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cab13367
10-16-2009, 06:22 AM
This is probably a dumb question but here goes. If my amp is rated at 100W per channel at 2 ohms and I wire two 4 ohm speakers in parallel to one channel so that the amp sees a 2 ohm load, does each speaker receive 100W or 50W?

Thx,

Al

jmvotto
10-16-2009, 09:49 AM
Al, I believe it would be 100w but here's and article that goes through the calaculation

http://www.termpro.com/articles/spkrz.html

correction 50 w each speaker ( i was using the 8 ohm Speaker load)

newty
10-16-2009, 10:06 AM
If you have a 4 ohm speaker wired to one channel of the amp, positive to positive and negetive to negetive then the amp sees 4 ohms. So in this case you will only be putting out 50w.
Now if you add a second 4 ohm speaker to that channel, with both positives of each speaker to the positive post on the amp and the same with negetives, then your amp would see a 2 ohm load.
The only way to change that up is to have 2 ohm speakers.

Here is a good online reference.
http://www.colomar.com/Shavano/spkr_wiring.html

jmvotto
10-16-2009, 10:53 AM
newty, question? ( excuse my ignorance)

how are most tower double ups wired for the tower, series or paralle and what do most people run them from 2 channelsat 2 ohms or 4 channel amps at 4 ohms?

also, how are the cabin speakers wired from the factory series or parallel?

I don't see too many speakers besides subs that handle 2 ohm loads?

sandm
10-16-2009, 11:09 AM
the questions you pose above depend on the speakers and amps. there are not many 2ohm door speakers, but they do come in 3, 4, 6 and 8ohm variants. how you wire them depends on how many speakers you plan to run and what the amp you are using can be configured for. I am planning on running the hollow points wired in parallel and a 2ch amp stable to 2ohms stereo. you could also run a 4ch amp and run it bridged, but most 4ch are not 2ohm stable bridged unless you spend some coin, and you would not get the same bang for the buck in series for an 8ohm load bridged.
not sure how the tower speakers are wired currently, but it's not hard to tell if you pull one side out. my in-boat speakers were wired with the bow on 2 channels and the 4 in the main lounge wired in parallel to the other 2 channels. presents a 4ohm load for the fronts and a 2ohm load for the main cabin on the 4ch amp(assuming they are 4ohm speakers, which I believe they are). my guess is this is how most of the boats are wired.

sandm
10-16-2009, 11:13 AM
and if you really want to get cute, some of the old school "cheater" amps are stable to .5 and .25 ohm loads. you can run an entire boat off one orion hcca225. rated at 25x2, but realistically more like 3-400x2. you start getting into runnning full range speakers in stereo and run the subs mixed mono across both channels. impedence gets real tricky then :)

cab13367
10-16-2009, 01:53 PM
If you have a 4 ohm speaker wired to one channel of the amp, positive to positive and negetive to negetive then the amp sees 4 ohms. So in this case you will only be putting out 50w.
Now if you add a second 4 ohm speaker to that channel, with both positives of each speaker to the positive post on the amp and the same with negetives, then your amp would see a 2 ohm load.
The only way to change that up is to have 2 ohm speakers.

Here is a good online reference.
http://www.colomar.com/Shavano/spkr_wiring.html

newty,

Thanks for the reply, but I think you misunderstood my question. I know that the amp is seeing a 2 ohm load in this configuration. What I am asking is how many watts is being applied to each speaker?


Al, I believe it would be 100w but here's and article that goes through the calaculation

http://www.termpro.com/articles/spkrz.html

correction 50 w each speaker ( i was using the 8 ohm Speaker load)

Thanks for that link JM. That answered my question - each speaker is getting 50W as you also concluded.


newty, question? ( excuse my ignorance)

how are most tower double ups wired for the tower, series or paralle and what do most people run them from 2 channelsat 2 ohms or 4 channel amps at 4 ohms?

also, how are the cabin speakers wired from the factory series or parallel?

