rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool - Page 267

chebum · 9th March 2019, 10:15 PM

Quote:

Originally Posted by pos

What convolution engine are you using?
What do your EQs look like? (maybe show us a rephase graph screenshot, with any measurement bypassed)
At what SPL and dBFS level are you recording these measurements?

Thank you for the input, Thomas.

I'm using Equalizer APO. It uses FFTW3 for convolution. I doubt that's the case since the convolution causes no distortion if there are only high- or low-pass filters. The first chart included a 3-way crossover generated with rephase yet the distortion level was lower.

I'm attaching a screenshot with EQ settings for the tweeter.

Amplifier's volume setting was the same. Actual volume was lower due to the equalization applied. I'm attaching a volume comparison chart as well.

pos · 9th March 2019, 10:32 PM

Quote:

Originally Posted by chebum

Amplifier's volume setting was the same. Actual volume was lower due to the equalization applied. I'm attaching a volume comparison chart as well.

You might just be seeing an increase in relative noise ratio then.

JohnPM · 10th March 2019, 03:45 PM

It's a good idea to include the noise floor when looking at distortion plots, and to check the plot without normalisation.

chebum · 10th March 2019, 06:59 PM

Quote:

Originally Posted by pos

You might just be seeing an increase in relative noise ratio then.

Thank you for the suggestions. This indeed improved THD values.

Rajapruk · 11th March 2019, 04:27 PM

pos, when do you plan to release the bugs implemented last week on high altitude in the alps?

thierry38 · 07:34 PM

A question (for fun/learning).

What about the :
Dolph–Chebyshev window (rePhase or REW) ?

Any trade-off ?

Juhazi · 08:25 PM

About the distortion measurements of chebum, they were the farfield measurement of loudspeaker's output. We saw only distortion curves with percentage, not dB.

Typical domestic ambient noise level is 30-35dB. Typical hifi-loudspeaker must play at 95dB/1m or louder to show "real" distortion above noise level. One standard is to measure/set spl to 95dB at 1000Hz with some smoothing of response. Another way is to use standard voltage, but then we must also see the measured dB values to compare.

In theory, loudspeaker equalization always leads to higher distortion levels (when we look at spectrum). There is no way to raise efficiency or lower distortion by eq. When input voltage is lowered, distortion gets lower too. With eq we typically suppress loud parts of spectrum which leads to effectively lower total efficiency. Then, to get same spl level in a measurement (say that 95dB/1m), we must use higher voltage and we will see higher distortion percentage.

If quiet parts of response are amplified, distortion rises just as well and for same standard spl, we get higher distortion again. The problem with this is that we might introduce clipping in loud parts of music signal, in digital domain. It is very common to see music playing very close to clipping of even badly clipping because of "the loudness war" in original signal, so there is not room for eq left. The propability of this depends on where in signal chain spl volume control and eq is performed.

pos · 13th March 2019, 10:39 AM

Quote:

Originally Posted by Rajapruk

pos, when do you plan to release the bugs implemented last week on high altitude in the alps?

soon enough

pos · 13th March 2019, 10:41 AM

Quote:

Originally Posted by thierry38

A question (for fun/learning).

What about the :
Dolph–Chebyshev window (rePhase or REW) ?

Any trade-off ?

I will look into that and implement it in the next release if it proves useful

arcgotic · 17th March 2019, 01:53 PM

Hello,
I noticed something when tested my DE250 on RCF H100 horn. Did a FIR and then an IIR high pass @ 1200Hz. The phase for the IIR filter is corrected with some 'compensate' 2nd order all-pass.

So the measurement looks the same but I can clearly say that the sound is more detailed/refined with the IIR filter. It has a better definition, 'bite'. I listen at low level, 70 to 85dB at listening position.

What is the cause? the pre-ringing of the FIR filter?

Thanks!

12th March 2019, 07:29 PM	#2666
thierry38 diyAudio Member Join Date: Jan 2006 Location: Grenoble	A question (for fun/learning). What about the : Dolph–Chebyshev window (rePhase or REW) ? Any trade-off ? Last edited by thierry38; 12th March 2019 at 07:34 PM.

12th March 2019, 08:18 PM	#2667
Juhazi diyAudio Member Join Date: Mar 2007 Location: Jyväskylä, Finland	About the distortion measurements of chebum, they were the farfield measurement of loudspeaker's output. We saw only distortion curves with percentage, not dB. Typical domestic ambient noise level is 30-35dB. Typical hifi-loudspeaker must play at 95dB/1m or louder to show "real" distortion above noise level. One standard is to measure/set spl to 95dB at 1000Hz with some smoothing of response. Another way is to use standard voltage, but then we must also see the measured dB values to compare. In theory, loudspeaker equalization always leads to higher distortion levels (when we look at spectrum). There is no way to raise efficiency or lower distortion by eq. When input voltage is lowered, distortion gets lower too. With eq we typically suppress loud parts of spectrum which leads to effectively lower total efficiency. Then, to get same spl level in a measurement (say that 95dB/1m), we must use higher voltage and we will see higher distortion percentage. If quiet parts of response are amplified, distortion rises just as well and for same standard spl, we get higher distortion again. The problem with this is that we might introduce clipping in loud parts of music signal, in digital domain. It is very common to see music playing very close to clipping of even badly clipping because of "the loudness war" in original signal, so there is not room for eq left. The propability of this depends on where in signal chain spl volume control and eq is performed. __________________ Radikal aktivist AINOgradient speaker project Last edited by Juhazi; 12th March 2019 at 08:25 PM.

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10th March 2019, 03:45 PM	#2663
JohnPM diyAudio Member Join Date: Oct 2008	It's a good idea to include the noise floor when looking at distortion plots, and to check the plot without normalisation.

11th March 2019, 04:27 PM	#2665
Rajapruk diyAudio Member Join Date: Jun 2011 Location: Gothenburg	pos, when do you plan to release the bugs implemented last week on high altitude in the alps?

17th March 2019, 01:53 PM	#2670
arcgotic diyAudio Member Join Date: Nov 2004 Location: Timisoara	Hello, I noticed something when tested my DE250 on RCF H100 horn. Did a FIR and then an IIR high pass @ 1200Hz. The phase for the IIR filter is corrected with some 'compensate' 2nd order all-pass. So the measurement looks the same but I can clearly say that the sound is more detailed/refined with the IIR filter. It has a better definition, 'bite'. I listen at low level, 70 to 85dB at listening position. What is the cause? the pre-ringing of the FIR filter? Thanks!