Pristine Mirrorphonic system

[bowtie427ss]

Interesting!

I recognized the components and divided cell horn as Jensen, but on the horn driver there is a word stamped in the label there that ends with .......phonic.

Does it actually say "orthophonic"?

[Steve Schell]

Hey bowtie, I owe you an apology! I grabbed an old service handbook, like an ERPI "bible" but published later by Altec Service Corporation. As soon as I got into the Motiograph section I found some literature for the "Motiograph Model 'MK' Mirrophonic Sound Reproducer" projector sound head. There is no date on this particular page but surrounding service bulletins are dated from 1945 to 1954. So evidently Motiograph did use the Mirrophonic trade name, at least in the postwar era.

Looking closely at that picture of the driver, it does appear to say "Mirrophonic." As Mark Twain said, and expert is "...just some guy from out of town." Sorry, man.

[bowtie427ss]

No apologies necessary sir, just sharing my own observations. It's folks like yourself and some of the others on this board who have taught me to look for the most subtle details as those are often the most significant.:thankU:

From the ebay pics it's impossible for me to be sure, only that it ends in "phonic".

[Horn Savant]

: Motiograph Mirrophonic Field Coil Speaker Theatre Audio - eBay (item 170493084777 end time Jun-29-10 09:38:50 PDT)

MOTIOGRAPH was a cinema supply/service company in Chicago

That massive 7 x 4 multicell horn seems to be without WE precedent (maybe Dukane ? also Chicago).

I've seen a MOTIOGRAPH catalog (1940's) where they did actually supply true turnkey MIRROPHONIC systems (calling them Diphonic) using 594A drivers which they described as "justly famous" & dual W.E.1086 pre-war Amps--and strangely this was for sale for $30k (big price in today's dollars). Must have been post-antitrust as WE used to state that equip "remained the property of ERPI".

[slowmotion]

Hi all

I think that stuff is probably Mirrophonic in name only.
Nothing there even remotely connected to Bell Labs or WE.

Also IMHO the WE Mirrophonic has nothing more in common with the Shearer systems
other than it being a two-way system with a multicell horn on top.
While the Shearer used a folded horn for the bottom,
the WE Diphonic used a kind of straight horn/open baffle.

In fact I haven't been able to figure out why the baffle in the Diphonic is like it is.
Any theories on that would be welcome.

Cheers

Jan

[Horn Savant]

..Also IMHO the WE Mirrophonic has nothing more in common with the Shearer systems
other than it being a two-way system... I haven't been able to figure out why the baffle in the Diphonic is like it is.
Any theories..
Jan

They actually did use those Shearer type "W" bins (usually two units stacked)

As to why they did it ? My theory would be its folded nature made for compact
depth (a consideration given limited stage space in smaller theaters converted to sound)

[slowmotion]

They actually did use those Shearer type "W" bins (usually two units stacked)

As to why they did it ? My theory would be its folded nature made for compact
depth (a consideration given limited stage space in smaller theaters converted to sound)

Well, no, they didn't.
The Diphonic bass unit might look like a Shearer bin from the front,
but in reality it's completely different. It's a straight "horn"/baffle.

http://www.moviemice.com/we/speakerB...iagram-224.gif

cheers

[Horn Savant]

Well, no, they didn't.
The Diphonic bass unit might look like a Shearer bin from the front,
but in reality it's completely different. It's a straight "horn"/baffle.

http://www.moviemice.com/we/speakerB...iagram-224.gif

cheers

I think I see what you're saying now: the Shearer was a re-entrant design ?
Wheras the WE has continual unidirectional expansion.
I don't know what a Shearer was like internally (would need to see blueprint like that for WE).
I think early RCA had a re-entrant Shearer-style ?

[slowmotion]

We can read about the Shearer system here:

http://www.nutshellhifi.com/library/...er_Theater.pdf

And the RCA bin here :

http://www.oswaldsmillaudio.com/imag...ers%201937.pdf


As far as I am able to figure out the Shearer bass bin and the RCA bin is the same.
But I'm not sure about that. Maybe Steve can enlighten us?

But the Mirrophonic was very different.


cheers

[robertbartsch]

The pictures of the old Altec 802 and 288 HF drivers are interesting.

I have recently restored some 802s w/ GPA frams and these "old" drivers out-perform lots of other stuff I am comparing them against using a "A Vs. B" tests including 902s, 806s, 806s with jbl slot tweeters, etc.

I worked in S. Korea as a CPA for a few years in the 2002-2006 time frame. ...strange place... ...not my favorite either....