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Which "Theater type loudspeaker" did PWK test to compare to La Scala?

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Does anyone know which "theater type speaker" Paul Klipsch measured for his early La Scala paper (he did not mention its name, but just called it a popular "theater type speaker").  Was it the Altec A7?  Or perhaps the JBL C55 with 154 and 375 with horn lens installed? It seems to me that the bigger ones would be just too big to be rivals of the La Scala in a home.  The La Scala did better, particularly in the frequencies above 10K.

 

Does anyone have that article they can post?  PWK did at least two articles on the La Scala.  In one he presented La Scala v. a "theater type speaker," and in the other he surperimposed graphs of the La Scala v.s. the Klipschorn in the bass, since that would be what everybody would be asking about.

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I know of only one paper by PWK regarding the LS. I posted it long ago.  It does report on a theater speaker and the K-Horn.

 

Two papers? If anyone out there has a second I'd like to see it.

 

 

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I can't guarantee whether this is the case, or not, but the only theater speaker around the plant was the old folded horn woofer (currently in the museum at Hope), but it was acquired right before they tore down the old Hope movie theater, which was well over a decade AFTER the LaScala prototype was born.  BUT, PWK had sent some of the engineers out to the old Hope theater PRIOR to the aquisition of that speaker to "have a look at" the speaker a few years BEFORE the theater was torn down when the Klipsch MWM component of the MCM1900 system was in development.  PWK may very well have used measurements from that same theater speaker by going out to the theater to get those measurements, since there was no anechoic chamber at the plant until well after the LaScala went into regular production. That horn woofer is an RCA unit, if I remember correctly. 

 

The reason I bring this up is that I was working at Klipsch from 1976-1983, and I never saw anything around the plant/offices/lab that looked like a theater speaker, except for a few VERY OLD museum pieces, until that unit from the theater was purchased.  And the old theater was actually still in business until not very long before that...it would have been a "no-brainer" to just go to the theater to do comparative testing when the LaScala was in its R&D stages.

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Thanks to both of you!

 

The article (1965 -- see the link in Gil's post), in discussing the comparison states that both speakers were tested "under the same conditions ... in the corner of a listening studio (not an anechoic chamber) ... input in each case was 0.25 watt, microphone distance was 4.0 feet."  It also mentions that the theater speaker had "several years recognition," and that it was, "a contemporary theater loudspeaker."    In 1965, the Altec theater speakers (most of which were far bigger than the A7) would be "contemporary."  I believe they started installing them in about 1953 (1952 for Cinerama), at the dawn of the magnetic release print era, when Fox was convincing people to install 4 channel magnetic sound for CinemaScope, and, at first, sharing the cost.  By 1965, most theaters had Altecs or JBLs, with Altecs outnumbering the JBLs, I think, and A7s were in many audio stores, and in many studios and universities.  

 

Gil, I may be wrong about a second article; I may be thinking about patent information I saw. 

 

Does anyone know when the Avedon improvement ("Avedon sonophase") began to be used in the T35 / K77.   Had it happened by 1965?  I believe PWK mentioned that the Avedon made the T35 better in some way, perhaps reducing a peak near 8K (???).

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See a section I started recently.  I'm not aware of PWK mentioning a peak.  In the Edgar interview he mentioned extended range. 

 

OTOH there is a Dope from Hope where the K-55 mid is shown as having improved high end response when the two-piece phase plug was added.  There seems to be some debate on whether all K-55's have a peak at about 7 kHz.  The DfH graph shows it in the "before" (push-button terminals) and "after" (solder terminals), though in the latter it has moved up in freq.  The Vacuum Tube Valley article describes a tank filter designed by Max Potter which eliminates the peak which is described as making the horn sound "shouty". 

 

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