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Multi-Way Conventional loudspeakers with crossovers

rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Old 28th October 2013, 04:32 PM   #521
pos is online now pos  Europe
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Originally Posted by ra7 View Post
Second that. I've used it before but I'm scrambling every time I open it up. Write something man!
Yes, I know I should write something but...
I do this software for fun, and writing documentation is not exactly my idea of fun

...And why should I bother to write something when the miniDSP team has already written a simple yet throughout tutorial that covers almost all possible use of rePhase (with an emphasis on hardware convolution engines, of course) :
The rePhase FIR tool | MiniDSP



I will put that link in good place on the project page on sourceforge...
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Old 28th October 2013, 04:38 PM   #522
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I've been testing this again tonight. Got good measurements and an impulse that seems correct. Been switching it in and out.

On my system is seems very dependent on the recording whether I hear it or not. Hard to predict. When I do hear it, it's always a similar effect. The linear phase gives me a stronger center phantom image and tends to move voices forward and slightly up. Space seems a bit better defined. If there are drums they seem more dynamic, live.

On some recordings I don't hear it at all. I've tried jazz, pop, rock, dance, classical, opera and lounge. Opera and classical seem to consistently reveal the difference, other genres are hit or miss. I can understand why some people say phase isn't audible, or at least not noticeable. It's not night and day, but sometimes a nice improvement. Further listening is in order.
Hi Pano,

I am not really sensitive to imaging and stereo illusion (or maybe am I too sensitive to comb filtering?... I prefer to think about it that way ).
Most differences I have heard were on percussive instruments.

Would you mind sharing references of some of these particularly revealing songs?
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Old 28th October 2013, 10:22 PM   #523
KSTR is offline KSTR  Germany
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Originally Posted by Pano View Post
[snip]
On some recordings I don't hear it at all. I've tried jazz, pop, rock, dance, classical, opera and lounge. Opera and classical seem to consistently reveal the difference, other genres are hit or miss. I can understand why some people say phase isn't audible, or at least not noticeable. It's not night and day, but sometimes a nice improvement. Further listening is in order.
Great to here people have similar experiences. Did you try just plain XO phase linearisation or did you make the bass rolloff also linphase? Further, any results when switching absolute polarity? These things matter as well, IMHO.

And as you say, it's maybe not "mission critical" but for sure a worthwhile improvement. Thumbs up for POS for this great piece!
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Old 29th October 2013, 02:49 AM   #524
Pano is offline Pano  United States
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
I'll look up the tracks I was listening to when I get home. Should be able to remember them.

I don't think I tried flipping absolute polarity, that's a good idea. I did do box, crossover and then straightening by hand for a decently linear phase. Did everything possible to phase, while leaving the amplitude the same.

When the measurement is taken in HOLMImpulse and exported with the phase unwrapped, all I see is a phase that is falling, falling falling. No big bumps or reversals. Correcting for the box phase fixes the bottom end, then correcting for the crossover gets a pretty flat phase. Some work is then needed by hand. Takes some practice, but it's not too hard.
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Old 30th October 2013, 07:40 PM   #525
weltersys is offline weltersys  United States
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Originally Posted by pos View Post
...And why should I bother to write something when the miniDSP team has already written a simple yet throughout tutorial that covers almost all possible use of rePhase (with an emphasis on hardware convolution engines, of course) :
The rePhase FIR tool | MiniDSP
Thomas,

What is the total latency (delay) created by flattening phase to say, 100 Hz, 50 Hz, 25 Hz, or 12.5 Hz ?
If the latency is dependent on processing speed, could you give a range for what could be expected with various computers ?

Thanks, and sorry if the question has already been answered.

Art
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Old 31st October 2013, 08:42 AM   #526
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Hi Art,

Well, it depends

It is "easier "(ie requires less taps and less delay) to linearize a closed-box phase shift than a reflex one. In general the "sharper" the phase shift the more taps (and delay) you will need.
The centering of the impulse also enters into play. The only way to really know what delay you can expect is to try with different settings (taps, energy centering or not, etc.).
A nice feature that could be added would be to let the user define a maximum (or precise) delay and see what can be obtain with that... maybe for a future release.
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Old 31st October 2013, 05:11 PM   #527
weltersys is offline weltersys  United States
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Hi Art,

Well, it depends

It is "easier "(ie requires less taps and less delay) to linearize a closed-box phase shift than a reflex one.
Thomas,

OK, the Ivan Beaver response, I deserved it .

I can understand that correcting phase for headphones with only 100 degree change from 20 to 20 K would be different than correcting my PA speakers.

So, specifically, what would the total latency to flatten phase from 31.5 Hz to 16 kHz with a speaker system that exhibits 1170 degrees of rotation over that range, such as the one below?

The phase response posted already uses about 9 ms to align the tapped horn LF to the front horn mids, my concern is for live use additional delay could become problematic.

A general answer like "an additional 3ms, or an additional 30ms" will suffice, just trying to get an idea of what order of magnitude the delay would be.

Art
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Old 31st October 2013, 05:19 PM   #528
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Weltersys. Use rePhase to create a filter to make the phase correction. You will see when there are too few filter taps because the generated filter will not implement the desiered curve.
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Old 2nd November 2013, 06:28 PM   #529
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Weltersys. Use rePhase to create a filter to make the phase correction. You will see when there are too few filter taps because the generated filter will not implement the desiered curve.
I don't have a MiniDsp, so I can't do it myself.
If I had it, I would have simply measured the latency, but I don't, hence the questions.
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Old 2nd November 2013, 08:48 PM   #530
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Export a FRD file or the impulse response.
Without that it's a little hard to guess.
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