Found by the kerb

[ppppenguin]

While out today I found a pair of Alesis speakers on the pavement by somebody's bins. Even if they're damaged (and they look like they haven't been at all well looked after) they may well be a source of spares for the pair that's now part of my main stereo system.

[Bushbaby]

Hi Jeffrey
Are they M1 active studio monitors at all? I've just had a very quick review and if so they are supposed to be excellent sounding speakers but have power supply issues?

Best Regards

[ppppenguin]

M1 Active Mk 2. I have a copy of the service manual which I found online.

They have switchmode PSUs which will need care if they need to be fixed. The woofer is driven by a LM3866T: https://www.ti.com/lit/ds/symlink/lm3886.pdf The tweeter is driven by a LM2676T: https://www.ti.com/lit/ds/symlink/lm2876.pdf Low level crossover using multipole active Sallen & Key filters.

[Bushbaby]

Good luck and sounds like a great find.

Best regards

[ppppenguin]

Took a closer look at them today. They've both been opened up and had somebody poking around inside.

One of them gives bass but no treble. The tweeter measures open circuit or a wire has dropped off. More likely o/c tweeter. The treble amp could also be faulty which may in turn have blown the tweeter.

I didn't bother to power the other one. All plug-in leads have been disconnected and the mains fuse has blown. Probably a PSU fault. Nothing looks overheated on the PCBs. On the plus side, both drivers show continuity.

So I've got what looks like:
2x good woofers
1x good tweeter
1x good PSU
1x good bass amp

The electronics is all fixable if needed and there are probably 3 good drivers so I'll treat them as a source of spares for my good pair.

[Bushbaby]

Its still a good result - well done.

Best Regards

[Diabolical Artificer]

I've got a pair of the bigger 3 way Monitor Two's, these use different drivers I think. They also use that thick rubber baffle/surround on the woofers, I think these are supposed to be some sort of baffle. On mine these baffles are coming unstuck having shrunk, I did try re-gluing them, a right faff. Anyway, although budget speakers they sound pretty good,you should have some nice parts there.

BTW, what make are the drivers? Andy.

[ppppenguin]

Don't know the makes of the drivers. Haven't looked that far inside.