Beyond the Ariel

Re: four Pi loudspeaker response curve





salas said:
What is the 0 deg reference axis? Between woofer and horn rims, or on horn's center?

It's directly between midwoofer and tweeter.

I have the Smith/Larson measurement system and LMS. Keith Larson is working on adding code to his measurement system to combine several sweeps to form a polar plot. LMS offers this feature right now. One of these days real soon I'll drag the LMS system outdoors so I can publish polars. I use psuedo-anechoic measurements to see what the crossover is doing, but never for full range. I prefer to use outdoor measurements to get the full range, including bass.

gedlee said:
But 100 dB scale - come on!! That makes the "little" glitch at about 2.2 kHz a 6 dB hole! And nothing on this plot falls below 0 dB. Whats the lower 50 dB for anyways?

The chart settings were autoscaled by the Smith/Larson measurement system. On one hand, it helps to show the bass rolloff but on the other hand, you're right that increasing scale would show any imperfections better. I'll get another sweep one of these days soon and scale it differently, providing only 50dB range instead of 100dB.

I will remind you though that no smothing was applied, whatsoever. Just adding 1/6th octave smoothing would remove that glitch completely. That's why most people publish response curves that have been smoothed - They don't show small features like that.

It's easy to tell charts that have been smoothed - If you see a curve that doesn't have any features like that, it has been smoothed. Even if the DUT generated perfect amplitude response, you'd still see random spikes at each end of the curve where amplitude falls below the noise floor if the curves were unsmoothed. Absense of these kinds of features is evidence of smoothing.
 
Woohoo!!!

Just talked to Bill at Great Plains Audio at 405-789-0221. The 414, 416, and 515 midbass drivers are now all available with Alnico magnets. Not only that, the 288H is available with aluminum diaphragm, tangential suspension, the Hendrickson/Tangerine radial phase plug, and ... Alnico magnet. I'll be ordering a set this week. Call to get the latest price and availability quote.

Some of you may be wondering what all this Alnico madness is about. Well, for those of you who have auditioned various linestage, input, interstage, and output transformers, it sounds very much like a different transformer core - a nickel vs M6 type of difference.
 
The Alphahorn, Betahorn, and Gammahorn all look interesting. There are PDF measurements of a Titanium driver and a Phenolic driver. The elliptical horn shapes are intriguing to say the least.

Interesting stuffs.

Here is the text from the Gammahorn

"the standard bass system uses a 15 inch driver in an innovative reflex cabinet, combined with frontal horn loading."

I am not sure what is an "innovative reflex" cabinet. But if it is bass reflex, then we are back to the A5, A7 land.

Also,

"we are developing a modified version for a classic altec alnico driver right now"

I guess that is what Great Plains just cooked up.
 
Just thinking out loud here:

What is the possibility of a modern interpretation of JBL Paragon?

JBL Paragon is essentially a 3 way speaker, with a tweeter, a mid horn, and a bass horn, for each channel. By placing the tweeter and mid horn in front of the opening of the bass horn, Paragon supposely achieves a single point source. Maybe a RAAL and an Azurahorn in front of a giant bass horn.


Catalog:
http://www.lansingheritage.org/images/jbl/catalogs/1967/ranger.jpg

Color pictures:
http://cgi.ebay.com/JBL-Paragon-D44...ryZ50597QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Construction Plan:
http://www.paragondrawings.de/plans/index.html
 

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badman said:
Except that then you have time alignment issues unless you take some pretty dramatic measures to avoid them.

Agreed. Para eq will be used, and time delay may be required. I found a thread with actual users/owners talking about its pro and cons.

http://www.audioheritage.org/vbulletin/showthread.php?t=7528

I just think Lynn's new speaker should be pretty enough to be displayed in a museum.
 
Just called 405-789-0221 and ordered:

One pair GPA 288-16H compression drivers with low-power aluminum 16-ohm diaphragm, Tangerine phase plug, Alnico magnet, and no bug screens (why remove them if they can be manufactured without them?). US$450 each, in a short production run now.

One pair GPA 414-16 Alnico 12" midbass drivers with 16-ohm voice coils (I may buy another pair in the near future, and GPA will make them in runs as small as two). US$320 each, custom made to order.

The 515 is available with Alnico or ceramic magnets, for those that want to go the full "Voice of the Theater" route. Price a bit below US$500, the last time I checked.

