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D1080 MkII 08 actives - under the hood

Posted 14th December 2010 at 11:46 AM by abraxalito
Updated 5th March 2012 at 02:55 AM by abraxalito

I've been spending my free time these past couple of days reverse engineering these speakers, as a prelude to devising the mods. The first stage in doing that is to photograph the PCBs both sides and have both images up on the screen at once, the underside is flipped horizontally so its as though I'm looking through the board. I then annotate the components by hand with the mouse drawing tool. Sometimes I'll write the values in this way too, other times just paste text for the value next to the component. Most of the time though I'm too lazy to add any annotation.

Here's the result for the volume/tone control PCB - one of two PCBs in the design. There are two quad opamps, TL084s - they're marked up in magenta. Interestingly there's no tone control circuitry as such, the bass and treble controls just act as volume to the woofer and tweeter respectively! I've never seen tone controls implemented in this way before...
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  1. Old Comment
    There's [I]nothing[/I] keeping the treble out of the woofer or the bass out of the tweeter?

    When I first read what you'd written I thought 'Hmm. Interesting. Sounds like the kind of crap I'd try,' but that's a bit extreme even for me...

    Can you put a swept tone into them and verify that?

    w
    permalink
    Posted 15th December 2010 at 01:32 AM by wakibaki wakibaki is offline
  2. Old Comment
    Quote:
    Originally Posted by wakibaki View Comment
    There's nothing keeping the treble out of the woofer or the bass out of the tweeter?
    Sure, that's what most of the sections of the TL084 are doing - they have 3rd order LP and HP. Just there's no opamp sections doing tone control - you know, a la Baxandall. I'll post up the schematics shortly.
    permalink
    Posted 15th December 2010 at 02:03 AM by abraxalito abraxalito is offline
 
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