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Multi-Way Conventional loudspeakers with crossovers

How to measure the loudspeakers actually work as they should?
How to measure the loudspeakers actually work as they should?
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Old 7th September 2018, 02:31 PM   #11
system7 is offline system7  United Kingdom
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We need pictures of this fine build. 3 ways sound initially dull, because they are so smooth and get so much right.

I think your ear gets trained to hear imaging and phasiness and dispersion and room response with experience.

And you need a well-treated (damped) room to hear everything on a recording, especially the microphone and studio acoustic. The room actually matters as much as the box.

This Finalists design is slightly vague on cabinet treatment. The BBC always did that well:
Interesting read I found on Lossy Cabinet designs by Harbeth

A bit of rubbery or felt panel damping stuck on goes a long way when a speaker is getting very good. Volume damping (fluffy stuff) depends on circumstances. Reflex doesn't want a lot near the port because the air needs to move. The mid in an open tube might benefit from a lot of wadding to control the organ-pipe type resonance near a quarter wavelength which here is going to be around 500Hz.

But all experimental. As is placement.
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Old 7th September 2018, 04:54 PM   #12
bentoronto is offline bentoronto  Canada
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How to measure the loudspeakers actually work as they should?
The glide sweep test does not lie, esp if it is a sweep-with-stop-watch glide. Not as helpful as REW, but I only mention it as a quick test needing no gear.

The questions are how to understand the gross results and then what to do about it for the coming year.

If things seem terrible, maybe the room is too bright like 95% of those pictured on this website. Does the sweep seem to have major octave-wide peaks or dips? Run out of steam much before your high-freq hearing does? And droop below 60 Hz, as it certainly will seem to if the speaker is performing for some wacky reason you've made it microphone-flat?*

B.
* "denial" of Fletcher-Munson effect is comparable to denial of vaccine effectiveness
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Old 8th November 2018, 06:39 AM   #13
lamir35 is offline lamir35  Israel
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I tried to place the speakers as far from the walls as possible, and still there's a deep dip around 40-50Hz and a big noisy spike around 60Hz... which is really unfortunate since that range really helps to give the music substance.
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Old 8th November 2018, 08:04 AM   #14
Juhazi is online now Juhazi  Finland
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^Those are "room modes" - interference of the sound waves bouncing between walls and floor-ceiling. Unavoidable, but you must find the best compromise for speakers and listening seat positions.

Room modes - Wikipedia

First you asked about measuring the speaker(s). My suggestion is to download the freeware Room EQWizard (REW), and use some USB microphone available (videocam?). Then follow instructions of REW, mic at 1m distance from a single speaker, record a sweep (computer's output to amp/speaker) and see how it looks. Then the other speaker too. For comparison, measure also some other speaker. Compare the result to what Jim Holz shows.

Actually REW is designed for measuring the reverberant sound in the room. You must make many measurements from each speaker to find out how room modes behave. If you focus to one frequency like 60Hz, set REW's sound generator to play 40/50/60Hz and walk around the room to hear how amplitude (strength) changes with modes. Then sit on your favourite position and as someone elso to move the speaker so that sound is fine. Etc. You can also use a SPL measuring application for a cell phone to support your ears.

Happy learning!
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Old 8th November 2018, 06:02 PM   #15
gedlee is offline gedlee  United States
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Quote:
Originally Posted by lamir35 View Post
I don't have a way to objectively judge them. Is it possible to measure and test them without special equipment?
To do a true "objective" assessment, you do need some equipment, but it need not be expensive. You could do a lot with < $100 expense. Many here can tell you how to do that.

To determine what to actually measure you should look to Floyd Toole and his books and Sean Olive and his publications. They lead the field in understanding the very complex link between what we measure and how it sounds.

As Toole and Olive point out, personal listening is a technique that is highly fraught with danger and likely to mislead more than direct an endeavor for improvement.
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Old 8th November 2018, 08:49 PM   #16
lamir35 is offline lamir35  Israel
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Thanks a lot guys, your advice has always been so helpful!
By the way I posted listening impressions of the Finalists here:

System Pictures &amp; Description
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Old 8th November 2018, 08:53 PM   #17
mitchba is offline mitchba  Canada
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Do you have a calibrated measurement mic, free REW, and a computer? If so, you can take some in-room measurements at the listening position to get a sense of the measured tonal balance.

