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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 13th September 2017, 05:53 AM   #2221
Kindhornman is offline Kindhornman  United States
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
fluid,
I'm not sure your explanation of the reason for that area between 600-1K is correct as it isn't causing the same response below those frequencies? As far as I remember doing waterfalls the windowing was scaled for frequency and shifting in time as the frequency increases. There was no having to make multiple response curves and having to stitch them together, it was a simple log chirp impulse in my Clio system.
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Old 13th September 2017, 06:21 AM   #2222
mitchba is online now mitchba  Canada
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Originally Posted by fluid View Post
I wonder which is more "correct" then

It would in the vertical direction that I would expect the multiway changes more. Byrtt has shown before that by using very steep filters a multiway can get more even vertical response too. Probably not much of an issue if you always listen at the same height.

In my system I have found that using a spatially averaged measurement across my couch in a similar way that SwissBear has written about here before is very useful to base a correction on. On a single measurement I would need to use significantly weaker correction to avoid it sounding "processed". I tested the same strong correction with a single measurement as the base and it was terrible.

My room is quite reflective and has zero treatment so in a treated room the differences might be less.
Hi fluid, my limited understanding is based on this research on acoustics and psychoacoustics of room correction: AES PNW Meeting Report - Acoustic and Psychoacoustic Issues in Room Correction The frequency dependent windowing is the acoustics part of letting in how much room sound relative to direct sound. The psychoacoustic part is an overall fixed filter applied to best represent what our ears hear in small room acoustics. My understanding is that for room correction, both FDW and psychoacoustic filtering are required to best represent what we hear. In the case of the software I use, the psychoacoustic filter is proprietary and different from REW's.


I have tried a variation of the spatially averaged measurements using a beamforming method: Quasi-Anechoic Measurement of Loudspeakers Using Beamforming Method (PDF Download Available) I got similar results to these published and does sound different. Does the spatially averaged technique you are mentioning produce similar results as in the linked article?
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Old 13th September 2017, 06:56 AM   #2223
fluid is offline fluid  Australia
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Quote:
Originally Posted by Kindhornman View Post
fluid,
I'm not sure your explanation of the reason for that area between 600-1K is correct as it isn't causing the same response below those frequencies? As far as I remember doing waterfalls the windowing was scaled for frequency and shifting in time as the frequency increases. There was no having to make multiple response curves and having to stitch them together, it was a simple log chirp impulse in my Clio system.
CLIO is different to REW and the window settings wesayso has used are causing what you see, I have not found a setting in REW that gives a similar type of response that CLIO etc. do when looking at the whole frequency range.

Here is the rest of the graph that you don't see in the screen shot from one of my measurements using the same window settings. See how the response ends at 333Hz which corresponds to the window setting, make sense now?

If you don't use REW and haven't looked at the manual section on waterfalls then I can understand your confusion.

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Old 13th September 2017, 07:20 AM   #2224
silverprout is offline silverprout  France
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Quote:
Originally Posted by wesayso View Post
Rephase is a tool, and exactly as mathematics, it is extremely tricky to get it totally pertinent and totally true or By abusing of 2D graphs and mathematical abstractions but I don't think that's entirely fair to those of us that literary have spend years to figure out what works and what doesn't. I try and share to possibly help others and I learn from the generous sharing of others.
My remark was about those who lack of rigor when they use such tools.
Show one global 20-20K FR or CSD graph d'ont tell anything about the linearity of the acoustic power rendering in a small room, there is some room mode at some measuring points of the room that gives you perfect CSD and FR graphs without any direct signal coming from the loudspeakers.
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Old 13th September 2017, 09:54 AM   #2225
torgeirs is offline torgeirs  Norway
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The time alignment listening window can be quite large for multiway's as well. Here is the step response of the same active 3-way I posted earlier, except I took 14 measures of both left and right speakers over a 6' x 2' grid which covers my couch area at the LP:


Click the image to open in full size.


The drivers are time aligned over the 6' x 2' listening area as indicated by the vertical "step" overlay at t=0. Moving the height of the mic up and down by a foot each way, produces similar results. I have overlaid the "ideal" step response as well. The peaks at 4ms and 8ms are the bounce off the rear wall from the measurements that were taken near the back of the couch area. i.e. the mic is (much) closer in distance to the rear wall versus the distance to the speaker.
Thank you for this measurement(s). It shows very well how the visuals of the time response measurements changes quite a lot inside the sweet spot. The sound is NOT perceived as very different inside the listening area, I guess.
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Old 13th September 2017, 10:18 AM   #2226
torgeirs is offline torgeirs  Norway
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As of the claimed progress using correction and linearray.
The implication is that:
Tweeter quality don't matter it can just be corrected.
Large cone movement don't matter for HF.
Output on the low side of speaker element Fs don't matter.
Combfiltering at HF can be corrected (without individual speaker element prosessing) to become a time coherent system at all frequencies and large sweetspot
This is not just progress it is an revolution or paradigma shift. So it's no wonder we want hard evidence for such claims:-)
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Old 13th September 2017, 10:31 AM   #2227
fluid is offline fluid  Australia
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Originally Posted by torgeirs View Post
As of the claimed progress using correction and linearray.
The implication is that:
Tweeter quality don't matter it can just be corrected.
Not what I would suggest although there is a lot of anecdotal evidence that if equalized to the same target it is hard to tell much difference.
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Large cone movement don't matter for HF.
Not the implication
Quote:
Output on the low side of speaker element Fs don't matter.
Kind of if you have enough cones to spread the load it matters much less than with a single speaker.
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Combfiltering at HF can be corrected (without individual speaker element prosessing) to become a time coherent system at all frequencies and large sweetspot
Comb filtering at high frequencies in a room at a reasonable listening distance is virtually inaudible so it doesn't really need correcting.
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This is not just progress it is an revolution or paradigma shift. So it's no wonder we want hard evidence for such claims:-)
No it is just a good balance of things in a speaker that matter and work well vs some that don't matter as much.

I would kindly ask (again) that if you want to continue the debate of line arrays that you do it on one of the dedicated threads rather than clog up this one.
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Old 13th September 2017, 10:41 AM   #2228
fluid is offline fluid  Australia
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Originally Posted by mitchba View Post
I have tried a variation of the spatially averaged measurements using a beamforming method: Quasi-Anechoic Measurement of Loudspeakers Using Beamforming Method (PDF Download Available) I got similar results to these published and does sound different. Does the spatially averaged technique you are mentioning produce similar results as in the linked article?
Hi Mitch, yes I did find the same result. It really works to reduce the amount of room influence in the measurement. It keeps the issues that are not position specific. The more measurements you use to average the more the room is suppressed. I have settled on Centre, 10, 30 and 50cm either side at ear level as being a good balance between room suppression and the time it takes to do the measurements. My first test had 22 in total and it took most of the day to do.

I posted an ETC on my thread here that shows the reduction quite clearly
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Old 13th September 2017, 11:06 AM   #2229
torgeirs is offline torgeirs  Norway
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Well just provide some counter arguments why arrays not nesecarily is better than multiway. We are in the multiway section:-)
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Old 13th September 2017, 12:04 PM   #2230
silverprout is offline silverprout  France
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Quote:
Originally Posted by fluid View Post
reduce the amount of room influence in the measurement
IMHO, It should be interesting to quantify the reduction of room influence.
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