise signals. Most other signals, e.g. sine waves from the REW generator or test tones on a CD or random noise, typically would not be periodic in the FFT length. Using a rectangular window when analysing such a tone would generate spectral leakage, making it difficult to resolve the frequency details
The Hann window is well suited to most measurements, offering a good tradeoff between resolution and shoulder height. If very high dynamic range needs to be resolved (very small signals close to very large signals) use the 4-term or 7-term Blackman-Harris windows. If the spectral peak amplitudes must be accurately measured use the Flat Top window, this will provide amplitude accuracy of 0.01 dB regardless of where the tone being measured falls relative to the bins of the FFT. The other windows only show the spectral amplitude accurately if the tone is exactly on the centre of an FFT bin, if the tone falls between two bins the amplitude is lower, with the maximum error occurring exactly between two bins. This maximum error is 3.92dB for the Rectangular window, 1.42dB for Hann, 0.83dB for the 4-term Blackman-Harris and 0.4dB for the 7-term Blackman-Harris.
The FFT resolution is also affected by the Window setting. Rectangular windows give the best frequency resolution but are only suitable when the signal being analysed is periodic within the FFT length or if a periodic noise signal is being measured. The Rectangular window should always be used with the REW periodic noise signals. Most other signals, e.g. sine waves from the REW generator or test tones on a CD or random noise, typically would not be periodic in the FFT length. Using a rectangular window when analysing such a tone would generate spectral leakage, making it difficult to resolve the frequency details
The Hann window is well suited to most measurements, offering a good tradeoff between resolution and shoulder height. If very high dynamic range needs to be resolved (very small signals close to very large signals) use the 4-term or 7-term Blackman-Harris windows. If the spectral peak amplitudes must be accurately measured use the Flat Top window, this will provide amplitude accuracy of 0.01 dB regardless of where the tone being measured falls relative to the bins of the FFT. The other windows only show the spectral amplitude accurately if the tone is exactly on the centre of an FFT bin, if the tone falls between two bins the amplitude is lower, with the maximum error occurring exactly between two bins. This maximum error is 3.92dB for the Rectangular window, 1.42dB for Hann, 0.83dB for the 4-term Blackman-Harris and 0.4dB for the 7-term Blackman-Harris.
Ron,
I hope that is sounds a lot better than it measures!
Are you using pink noise or withe noise in the measurement?
Ron,
I hope that is sounds a lot better than it measures!
Are you using pink noise or withe noise in the measurement?
Why don't you like that curve? (The 60 Hz bump needs work, obviously.)
That generally downward sloping curve looks a lot like the Harman Curve I like.
Please post your frequency response chart on the frequency response curve thread I started today so I can see the curve you like.
I listened to this over my HD800S.
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There is a 30db difference between the bass octave and the 10 KHz level.
The slope is too steep. It is why I asked about the type of noise you are using in measurements.
The XLF initial weighted responses in my room. The steep cut off at 30 Hz was corrected by reversing the bass port to the back position and adding subs.
I am with you Ron. A gentle downslope is preferable. Flat usually translates to bright.
Information and amazing help in all sorts of endeavors, without Peter and Ians help on the ground in Boston i would not have dared buy my latest speakers. And without Davids help i would probably still be waiting to have them shipped. I know these kind gentlemen trough WBF only !
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