How Does 'PASCALITE' Diaphragm Sound ?

[Todd W. White]

Hi Bob,

You wrote -

"I will agree that the MantaRay horns do have superior directivity control over the Bi-Radial but not by much -- "

Well, not quite. The MR's have superior control in the horizontal plane, and a huge amount of driectivity control over the the BR's in the vertical. In fact, the BR's are SO sloppy in the vertical that they can't be aimed down in a cluster of a livesound reinforcement system anywhere NEAR to the front rows, or the vertical spillover will destroy system gain.

You also wrote -

"...in fact, the difference in DI, power response, etc. between both CD horns and their predecessors (radial, multicell, exponential, etc.) easily swamps any significant difference between the two CD designs. To sum, both designs are excellent and are a vast improvement over radials, multicells and other horns that have rising DI vs. frequency."

Sorry - again I don't totally agree: the lobing that MC's are supposedly so tainted with is only really hearable in large installations if you play pink noise through them and walk around - not really a true-to-life condition.

By the way, ALL CD horns have a problem with apparent-apex, something the MC's do NOT have!

The guys at WE really knew what they were doing..

Then you wrote:

"However, precision coverage was only one aspect of sound system design; space efficiency and even response near crossover is also very important as well."

True, but the real push in the new designs was to get rid of the supposed lobing of the MC's - something that really wasn't that big of a problem.

You then wote:

"In the AES paper "The Manta-Ray Horn" (Henricksen, Ureda. J. Audio Eng Soc., vol 26, p. 632, 1978 Sept.), Henricksen and Ureda state that the horn is 'designed with low-frequency response as a secondary consideration'. Unfortunately, this would be an important consideration for system designers.

For the same physical volume that each Manta-Ray consumed, the Bi-Radials provided a much lower cutoff frequency giving the sound system designer far more latitude in selecting crossover frequency (and ensuring even response below crossover) and controlling coverage in the difficult-to-control lower mid-band, facilitating an easier transition from the cone to horn/compression drivers in both amplitude response and directivity."

Perhaps, but I've used MR's with variable XO freq's with great success.

Just remember - in the era in which they were designed, there were only two standard xo frequencies: 500 & 800 Hz. For those, they do VERY well (the large ones, I mean).

I've never agreed with Keele's assertion that the sharp changes in the MR geometry cause diffraction disturbances in the response. Most of that was JBL's double-talk for getting around the Altec patents, IMHO. And, yes, I know that Henrickson wrote that, but I still didn't find it to be the case in real life installations...

[Murray Keidge]

Hello,
The discussion is very interesting concerning the different types of horns & diaphragms available.

In my company we use nearly every type of horn ever made by Altec Lansing. They all have their good and bad points and in most cases, either fixed installation or touring sound, the problems heard are not normally to do with the horns used, but how they are used.

I have seen and heard, or not heard, in some instances, horns being correctly used and not being used correctly. In Australia, like most other countries, there are those that know how to correctly use audio equipment and those that do not.

My personal favourite is the good old multicell horn. Even with their faults, they seem to outperform nearly every other type of horn available.

Much of our companies work is large outdoor concerts. These range from festivals to orchestral performances and opera. The ability of the multicell to deliver sound to the audience over a large area and to not be severly affected by wind is amazing. There is no other horn, including the Altec Lansing Mantaray's, that can achieve this result in this outdoor setting.

Our system has been put up beside many other "contemporay" competitors and has performed extremely well in terms of audio quality & coverage.

For those of you interested, you could have a look at www.cpcproductions.com and read some reviews from some of our concerts and also have a look at the Altec Lansing section to see pictures of some of our Altec Lansing systems and how we use all types of Altec Lansing product.

I do appreciate all of the theory that has gone into the development of horns. I firmly believe, and have proven in practice, that if you know how to work with each piece of equipment and use it in it's correct place it works.

In the live audio application the major downfall in achieving a great result is not normally the equipment used but the engineer behind the console and the performer behind the microphone.

There have been just as many faulty audio engineers and performers, as there has been faulty or bad equipemnt, responsible for the "bad" sound delivered to us all over the years.

