[Boatanchors] OT EV Aristocrat cabinet

[Richard Knoppow]

       Up until the 1950s speaker efficiency was very important because 
amplifiers were expensive.  The problem is that the overall efficiency 
of a speaker system depends on its size and the lowest frequency its 
supposed to reproduce.  Small direct radiators are just not efficient at 
low frequencies.  By improving the acoustical impedance match with a 
horn or bass-reflex the low end efficiency can be increased.  For years 
the standard speakers for motion picture theaters were two way horn 
systems with a low cut off of around 50 Hz.  In a typical neighborhood 
theater the amplifier would be on the order of ten watts.  It was enough 
considering the limited dynamic range of the sound tracks.  The 
Klipschorn was inspired by the standard theater speaker.  The idea was 
to provide similar bass response in a smaller package.  The main trick 
Klipsch used was to take advantage of corner placement to extend the 
effective mouth size of the horn.  Also, at the corner the reflections 
increase the effective acoustical impedance so that any speaker in a 
corner will have more bass.   A horn is the acoustical analog of a 
transformer. A Bass-Reflex enclosure is the analog of a L network 
impedance matching section in a transmission line.  The Acoustical 
Labrynth enclosure patented by Stromberg-Carlson, is the equivalent of a 
quarter wave impedance matching section and is the distributed constant 
equivalent of a Bass-Reflex.  In both cases the acoustical impedance of 
the enclosure is important if the bass is to be extended effectively.   
Small bass-reflex enclosures can be effective but there is an optimum 
size which is dependent on the speaker.  FWIW, I have a small 
bass-reflex box made by RCA for use as a projection room monitor in 
theaters.  I t has a Permo-Flux speaker in it.  Its about the same size 
as the Hallicrafters speaker and is fairly flat down to about 70 Hz but 
without the resonances typical of an open box.  I use this on an RCA 
AR-88 where it sounds fairly good.  Since my hearing is not so good its 
hard to evaluate it.   I also have in storage a pair of RCA c.1936 
Shearer horns. These are two way systems with folded horn for the low 
and driven by two 15" speakers.  This type of system was made by at 
least half a dozen companies and was the standard theater speaker from 
about 1936 until they began to be replaced with Altec and other speakers 
in the 1950s.  I've measured the response of these horns. They go down 
flat to about 50 hz but maintain enough coupling to radiate 40 hz 
reasonably well.  They are very convincing in a small room.  My speakers 
came from a movie studio and have higher quality treble drivers than RCA 
supplied for theaters.  The high horns measure out to about 13 khz.   
These things will play loud from the output of a pocket transistor radio.
      I am surprized you get any bass from the Aristocrat with the 
tweeter port left open.  It may make it into a sort of bass reflex but 
it certainly will not be optimum.  I can almost guarantee the speaker 
would sound better in a large closed box.
       WSM is the home of the Grand Ol Opry so one would expect them to 
have some consideration for sound quality.  It would be interesting to 
know what kind of speaker this is and how big you mean by big.  Speakers 
used for broadcast and recording monitoring were typically 15" cones in 
6 to 8 cubic foot boxes.  Not always too good.  Probably the most common 
was the Altec 604 series.  I have a 604C here in an awful enclosure 
called a RJ.   If I could still hear I would consider building a better 
box for it.
      I am not really awake and am maundering so enough for now.


On 3/15/2015 3:05 AM, Rob Atkinson wrote:
> I believe Paul Klipsch let EV use his designs.  Originally the
> Aristocrat was meant to be placed in room corners about a foot out
> from the wall.  The baffle was closed and the cabinet had an exit out
> the back and used the corner walls.  If you have the cabinet out in a
> room and close the baffle the sound isn't right.  I found that a small
> port in the baffle, originally intended for a horn tweeter, made the
> difference.  About a year and a half ago I spent a lot of time working
> with an Aristo cabinet and various speakers I had brought home from
> hamfests.  What I posted was what I figured out from that.
>
> What got me started was a visit to K4KYV in 2012.  Don has a huge old
> cabinet from WSM with a 15 inch speaker driven by a p.p. 6V6 amp
> getting audio from his 75A-4.  the sound and volume from that thing
> can be almost deafening and overwhelming if he turns it up.  I
> returned home convinced these hi-fi speakers I had were power wasting
> dogs.  That's what got me searching for old cabinets and old speakers.
> I read in ER once, that Ozona Bob swore by the Hallicrafters R42.
> That's a smaller radio speaker but bass reflex.
>
> Rob
> K5UJ
>
> On Sat, Mar 14, 2015 at 8:26 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:
>> Looking at those plans, the Aristocrat is more akin to the Klipsch Rebel,
>> which was much simpler and cheaper than the Klipschorn.

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL