I recently bought a QSC RMX-1450 which has Speakon outputs. I am building some new cabinets annd have never dealt with Speakons before, but I've heard they are the current good technology for connections. Why would I choose to use a 4/8 pole Speakon instead of an 2 pole? It looks to me like I need 2 poles for a typical speaker, but perhaps I'm missing something.
I'm pretty sure that the model you want to use are NL4FC's ....ok maybe that's not the exact name but yeah, you want to use the 4 pole connectors. In reality you're only using two of the poles but it depends on how you're using the amp to determine which two poles. In bridged mono mode you need to connect the cord differently than you would for conventional use. As far as the receptacles... I believe they're two pole receptacles but they are compatible with the four pole connectors sizewise so it doesn't matter. I'm no electronic engineer... I hope this makes sense.
Get the four pole jacks, here's why: Some Speakon connectors won't work with the 2 prong jacks, but ALL will work with the four pole jacks. Doesn't matter if you only use two of the connections inside it. I found this out the hard way after I installed a 2 prong speakon jack on a cabinet, just to find out that none of my three standard speakon cables would fit.
On that amp, the upper Speakon has all four pins active: channel 1 on 1+ and 1-, and channel 2 on 2+ and 2- (this is so you can run one channel, both channels, or bridged mono off this one Speakon). The lower Speakon has just channel 2 on pins 1+ and 1-. The 2-pin Speakon plugs for speaker cables have only pins 1+ and 1-. They're perfect if you only need to run one speaker system per channel, but you can't use them for bridged mono, for example, because that would require pins 1+ and 2+. So decide how you want to operate your rig and choose your Speakons accordingly.
One thing I did was unclear: I had a typo (it's corrected now). I'd said the lower Speakon had channel 2's output on pins 2+ and 2-; that should've been 1+ and 1-. I apologize for any misunderstanding!