[ARC5] Crystal Headphones

[Richard Knoppow]

    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://www.prc68.com/I/HomeTheater.shtml#VOT
> 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