Crystal Radio
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"Homebrew" Balanced Armature Speaker

The Model 711-16
nick named "The Gulp"

Balanced Armature
Sound Powered
Controlled - Reluctance Transducer




Does it work? Yes it does. On both Crystal sets and Tube sets

Does it have high volume?   Well, no, not on a crystal set, but a tube set will run it OK.

Will it replace a headset on a crystal radio?  Not hardly.

If you turn everything in the house off (including the Grandfather clock) and all the windows are closed and there is no one in the house but me I can hear something. No not really!!! I can hear 4 of my strongest station on my best crystal set for locals. Not real loud, but OK.

It works quite well on a transistor radio. A bit distorted on the lows, but OK. Also it has an annoying "rattling" sound when on a tube radio. If you place your finger just so lightly on the end of the armature, it stops.


This unit was made for a couple of reasons:

I wanted to understand the engineering a little more on Balanced Armature speakers and elements. I have learned a lot on  principals and adjustments just trying to get it to work.

2  I plan to "play" with it now and see if there are things that can be done to improve it. It is much easier to play with than say a element from a decktalker. It is very modular and adjustable making it easier to change out things such as magnets etc.

I wanted to see if I could do it.

The 711-16 actually works better as a "mic" unit than a speaker if hooked up to a "ear" unit from a Sound Powered element.
I wonder what two of them hooked together would do???  Hey, maybe a headset!!  No way I'm building another one!!!

Crystal Radio
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