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geoff geoff is offline
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Default [OT] Adding volume control to electronic device

On 14/01/2021 2:39 pm, gray_wolf wrote:
On 13/01/2021 5:43 pm, geoff wrote:
On 14/01/2021 4:52 am, Scott Dorsey wrote:
gray_wolfÂ* wrote:

Remember the old drive in movie theater speakers with the volume
control?=

Those were 70V system.Â* 70V constant power going down the cable, each
tap
has a step-down transformer, then an L-pad (not a simple pot but a three
element pad so the transformer always sees an 8 ohm load) and a crappy
speaker.


Not switched tapped transformers ?

Â*Because they were all parallel loads, if the main cable was shorted
Â* by someone driving away without removing the speaker, it would take
Â* all of them down.

A bit like any singel speaker cable system in that regard !

geoff


I ran the snack bar at the local drive-in when I was a kid. I don't
recall any real
speaker loss.Â* I heard that driving off with the window rolled up and
speaker inside
would break the glass. I remember the tube power amp ran four 807s



The cable wasn't shorted then.

geoff