There are subs with two presets. Full & LFE. If Your amp has sub processing (sub out) use it in the LFE position (crossover disabled). If it doesn't have a sub out use the Full position and adjust crossover knob.
My set up is probably similar internal to the speaker but I don't know for sure since I have not pulled it apart. I appreciate the schematic. That said, what I'm looking for is how to connect a speaker out (on an amp) to a device (the sub-woofer) that wants a line level in?
I have a similar question - I may have inadvertently posted it to the wrong place so I am reposting. My home stereo receiver amp is a Sony STR-DH190 (100W/channel). It has both an "A" and a "B" speaker outputs, that is it can drive two independent speaker systems (both left and right). The Sony has no sub-woofer out. My speaker is an Infinity RS8A which has in each tower, a built in powered sub-woofer (you plug the Infinity sub-woofer amp into an AC outlet for power). The connection to each sub-woofer is normally a line level sub-woofer out from the amp, which when using the Sony I do not have. The Infinity can use either a line level low pass signal or a full range signal. I have connected the Sony "A" out to the Infinity, minus any connection to the sub-woofer. It works but I'm missing that fuller low end. My question is, is there a way to connect the sub-woofer using the "B" speaker connections? Discussed in this thread is a resistor bridge but I was not clear if this bridge could only be used if a speaker was also attached or if it could be used directly without a speaker attached (obviously I want to make sure I don't hurt the source amplifier by incorrectly loading it)? ....or is there an adapter out there that can load the "B" speaker out correctly and convert the "B" output to the line level appropriate to drive the Infinity sub-woofer? ...any other thoughts or options I missed?
You can leave system A without any modification and use system B with a voltage divider. (or vice versa) Look here.
In my case I calculated it for an OPT (valve) output but the calculations are the same for the SS output.
The resulting impedance (somewhat lower) when using the voltage divider is absolutely negligible, it will not modify the impedance required for the amplifier. Keep in mind that when a speaker works, sometimes its impedance drops to around 3 Ohms, depending on the design of the crossover network and the speakers used)
Try with the online calculator, until you find the final value in the output voltage to power the subwoofer. Buy suitable resistors for power dissipation.
It works fine since I built it.
How to take low level signal from an OPT ?
In my case I calculated it for an OPT (valve) output but the calculations are the same for the SS output.
The resulting impedance (somewhat lower) when using the voltage divider is absolutely negligible, it will not modify the impedance required for the amplifier. Keep in mind that when a speaker works, sometimes its impedance drops to around 3 Ohms, depending on the design of the crossover network and the speakers used)
Try with the online calculator, until you find the final value in the output voltage to power the subwoofer. Buy suitable resistors for power dissipation.
It works fine since I built it.
How to take low level signal from an OPT ?
Old thread, just to thank the contributors as it assisted me in putting together the circuit I needed. Used the diagram from post 14 with 8.9k and 860 values as that’s what I had lying around. Subwoofer volume set to 4 out of ten so maybe a bit sensitive but works perfectly.