12 volt speaker selection box..feedback needed

i noticed most boats use external volume pots or the fader to control the tower speakers...so after after giving a lot of thought to a boat system and tower speakers....

came on the conclusion it would be very cool to have a speaker selection switch to go between the tower speakers and the boat speakers(not the sub) instead of external seperate volume controls or the fader..

this would allow the same amp/amps that power the inside boat speakers to power the tower speakers. here are the advantages...

1. use the same amps (HUGE ADVANTAGE !!!)
2. use the same volume control
3. fader(wouldnt have to use the fader)

Disadvantages:
1. cant listen to tower and the boat speakers at the same time ( you could if you used some big, big, big, amps and the switch could run a+b)

questions:

-has any one done this ???
-does anyone see any drawbacks ?
-do they make a 12v speaker selection box that can take a hugh amount of power ?

input would be appreciated.

thanks,

mike


(Message edited by clubmyke on March 21, 2005)

Mike,

The speaker selector box you are describing would be analog so there would be no difference between a unit designed for the home and one designed for a boat. I guess there are some advantages to this approach but I am hesitant to push the kind of power I will be running to the tower through my boat speakers. Most tower volume controls I have seen are on the input side to the amp (ie. PAC-LC1).

On my next boat I am planning on using a pre-amp EQ/XO unit with a fader to the tower so I can fade between the boat speaks and the tower, but you are right this requires an additional amp for the boat.

One thing to keep in mind is that the tower speaker impedence and the boat speaker impedence should be identical if you want to A/B them off the same amp. It's a pretty good idea if you are running something like four 4 ohm boat speakers and four 4 ohm tower speakers. This seems like it would be a common situation for most stock or dealer installed systems.

Something like this should work: http://www.smarthome.com/9725780.html
http://www.hiddenspeakers.com/product/268

Consider I use a cheap $100 amp for my boat speaks a simple toggle on the amps turn on wires can accomplish more for less.

Good idea in the right situation!

the pac LC1 is nice but you have to run the additonal amps and the fader still has the other amps on...

i think this is the way to go because i dont have to run 2 additonal amps for the towers...(jl, zapco- $$$$)

the trick is finding a passive unit that can take hign power (350 rms per channel)

You can build a fader control for the input of the amps for next to nothing. You need a Linear taper, dual ganged, center tapped, potnetiometer (probably about 100K ohms), some rca cables, and a soldering iron. I am running two amps, a 5 channel for in the boat and a four channel for the tower. I use the fader control on the head unit with the tower being the rear and the cockpit being the front. It works well but it is kind of a pain in the butt is pushing the audio button several times to get to the fader

kj,

any suggestions on building a speaker selection box that can take 350 watts rms??

-i really want to avoid the use of a fader which would require 2 additonal amps.

Building a fader behind an amp is hard if not impossible to do. You are talking about find a potentiometer that can handle that kind of load and unless you have one of those hugh dials like you see in the frankenstien movies, that ain't gonna happen. You can build a switch. You are going to need switches that can handle going to hanlde the current. I assume you are running 4 ohm speakers. Is the 350 total rms power or is that per channel? How many channels are we talking? The calculation for the current is the square root of power over resistance. So if you are talking 350 watts per channel (speaker) then 350/4 = 87.5 and the sq rt to 87.5 = 9.3 amps. so figure out the watts per channel and the load on each channel. Once you come up with the current rating you can figure out how much current your switch will have to handle. i would increase that by 50% to be safe. So if you calcualte 10 amps, i would buy a switch capable of handleing 15. The switch basically has to act like a piece of speaker wire when it makes contact. Those shouldn't be hard to find. What is going to be hard is finding a switch with enough poles on it to throw all of the speaker connections all at once You need a double throw switch and the number of speakers you are switching will determine the number of poles you need. For instance a double pole double throw (DPDT) switch will switch two speakers to one source. the switch will have two rows of three leads on it. The center two are the + & -of the source and the speakers would go on either side. then you could switch between speaker A or B. So you could end up having a few switches. By the time you mess with all of this, I would buy the second amp. I just got a soundstream 5 channel off of ebay for the houseboat for $100. You will probably spend more money than that in time messing around with making a switch set up.

i wish it was that simple....my deck has fader capabiltiy (eclipse 8053) and enough preamp outs ( 8 sets !!!!)

but running 4 mono blocks and a sub amp is costly and space prohibative (need 350 watts a channel for the boat speakers(2 channels) and 350 watts a channel for the towers(2 channels)...

the idea of running 2 350 watts amps (1 per side) and switching between tower and boat makes a lot of sense...it just finding a way to switch between the 2..

I run two amps and have total of about 1100 watts. I am running a soundstream refrence 705 and a soundstream reference 404. The 705 runs the boat and the 12" jl audio sub. The 404 runs the 4 polk 6x9's in the tower. With hi pass and low pass filters built in the amps and the ability of the amp to get input for all channels from just two preamp leads from the deck its the way to go. I have my amps mounted on the sidewall in the storage compartment and there is plenty of space

Clubmyke,

Why don't you just use a 20A DPDT switch? Wire the negative speaker wires directly to the amp and switch the positive leads.

mikeski,

thanks for info and the drawing !!!!!