TS> As to driver type efficiency and accuracy of 
TS> reproduction considerations,
TS> some of the best discussions I've seen have come 
TS> from white papers written
TS> by JBL engineers, usually in the context of 
TS> comparing desirable design
TS> traits of compression drivers with various alternatives.
 TK> Hmmm...this is not about balancing but high 
 TK> efficiency...NOW you got my attention :)
It is more of a theoretical engineering and manufacturing technology topic, 
out of reach of end user-technicians, other than as to learning some clue as 
to how it affects various products.  
 TK> I'm very interested in these 'white papers'...do you 
 TK> happen to have a copy of it ? Preferably in an ASCII-
 TK> text file ? =)
Sorry, nope.  Some I would have in my upstairs archives mixed with tons of 
other info, in printed "white paper" form, while others I couldn't even 
locate in the several hours of searching finding those would take.  I was 
talking about an assortment of things I've read over a couple decades, and 
stuff found in archives of older family and associates as well, plus 
discussions with factory service folks and engineers at AES conventions and 
elsewhere.  
Another interesting exposure I had was a 75 minute toll call where I got 
Irving Fried personally, calling his company when he was semi-retired about a 
minor service problem.  When he found out I had used some of his products for 
years, was active in pro audio, and my dad as a grad student in Philly had 
been a customer for hand picked Altec product from his old retail store, he 
gave me some interesting insight into his ideas for using transmission line 
theory for cabinet design.  I haven't run across anyone else in audio 
promoting the same type of physics applicable to RF, light refraction, water, 
and audio wave theory by similar coupling as I. M. Fried (consider jokes 
people have played on his name as he listed it on public documents and 
speaker labels).  Irving goes back to the era when it was popular to build a 
large horn into the architectural corner of a living room, and worked on 
design ideas to collapse such efficient coupled front loading into boxes not 
much larger than mid sized sealed acoustic springs (of terribly low low end 
efficiency, but cheap to control distortion).  Hmmmm....  thinking back, he 
even mailed me some of his less well known white papers after that 
discussion, which I also have buried upstairs somewhere.  I'm not sure if 
he's even alive any more though, but was a less known serious audio 
contributor for decades.  
Some of the most interesting as I recall date to the time JBL changed from 
swirl to symmetrical diamond pattern surrounds in 24xx series 1 and 2 inch 
throat compression drivers, and went into extensive detail as to design 
compromises in such drivers.  While I've seen JBL release some defective such 
product, like replacement diaphragms that rubbed due to an oversize varnish 
drip on the voice coil even when properly centered with a correctly 
positioned pole piece, I tend to respect their engineering more than most 
competitors in that product line moreso than larger cone products where I 
don't see them as having as many singular competitive edges.  
One of the key details that stuck in my mind was an optimal efficiency of 
compression drivers (which some of the upper bass and lower mid phase plug 
front loaded cone driven boxes of the past decade emulate) of about 33%.  
Above that and resonance and transient damping become impractical, and below 
that and you're buying Emilar or similar economy lines that offer false 
economy if it results in a need for more drivers taking space and amps for 
the same acoustic output.  Details could be difficult to recall precisely or 
discuss without supporting data and graphs of test results.  
TS> Thiele and Small certainly have considered such things, 
 TK> As far as I know, those guys were the inventors of the 
 TK> standard parameters we use nowadays to design acoustic 
 TK> solutions.
Although their work is used more often it seems designing 3rd order harmonic 
compromises against box size in tuned port bass bin design....  
TS> I sort of wonder if white paper style material was 
TS> widely published back
TS> when Klipsch was first competing with products 
TS> like the EV Patrician on low frequency products.
 TK> Don't know...btw this EV you mentioned happens to be Electrovoice ?
Yes, before it became a division of Gulton Industries, later to be a child of 
that parent as acquired by a Japanese backed holding conglomerate.  Foreign 
ownership (though masked) was a serious concern because other Gulton sister 
companies were defense contractors.  
In that era there was a move toward 30" low end drivers, as opposed to more 
recent theory and practice that multiple smaller drivers proximately located 
for efficiency gains of mutual acoustic coupling are better for reasons of 
beaming and transient accuracy.  A 30" driver would be used with a loaded 
horn tuned to a cutoff between 15 and 30 Hz.  LARGE, especially for home use, 
and perhaps a child of an era of expensive tube amps where 100 watts was a 
larger than average amp, begging for efficient speakers in lieu of today's 
cheap kilowatts of amp power.  
TS>> Of course, I was thinking about bone conduction
TS>> of sound to influence brain waves,
TS> That's a serious factor when considering why 
TS> headphones can't produce the
TS> same perceived sound experience as a good speaker 
TS> system and environment
TS> for some music, despite generally being easier to design for better TS> 
response, distortion, stable platform, and freedom 
TS> from room artifacts.
