Connecting Sub Woofer into Sound System

[JimCurrent]

I have to 2 older Yamaha floor speakers connected to an Yamaha receiver/amp via speaker wire. The amp is 100 RMS, 145 Max @ 8 ohms, and the speakers are 100 RMS/140 max, 8 ohms, I am aware that I could blow the speakers and I never push it. The amp has no "SUB OUT" terminals. I was thinking about adding a sub woofer to the system. My question is how do I do this? And what powered sub woofer should I get? I understand that some sub woofers have built in amplifiers. So I was curious how to do this, and the amount of power one should have if connected. I attached the back in the amp with all the terminal ports. Thanks

 

[lini]

A typical powered/active subwoofer for hifi use should sport "high-level" (= loudspeaker level) inputs with pass-through outputs for the speakers (or even filtered ones, so that especially smaller speakers can be relieved from bass duty...), so that you'd basically run your speakers through the sub, while the integrated power-amp section of the subwoofer will typically tap the speaker signals in parallel via voltage dividers. Further features a good subwoofer should sport for good integration is a control knob for the frequency up to which it should work, volume level control as well as at least a phase switch, better a phase control.

Greetings from Munich!

Manfred / lini