They take credit cards over the phone, and ship all over the world. E-mail doesn't seem to be a very efficient way of communicating with them, I recommend phone calls instead. Oklahoma City is located in the Central Time Zone of the USA.

You will find out during the phone call (they seemed pretty busy when I called them) that there are a lot more goodies being made than the Web-page shows - I suspect they are doing a lot of OEM business, particularly to Europeans and Asians, where the classic Altec line is held in higher regard than here in the USA.

Be kind to the person on the phone - they are very very busy, so don't ask long, pointless subjectivist questions about which is better, XYZ or ABC. Do the research on the Great Plains Audio (Oklahoma City), Altec Lansing's (Unofficial) Webpage, Iconic Manufacturing Company (Seattle), the Altec User's Board, the Lansing Heritage Forum and decide exactly which version what you want before picking up the phone.

The vintage versions of the 288 that combine the Tangerine/Hendricksen phase plug with the Alnico magnet were only made a short while before the magnet was replaced with ceramic, and command very high prices - the single one I saw on Jammin' Jersey was $800, for example. Do a little shopping, and you'll find that GPA is priced very competitively - and they recharge old Alnico magnets and refurbish the original Altecs on a regular basis.
 
I want to clarify my comments that I felt that speakers using 15" woofers mated to a 1" compression drivers and horn combinations sounded disconnected and had a smeared upper midrange and lower treble region when crossed over above 1kHz.

That was in no way was meant as a blank statement disqualifying all 15" with 1" CD horn combinations as being deficient because they are crossed over above 1kHz.

There are to many variables to be able to consider that as a fact.

I do not have enough experience to make such a statement.

I too have heard the GedLee Suma, and felt the high frequencies blended seamlessly with the 15" woofer. But, I think they are crossed below 1kHz.

I have heard the latest version of the Four-Pi two-way designed by Wayne Parham of Pi speakers at LSAF. I feel this two-way speaker with a 15" woofer and 1" CD horn is a very good sounding speaker that blends extremely well crossed over above 1kHz.

We live and we learn.

Sorry if my previous statement was confsing or offended anyone.

Norris
 
Lynn Olson said:
Little bit of Photoshop ...





For 99% of Photoshopping you don't have to pay Adobe.

colour, contrast, brightness correction
cropping
size alignment
format conversion
and a lot more if you are more advanced

All provided by the not so well known, fast, small and FREE Irfanview
http://www.irfanview.de/

:D



--------------



Lynn to improve colour noise, force your camera to low ISO settings and use a fast lens or a tripod. Its hard to get rid of by "postproduction".
;)


---------------------


Have you auditioned any of your catches (midwoofers) yet? Any first impressions?




Greetings
Michael
 
caninus80 said:
My friend has pentax k10d and he recommend it to me...


Uuupps, sorry,

artefacts were from compression (at heavily cranked up contrast) not noise from the camera sensor at low light condition.
No need for a tripod here - just correct exposure by one stop or so or force the flash to get slightly more light (second take was perfect right away, no?).


Caninus, also no real need for bulky SLR (most of the time :D ) – there are several pocket cameras out there that perform amazingly well – some with Leica or Zeiss lenses some with genuine lenses.

Best review pages I have found so far:

http://www.dcresource.com/reviews/cameraList.php
http://www.dcviews.com/cameras.htm
http://www.dpreview.com/reviews/specs.asp

Go for the pictures more than for the tec specs.. Download / examine "all day subjects" at full resolution to compare. This is what you want from your new camera in the end

Same as in audio – you just want to have close to life like experience – or at least something that reminds you to those experiences without too big obstacles.
;)

End OT...


Greetings
Michael
 
Hi Caninus80!

One experiment you might want to try in the future is placing the diaphragm of the 399 a few inches behind the dustcap of the midbass driver - I'd start with 4~6 inches based on my fooling around with time-aligning a Klipsch Chorus, which combines a 15" midbass with a mid and HF horn. (See results here.) It was the relative simplicity of the brief experiments with the Klipsch that gave me the confidence to even try horns in the first place.

