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Old 13th September 2007, 05:01 PM   #1981
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Quote:
Originally posted by mige0

Surprisingly the flat foam surround is still like new . Compare that to old Dynaudio foam surrounds !

Or Focal foam...
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Old 13th September 2007, 05:15 PM   #1982
mige0 is offline mige0  Austria
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Hi

Quote:
I have to disagree with you here. The resonance in most drivers are a linear phenomenon and as such can be equalized.

JohnK, thanks for correcting me and giving some theoretical background.
From plain measurement its hard to tell whether the resonance is really corrected or just disappears in the dust. You are sure the break up is within linear operation as the whole area looks rather chaotic ?


The measurements below show an ancient 9" cone driver – pure paper, no exotic blend - no coating. - more relevant to this thread than metal cones I think.



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As can be seen, there is break up resonance not only with metal cones. Though for clarity I had to bring it up with a shelving filter as this driver rolls off at about 800 Hz thanks to the simple motor with no faraday rings. The resonance peak normally is around 10 – 15 dB down.

The tail of the resonance disappears with a notch at around –9 dB.


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What can be seen here is that the adjustment of the notch filter is VERY critical.
The tuning frequency in the Behringer DCX allows for center frequencies of 2,85 kHz / 2,79 kHz / 2,73 kHz which is not stepped fine enough and further more the Q is limited to 10 what also is not sufficient in this case.

You can not achieve a perfect linearisation with this tool instead the peak and the two dips at its side are only lowered. Still an audible improvement.

Any better tools out there?


Greetings
Michael
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Old 13th September 2007, 05:26 PM   #1983
mige0 is offline mige0  Austria
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Hi

Quote:
I agree from looking at this data, resonance in most drivers can be equalized; however, due to the fact that resonances occur after the first refleced wave in the cone, an equalized driver will never sound as good as the driver without this resonance. Since we may never be able to do this kind of comparison in reality, knows what we may be missing.

Soongsc, if I understood JohnK right this isn't the case and the correction is theoretically perfect.

It's not kind of feedback loop but rather a complimentary IN TIME balancing.

Greetings
Michael
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Old 13th September 2007, 05:59 PM   #1984
AJinFLA is offline AJinFLA  United States
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Variac, beg your pardon.

Hi Jim, I was not so much referring to that speaker so much as I was the design.
IIRC, this was the OB speaker you heard which had some sort of malfunction in the bass. If it was corrected, perhaps a re-audition would be beneficial. Or perhaps an audition of an Orion to hear dipole radiation extended further down into the rooms acoustics and put things in perspective.

John, the NaO that I remember from the halcyon days of Madisound was the W18 version. When the inevitable Orion comparisons were made, it was not with the SS version. When I first viewed your Music and Design site, it was the W18 version for sale, with the SS option IIRC. Hindsight is 20/20, although I still can't see how you could consider this a "mistake". An option maybe.

Quote:
Originally posted by john k...
Anyway, the Seas metal cones are very smooth in the pass band. There is no question that the W18 and the SS sound different and you’re not the only one who prefers the W18. But I bet you like a Steinway compared to a Baldwin.
That answer sits much better with me. It's more a subjective preference than measured distortion components. We each have our ideas of what things should sound like as referenced against our memory of live sound.

Quote:
Originally posted by Tom Danley
Several answers;
While at Intersonics my job was to develop new kinds of transducers, “officially” these were for acoustic levitation but I also develop the Servodrive woofer and Phoenix Cyclone rotary woofer and some others while there. I guess from that perspective, I cannot under emphasize that damping is a very important quantity and is not associated with some of the cool looking cone materials.
If looks weren’t apparently more important than sound in some cases, then drivers with nasty behavior wouldn’t be sold based on a “New cone technology”.
It has been a while since I measured any, but I don’t see that they have changed fundamentally since then and if I were building something that used them, I would sample the ones I was interested in.
Your work shows ingenuity, from the rotary to the unity. However, this has little to do with soft vs hard cone behavior and driver design in general. Do you have any data on the drivers you are critical of from the Madisound catalog that you believe are all looks? John K presented his summary that it is a largely subjective choice, rather than a deficiency in the driver design.
Quote:
Originally posted by Tom Danley

