If a sub is connected via speaker level connections, does the receivers internal amp still power the mains, or is the sub's amp now powering the mains? Just curious.
If your receiver has no sub-out, then the only option is to use speaker level connections, like I do. The XO in the sub will taper the low level cutoff, but the mains will still see the full spectrum. If your mains do not like the full bass, of if you want to tailor things a bit, then a cub with mains in and out will let you tailor the response that the mains will see. However, the bass will sometims roll-off a full octave, muddiying things up a bit. A good sub can filter this, if it has a 4th order filter.
Always look for 4th order or higher in a sub for a sharp roll-off.
i have a 4 ohm, dual voice coil sub which i'd like to connect to a separate two-channel 8 ohm stereo amp directly...how do i go about wiring the amp's L & R speaker outs to the sub L & R terminals?
Yes, if each VC is 4ohm, that's what each channel will see. In parallel, it'll be 2ohm, than with the customary dip, lower and an amp killer (potential) In series, add 'em up for a total of 8ohm.
by running the voice coils in series, it gets me the desired 8 ohm load, but it also decreases my connections to a single channel; what to do with the other? (L/R). by maintaining the two separate voice coil connections to accomodate each channel (L&R), I'm stuck pushing 4 ohms each from the 8 ohm amp. I hooked it up this way o'er the weekend and it seemed to function o.k., albeit hungry for power. the amp didn't seem to mind, though. warm-ish, but by no means marshmallow-roasting temps.
the setup is a passive 15" dvc (4 ohms each) in an infinite baffle box sized accordingly, powered by a separate stereo amp (yamaha M-80) that's been collecting dust.