 TK> I do not quite agree with you:
 TK> Low frequencies are a sensation to the whole body, and 
 TK> furthermore headphones can't give the acoustic 
 TK> sensation of a room or hall due to the lack of 
 TK> reflections.....a mostly underestimated fact
In reproducing sound the room is usually a problem, and not a controlled hall 
optimized for specific performance types.  Therefore "cans" have the 
advantage of bypassing sheet rock cave standing waves, vibrating glass and 
radiator parts, speaker positions to placate a wife or not be mangled by pets 
or kids, etc.  Sure, a few people have decent rooms.  For most headphones are 
of higher relative quality than crappy speakers and acoustically uncontrolled 
space.  
We can process audio to simulate a desired space into a known reproduction 
system, such as headphones, as to almost all factors involving amplitude, 
balance, and timing, including simulated reverberation and decay.  Low end 
bone conduction is the one factor we simply can't include in that otherwise 
cost/quality effective balance.  
Another analogy would be broadcast processing.  For AM, what bandwidth and 
distortion level radio will be used?  For AM or FM, or TV, what kind of 
speaker system and room will be used?  There is no answer as specific as what 
can be expected with midrange to good headphones and any but the worst line 
level equipment.  
Any clearer as to the attempted implied comment I didn't spell out in detail 
before?  
TS>  Of course, the NASA lauch pad where they use unusually high bias TS> 
voltages on B&K condenser mics so as to not 
TS> overload at 180 dBspl's could be another real world example,
 TK> Huh ?!? Example of what ?
High energy level real world challenges to accurate transducer technology.  
The raw power for reproduction would be more of a challenge than the small 
diaphragm high precision $3,000 mics which are readily available.  B&K does 
some super high bias voltage mods to standard product line instrumentation 
mics for that NASA application, which allows low distortion monitoring of 
rocket liftoffs from various elevations right at the lauch pad and tower, as 
opposed to the old days of distorted audio from mics spaced back a ways and 
less useful at helping document takeoffs and analyze time-vibration-stress 
issues.  
TS> not to mention my old high school classmate who tests solid rocket TS> 
boosters fired sideways at ground level out in the 
TS> SW US deserts, working for Morton-Thiokol.
 TK> I always wanted to use a J-1 or F-2 liquid fuel 
 TK> rocketmotor as a subwoofer 
Just make sure you've got plenty of cooling water, or a couple miles of flame 
resistant materials you don't mind melting downrange.    (One of my 
grandfathers used to supervise 10" deep wells used by Pratt & Whitney for jet 
engine testing cooling.  I'd imagine those needs were trivial by comparison.) 
 
Personally, I still respect the energy concentration of basic gunpowder, 
though reading about .60 caliber elephant rifles used early this century by 
British game hunters and realizing they had less energy than .30-'06 or 
7.62x51, and comparing .380 ACP with .38 Special, or .40 S&W with .357 Magnum 
cartridge sizes and energies, I can only speculate on how dramatic an 1812 
overture we could produce with modern guns and powder versus historical black 
powder.    
Even a few herald trumpets on a roof top are impressive, but they of course 
are resonance devices.  
TS> Pistol shooting alone outdoors can be another interesting acoustic TS> 
scenario, as short duration intense sounds can 
TS> have much more energy (and
TS> cause more damage) than we realize hearing them.
 TK> Yep....over 148 dB....deafening isn't it ?
Actually, it doesn't seem as loud as it is (as indicated by tinitus for up to 
weeks later.... don't try what they show on TV, kiddies).  It takes about 100 
mS duration for audio or light for us to perceive the intensity fully.  
There's a lot of similarity to why a bright photo strobe may appear dimmer 
than a weaker flashbulb.  (The psycho-perception of light and sound seem 
rather similar, based on my studies, and discussions with folks like Bronwell 
Jones (former CBS labs perceived acoustics researcher) and my dad 
(Optometrist).  Only the physical human transducers seem really different in 
performance quirks.)  
TS> Of course, I was suggesting how sound can trigger subconscious alpha,TS> 
beta, delta, and other brain wave patterns, 
TS> pleasurably or with possible
TS> pain stimuli that aren't directly sensed as well 
TS> as possibly with others that are.
 TK> Try to contact a neurologist....he should know about these things.
I wouldn't count on it.  Few people study not usually mixed aspects of 
various forms of technology and perception.  How many neurologists understand 
Fourier transforms to sort body electrochemistry from noise floors, and 
timing of other than common neuro-transmitters and nerve junctions?  How many 
chakra healers understand enough of the same topics to know the difference 
between spiritual hypnosis and human function related to quartz resonances in 
their art?  
