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Multi-Way Conventional loudspeakers with crossovers

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Old 23rd September 2007, 06:00 PM   #2191
Giarsun is offline Giarsun  France
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Default 8NMB420 massive basket

Quote:
Originally posted by Lynn Olson
..., internal reflections in the driver, unwanted radiation from the spider, dustcap resonances, etc. etc. etc. [/B]
Don't you think Eighteen Sound's 8NMB420 is a questionnable choice regarding these kinds of problems ? Its basket looks more of a bell with few holes than a modern areated basket (the kind most of the rest of their line has).
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Old 23rd September 2007, 06:20 PM   #2192
SunRa is offline SunRa  Romania
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Quote:
Don't you think Eighteen Sound's 8NMB420 is a questionnable choice regarding these kinds of problems ? Its basket looks more of a bell with few holes than a modern areated basket
Actualy the drawing in the pdf. file doesn't look that bad...
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Old 23rd September 2007, 08:41 PM   #2193
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Default BD15 bass from BD-design

hello Lynn

you might also consider BD15 Bass from BD-design :

http://www.bd-design.nl

he uses it also in a open baffle model. His homepage is under construction, so the picture might not be available of the finished speaker. He uses 2 of his woofers in a open baffle, and a lowther driver for mids / treble. i asked in his forum about OB, here his answer:

All depends on the design of the box and the panel.... you can create a worse sounding open baffle system compared to a good designed and well build "boxed" system.

You'll have a bigger change to get "cleaner" bass from an open panel but in return you will get more distortion from the driver as it needs to move a lot to compensate for the loss in bass (cancellation) and more power to handle.

Everything is a compromise in speakerland...


rds Angelo
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Old 23rd September 2007, 09:54 PM   #2194
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Quote:
Originally posted by mige0
Hi


JohnL, What bass driver is this ?
Are you satisfied with it ?



Greetings
Michael
Michael...

it's a 10" reclaimed driver from an Infinity RSII from 25 years ago...

measures ~36Hz Fs, ~.68 Qts

Click the image to open in full size.

bass is reasonable, given the baffle size (18" at top, 32" at bottom). These two OB's are augmented by a sonotube sub, crossed @ 80Hz, so low bass is not expected.

John L.
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Old 23rd September 2007, 10:17 PM   #2195
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Quote:
Originally posted by Lynn Olson
This one is so simple it looks really stupid. That doesn't stop me when nobody is looking.

4) Cabinets have really weird-sounding internal standing wave colorations, and especially cabinets where multiple drivers share a common chamber (line arrays, I'm looking at you). If you visit the proud audiophile or manufacturer when the drivers are pulled out, if the baffle opening is big enough, put your head inside (don't get stuck!!!), or if you want to play it safe, put your ear right at the aperture.

Listen for awhile. Note just how different it sounds than when you're several feet away in free air. The cabinet, even if is filled with Miracle Absorbing Material, has a hollow, muffled, resonant - well, boxlike quality, but with odd colorations from the damping techniques themselves. It's not really a simple "box" sound - there's other stuff, too, and hard to describe.

Speaker diaphragms are acoustically transparent, no matter what material they are made from. These weird boxy qualities are there all the time, overlaying their signature on the honest sound of the driver. This is especially severe in line arrays with a common rear chamber - the best reason for using multiple, small, isolated chambers, preferably of dissimilar dimensions.

There. Four listening techniques that will reveal a great deal of the gross and obvious defects of speakers from $100 to $100,000.
Lynn...

Interesting observations... and mostly what drove me to build these BG75 dipoles 2 1/2 years ago...

Click the image to open in full size.

They sound pretty much the same while circumnavigating, essentially have no cabinets (other than the smallish bass boxes for the peerless 6 1/2" mid bass, have minimal xover components (the planars run from 400 Hz on up with 1st order xover. Low bass is augmented with two large sonotube subwoofers from ~80 hz down to < 20Hz.

Hope the surgery heals well. I have a 6" ss plate in my left arm from 1985 auto accident. Luckily, my left arm was only paralyzed for a year while the radial nerve grew back to my fingers and wrist. The pins and plate cause only minor discomfort from the occasional low pressure system about 2 days before it arrives. Seeing your xray brought back memories of looking at my upper arm and seeing those deck screws holding it together

I've noticed the tweeter effect b4, I use this often, and have found the source material often is contaminated as well... as in the recording technique.

John L.
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Old 25th September 2007, 08:43 AM   #2196
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Quote:
Originally posted by gedlee
Lynn

I too applaud your "tests" for audibility as attempts to determine what truly matters in sound quality. However, I would caution about the potential pitfalls with almost every one of them. The cause and effect relationships are never really well established. Like listening to the cabinet very close. There is no guarantee that the sound you hear in this test is actually what is heard in the far-field.

Your tests are useful when one lacks the sophistication of doing things more scientifically, but I, for one, would not bet my designs on tests like this. They lack the quantification and proven correlation that I look for in my subjective testing.

Almost any data is better than no data, but we must always keep in mind exactly how much validity we can put in this data. Not all data has equal validity.
All four of the "tests" are more ear-training than anything else. They make no pretension to replace any measurement, and are not intended as such. I have gradually realized, with something of a sinking sensation, that most audiophiles are genuinely unaware of what a highly colored loudspeaker sounds like.

