[ARC5] Crystal Headphones

[Fuqua, Bill L]

     I worked for EDCO before taking a job at University of Kentucky. We designed and built Big Bertha, as it was called for

Rupp Arena here in Lexington. It was the largest single source speaker system east of the Mississippi River at the time. It was made of all Altec Lancing speakers and very heavy.

    73

    Bill wa4lav


________________________________
From: Richard Knoppow <1oldlens1 at ix.netcom.com>
Sent: Thursday, September 20, 2018 2:32 AM
To: Brooke Clarke; Fuqua, Bill L; ARC5 at mailman.qth.net
Subject: Re: [ARC5] Crystal Headphones

    The A7 (small VOT) was a good sounding system. I had for
years a set of RCA c.1936 theater speakers with M-G-M spec high
end drivers. The M-G-M spec drivers were made by Lansing and had
aluminum diaphragms. Mine measured out to 15 Khz on a home made
impedance tube. Standard RCA speakers used Bakelized linen and
were pretty much gone at 6Khz. OTOH, they were unbreakable.

  These were of the type called Shearer horns. I had to sell them
recently but can't hear any more anyway. I did not have problems
with noise from them but I was able to hear amplifier noise from
many high efficiency speakers.
    All these old theater speakers were designed at a time when
amplifier power was expensive. The A7 was intended to service a
500 seat theater with about ten watts of power. It used a
different driver than the large VOT systems meant to have better
high end but could not take the mid range power of the 288.
     I never tried connecting a crystal set to one of these
speakers but the RCA horns would play quite happily from a pocket
radio. Don't remember the brand of amplifiers, I think they were
Citations, maybe also Scott. When I had good hearing I found that
McIntosh amps were by far the best. Now everything sounds like
its coming through a kazoo so I am hors de combat as far as audio
goes.

On 9/19/2018 4:23 PM, Brooke Clarke wrote:
> Hi Richard:
>
> I said it was room filling.  That's to say I could hear it from
> across the room.  No way was it loud.
>
> PS.  My first Hi-Fi system used Voice of the Theater
> loudspeakers, but when the music was quiet there was noise.  The
> problem was that the noise output of the H.H. Scott amplifier was
> specified as so many dB below full output and that translated to
> about 20 millivolts which the VOT speakers could easily turn into
> sound.  The solution was to replace the Scott map with McIntosh.
> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.prc68.com%2FI%2FHomeTheater.shtml%23VOT&amp;data=02%7C01%7Cwlfuqu00%40uky.edu%7C3fe9c16ddf9e4c52234508d61ec2e1e5%7C2b30530b69b64457b818481cb53d42ae%7C0%7C0%7C636730219691652079&amp;sdata=zaowGI0lAM%2Feu76QSvZoTdGvcgiHaB49NIOujKOdIgI%3D&amp;reserved=0
> The point is that the VOT speakers were extremely efficient. I
> should have tried them on a crystal radio.
>

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