How many artist types who are good at creative sides of audio understand how 
any of the above relates to their product?  
 TK> Oh bugger....I have trouble enough to find out how our 
Look out.  One of our Congressmen called our Liar in Chief, Klinnochio, that, 
after posting charts with examples of contradictory double talk during 
Congressional debate.  They wasted half an hour debating whether it was an 
inappropriate description of Bill the Cat being some kind of rascal, or 
whether he had an unnatural affection for the posteriors of young boys, and 
whether as such the remark should be stricken from the record.  
TS> Some people want pain, as a masking pattern, as a 
TS> perceived need (kids
TS> associating high frequency distortion with desired 
TS> loudness due to too
TS> many crappy stereos, masking more annoying 
TS> physical pain, to interrupt
TS> and prolong pleasure stimuli, etc.), or for various other reasons.
 TK> You lost me here....I'm definitely not into the art of 
 TK> pain-causing..sorry
I actually listened to an entire Nine Inch Nails album twice at low and 
moderate volumes to help understand that style of music a bit.  As a 
broadcaster, it helps to understand how some demographics associate 
irritating distortion with 'good, loud music' (as reproduced by crappy 
stereos), while others of us much prefer low distortion more natural balance 
of low duration high end.  That NIN sample helped me understand why a 
nightclub popular with certain college crowds always sound like shit despite 
plenty of JBL biradial monitors and loads of clean power amps.  
Of course, I might also study bioenergetics and similar psychotherapies, 
Russian therapeutic beatings and similar Western S&M practices not considered 
massage as such, among other human experience practices.  
TS> I've thought about painful but also 
TS> psychologically disorienting acoustic
TS> stimuli as having possible applications in a 
 TK> No problem....try 100W/12kHz feeding it through a long-
 TK> throw horn. But I still don't believe this is a good 
2-5 kHz is a more sensitive region for most people, and less easy to block.  
Sweeping through that range at a Beta wave like rate and moderately high 
amplitudes I find much more disorienting than a steady state noise of any 
type.  We have a natural ability to mask steady sounds, while that sweep 
pattern is a multiple trigger to disorientation and pain based on the 
pattern, and not just the high senstivity frequencies.  In a 2000 ft^3 room, 
a debilitating response can be generated with only 1/20th watt of audio.  
Are you familiar with how certain disco strobe flash rates can trigger 
psychotic or psycho-physical disabling responses in some people?  Swept audio 
at mildly but not damagingly painful frequncies and levels can be used for 
similar effect.  
While pain is usually something we'd want to avoid triggering in audio, 
knowing what triggers it can both be helpful in avoiding those patterns, or 
in realizing how quickly and strongly pain can be triggered in most people 
compared to pleasure reponses.  
TS> Pain is a more basal reaction than most other 
TS> human responses to stimuli.
 TK> You definitely should contact your local university about neurology.
I was having trouble finding the Marquis DeSade or some old Viet Cong 
Colonels in the local Yellow Pages.    
TS> Raw energy!  OTOH, something like phaco-
TS> emulsification is very focused
TS> sound used to remove cataracts from eyes without cutting.
 TK> What are cataracts ?
Deteriorated/clouded portions of the lens in animal eyes.  In humans they 
usually try to remove the natural lens, use temporary contacts or high plus 
limited field spectacles temporarily, and then imbed replacement lenses 
requiring a less severe correction thereafter.  (Sometimes confused with 
glaucoma, or abnormally high intraocular pressure best cured in mild cases by 
smoking marijuana, any fraudulent 'war on drugs' BS blocking such medical 
treatments aside....)  
TS> Are you familiar with the Crown 10 KW 3-phase 
TS> input power amps, used more
TS> for industrial vibration tables than audio?
 TK> Nope...what is the 3-phase deal ?
Most commercial equipment starts using 3 phase power around 5 KW or so.  3 
phase reduces line currents per leg, is more efficient for wiring at high 
power levels, and requires lower current rectifiers and less filter cap time 
constant due to the 180 or (more often) 360 Hz ripple rate.  
Powering linear solenoids vibrating military/aerospace equipment, cars, and 
such during testing benefits from large singular amps.  Speakers can better 
make do and optimize damping factor by a larger number of smaller amps more 
closely coupled to small numbers of drivers, allowing units that can function 
within 15 or so amps of single phase 120 VAC.  
Those Crown amps as I recall (without chekcing) have an output Z of 0.67 ohm. 
 
TS>  Could you picture a human attached to a table 
TS> driven by 12 of those (4
TS> corners by 3 axis directions)?