I blame the Big Two magazines, which routinely describe expensive loudspeaker systems with measurable, gross, and quite obvious peaks and resonances as "detailed" and "accurate". As James Boyk perceptively remarked, there is no sound too ugly to be described as 'accurate'. This word in particular has come to mean "unlike a live, acoustic instrument", and something closer to a disco PA system with multi-kilowatt amplifiers.

As a result of the gradual debasement of audio-language over time, many people think that brutally harsh sound has something to do with reality, or literally, fidelity to the original, when all they've done is accustom themselves to technically defective reproduction. Most of the folks I meet at trade shows really do think the $100,000 speakers on exhibit represent good engineering, when all they represent is glossy packaging and successful marketing.

This is different than cars, for example, where a $100,000 sports car really is a very fast car representing advanced engineering. In audio, we routinely have Pintos, Yugos and Trabants dressed up as Ferraris, priced accordingly, and worst of all, the market accepts this.

So I gently try an re-acquaint people with the basic elements of a loudspeaker intended for enjoyment of music: freedom from the most obvious resonances, cabinets that work as intended, and freedom for phasey-sounding dispersion and diffraction problems. When I see flagrantly bad-performing loudspeakers get top reviews and command astonishing prices, the problem is deeper than the manufacturers and the reviewers; it's the listeners, who aren't demanding better.

The first steps are to break free of the miasma of pseudo-technical "reviewer language", realize that cost, prestige, and famous-name recognition have almost nothing to do with good taste and good engineering, and listen with fresh ears. The four "tests" I described are one way of experiencing loudspeakers without all the baggage of reviewer-speak.
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Old 25th September 2007, 09:40 AM   #2197
mige0 is offline mige0  Austria
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Hi

Yes clever marketing and lawyers power overrules basically EVERYTHING.
This also is true in cinema sound widely accepted as kind of audio reproduction reference for the crowd.

There, for decades, Dolby has successfully managed to place the term " Dolby Digital " as synonym for top notch sound.
Almost nobody knows that the AAC3 format used there is nothing better than MP3 just extended for surround sound.

All it was better for compared to the usual 35mm optical sound tracks was noise and bandwidth in addition to the digital inherent advantage of long lasting without loss..

The competing digital formats from Sony and DTS are way better due to less compression rate and the ancient analog 70mm magnet tone was superior to all of them.


Greetings
Michael
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Old 25th September 2007, 12:48 PM   #2198
gedlee is offline gedlee  United States
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Lynne

I couldn't agree with you more. People often rejected my loudspeakers because they don't sound like other loudspeakers - hence they must not be any good. "Expectation" is the bottom line - if the speakers sound as people have come to expect, then they are deemed to be high quality even though they offer very poor reproduction of sound.

I am often criticized because I downplay the subjective, but I do this for precisely the reasons that you state. The audio media and its jargon allow people to accept poor reproduction as sound quality because "it sounds good to me" - a position that cannot be argued with. But remove the subjective and its not so easy to support this erroneous point of view - in fact its pretty much impossible. It's the bottom line "I know what I like" that allows for the situation that you describe.

In reality I am a passionate listener, I just will not argue audio from this standpoint since the trump card can then be played at any time. I don't like to play when the cards are stacked against me.

Mige0 - AAC really is a much better codec than MP3. Your comparison is not fair or accurate. Dolby Labs is a very respectable organization who do first rate work.
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Old 25th September 2007, 01:52 PM   #2199
MBK is offline MBK  Singapore
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Quote:
I have gradually realized, with something of a sinking sensation, that most audiophiles are genuinely unaware of what a highly colored loudspeaker sounds like.
I've had the same sinking feeling. It's especially disturbing when parts of the system have potential, are even excellent, only to be demolished by absurd mismatches to the other components.

In fact I sometimes have epiphanies that show that run of the mill solid engineering can produce substantially better results than audiophilia. For instance some ceiling speakers in stores can have quite decent reproduction of the essentials: great, certainly not, but at least, not absurdly distorted.
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Old 25th September 2007, 04:50 PM   #2200
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Default observable pontification

Not sure I totally agree with the Boyk model (or parts therof) wherein ultrasonics out well beyond human audibility have an impact on what we actually hear in the 20 - 20Khz alledged human range (or ~25 - 14K for myself ), notwithstanding generation of beat frequencies between ultrasonic components in a live performance influencing the timbre of instruments when heard. If those in-band frequencies are there, they will be captured w/o the need to reproduce the ultrasonic signals per se.

Not all of us "audiofools" are gullible enough to buy into the Julian Hirsch model of review, wherein all speakers are, to paraphrase Garrison Keilor's Lake Wobegon Days' "all the drivers are strong, all the cabinets are good looking, and all the technologies are above average"... often followed on the opposing page with a large ad for the device being reviewed.

Having played several instruments (reed) in orchestral works, listened to many more in person, and owned or listened to hundreds of systems over several decades, I personally have never been under the illusion that what I hear from a system is close to what I experience at a live event. Two different beasts altogether.. always will be. I have managed to build systems that reproduce some of the "you are there" attributes, (see pic previous post) sometimes even sounding subjectively better than a live performance ever will.

Having been involved in electrochemical and aerospace engineering for 35+ years, all I can say with bemusement is the level of "ingineering" exhibited in many (especially loudspeaker) audio components is laughable at best.

It's almost as bad as dealing with the health insurance morass we're all currently living through (my current endeavor )
with respect to accountability and accuracy.

John L.
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