Your mention of a blaring pa system is spot on in a way.
Most of all the things that are wrong with speakers, get worse as the volume is increased and as the size and complexity of the speaker system increases and also as the room size increases. Often the sale of speakers in this kind of situation is based on hearing side by side demonstrations in the venue. If you can demonstrate better sound, you get the sale most of the time. That kind of puts the focus on better sound and is why I went the way I did.
My point was that even if a PA driver has 10X the headroom of some dainty Home Hifi unit, does that automatically make it the better choice in a living room? I agree that for my own audio requirements, a mixture of pro and home drivers are required for the headroom target, but my listening room and requirements may not be my neighbors. Who cares if a PA driver can achive 130+db with minimal compression if it sounds like s***?
Quote:
Originally posted by Tom Danley
Well, all the horn style speakers I build, like the SH-50, only operate the drivers in the piston band. In fact, to reduce distortion, each cone driver feeds into the horn through an acoustic low pass filter comprised of the air volume trapped beneath the cone and a hole which connects to the horn. This low pass filter in front of the driver is above the low pass crossover point and has the effect of attenuating the harmonic distortion the driver produces which comes out above crossover frequency.

With a TEF, one can see a driver which is transitioning to non-piston motion, the old
TEF-10 /12 machines (which were much better in time than the modern ones) one could see the small change in time taking place in a mid range soft dome that had nice smooth response, as the dome de-coupled.
I would think that if you can, you would want to avoid that kind of operation (non-piston) at least where your ears are most sensitive, more or less 300Hz – 3KHz
Bottom line, if you have a mound of acoustic gain between the motor and the net radiation, you magnify the nonlinearity and sub multiples of that F.
On the other hand, if that acoustic gain is in the middle of the band and is broad (low Q) enough, then that can (if eq’d flat) can lower distortion by reducing the drive / excursion of the motor (who’s non-linearity is tied largely to motion).
This is what horns do (one thing), a bass horn that raises the drivers sensitivity by 10dB can reduces its excursion for a given SPL to 1/3 the direct radiator case.
You did not address my question. Are soft, flexing, lossy paper cones without sin? How you chose to use them in your synergy design is the same as how someone else, like a Toole, Thiel, Linkwitz, John K, etc. decides upon their design. I see no crossover frequencies for the SH-50. Nor do I see a laser scan of the mids, whatever they may be. As a matter of fact, based on the Yorkville design, I see what appears to be closed back mid drivers. Is this the same in the Synergy? If so, can you tell me how the rear wave off the driver cone is 100% absorbed in that minuscule chamber and not reflected and re-radiated through the paper thin membrane, delayed in time to the original?
Quote:
Originally posted by Tom Danley
Your comment about compression drivers is related to using metal dome tweeters too.
A dome in a compression driver is one case where strength to weight is a controlling factor as the radiator as mass is more important than in a direct radiator tweeter.
Here, metal or mylar domes are used. A good one inch exit dome type compression driver will have a dome stiff enough (to act like a piston) to reach 17-20KHz before the first resonant mode. Realistically, if you’re an adult, your hearing rolls off before 20KHz and then drops like a rock above 20KHz. I’m not talking about can you detect anything up there under the best case but rather can you hear anything up there under normal conditions, no.
As a result, distortion produced at 5KHz and above has to be at an enormous level to be detectable at all. Similarly peaks and dips associated with breakup, that high, are not generally detectable.
So ringing like a bell tweeters are benign (and usable in your design, as opposed to say John K's) due to Fletcher Munson, but metal mids, with no corroborating data, are not?
Paper is this perfect, lovely material that folks wax poetically about, but no one uses in tweeters outside of Dr B (twiddlers, to be exact) and some hideously expensive fringe "fullrange" drivers with piezos?
Quote:
Originally posted by Tom Danley
This is not what Earl Geddes is on about, that (HOM’s) are a variable that on one given horn, may make 5 different compression drivers with similar end responses all sound different.
Not sure how Earl got dragged into this, but he uses BC drivers, which I looked at and IIRC the woofer has that nice 'ol soft cone edge resonance. Is that benign also?
Quote:
Originally posted by Tom Danley
“What if the goal is reproduction of acoustic instruments?”
An ideal reproducer reproduces whatever it is asked to, without alteration in any way.
Actually, the alteration of the signal begins at the speaker terminals through the drivers 3D radiation of acoustic power.
For me, rigid low loss cones offer the least alteration to my illusion of what a live acoustic instrument sounds like. To me, paper coloration is an association of amplified music.
Quote:
Originally posted by Tom Danley

