Weird audio question
 

I am working with my father to get some music into his 42' Ocean Alexander. He has a basic CD deck in the salon. It will be running a set of in ceiling speakers and a couple speakers down in the stateroom area. Instead of trying to run an amp and a remote up to the fly bridge I think we are just going to buy another cheap deck to put up there and run 2 speakers off the deck. My question is I was walking by a garage sale today and they had a set of brand new in the box boston acoustics in ceiling home stereo speakers. They were $10 so I said what the hell and picked them up. They are 6.5" coaxials but the hang up is they are 8 ohm. Can I run them off of the deck power even though it will be 4 channels and 4 ohm? Is there anyway to use all 4 channels to the 2 speakers and make them run 4 ohm? Will it damage the deck if I just run 2 of the channels to the the 2 speakers like normal? Can I bridge the deck channels together and run them at 8 ohms to get the same amount of power to the speakers as I would running a pair of 4 ohm speakers?

Brett,
You cannot bridge a source unit. In a sense, the source unit is already bridged to get the power that it has without a switching power supply (The source unit is BTL= bridged transformerless).
The only way you could run two channels to one speaker is if the ceiling speaker has a dual voice coil midbass and two tweeters, which are commonly found in hallways and bathroom applications.
You cannot run a 2-ohm load with a source unit.
You can run an 8-ohm load with a source unit with a reduction in power.
You can run two channels into a 4-ohm load with two channels into an 8-ohm load without issue on a source unit. The load does not have to be equal.
The source unit can have two occupied and two dormant channels without issue.

David
Earmark Marine

Brett,

yes
no
no
no

Either hook the speakers up each to a single channel off the deck (will not damage either the speaker or the deck)
or
wire them both together in parallel and run them to a single channel off the deck (making them a 4 ohm load)

David,

Isn't 2 channels bridged running an 8 ohm speaker the same as 2 separate channels each running a 4 ohm speaker?

Brett,
In a typical external amplifier bridging into an 8-ohm load times one will deliver the same collective power as running two discrete channels into a 4-ohm load. However, you cannot bridge a source unit.

David
Earmark Marine

OK, thanks David. So using just 2 of the channels and running them normal to the speakers is going to be my best option although that may suck as well since it is going to lower the power into the speakers and the speakers may only get 25 watts max. Huh. I might be better just buying a cheap set of 4 ohm coaxials.

David, do you have a suggestion for an inexpensive speaker that will sound ok on deck power?

David, what is the outer dimensions of this piece of ABS? I wonder if this would work for what I PM'd you about? I need something about 4x8.5.
http://store.earmarkcaraudio.com/Xca...cat=299&page=1

you can wire the speakers parallel off 1 channel so the deck sees 4 ohm, but those 2 speakers won't be in stereo. on the plus side you have the other channels on the deck if you want to add more speakers. different speakers is probably the easiest alternative.

Yeah, I think I am going to have to just buy a cheap set of 6.5's or 6x9's and run them off 2 channels of the deck. That will leave me with the option of maybe adding some cheap pod speakers later that I can direct down to the cockpit.

Brett,
Odin, who administrates the Earmark on-line store, can give you the specifics on that - which is a special application piece rather than a universal plate (which is why there are no dimensions listed). But it could work. Obviously the corners are radiused, and so are the sides.

David
Earmark Marine