5-Channel amp, different loads?

[mdk681]

I am looking at buying a 5 channel amp to power my 4 in boat speakers, and 1 sub. The 4 in boat speakers have a 4 ohm impedance, where my sub has dual 4 ohm voice coils. So in theory, I could wire my sub to get either an 8 or 2 ohm impedance, and 8ohm makes no sense for this application so 2 it is.

I have been looking at amps with specs similar to this:

5-channel amplifier
-50 watts RMS x 4 at 4 ohms + 200 watts RMS x 1 at 4 ohms
-75 watts RMS x 4 at 2 ohms + 300 watts RMS x 1 at 2 ohms
-150 watts RMS x 2 bridged at 4 ohms + 300 watts RMS x 1 at 2 ohms

My question is, it appears the amp can power 4 channels with 50w RMS @ 4 ohms. Does this mean that in order to have a stable load on the amp I will have to run a 4 ohm load on the 5th channel as well? Or can I mix and match, such as 4 ohm load on 4 channels, 2 ohm load on the 5th? I have never worked with 5 channel amps so I am a little lost here. Any help or insight would be appreciated!

[chpthril]

Most 5 chnl amps are what we call a hybrid, meaning they have 4 full-range chnls and a dedicated sub-woofer chnl. You can your four 4 ohm full-range speakers on chnls 1-4, with each receiving 50W rms @ 14.4V. You can also add a 3rd pair to that amp. Wire them in parallel on chnls 3 and 4. Each speaker would then net 37W rms. For the sub, yes, wire it in parallel to a 2 ohm load. This will net the sub the available 300W rms @ 14.4V.

[ds@earmark]

mdk,
Almost all amplifiers are unregulated which means that the load on any one channel has no impact on any of the other channels.
I think the only concern would be running all five channels hard (full output) at the lowest 2-ohm load. In that case, you would run a larger amplifier in order to operate at a more conservative level. In your scenario with a 2-ohm sub load, a good amplifier should breeze through it.

David

[mdk681]

So I ended up buying the 5 channel amp that I posted in the main thread. I got it installed over the weekend along with the sub and had run wires to each speaker. When I have it in 5 channel mode, I get a solid sub playing, but only 2 speakers. When I put it on 2 channel mode I get weak sub (I think), but all 4 speakers. Currently I have one pair of RCA's run to the sub input, CH5, and one pair running to plugs CH1 and CH2. Do I need to get a splitter to split the RCA that is currently going into CH1 and CH2 so it will be on CH1 through CH4?

Here is a picture of the inputs on the amp:
BRX5000-5_02_zps5b63477a.jpg

[chpthril]

Try it and see, it wont hurt a thing.

[mdk681]

Try it and see, it wont hurt a thing.

Ended up grabbing a couple splitters on my way home today and everything is good to go!

I was so anxious to test the completed system I dropped her off the lift in the rain and headed for the middle of the lake. Will post pics of all of the mods and install if it ever stops raining...