Like John K. said so well “Door bells and tuning forks should ring, not driver cones.”
No one can convince me that what we have no is so close that we can all give up.
Then there is the recording process and how the speaker interacts with the room, layers which make what the ideal speaker needs to do, less clear.
He also said this is based on subjective preference, rather than any objective data yet ascertained. Agree with the rest.
BTW, there was another recent thread about cone materials cones and data so as not to rehash it all. I have heard good and bad designs in both soft and rigid cones. I simply put a greater emphasis on transparency and not wanting to hear the loudspeakers whatsoever, than something more romantic, a filter that makes poor recordings more palatable.

cheers,

AJ
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Old 13th September 2007, 07:47 PM   #1985
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Quote:
Originally posted by AJinFLA


I simply put a greater emphasis on transparency and not wanting to hear the loudspeakers whatsoever, than something more romantic, a filter that makes poor recordings more palatable.

cheers,

AJ
Ah! I think we come to the heart of the matter here.

By now it should be evident we hear - or at least, expect to hear - reproduced music in different ways. Speaking only for myself, I find all hifi systems not very close to the real thing - which for me, is live, un-amplified symphonic and choral music. When I go to a concert, it's at least a couple of days before I can stand to turn the hifi on again, it sounds so grossly artificial. Once I re-adapt, there is always at least some suspension of disbelief when listening to mechanical sound reproducers - and I use the word "mechanical" quite deliberately, since that's exactly what's wrong with hifi in general - a mechanical, "canned" quality that is always there.

This isn't to say all hifi sounds the same - hardly. Some, and a lot of the very expensive mainstream systems, are completely unacceptable and artificial sounding, with timbres and tone colors that don't sound like any acoustic instrument at all. I can tolerate these for no more than a few minutes, fighting an urgent desire to leave the exhibition room immediately, while right next to me, an audiophile (or magazine reviewer) is grinning from ear to ear.

What can I say? There's no accounting for taste. Since I find even the very finest systems removed from reality to a fairly obvious degree, I prefer systems that have colorations that land in the "musical" direction, as opposed to metallic, sizzly, grainy, flat-sounding, or other "electronic" or "mechanical" sounding colorations. In presence of obvious and hard-to-ignore colorations - which, again, I find in all systems compared to the real thing - the whole discussion of "transparency" doesn't seem as relevant.

Oddly enough, when it comes to amplifiers - where colorations aren't as gross and severe - then transparency as a desideratum becomes more relevant. In my limited experience, I find bigger transparency differences amongst amplifiers, which really can have a sort of remarkable MP3-like ability to erase fine detail and subtleties of musical expression.

In technical terms, though, not so surprising. Speaker drivers add distortion and resonances - lots of them - but don't have the ability to actually erase resolution. Electronics can perform this feat, thanks to Class AB-transition crossover distortion, nonmonotonicity in ADC and DAC conversion, digital jitter, and assorted low-level signal bending mechanisms that just don't exist in passive electroacoustic transducers.

Measurements confirm this - in most electronics with Class AB and/or quasi-complementary elements (this includes nearly all op-amps), distortion (not just noise!) starts to rise at low levels, while this is not seen in electracoustic transducers, where distortion falls monotonically with level (and of course there is no addition of noise, either).