I don't see too many speakers besides subs that handle 2 ohm loads?

jm,

In the last sentence of your question above, the issue is how much impedance the amp sees, not how many the speakers can handle. So if you wire two 4 ohm speakers in parralel, the amp will see a 2 ohm load but the speakers are still 4 ohm speakers. From the speaker's perspective, we want to make sure it can handle the amount of watts the amp is feeding it.

jmvotto
10-16-2009, 02:03 PM
thanks,
got it . I just got two more aerial tower cans and i thought this thread through me for a loop on how i wanted to wire the 4 tower pods from two channels( 3& 4)

I had a brain F$%T, all is good now.

newty
10-16-2009, 02:27 PM
oh I see that now Cab.
The amp will putout 100w @ 2 ohms, but will the speakers see 100w or do they spilt the load essentially getting 50w each?
Good question, I'm not really sure. I think because each speaker acts as a resister they each will (provided they are the same ohm load) each draw half the power.

cab13367
10-16-2009, 02:27 PM
Jm,

No worries. So are you running the 4 tower speakers in parallel with channels 3&4, the 4 rear cabin speakers in parallel with channels 1&2, the sub off channels 5&6 bridged, and the bow speakers off the head unit?

cab13367
10-16-2009, 02:28 PM
oh I see that now Cab.
The amp will putout 100w @ 2 ohms, but will the speakers see 100w or do they spilt the load essentially getting 50w each?
Good question, I'm not really sure. I think because each speaker acts as a resister they each will (provided they are the same ohm load) each draw half the power.

newty,

Based on the link provided by JM, that's correct - each speaker will get half the output of the amp provided they are the same impedance.

jmvotto
10-16-2009, 03:19 PM
yep, that's exactly how i am running it.

cab13367
10-16-2009, 03:29 PM
jm,

So each speaker wired in parallel will receive 37.5W at 12.5V (basically, when the engine is not running). I'm not sure that's enough. I am reconsidering using the M6600 to run all my speakers now. I may use it to run all the cabin speakers at 4 ohms so they are getting 55W at 12.5V and then use my current 50x4 amp to run the 4 tower speakers. So everything will be wired one speaker per channel to get the most out of the amps. But that means I will probably need a second battery, a battery switch, an EQ (for more pre-outs), etc. Plus I still have the third amp running just the sub. This suddenly got more complicated :)

jmvotto
10-16-2009, 03:55 PM
what are you using to power the sub. My cockpit speakers are wired that way and it pretty defening in the boat . I don't have a real need when the boat if off to project the towers, so when the boat is on, the amp should push 50w per channel.

I figured 4 speakers @ 50 rms, would be louder than 2 @ 75rms.

Its trial and error. i have looked a the 4 channel JL m4500 as well if its not enough. I don't want to add another amp if i don't have to, the hole on the OBV is tight as it is I did the dual battery setup with the BEP marine vsr and switch.

cab13367
10-16-2009, 04:22 PM
what are you using to power the sub. My cockpit speakers are wired that way and it pretty defening in the boat . I don't have a real need when the boat if off to project the towers, so when the boat is on, the amp should push 50w per channel.

I figured 4 speakers @ 50 rms, would be louder than 2 @ 75rms.

Its trial and error. i have looked a the 4 channel JL m4500 as well if its not enough. I don't want to add another amp if i don't have to, the hole on the OBV is tight as it is I did the dual battery setup with the BEP marine vsr and switch.

You mean the amp should push 50W to each speaker when the boat is on :)

I have a Boss R-635 rated at 200Wx2 rms that I am running bridged to the sub. It's a low quality amp, I know, but it seems to work just fine. I have the subwoofer output set between 0 to -5 at the head unit because it hits so hard.

Yeah, I'l give it a try running all the speakers from the M6600 and see how it sounds before going thru the trouble of adding a third amp.

Thanks,

Al

jmvotto
10-19-2009, 09:38 AM
Al,
if you get the chance.could you post pics of the aerial tower speaker clamps, I now have two different sets, i believe one os for the larger tower and one for the obv 1 5/8 tower.

Thanks

joe

cab13367
10-19-2009, 03:43 PM
jm,

Here's a pic from an old post of my old aerial cans with the larger diameter brackets. This is on a 2-3/8" diameter LSV tower.

Is that what you're looking for?

http://i250.photobucket.com/albums/gg276/cab13367/IMG_0902.jpg