Question about amp wiring....6 ohms??

[brchd]

Hey i'm usually pretty good at this but i'm stumped here...i have a RD Audio 4 channel amp that does 50x4 at 4ohms and 170 x2 at 4 ohms bridged to 2 channels. This is what i wanna do... I have Infinity 2 ohm front plates, and 4 ohm Polk 6.5's . I want to run 1 (2 ohm) Infinity, and 1 (4 ohm) Polk in series to one channel of the amp at 6 ohms, and the same on the other side. My question is this, if the amp does 170 x 2 at 4 ohms bridged, how much would each speaker be getting @ 6 ohms? i figured around 40 each....is this even close to being right? The reason I'm not going to run all 4 channels regularly is that the amp puts out 85 WRMS @ 2ohms and running 85 watts to each of those plates when theyre rated for 45 rms will probably result in a small problem. HELP!!//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

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[Prowler573 5,000+ posts]

Running a 2 Ohm speaker and a 4 Ohm speaker wired in series with each other will result in a 6 Ohm load...but each speaker isn't going to receive the same power when being driven by the same amp channel.

If your amp does 85w/channel @ 2 Ohms then the 2 Ohm speaker will get around 56 watts (2/3 of 85) and the 4 Ohm speaker will get the remainder.

Reason being is that the 2 Ohm speaker presents a lower resistance as compared to the 4 Ohm speaker when fed off of the same output thereby its easier for the wattage to flow into the 2 Ohm driver than it is to flow into the 4 Ohm unit (electricity always follows the path of least resistance first, remember...)

 

[brchd]

oh okay. that makes sense. i really don't care that the 6.5s don't get much power since they're my rear fill. but the amp is going to be bridged @ 6 ohms.....see what i mean. if it does 170 x2 at 4 ohms how much will it do at 6 ohms? about 120? i'm not going to be running 6 ohms at 85 watts, 6 ohms on the bridged channels...

 

[helotaxi 5,000+ posts]

If your amp does 85w/channel @ 2 Ohms then the 2 Ohm speaker will get around 56 watts (2/3 of 85) and the 4 Ohm speaker will get the remainder.

Actually that's backwards. Wired in series the 4 ohm speaker will realize the greater voltage drop and the current would be the same between them. Since power is V*I and I is the same for both, the higher voltage would get more power.

Reason being is that the 2 Ohm speaker presents a lower resistance as compared to the 4 Ohm speaker when fed off of the same output thereby its easier for the wattage to flow into the 2 Ohm driver than it is to flow into the 4 Ohm unit (electricity always follows the path of least resistance first, remember...)

If they were wired in parallel, this would be true, but we're talking series. There is only 1 path in a series circuit so there is no "path of least resistance."

To the OP, the amp should do around 115 watts @ 6 ohms bridged. Of that, 75 watts would go to the 4 ohm driver and 40 to the 2 ohm driver.

 

[brchd]

Actually that's backwards. Wired in series the 4 ohm speaker will realize the greater voltage drop and the current would be the same between them. Since power is V*I and I is the same for both, the higher voltage would get more power.


If they were wired in parallel, this would be true, but we're talking series. There is only 1 path in a series circuit so there is no "path of least resistance."

Gotcha! so, back to my original question...if the amp does 170 x2 @ 4 ohms bridged, what will it do at 4 ohms bridged?, and will both speakers split that amount of power?

 

[Prowler573 5,000+ posts]

Actually that's backwards. Wired in series the 4 ohm speaker will realize the greater voltage drop and the current would be the same between them. Since power is V*I and I is the same for both, the higher voltage would get more power.


If they were wired in parallel, this would be true, but we're talking series. There is only 1 path in a series circuit so there is no "path of least resistance."

Alright.

I hate getting "schooled" but at least I'm learning something so thanks for that at least. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[brchd]

LOL i appreciate both of your input. i am learning too.

 

[helotaxi 5,000+ posts]

You caught my edit to answer your question?

 

[brchd]

great. thanks man. i'm gonna be taking pictures as i lay in the 0 gauge today and redo all the wiring and 4 channel. i'll postem tonight.

 

[XanderMoser 10+ year member]

Wait. I still don't see why you don't run your amp in 4 channel mode. It takes care of all of the problems with speakers in series with different resistances and power levels. You should have separate gains for the front and rear channels. Set them independently. You can send more power to your front components and less to your rear coaxes this way. Just lower the gain on the coaxes. An amp does not always send its rms value. That value is just the estimated maximum value that it will do unclipped for a continuous amount of time. Or something like that.

 

[helotaxi 5,000+ posts]

^^^That's what I would do. I just answered the question as asked. That is the better solution.

 

[konechiwa 10+ year member]

just set your gains right and your good to go.

 

[dipitydoo 10+ year member]

Running in either 4channel mode and 2channel mode will net you the same power (85w to the 2 ohm speakers and 50w to the 4 ohm speakers), but running them in 4ch mode allows you to individually set gains for the front/rear speakers, so that would be the recommended way to go.

 

[brchd]

okay. now you tell me. well i already did it. but i guess i can redo the wires tomorrow. i'm glad i ran them in series AT THE AMP, and not up in the dash/doors. I already have the gains almost all the way down and its wangin'. sub gain on my amp is ATW down. i'll change it around tomorrow and change the rca's. thanks guys.

 

[helotaxi 5,000+ posts]

Running in either 4channel mode and 2channel mode will net you the same power (85w to the 2 ohm speakers and 50w to the 4 ohm speakers), but running them in 4ch mode allows you to individually set gains for the front/rear speakers, so that would be the recommended way to go.

2 channel mode runs more to the 4 ohm than the 2 ohm.