Just my 2¢…
Originally Posted by XBR11
My Buttkicker mini-LFE needs 4 Ohms impedance.
My Dayton Audio APA150 can do either 4 Ohms or 8 Ohms. "delivers 75 watts per channel in its full-range stereo configuration, or 150 watts into 8 ohms when in bridge-mono mode. "
So how do I wire the amp to get 4 Ohms? Of course there is nothing in the instructions on how to do this.
The back of the amp has a Left-Speaker Output and a Right-Speaker Output; each output has a black and a red speaker wire connector. And the amplifier has a Mono/Stereo Speaker Output Switch.…
You're misunderstanding impedance and electrical resistance. There's nothing you do to your AVR to "give" 4Ω. That's a measurement of your speaker's inherent resistance. Any peculiar wiring to try to change the speaker's resistance may damage your equipment or, worse, start a fire IMHO.
"150 watts into 8Ω load" is simply a measurement of how much power the amp can produce into that amount of resistance. With a lower resistance, the amp could potentially produce more, before cooking itself to an early death.
Some AVRs like Yamahas have an adv setup switch to accommodate lower-impedance speakers. I used to use this, until learning that this is really just a setting to allow the AVR to pass UL testing of a sustained power output to low impedance speakers, by limiting internal signal power. In your case, you can use the AVR switch, or just remember not to set the trim or volume to the low impedance speakers too high, as it will make the amp work harder, build up more heat, maybe damage itself and/or the speakers. I did this for years with my ~6Ω speakers on AVRs without an impedance switch.
Follow the AVR instructions for wiring subwoofers, either as active/passive inline with the main speakers, or from an LFE/subwoofer line out connection.