Murray.

[thevott]

Hi all,
It is my opinion, and take this with a grain of salt if you prefer, that most tour sound systems (and I mean the vast majority) are poorly executed. This includes physical alignments/phase anomalies, equalization, overdriving, and just plain lack of know how by the sound directors. Some of this is due to an abandonment of common sense old-school thinking which includes the use of horns and horn cluster application. The over use of direct radiators, time-alignment, and full-range portable enclosures often turns indoor venues into big nasty sounding echo chambers. Oh, don't forget the industry practice of spiking harsh frequencies on the warm-up groups to make the main act sound better.

Also, though constant directivity horns do have advantages over multicell horns---and are probably less expensive to manufacture---I believe that multicells have excellent sonic virtues that simply cannot be overlooked. Though often deemed obsolete within the industry, their use---IMHO---can significantly improve the 'state of the art' hit and miss tour systems that are currently in use. But I'm a biased Altec freek.

[Mirrophonic Sound System]

The critical question is: Which horn has the HIghest FIdelity ?

In other words what horn is The Evil Empire [EE] using in their 'Ultimate HI FI Speaker', the K2 ?

They say it's a "Bi Radial" but, excuse me, it looks just like their old "radial" horns !

That is to say: If their Bi-Radial Constant Directivity is the last word
in horn technology, then why doesn't the EE have the guts to
put it in their 'ultimate fidelity' speaker ?

Why are they using an MR horn that has a CONSTANT exponential expansion without
the diffraction splatter design in their "horn to replace all other horns"?

Why is it almost identical to their old 4390 - a proven design that is essentially
similar to other classics like the Altec 511 and the TAD TH-4001 for that matter ?

Have you also noticed that they have eliminated the "Bi-Radial Constant Directivity"
horn from their Studio Monitors ! (seems it has gone the way of the "Acoustic Lens"
when it comes to critical High Fidelity applications).

[joyspring]

Hi Todd,

You wrote:
"Well, not quite. The MR's have superior control in the horizontal plane, and a huge amount of driectivity control over the the BR's in the vertical. In fact, the BR's are SO sloppy in the vertical that they can't be aimed down in a cluster of a livesound reinforcement system anywhere NEAR to the front rows, or the vertical spillover will destroy system gain."

There was no dispute regarding the fact that the Manta-Ray horns do have better directivity control, particularly at frequency extremes (near cutoff and above 10kHz). However, I will stand by the assertion that BOTH the Manta-Ray and BiRadials have much better directivity control than the traditional radials and multicells; that's been proven objectively.

"Sorry - again I don't totally agree: the lobing that MC's are supposedly so tainted with is only really hearable in large installations if you play pink noise through them and walk around - not really a true-to-life condition."

Actually, the lobing becomes apparent in small, studio settings and manifests itself as perceived changes in imaging when moving laterally (and vertically) between the left/right loudspeakers. I've heard this on a pair of A5s in a recording studio that was still using them as studio playbacks in the early 1980s. Please note that the changes were subtle and affected imaging rather than overall timbre.

Nevertheless, this is why I've never considered multicells high-fidelity by any means though they are appropriate for high-intelligibility sound reinforcement where they excelled.

"By the way, ALL CD horns have a problem with apparent-apex, something the MC's do NOT have!"

Only the Manta-Rays and Bi-Radials (and other horns that have separate horizontal/vertical apices) suffer from problems with apparent apex; Keele's first CD horn (commercially produced by Electro-Voice) did not as both horizontal and vertical apices coincided. Also, the JBL 2344A (Bi-Radial 100x100, 1" exit, 800hz cutoff) has apices that are very close and has very little wavefront distortion from apparent apex problems; it is one of the best-sounding horns IMHO.

(Regarding space efficiency and even response near cutoff)
"True, but the real push in the new designs was to get rid of the supposed lobing of the MC's - something that really wasn't that big of a problem."

From recollection, the literature and trends indicate that even power response and better, more accurate coverage were the over-arching goals of the push towards CD horns; overcoming the `lobing' of the multicells was an ancillary benefit of achieving even power response.