There is good scientific research from Toole and Olive on correlating subjective listening preferences with in-room acoustic measurements, cross correlated back to anechoic speaker measurements. I wrote a summary here: The Science of Preferred Frequency Responses for Headphones and Loudspeakers.

At the end of the summary are links to several of Sean Olive's presentations which contain links to over a dozen AES papers on the topic. Sean peer reviewed my article for accuracy.

Putting room modes aside for a moment, a neutral sounding speaker will have a measured downward tilting response, at the listening position from 20 Hz to -10 dB @ 20 kHz. That's the findings from repeated subjective listening tests, correlated to objective in-room measurements from Harman's listening room. The test methodology they used is fascinating and in the links at the end of the summary above. As Toole says, accurate and preferred are synonymous.

Further, Tooles and Olive's research spawned a Standard Method of Measurement for In-Home Loudspeakers. That's a preview presentation as the standard costs about $100. I wrote a little summary about that, as I am really tired of bright sounding speakers and hoping speaker manufacturers adopt this new standard.

Anyway, hope that helps and good luck!

Mitch
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Old 8th November 2018, 09:03 PM   #18
bentoronto is offline bentoronto  Canada
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How to measure the loudspeakers actually work as they should?
Quote:
Originally Posted by mitchba View Post
At the end of the summary are links to several of Sean Olive's presentations which contain links to over a dozen AES papers on the topic. Sean peer reviewed my article for accuracy.

Putting room modes aside for a moment, a neutral sounding speaker will have a measured downward tilting response, at the listening position from 20 Hz to -10 dB @ 20 kHz. That's the findings from repeated subjective listening tests, correlated to objective in-room measurements from Harman's listening room. The test methodology they used is fascinating and in the links at the end of the summary above...
Thanks for links. Psychological testing is tricky.

If we had only that downward slope north of say 1kHz, it would hardly be noticed. On the other hand, HiFi's always sound bass deficient unless you boost the bass. Might be nothing but good old Fletcher-Munson.

Also, the Harman people showed that even experienced listeners can't tell bass boost from treble cut, not that any of us believe we would be confused.

So what I think is that systems never sound right without bass boost and only maybe with some lessening of the treble which cuts noise, sibilants, and other mic artifacts.

Basic problems are that there is no reference sound, no such thing as a "true" recording of Mahler in my living room, no reliable good memory, no adaptation level, no good language of sound....

B.
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Last edited by bentoronto; 8th November 2018 at 09:09 PM.
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Old 8th November 2018, 09:51 PM   #19
gedlee is offline gedlee  United States
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Hi Mitch

To me the downward slope comes about when we transition to more constant directivity (CD). CD puts a lot more sound into the room at HFs when compared to the older piston radiators which beam greatly. This means more sound in the reverb for the same direct sound - hence, CD sounds brighter.
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Old 8th November 2018, 11:54 PM   #20
mitchba is offline mitchba  Canada
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Ben, with Tooles and Olives research, there is indeed a standard referenced in the links above. The subjective/objective controlled tests in Harman's "typical" listening room using hundreds of listening test subjects shows there is. The results are repeatable and the prediction of those results are embodied in the new ANSI/CTA-2034-A standard. Olives slides are really worthwhile as are the AES papers.

Note these target responses are calibrated at reference listening level in which are ears response are the most flat - around 83 dB SPL C weighting on average at the LP. As you know, our ears frequency response changes with changes in SPL. That's why I use JRiver's dynamic loudness control as I may not want to be listening at reference level. So even at 65 dB SPL, my subs still respond, and the sound remains full and balanced, but at a reduced SPL.

Hi Earl, one would think that, but in Toole's research, as long as the speaker exhibited good directivity control, whether lower or higher directivity did not factor into the neutral preference. I have tried it on cones and domes and constant directivity speakers and the same target applies with no changes. The tonal response sounds the same to my ears. But the stereo presentation sounds different to my ears. Cones and domes more distant or diffuse, whereas waveguides more direct is how I would subjectively characterise it.

Sorry lamir35 if this is too much OT.
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