I have this amp: Blaupunkt PCA2120
I am getting this sub: Alpine SWR 1542D
What would be the optimal way to wire these two? TIA

 

wrong amp for that sub. Dual 4 ohm coils, so you need an amp that does 2 ohms mono.

 

so will the amp be (alright for now?) If so, how do I wire it up until I can get a better Amp.?

 

You've got two options since that amp is not stable at 2ohm mono.

First, since it's a stereo amplifier, you could drive each voicecoil with a channel of the amp, however the input signal to each channel of the amp would have to be identical (as in, mono)...and even then you're taking a chance of damaging your woofer doing this. I recommend against it for several reasons however...

Your second, and much safer bet is to wire the voicecoils in series, and run the amplifer in 8ohm mono. You're going to produce less power however that configuration is guaranteed to work. Connect the + of VC1 to the - of VC2, then connect the - of VC1 and the + of VC2 to the amp's bridged speaker output.

When purchasing a replacement amplifier, make sure you get one that is designed for 2ohm mono operation. Alpine's MRP-M850 would be a perfect affordable match for your subwoofer.