[ARC5] Crystal Headphones

[Brooke Clarke]

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.

-- 
Have Fun,

Brooke Clarke
https://www.PRC68.com
https://www.end2partygovernment.com/2012Issues.html
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------
> My dad and I built a crystal set around the late 1940s. I think this is when he took a class in radio somewhere. It 
> was a breadboard on a piece of plywood. Coil wound on a toilet paper roll. Fixed crystal diode, have no idea what kind 
> and a pair of headphones. Long wire antenna from a second floor porch to the garage. Got all the local stations 
> (Detroit) very loudly.
>    There were many loudspeakers made based on phonograph horns and, in fact, some radio adaptors that fit in place of 
> the pick up and attached to the radio.
>    Typical radios of the time used the speaker or phones connected directly to the plate of the output tube. That's 
> right kids, full B+ running right over your head. Typical plate load impedance about 5K ohms. Some of these were 
> bi-pole magnetic but others, like the Baldwin speaker, were balanced armature.
>    I can imagine a sensitive driver on a horn being loud enough to listen to directly but I can't imagine it being 
> very loud.
>    There are many circuits for simple crystal receivers, the more complex ones attempts to improve the selectivity and 
> sensitivity by using multiple tuned circuits. Probably the place to look is at circuits for lifeboat and ship 
> emergency receivers. I passed up a loose coupler at a swap meet several years ago and have regretted ever since. No 
> problem here with a crystal set since I am maybe two miles from a site with three radio stations duplexed on the same 
> antennas, one a 50KW.
>    It would be interesting to know the actual source impedance of a crystal set.
>>
>