stereo question

[smoker62]

I have a pair of Yamaha 390 outdoor patio speakers. Not being much of an audiophile, will a 12v marine/car stereo drive them ? No , Im not blasting the bay with them LOL.

[crspang]

Yes, this is perfectly acceptable. You can always go up but never down from any amplifier's rated minimum speaker impedance. Typically home audio speakers have an 8 ohm rating and car or boat speakers have a 4 ohm rating. To understand the principal; The speaker is in simplified electrical terms a length of wire (the voice coil.) The longer and thinner it is the higher it's resistance (a high Ohm number 16.) The shorter and thicker, the lower it's resistance (a low Ohm number 4.) Lower resistance simply means that it returns more electrons back to the amplifier. The more electrons that flow through the final stage of an amplifier - the transistors - the hotter it gets. Heat is it's enemy. In my trade we use transistorized output controls to open and close electro-magnetic valves. These valves are usually from between 40 to 120 Ohms. If, in the course of repairs or installation one gets shorted or jumped to the next valve the output transistors will literally explode. Pop! Like a Chinese "ladyfinger" firecracker. This because the resistance has become far less and the current coming back to the transistor has become far greater than it can handle. 0 Ohms is a direct short and an open circuit is infinity Ohms.
There is one caveat to lowering the resistance of speakers connected to audio amplifiers however: Because of the way they are designed the higher the resistance of the speakers the less power they will deliver to them. In the case of 4 ohms to 8 Ohms the difference is nominal. This is why car audio amps and speakers are usually rated at 4 to 2 Ohms. More power Boom Boom!

[smoker62]

Ok, thanks. You lost me after yes. I was thinking of wiring them under my rear seat and only using them when we are by ourselves floating behind the boat.I could pull them out and set them on the rear sun deck. I looked at the marine box speakers at Rock the Boat audio and they looked to be the same thing . I already had these so figured why not use them

[HandymanHerb]

[tuned]

crspang, you are right on the money. one of the better impedance descriptions I've seen. This band technician gives TWO THUMBS UP, although I would venture that you might get some blank stares as well

[smoker62]

Let me add another question since you guys seem to know way more than I do. I was going to use these Yamahas on an older Panasonic micro stereo . It is an SA-DP1 I had in my office for years. My plan was to put this stereo in a new shed and run the Yamahas on the outside. The problem is the Panasonic speakers have two pos and neg each speaker. The tweeter and woofers must be driven individually. I am not sure how this will work with a regualr two wire speaker. I really have never seen a 4 wire speaker before.

So left channel has two positeve and two negative terminals and right channel has the same. Can you hook a regular two wire speaker to this or will it be missing some input ?

[tuned]

Let me add another question since you guys seem to know way more than I do. I was going to use these Yamahas on an older Panasonic micro stereo . It is an SA-DP1 I had in my office for years. My plan was to put this stereo in a new shed and run the Yamahas on the outside. The problem is the Panasonic speakers have two pos and neg each speaker. The tweeter and woofers must be driven individually. I am not sure how this will work with a regualr two wire speaker. I really have never seen a 4 wire speaker before.

So left channel has two positeve and two negative terminals and right channel has the same. Can you hook a regular two wire speaker to this or will it be missing some input ?

Nope. But it is an easy fix. You need a cheap 'passive 2-way crossover' to split the signal to each individual speaker. Something like these http://www.ebay.com/sch/i.html?_sacat=0 ... ay&_sop=15
You need one for each speaker box. If you look at the list, you can get them to mount internally in the speaker box or externally. If you go external, you will want to protect it from moisture.
You might also note that some will say something like 8ohm tweeter and 4ohm woofer. This particular rating will probably work well for you.
Check your amp and speaker wattage rating and make sure that your crossover has at least this much rating. Most will be rated for substantially higher power which is fine.
Each one will have six connections. One pair for 'input' from the amp. One pair for tweets, one for woofs.

Edit: This might be wrong advice. Hold off on any purchase for a day or two until we can sort this out. I am heading out on boat for couple days but will get back to you. My question is--does your original AMPLIFIER setup have four output wires going to each speaker? In other words, is there a plus and minus for left tweeter, plus/minus for left woofer, plus/minus for right tweeter, and plus minus for right woofer coming FROM the amp? If this is the case, you don't need a crossover and can wire DIRECTLY to each individual cone in the new boxes. Please provide a bit more info (pictures always help) when you get a chance.

[tms0425]

Those Panasonic speakers are bi-amped but the amps and the crossovers themselves are built into the receiver. I don't see any settings that would allow you to run the amps full range so that the external passive crossover would work. You definitely don't want to tie the high and low outputs together or it will kill the amps in there. Without a lot of change to the speaker, crossovers, etc that's not really going to work because connecting the speakers to one or the other output gets you just the highs or lows only.

[tuned]

Those Panasonic speakers are bi-amped but the amps and the crossovers themselves are built into the receiver. I don't see any settings that would allow you to run the amps full range so that the external passive crossover would work. You definitely don't want to tie the high and low outputs together or it will kill the amps in there. Without a lot of change to the speaker, crossovers, etc that's not really going to work because connecting the speakers to one or the other output gets you just the highs or lows only.

Yep. That is where I was heading. Each speaker box would have to be opened so that the wires could hook directly to EACH cone. The passive crossover existing in each speaker box would have to be unhooked.

[smoker62]

Wow , you guys are good. Sounds like the best idea is to get a new cheap stereo receiver and another set of Yamahas for the shed. I temp wired the Yamahas I have now to the boat system after your go aheads and they sound great and nothing caught fire LOL.


Guess Ill keep the Panasonic with its matching speakers . It does have two pos and two neg per channel. I hooked up an old speaker and it was real bad on one set of terminals and so so on the other but not a good setup. Didnt want to damage anything in the Panasonic so I just did a quick check. It is a great sounding little unit so I guess back in the office for now.



Thanks guys,