P.S. One area where we could legitimately discuss loss-of-resolution in transducers is "stiction" in the spider - that's plenty real, but I haven't seen any measurements of the phenomenon. Spiders could certainly stand a re-design to get rid of stiction and other low-level nonlinearities, as well as unwanted re-emission and self-resonances. Maybe that's why some prosound drivers use stacked spiders with a layer of silicone damping between them, to help control some of the spider nonlinearities and break-in weirdnesses.
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Old 13th September 2007, 09:12 PM   #1986
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Hi Lynn,

have you considered an electrostatic driver for the mid/highs? It may be tough to match with dynamic drivers in an OB and no, you won't get high efficiency. But to my ears an electrostatic driver, like for example the treble panel from a Quad ESL, has the most natural sound I've heard yet.

Regards,
Arend-Jan
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Old 13th September 2007, 09:27 PM   #1987
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Quote:
Originally posted by arend-jan
Hi Lynn,

have you considered an electrostatic driver for the mid/highs? It may be tough to match with dynamic drivers in an OB and no, you won't get high efficiency. But to my ears an electrostatic driver, like for example the treble panel from a Quad ESL, has the most natural sound I've heard yet.

Regards,
Arend-Jan
Oh so tempting, I agree about the wonderful sound of electrostats. But ... since the mids and bass are being designed for a 110~115 dB headroom with many dB to spare, I think the electrostat would get crushed, or more accurately, zapped.

The efficiency mismatch is also great - more than 10 dB - the system would require yet another amplifier, a dismaying prospect. The bass array amplifier and associated equalizer don't need to be the last word in subtlety and beauty, since they only cover 80~400 Hz, but the quality requirements for an electrostatic-tweeter amplifier are not trivial.

The best ribbons have nothing to apologize for sonically, and it looks like the double-high RAAL at 100dB/metre is in a class of its own in terms of impulse response, very wide horizontal dispersion, and peak SPL capability.
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Old 13th September 2007, 09:42 PM   #1988
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Default Some Subjective Measurements


Made with the best-quality measuring tape, but unfortunately not traceable to NIST standards.

Sitting on the floor meditation-style (but without the fancy leg moves, which I can't do), my ears are 32.5~33" high, depending on position.

Sitting on different chairs and couches, my ears are 40~49" high, depending on how much I lean back and the recline angle and height of the couch or chair.

Generic 1" dome + 7" midbass speakers (Magico Mini to Cambridge SoundWorks Model Six) typically aim the crossover lobe downward, unless the designer took special steps with the phasing to aim the beam upward (not very common). Since these things usually sit on short stands, I can see why they usually sound better when I sit on the floor, instead of a chair, looking down on them. Pointing them upwards is probably a good idea.

P.S. I'll take the CSW Model Six at $299/pair instead of the Magico Mini at $20,000/pair, thank you very much. I'm a big fan of Henry Kloss and his work.
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Old 13th September 2007, 10:17 PM   #1989
Salas is online now Salas  Greece
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My reference axis on my current system (the one that you saw as OT earlier in this thread when some more info was asked), is 47'' high.
I am with you in that high axis thing obviously.

Earlier in the posts I have shown the Bastanis naked back compression driver 'Gemini' dipole tweeter approach. What about something like that for HF? Not strictly for the ''Beyond'' speaker that needs a fairly low cross. Your opinion in general. Bastanis's wide range crosses high and there are many (almost FR) 8 inch options if making a less dynamic OB. What do you think?
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Old 13th September 2007, 10:21 PM   #1990
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Quote:
Originally posted by soongsc
I agree from looking at this data, resonance in most drivers can be equalized; however, due to the fact that resonances occur after the first refleced wave in the cone, an equalized driver will never sound as good as the driver without this resonance. Since we may never be able to do this kind of comparison in reality, knows what we may be missing.
Well it all comes down to whether the resonance is minimum phase or not. And I will suggest that is based on my measurements. Given that, minimum phase equalization of a minimum phase resonance corrects the response. The equalized driver and the ideal electrical bandpass filter have the same CSD. Since the CSD is just another way of post processing the impulse response then the two must also have the same impulse response. If its a linear system, then it can be corrected linearly.

However there are caveats. Although the breakup is primarily a linear phenomenon there are certainly nonlinear components, which, while not dominant, can not be corrected by application of such equalization. There are numerous other potential sources of problems too. As you say though, it's academic and there really isn't any way to definitive test it. All you can do is listen.
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