2012 Road Glide Ultra,stock HU, putting speakers in fairing and lowers. Best use of amp, would I use 4 6MR500-NDY-4 4ohm PVR's ch 1-4, B3's on 5&6 ? Or 4 8ohm PVR's, 2 speakers in series on bridged 1&2 and 3&4 (4 ohm load) for extra power and B3's 5&6 ? Probably missing something but its a start.

 

6 one half dozen another.
I would keep fairing on 1-2, lowers 3-4 and horns on 5-6. Use your fader control to turn lowers up or down compared to fairing. and horns on thier own so you can tame them.
What about the tourpak?

 

Tour pack was removed and set up for quick detach. Just want to make I'm getting most out of amp.

 

Ok,
With everything on their own channel, you get to keep stereo mode and 75 watts on those PRV's and horns is plenty loud.

Can you run it the other way with bridged on 2 pair of 8 ohm speakers (and get 100 watts to each PRV) sure. But, I think it will sound great and more opportunity to tune with each set on their own channels.

 

They're stupid loud running on their own channels.

 

Also, juat a heads up. Running speakers in series keeps them at the same ohms. But running them in parallel will drop the ohms.

 

Doesn't running them is series double the resistance? Did you mean to say series-parallel?

 

bridged if amp see's half the ohm valve I should run 2 4ohm speakers to have a 4 ohm load

 

If you run speakers in series the resistance is additive. With two 4ohm speakers in series, the amp will see an 8ohm load. With two 8ohm speakers in series, the amp will see a 16ohm load. As the resistance increases, the effective power of the amp decreases. If the amp is rated at 75w into a 4ohm speaker, it would produce roughly 37.5w into an 8ohm load.

If you run speakers in parallel, the resistance is lowered. With two 4ohm speakers in parallel, the amp will see a 2ohm load. With two 8ohm speakers in parallel, the amp will see a 4ohm load.
If you want to bridge the amp, you would need to run 8ohm speakers in parallel. In this instance, the amp would produce 200w per bridged channel and each speaker would receive 100w.

I think you alluded to this in your post but I wanted to clarify on the series vs parallel piece.

If you choose to run each speaker on it's own channel, you would have the ability to tune the fairings, lowers, and horns separately. If you go with the bridged option, you would be tuning the fairing and lowers together and the horns separately.

 

I would wire each speaker to it's own channel as Juice suggested for better control.

As it has been said time and time again ALL WATTS ARE NOT CREATED EQUALLY.

75 watts from that JL will be PLENTY for those PRV. The more power you throw at the speakers the higher you will have to cross them over.