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Multi-Way Conventional loudspeakers with crossovers

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Old 30th October 2012, 04:31 AM   #41
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Quote:
Originally Posted by Barleywater View Post
Small speaker, cross very steep 1kHz, linear phase, and drivers 1/4 wavelength apart at crossover.
Andrew,

When i 1st saw that my thot was that that looks scary. The graphs themselves make me apprehensive, and only suggest an awful lot of processing to get a real flat on-axis curve, which is meaningless without a set of off axis curves. And there is a whole lot more to a speaker than flat-frequency response. I would expect lots of digital artifacts, but i'd have to hear it to really judge.

dave
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Old 30th October 2012, 04:36 AM   #42
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Originally Posted by theaudiophile View Post
So what do you mean by that? Do you mean the tweeter has a different dispersion pattern to the woofer and that gives it away?
Yes.

Quote:
But you can hear a lack of coherence even on axis.
That doesn't matter.

Your brain hears timbre as a weighted combination of what it believes to be a direct sound and its reflections with accommodation for less high frequency energy in later reflections as one gets in nature with increasing absorption and diffusion.

Where the reflections' spectra don't have monotonically decreasing energy with increasing frequency it does not sound natural.

This is why both the ubiquitous 2-way with a 6-8" midrange, 1" dome tweeter with a 4" face plate, and 2.5 KHz + cross-over and 6-8" full-range speakers don't work well.
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Old 30th October 2012, 09:30 AM   #43
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Quote:
Originally Posted by planet10 View Post
Andrew,

When i 1st saw that my thot was that that looks scary. The graphs themselves make me apprehensive, and only suggest an awful lot of processing to get a real flat on-axis curve, which is meaningless without a set of off axis curves. And there is a whole lot more to a speaker than flat-frequency response. I would expect lots of digital artifacts, but i'd have to hear it to really judge.

dave
Measurement at 42", no smoothing:

Click the image to open in full size.

Same measurement, gated to 3ms:

Click the image to open in full size.

45 degrees off axis horizontal: Gated and un-gated results are shown. Rest of results are all gated. (Click on picks to enlarge)

Click the image to open in full size.

90 degrees off axis horizontal:

Click the image to open in full size.

30 degrees horizontal and 30 degrees vertical above:

Click the image to open in full size.

15 degrees below:

Click the image to open in full size.

Speakers do square waves within bandwidth constraints, waveform fidelity to what is on CD/normal listening material is extremely good, and they sound fantastic, no audible digital artifacts.

They are easy to build. I can get this performance using multichannel soundcard ranging from $30 upwards, and four channels of amplification.

Filters are small enough that this will run on antique 500MHz P3 laptop.

Regards,

Andrew

Last edited by Barleywater; 30th October 2012 at 09:32 AM. Reason: typo
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Old 30th October 2012, 10:08 AM   #44
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Thanx,

Andrew, can you stack those off axis onto a single graph so that they can be compared? And can you make the graph larger?

dave
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Old 30th October 2012, 10:36 AM   #45
Rudolf is offline Rudolf  Germany
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While we are at it - are those off-axis measurements made by moving the microphone or by rotating the speakers? If the latter, I wonder how much measurements at say 50 or 100 cm left/right from the "EQed" position would differ from the "ideal" one.

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Old 30th October 2012, 10:39 AM   #46
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Originally Posted by planet10 View Post
With such a large amount spent on drivers & XOs it seems a shame to put them in such a mediocre box.

dave
The box is not mediocre. It's been mistaken a number of times by audiophiles for Sonus Farbers and my wife loves 'em. xo $$? don't think so. One resistor, and two coils don't add up to much compared to many high order xo's I've seen with various cr*p trap circuits included to address typical anomalies associated with mediocre drivers. Get good drivers and the xo doesn't need to be complicated. The simpler the xo, the more coherent the sound - most of the time.

I think I explained the reasoning behind "The Intimates" fairly well in my TT write up.
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Old 30th October 2012, 10:40 AM   #47
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What measurement software do you use barleywater? Yours looks different than most I've seen.
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Old 30th October 2012, 01:45 PM   #48
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Overlays of axis/off axis measurements, ported to REW:

off axis overlays 30h30v 45 90.png

Plots referenced to 100dB at 500Hz, 20ms Blackman-Harris windowing, and 1/12th octave smoothing.

Speaker stationary, microphone moved.

Workhorse software is Cool Edit Pro2.1 with Aurora plugins, and Sourceforge Convolver plugin.

Microphone is Earthworks OM-1, older, but very similar to M30. Extremely flat response.

Sound Card is E-MU 0404 USB used with Cakewalk Sonar for measurements.

Playback on Roland Octacapture USB using Windows Media Player with Convolver plugin. Octacapture clock is synchronized to E-MU clock.

Also works perfectly fine with ancient Creative SoundBlaster Extigy USB.

Also Octacapture works with Console hosting Convolver, allowing standalone operation with selection of analog or digital input.

Phase overlays:

phase overlays.png

Regards,

Andrew
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Old 30th October 2012, 06:49 PM   #49
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Quote:
Originally Posted by speakerdoctor View Post
The box is not mediocre.
I've had a number of those actual boxes thru here, they are OK for what they are, but they are still medicore quality -- higher quality than other the 6 layer MDF plywood on the sides.

As to the XOs, even simple ones can cost. 3 parts per in the XOs i am working on now ran close to $100 each.

dave
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Old 30th October 2012, 09:15 PM   #50
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Originally Posted by Wavebourn View Post
I use arrays of 16 Foster 402S01 drivers as tweeters, and don't hear any "incoherece" with arrays of 8 x 4" drivers with poly cones and pair of 12" woofers in concrete boxes. I don't hear speakers at all, I hear stereo image. Why? Because if speakers "give away" themselves they "give away" because of their distortions. In arrays displacements are tiny, so distortions are much lower than from a single driver that produces the same pressure level.

PIPEDREAMS by Nearfield Acoustics

what about these speakers? These are very tall yet they did not sound like a multi way with 100 drive units. Why?
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