The horns in the Klipsch Chorus are pretty low-end PA drivers, so there's every reason to expect decent professional-grade drivers (which the GPA399 certainly is) to give a better result. It was very common during the Fifties for hifi enthusiasts to upgrade their Klipschorns with Altec drivers and horns - the fact that Paul Klipsch himself routinely swapped one PA driver for another during the production run of the Klipschorn shows he had no real attachment to this or that CD+horn combination.

P.S. About cameras - just about impossible to go wrong with Canon, Nikon, Pentax, or Sony DSL's. They are all really, really good, and can yield professional results in skilled hands. But they have a very long learning curve, which I found out after buying my Pentax K10D. My first SLR was a Pentax Spotmatic that I bought new in 1964, my second was a Nikon FE2 that I bought new in 1984, I've developed my own Tri-X and printed my own prints on DuPont and Ilford papers during the early Seventies, and I've used full Photoshop on a high-end Macintosh since 1999.

With this background, I thought I'd master the K10D in a matter of days. Wrong. Using digital to its full quality takes a different set of skills than film. In terms of tonal qualities, it's a bit like shooting very fast Kodachrome that is much easier to color-balance. It took me six months to finally graduate to shooting everything in RAW mode, and the skills to master Photoshop so that I could take advantage of the extra quality and flexibility. The DSLR's above entry-level take a surprising amount of time to master - they are very different animals than point-n-shoot cameras.

I will mention that each brand of camera seems to have a different color palette from each other, and it take a fair amount of time in Photoshop to make the shots have a similar color "character". I like the rendition of Canon and Pentax best, and am less fond of the Nikon and Sony look. Yes, you can make one camera look like another - but it's rather tedious and pointless, and saves time if you like the inherent set of choices that the camera vendor built into the camera as color-processing defaults.
 
agent.5 said:
Just thinking out loud here:

What is the possibility of a modern interpretation of JBL Paragon?

JBL Paragon is essentially a 3 way speaker, with a tweeter, a mid horn, and a bass horn, for each channel. By placing the tweeter and mid horn in front of the opening of the bass horn, Paragon supposely achieves a single point source. Maybe a RAAL and an Azurahorn in front of a giant bass horn.

Well, I hate to throw cold water on this and antagonize the JBL fans, but the Ranger-Paragon was one of the biggest disappointments I've ever had in audio. They are absolutely stunning-looking loudspeakers "in person", far more beautiful than the pictures suggest. Most definitely Museum of Modern Art-worthy - the only word I can use is "icon", like an iPod or iPhone.

Unfortunately the magic ends when the music starts. When I heard them back in 1963 or thereabouts, they were the shrillest, honkiest, and harshest-sounding speakers I had ever heard. Granted, I was used to the sound of Quad ESL57's, Tannoys, Celestions, and AR-2's, and was a classical music fan long before I got into the Beatles, but the disparity between the beautiful looks and ugly sound just floored me. By comparison, an Altec 604 Duplex is a model of refinement.

To some extent that experience soured me on JBL - I felt it wasn't ethical for a big, famous company to make a speaker that was "all show and no go". A "show" car can at least be driven slowly and impress the neighbors. But a harsh, shrill loudspeaker will always sound that way. A few years later, the L100 and L200 only deepened the impression that the shrillness and harshness was no accident, but a deliberate corporate "sound" that was there for marketing reasons.

Imaging? None. The theory of the curved panel doesn't work - it just creates a zillion reflections, a very hollow-sounding midrange, and scrambles the stereo even more. The Ranger-Paragon is an object example in the sound of early reflections combined with large, resonant structures that are close to the drivers.

Well, now that's I've knocked one of the most iconic (so to speak) speakers ever made, I'm not expecting any love letters from JBL fans. But I heard what I heard, way back then, and it really sounded pretty awful. In terms of a huge gulf between ambitious advertising claims and the acoustic results, the Ranger-Paragon is right up there with the Karlson.
 
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Lynn Olson said:
It was very common during the Fifties for hifi enthusiasts to upgrade their Klipschorns with Altec drivers and horns - the fact that Paul Klipsch himself routinely swapped one PA driver for another during the production run of the Klipschorn shows he had no real attachment to this or that CD+horn combination.

Like the Mercury people monitoring on Altecs producing enduring classical masterpieces, the avid listeners could just enjoy them on anything dynamic that did not give their valve amps a hard time.
Back then, music mattered and enthusiasm was strong. Maybe they knew nil of what is an impulse response but they responded to music on an impulse.