 TK> Yep...he will definitly be shooked up 
TS> What would the acoustic experience be like if such 
TS> an arrangement were
TS> used to reproduce audio by vibrating the listener 
TS> in the surrounding air,
TS> rather than the other way around?
 TK> I think he will be sick within a few minutes...you 
 TK> better spend some money on vomit-bags then..
Seriously, would that be the ultimate subwoofer, with regard to the headphone 
versus loudspeaker discussion above?  What would the directional quirks be 
like at high frequencies, and how would coloration artifacts vary from 
speaker reproduction in a fixed room to a non-moving human?  
I'd bet Air Force and NASA studies have shaken humans that way, though 
attempting to determine other limits and not study exactly those audiophile 
questions.  
TS>> If the above spec's could be met without using 
TS>> more than 150 KW of AC TS>
TS>> power, I'd qualify the system as having an 
TS>> extremely efficient design
TS>> if based on speaker cabinets.  Consumption of 
TS>> under a megawatt max would
TS>> place it in the realm of average small commercial systems.
 TK> Get real, terry...it's like decorating the walls by 
 TK> holding the paper and glue the wall onto it 
Wait a sec.  That response was to a different part of this thread, about 
cabinet and system efficency of transducers and resonance systems, and not 
related as suggested by subsequent editing of quotes to the vibration table 
topic.  
System efficiency is usually a topic of pro systems, and affects rigging 
points on colliseum roofs, number of 18 wheelers and roadies to be budgetted 
operating a tour, and whether the sound will require more or less generator 
power than the lighting at a remote outdoor show.  I was sort of trying to 
see if any consumer types here had any clue about the topic of absolute audio 
power and transfer efficiency, or realized that it had more to do with real 
audio performance than amp ratings.  
TS>> picture a more efficient way of producing that energy?  How about a TS>> 
pipe organ with about 40 HP of blowers, and a 
TS>> rank of pipes out to 64'
 TK> Correction: Largest pipe in the Sydney Opera House organ is 32'
Which would handle about the lowest frequencies thought of as musical audio.  
I was suggesting 64' pipes as capable of handling subaudible frequencies 
useful for psychoacoustics.  Most musicians wouldn't consider such things, 
though some of the Universal Studios FX types might.  
TS> What's the Sydney organ like?
 TK> The Opera House grand organ is the largest mechanical 
 TK> action organ in the world, it weights 37 tonnes, 15 
 TK> meter high, 13 meter wide and 8 meters deep. It has 
 TK> six departments: Pedal, Ruckpsitiv, Hauptwerk, 
 TK> Brustwerk and Kronwerk.
Mechanical action meaning solenoid remote driven stops, or electropneumatic 
valving, or what?  
15 M high sounds like it could just accomodate those 32' pipes without being 
bent, with a walk in sized air chest underneath.  Does it use a high volume, 
inches of water column pressure air chest regulator/plenum in the Austin 
style?  
How many ranks are over what sized air chest(s), or otherwise arranged?  
  What's the conversion from tonnes (weighs, not 
weights, BTW, at least in American English) to pounds or KG?  (Or US tons, at 
2000 lbs. = 1 ton)  
 TK> Designed and build by Ronald Sharp during 10 years. Finished in May 
79.
 TK> Piston recoring facilities: Complete pistonsettings 
 TK> recorded or reset in 12 settings....100 settings may 
 TK> be stored on 1 tape.
 TK> Organ key action can be recorded on tape or computer 
 TK> and relay as recorded.
 TK> Of course this can only be done by additional electric key action. 
 TK> The power supply of the 8000 CMOS IC's (8V) is derived 
 TK> from the 17V/400ADC powersupply for electric action. 
Amazing how archaic this sounds already, for such a relatively new organ....  
 TK> Wind supply: 9 extremely silent blowers housed in silencing boxes in the 
 TK> main case of the instrument, each of which is provided 
Any idea what separate and total horsepower, and whether the nine sum into a 
single plenum, or are used to power different sections with different 
pressures, flow rates, or to reduce intermodulation?  
 TK> with temperature sensing alarms and automatic BCF gas 
 TK> fire extinguishers.
Is that like Halon, which is perhaps the most effective for such uses, but 
already banned in many countries to reduce CFC output?  
 TK> Apart from the 5 manuals and the pedal system there 
 TK> are 2 CCTV monitors a telephone/intercom and a 
 TK> talkback mic. to P.A. system
Why should such things be needed?  Anyone at the keyboard has to play from 
experience and imagination of sounds in the future it'll be too late to 
change by the time he hears them.    
What's the distance/time delay back to the console, and relative hall, pipe, 
and console orientation?  What style hall is it acoustically and as to 
typical uses?  
Terry
--- Maximus 2.01wb
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