alpha speaker wiring

[JDProvorse]

ok, so I was dinking around with my alpha 112p the other day, just opening it up to see what's under the hood (I love to tinker, what can I say?).  Anyway, I managed to disconnect the speaker wiring without bothering to note which wire went where, and no I'm afraid I'm gonna screw something up if I don't wire it back together correctly.  I've got a green wire, a black wire, and a white wire coming out of the amp.  I've got three terminals on the back of the speaker: one on the bottom, two on the top, and one of the ones on top has a little red sticker next to it, I would assume to denote positive from negative.  so, can anyone help me make sure I hook this thing back up correctly?  I'll owe ya one, thanks!

[rick.heil]

green, black, and white sounds more like a power cord than speakers....what are the wires coming out of?

[Don T]

Hello,
Assuming that you are talking about the speaker wires;
white = positive > terminal w/red dot
black = negative > terminal next to the one with the dot (on the insulated board, connected to tinsel wire)
green = ground > speaker frame (to prevent feedback to the reverb)

Don T

[JDProvorse]

thanks Don!

green, black, and white sounds more like a power cord than speakers....what are the wires coming out of?

They come off the amp board and into the speaker cabinet.  I know they're speaker wires because they're the same wires I disconnected from the back of the speaker, and they're the only wires in the speaker cabinet.  I just forgot to diagram which one went to which post.

[JoeArthur]

Hello,
Assuming that you are talking about the speaker wires;
white = positive > terminal w/red dot
black = negative > terminal next to the one with the dot (on the insulated board, connected to tinsel wire)
green = ground > speaker frame (to prevent feedback to the reverb)

Don T

Hey Don T!!

How does grounding the speaker frame prevent feedback to the reverb?

I have another amp, the only one I have with grounded speaker frames.  On the power amp schematic, it does state that the speaker frames must be grounded, but it doesn't state why.  I haven't been able to figure out a reason for it.

BTW - the reverb tank is mounted to the side of the speaker section of the enclosure.

Thanks for any info

[Don T]

Hey Joe,
I haven't been around for a while, although SoundmasterG can always get ahold of me. Speaker baskets are gounded for 2 reasons that I know of.
1. To help shield the reverb pan from screeching.
2. To stop high gain microphonic input circuits from screeching / oscillating.

A friend of mine brought his Matchless amp by because of that very problem. Once the speaker was grounded it was back to ity's old smooth self.