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06-03-2014, 01:26 PM
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#1
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2 Rivet Member
1989 25' Excella
Austin
, Texas
Join Date: May 2011
Posts: 36
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Speaker wiring/common ground?
Looking at replacements for original 5.25 inch speakers in my 25ft 89 Excella, and speaker vendor says the trailer's common ground for speakers is not agreeable with newer speakers which are set up for individual grounding. If not rewired, the receiver will overheat and burn up he claims.
Anyone dealt with this, and if so, is there a simple solution?
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06-03-2014, 04:50 PM
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#2
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Rivet Master
2006 23' Safari SE
I'm In
, Kentucky
Join Date: Dec 2012
Posts: 4,251
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The original speakers use the trailer's electrical 12 volt ground? Only the positive speaker wire goes between the speaker and the source?
If you are just replacing the original speakers and keeping the original receiver (which was using the common trailer ground) I don't see how the receiver would know/care. A speaker is just resistance in the wire, usually 4-8 ohm.
If it was me and the receiver was original, I'd just replace the speakers and wait and see. You might consider posting in a stereo forum, see what they have to say. You could also consider asking a different vendor.
__________________
-Rich
Rich & Yvonne
2006 Safari SE -Dora-
2004 4Runner SE 4.7L V8
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06-03-2014, 05:04 PM
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#3
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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Quote:
Originally Posted by PAL07
Looking at replacements for original 5.25 inch speakers in my 25ft 89 Excella, and speaker vendor says the trailer's common ground for speakers is not agreeable with newer speakers which are set up for individual grounding. If not rewired, the receiver will overheat and burn up he claims.
Anyone dealt with this, and if so, is there a simple solution?
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Speakers don't care, but a newer radio might. I've not seen a radio in a long time that will recommend the negative side of the speaker output be grounded. Not saying it won't work, but it might be a problem with a newer radio.
__________________
Regards,
Steve
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06-03-2014, 11:11 PM
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#4
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2 Rivet Member
1989 25' Excella
Austin
, Texas
Join Date: May 2011
Posts: 36
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The receiver was replaced two years ago, so I'm dealing with new unit. Now looking to replace original speakers, which apparently share common ground. How will the new receiver respond to commonly grounded speakers?
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06-04-2014, 12:25 AM
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#5
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Rivet Master
1974 Argosy 20
2014 20' Flying Cloud
Kooskia
, Idaho
Join Date: Jul 2009
Posts: 4,591
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I don't know the '89 excella system but on all of my old 60's and 70's Argosy's and Airstreams, the speakers each had two wires from them and were not common ground. Are you positive that the speaker wires are not a pair for each speaker?
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06-04-2014, 02:45 AM
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#6
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Rivet Master
1973 23' Safari
1977 23' Safari
2018 25' Flying Cloud
Palmer Lake
, Colorado
Join Date: Oct 2005
Posts: 4,092
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Quote:
Originally Posted by PAL07
... speaker vendor says the trailer's common ground for speakers is not agreeable with newer speakers which are set up for individual grounding. ...
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There is no "individual grounding." Neither speaker wire is grounded. There is no connection to the 12V system, ground or otherwise.
Most solid-state (bet you haven't seen that phrase lately) audio amplifiers have floating speaker outputs. That means you have to have two ungrounded wires going separately to each speaker. There is no common connection between the speakers, eg, you can't use three wires for two speakers, like you would for stereo headphones.
All my 70s Airstreams have this method of wiring for the front and rear speakers (8 wires for 4 speakers). I would bet your '89 has the same.
If you ground one side of each speaker (like using the shell as a common ground) you will have connected the floating output of the left and right amplifiers together and they will burn out.
Zep
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06-04-2014, 05:27 AM
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#7
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2 Rivet Member
1986 34.5' Airstream 345
Pittsville
, Maryland
Join Date: Sep 2013
Posts: 53
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I just finished changing out my sound system in a 1986 345 . The speaker wiring neg is the black wire . A good way to figure this out is take a AA battery , take and hook up the speaker wires to speaker , hold one wire to - side of battery the other to + side of battery , if the speaker pulls in the polarity is correct . That tech tip came form the tech form Best Buy . The sound system sounds great but there is a rattle on one side . The speakers mount on the bottom of cabinets and they have a false floor in them , cause of rattle . So going to try using some insulation there to stop rattle .
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06-04-2014, 05:36 AM
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#8
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Rivet Master
Vintage Kin Owner
Lin
, Ne
Join Date: Dec 2009
Posts: 2,430
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The speaker ground wire goes to the amp-radio not the chassis ground.
__________________
The higher your expectations the fewer your options.
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06-05-2014, 07:55 AM
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#9
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Rivet Master
2006 23' Safari SE
I'm In
, Kentucky
Join Date: Dec 2012
Posts: 4,251
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Quote:
Originally Posted by Zeppelinium
There is no "individual grounding." Neither speaker wire is grounded. There is no connection to the 12V system, ground or otherwise.
All my 70s Airstreams have this method of wiring for the front and rear speakers (8 wires for 4 speakers). I would bet your '89 has the same.
Zep
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That's what I thought. I wonder why the OP's speaker vendor is assuming that his speakers share a common ground. I've always seen 2 wires per speaker and they always went back to the receiver. I've got some pretty old equipment here at the house and nothing shares a common ground.
__________________
-Rich
Rich & Yvonne
2006 Safari SE -Dora-
2004 4Runner SE 4.7L V8
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06-05-2014, 09:03 AM
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#10
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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It think you have to go all the way back to when audio equipment had transformer outputs to find negative grounding on the speakers (think tube equipment).
__________________
Regards,
Steve
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06-05-2014, 09:21 AM
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#11
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Overland Adventurer
1991 34' Excella
2009 34' Panamerica
Telluride
, Colorado
Join Date: May 2012
Posts: 2,476
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You need independent grounds due to the fact most modern head units use discreet MOSFET output devices.
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06-05-2014, 11:21 PM
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#12
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Rivet Master
1973 23' Safari
1977 23' Safari
2018 25' Flying Cloud
Palmer Lake
, Colorado
Join Date: Oct 2005
Posts: 4,092
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SteveH is correct. Back in the day you needed a transformer to keep the B+ voltage off the speaker wires. With solid state amplifiers, the collector voltage is low enough that you can drive the speakers directly, but the outputs (both the + and the -) are floating, eg, they are not connected to ground nor are they at ground potential.
It would be a good thing if we stopped using the term "ground" when what is really meant is "speaker minus." In the old days speaker minus (speaker -) was connected to common ground, but not any more.
Zep
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06-05-2014, 11:29 PM
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#13
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Rivet Master
1974 Argosy 20
2014 20' Flying Cloud
Kooskia
, Idaho
Join Date: Jul 2009
Posts: 4,591
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Quote:
Originally Posted by Zeppelinium
SteveH is correct. Back in the day you needed a transformer to keep the B+ voltage off the speaker wires. With solid state amplifiers, the collector voltage is low enough that you can drive the speakers directly, but the outputs (both the + and the -) are floating, eg, they are not connected to ground nor are they at ground potential.
It would be a good thing if we stopped using the term "ground" when what is really meant is "speaker minus." In the old days speaker minus (speaker -) was connected to common ground, but not any more.
Zep
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Zep: Excellent comments, well stated, thank you
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