There were other issues with multicells, particularly midrange DI anomalies -- I believe that many attributed this to diffraction effects from the convergence of cells at the horn mouth which does seem plausible considering its construction.

"Just remember - in the era in which they were designed, there were only two standard xo frequencies: 500 & 800 Hz. For those, they do VERY well (the large ones, I mean)."

Point well taken as it is indeed unfair to consider the merits or disadvantages out-of-context.

"I've never agreed with Keele's assertion that the sharp changes in the MR geometry cause diffraction disturbances in the response. Most of that was JBL's double-talk for getting around the Altec patents, IMHO. And, yes, I know that Henrickson wrote that, but I still didn't find it to be the case in real life installations..."

I'll have to defer to you on your real-life installed sound experience as my experience is relegated to the recording/mastering environment.

BobR

[joyspring]

VOTT:

I only agree somewhat that most tour sound systems are poorly executed; the majors (Stanal, Audio Analysts, etc.) do an excellent job IMHO.

Some of your gripes are warranted, particularly those regarding sound directors and many live sound engineers and sound reinforcement staff -- personally, I note that many do not have much quantitative analytical skills, knowledge of physics/acoustics/electronics, or music for that matter... they'd fit right in with many audiophiles ;-)

" Also, though constant directivity horns do have advantages over multicell horns---and are probably less expensive to manufacture---I believe that multicells have excellent sonic virtues that simply cannot be overlooked."

Manufacturing cost is indeed a big consideration as individually cut and hand-soldered horns are a labor-intensive product. Rest assured that CD horns do cost less to manufacture than multicell horns.

Sonic virtues are subjective, though if they did indeed sound *appreciably* better than CD horns, you can bet that the *top* tour sound companies (and top theatres for that matter) would still be demanding and using them, for competetive advantage of course.

"Though often deemed obsolete within the industry, their use---IMHO---can significantly improve the 'state of the art' hit and miss tour systems that are currently in use. But I'm a biased Altec freek."

If anyone on this forum hasn't noticed already, the trend in both sound reinforcement and control room monitoring over the past decade has been waveguides, and for many good reasons...

Waveguides may be optimized for directional control rather than loading and do not have to act (quite so much) as acoustical transformers.

Newer drivers have high power handling capability, requiring less compression loading and horn loading as well, mitigating traditional sources of distortion.

Finally, for better or for worse (for better IMHO), cone midrange drivers, some compression and waveguide loaded (a la Turbosound, Community, EAW, etc.) have raised compression driver crossover frequencies and allow proper transition between LF and HF drivers DI-wise.

BobR

[joyspring]

Mirrophonic,

Which horn has the Highest Fidelity?

I can assure you that if it were multicells, they'd be ubiquitous in every recording and particularly mastering suite.

So which horn sounds best? None, as will be described somewhere below...

"In other words what horn is The Evil Empire [EE] using in their 'Ultimate HI FI Speaker', the K2?"

"That is to say: If their Bi-Radial Constant Directivity is the last word in horn technology, then why doesn't the EE have the guts to put it in their 'ultimate fidelity' speaker ?"

Well, they state that these horns are Bi-Radials in their sales literature. Suppose that an engineering drawing and polar plots would bear this out though a convergent horizontal/vertical apex could still qualify as `Bi-Radial' if the horizontal and vertical expansions do indeed conform to the y=a+bx+cx^n specified by Keele.

"Why are they using an MR horn that has a CONSTANT exponential expansion without
the diffraction splatter design in their "horn to replace all other horns"?"

How can you tell that the horn has a constant expansion without a scaled drawing?

`Horn to replace all other horns?' You must be referring to the 2397, which was a nice horn though not without its idiosyncracies...

"Why is it almost identical to their old 4390 - a proven design that is essentially
similar to other classics like the Altec 511 and the TAD TH-4001 for that matter?"

Again, without a scaled drawing, how can you make any such assumption?

"Have you also noticed that they have eliminated the "Bi-Radial Constant Directivity"
horn from their Studio Monitors ! (seems it has gone the way of the "Acoustic Lens"
when it comes to critical High Fidelity applications)."

