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kedwardsleisure View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Topic: dynacord xover
    Posted: 04 August 2020 at 11:30am
At first glance it seems like a pcb from an active speaker, but its actually passive. Probably the world's most complicated. 19 transistors, 17 capacitors, 21 diodes...Why, please?




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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 1:47pm
I see three sections of circuitry and three relays so I would guess....it's a three way driver protection system? But without any components that need replacing after a "protection event". 

Probably making a DC rail from the AC input to power the circuitry, then sensing AC RMS voltage after the passive filters - this involving the small transistors, and then using the larger transistors to operate the relays? I've seen similar circuits that use a MOSFET as the switching element. 

Mind you, I usually *see* them after the MOSFET has blown!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 2:07pm
What AC input, this is a passive network is it not?

Either way, i agree, this is complex in the extreme!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 2:56pm
well it didn't work, the mid is blown....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 3:09pm
the old 'hot melt glue inside a cab' gotcha

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BJtheDJ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BJtheDJ Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 4:21pm
Originally posted by csg csg wrote:

What AC input, this is a passive network is it not?

The AC input would be tapped from the speaker input, aka the output from the amplifier; hopefully no DC at all LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 4:46pm
Originally posted by csg csg wrote:

What AC input, this is a passive network is it not?

Either way, i agree, this is complex in the extreme!


Passive networks tend to take an AC input :) Think of it as stealing a little extra from the amp into a savings account (or something, I don't know).

Edit: Beaten!


Edited by odc04r - 04 August 2020 at 4:47pm
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Conanski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 6:47pm
Audio is an AC signal... newsflash for those that didn't know.

So yeah it is possible to power some small signal electronics from the output of a power amp, all takes is a sustained continuous average of 5-15v, enough to produce voltage rails for the circuit after rectification and filtering... which is no problem at all for most pro power amps. This electronics could be a crossover, EQ filtering, or provide protection.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 8:00pm
Im well aware that a loudspeaker signal is AC....naturally i was talking about the lack of an input from a PSU/mains 
“The fact is this is about identifying what we do best and finding more ways of doing less of it better”
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 9:08pm
Originally posted by Conanski Conanski wrote:

Audio is an AC signal... newsflash for those that didn't know.

So yeah it is possible to power some small signal electronics from the output of a power amp, all takes is a sustained continuous average of 5-15v, enough to produce voltage rails for the circuit after rectification and filtering... which is no problem at all for most pro power amps. This electronics could be a crossover, EQ filtering, or provide protection.  Or LEDs!!!  LOL LOL LOL



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madboffin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote madboffin Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 9:15pm
Looks like some quite clever level sensing and protection. The whole board uses high quality components, shame it fell to bits...


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2020 at 9:25pm
Originally posted by csg csg wrote:

i was talking about the lack of an input from a PSU/mains 
That's just it, any continuous AC signal can be a "PSU/Mains" of sorts.
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