Cautionary tale; 808-8a green wire to positive?

[aeyb701]

Hi:
I thought I'd share my woe: I connected my Marantz 2270, "refurbed" I won't say by whom on eBay, to my A7-oid 825's (remember the broken-up cabinets from Quebec in an older thread?) and stupid me I thought the right channel intermittent popping and humming was cured, having checked out the speaker relay...anyway, a pop. a 120-Hz hum, followed by a banshee-like screeching from the 807-8A and sputtering and melting-smell of the 416-8C's voice coil, as well as the-I think-opening up of something in the LF circuit of the N801-8A network (infinite resistance at LF posts).
Well sir, let me tell you I'm not trusting that receiver again-it already caused me to send a 416-8B to Bill for a fine recone job.

Interestingly both the 807's arrived with the "light" aluminum 23744 dia's, topped with loading caps.

QUESTION: Was that a production variant?

Anyway I thought it was toast but saw the little wire to the coil itself was open-must have acted like a fast-blo fuse. Anway I was able to solder it together again and it works fine now.

The 416-8C is going to Bill for a recone-that'll be my third in 6 months!

In looking under the cap of an 808-8A (34726 Symbiotik) I saw the green wire was soldered to the "minus" terminal of the coil, connecting it to the Number "1" binding post outside.

QUESTION: Isn't the "1" post supposed to be connected to the "+" side of the diaphragm ring?


Thanks,
Jon

[Steve Mac]

No, my understanding is that:
2 = +
1 = -

[timp]

Hi

Yeah. I too have an old Marantz sitting in my garage. 120w pc, I think. One of the side is blown. One time, it literally smoked one of my polk speakers. Since then, I've been afraid to use it again.

Tim

[gamalot]

My experience with this tells me, as long as both wires going to the HF side are comming from the XO HF side then it should not have any ill effect for the driver except to get it out of phase.

I know of no damage that could be caused by misphasing the HF side. All it should do is cause the diaphragm to pull instead of push when it may need the exact opposite.

Old receivers that are producing DC current to the speakers is an entirely different condition aside from the + or - phasing of the HF driver.

Others here may be able to guide you better in these situations but switching the correct HF driver + & - leads only changes phasing.

Gary

[aeyb701]

Thanks to all for your replies.
Sorry if I appeared to link the phase issue with the smoke issue-they were two separtate questions and I should have posted 2 new topics.
I checked the marantz after that and sure enough 60 millivolts DC on one channel, but I'm not sure if that's enough to toast two voice coils and a network
After that I replaced the 807's with 808's and the Marantz with a Yamaha A-1000 integrated. It sounded flabbier than usual so I substited that amp with a Bryston 0.5B pre and Yamaha PC2002M (pro) power amp and it's been pumping all afternoon long, sounding clean, crisp, with tub-thumping bass from 200 feet away (it's Canada Day-Dominion Day to some- and I've got the rig set up in the barn facing outside).

I dunno, I really liked the sound of the 2270 WHEN IT WORKED but as Tim pointed out I don't trust it now.

The symbiotik dia's don't sound bad at all. I've got them hooked to an N1285B set at 800Hz xover.

BTW have a great July Fourth everyone south of 49!

Jon

[bfish]

Hi Jon,

60mv DC certainly isn't ideal, but it wouldn't fry your Altecs. For example, the adjustment tolerance for a 9440A is +/- 75mv.

Have a good Canada Day (evening)!

Added;
"QUESTION: Was that a production variant?"

No, not in an 807.

<font color="#FFFFFF" size="1">[ July 01, 2008 08:03 PM: Message edited by: bfish ]</font>