Yes, I have noticed that BiRadials are no longer in their studio monitors as they've been replaced by waveguides! The JBL 4400 and LSR-series both utilize waveguides.

In fact, this is an industry-wide trend that is focused in reducing distortion, which is a good thing IMHO.

And speaking of noticing things, have you noticed that apart from the Iconic and earliest 604s (the -C,-D,-E,-G are not true multicells) that multicells have never appeared in high-end control room monitors or mastering suites?

BobR

[Mirrophonic Sound System]

Bob R,
Yes the horn I was refering to was the 2397 ( I have a whole slew of them)

The cross section of the K2 midrange (MR) horn shows
a continuous contour making it look
more like a good old radial type . Perhaps A BiRadial CD type would would
have to be too large to load down to the desired 800hz crossover. Anyhow
they have a supertweeter to help overcome HF narrowing
and it is, after all, a sweet-spot Hi Fi speaker.

Yes, it looks like compression drivers/horns are out as far as studio monitors go !
The tradition lasted over 40 years - paying homage to the precedent set by WE
in professional sound !

I agree that the "multicell" in the 604s is a joke as the cells would be ultrasonic
- never mind that the 604 is dying badly at 15khz & beyond !

I have original brochures for the UREI 811,813,815 and the 809 and JBL 4430,4435 monitors
I also have an original "subwoofer" for the (pre JBL?) UREI that has the square magnet (& UREI sticker)
Maybe you might be interested since your avatar is UREI ?

[joyspring]

Mirrophonic,

The 2397 has a very interesting polar response with even horizontal dispersion and a subjectively smooth sound. It became popular for control room monitors in the 1980s, especially as mixing desks became significantly wider.

It is difficult to discern what the rate of expansion is in the K2 horn; it may be a Bi-Radial with very small expansion polynomial coefficients. It's important to recall that the Bi-Radial horn has no distinct break points as the E-V and Altec Manta-Rays do.

Also, I doubt JBL would advertise a plain radial horn as a Bi-Radial. No matter how much the Altec advocates on this forum may malign JBL, they are still a relatively honest, engineering and research focused company and are truly a pro audio leader. They are now what Altec would be today had it not been for LTV's mismanagement that allowed JBL to assume its leadership role.

And nobody forgets the contribution of W.E. The principle designs remained relatively unchanged since the 1920s; however, technology does move on. At least we still pay homage to the early innovators by continuing to use a diaphragm attached to a coil of wire in a magnetic field to produce acoustic output from electrical input ;-)

"I agree that the "multicell" in the 604s is a joke as the cells would be ultrasonic
- never mind that the 604 is dying badly at 15khz & beyond !"

UREI improved upon the 604 by adding a nice radial horn, and then Altec finally attached a Manta-Ray in tandem with the Tangerine phasing plug to the 604-8H and above finally giving the 604 true high-fidelity HF response. However, this still did not address the difference in DI between the LF and HF sections owing to the relatively high crossover frequency imposed by the maximum horn size that may be fitted to a 15" coaxial driver!

Eventually, even the venerable UREIs were surpassed and fell out of favor with most except for old relics like myself ;-)

"I have original brochures for the UREI 811,813,815 and the 809 and JBL 4430,4435 monitors"

Yes, definitely interested! You managed to mention all my favorite control room monitors in a single sentence!

"I also have an original "subwoofer" for the (pre JBL?) UREI that has the square magnet (& UREI sticker)"

Definitely pre-JBL though post-Alnico, fitted to the 800 A- or B-series monitors. That particular driver is OEM Eminence 800W or 802W used either in the 813A/B (coax + one LF driver) or the 815A/B (coax + two LF drivers) respectively.

It's actually a nice driver despite its stamped frame. Not really a low frequency thumper (low XMax, high compliance, very low Q) but it would make a nice, moderately-powered and impressive-looking subwoofer nonetheless.

BobR

[Mirrophonic Sound System]

Bob,
If you send me your postal address, I can send you the UREI flyers.
They are marked but the price is right - free .