[OT] Adding volume control to electronic device
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 ?
Because they were all parallel loads, if the main cable was shorted
by someone driving away without removing the speaker, it would take
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. 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
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