2.1 setup with subwoofer. do i need subwoofer's amp or can i power with just receiver?


New member
Username: Erniemink

Post Number: 1
Registered: Sep-12
When I just want to use a 100 watt stereo receiver to power a subwoofer and two speakers, thus a 2.1 setup, do i need to use the amp built into the subwoofer or can i just use the crossover in the sub with the line level inputs and outputs and have the receiver's volume power the sub and speakers together?

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17406
Registered: May-04

If the active sub has a plate amp with crossover, then the plate amp is going to power the sub. Only in the case of a "passive" subwoofer would the receiver power the sub.

Gold Member
Username: Magfan


Post Number: 2877
Registered: Oct-07
Line level doesn't provide 'power'.
If the sub plugs into the wall, it's got an amplifier which you must make use of.
A passive sub will just have terminals for speaker wire.

Some of the 'new' generation of Stereo components do provide for bass management. They will have a sub out and a crossover so the burden of bass frequencies can be removed from the 'main' speakers.

Gold Member
Username: Superjazzyjames

Post Number: 1967
Registered: Oct-10
Even if you connect the sub at the speaker level, the sub amp will power the sub. The signal will be attenated internally and re-amplified, but you don't have to do anything other than run speaker wire to the sub. You can either "daisy chain" it which is to run wires from the receiver to the sub and from the sub to the speakers. Or you can connect your speakers to the "A" terminals of the receiver and the sub to the "B" terminals provided the A & B terminals are in paralell when both outputs are on.

Gold Member
Username: Magfan


Post Number: 2880
Registered: Oct-07
the INPUT impedance of a powered sub thru the speaker inputs is very high, so no worries about dropping the impedance at the amp or sucking 'too much' power.

New member
Username: Berniew

Perth, Western Aust... Australia

Post Number: 10
Registered: Oct-12
If your receiver can amplify the left and right mains and simultaneously provide a line or aux output, then just connect that output to the sub, and the sub will use its own inbuilt amp and crossover filter. Then the main volume should be controlling the amount going to the sub anyway through that line output.
The stereo receiver/amp will power your main left/right speakers, but not the sub. It's a stereo amp, which is 2 channel, so it doesn't have a third powered (amplified) output for the sub, so you'll want the sub to use its own.You just want to put it on a connection controlled by the volume knob. Then the volume on the sub can be used to control the ratio of sub to mains level.

You could use a passive sub with its own passive stereo crossover for the mains driven by the receiver/amp, if you had one, but your sub is active and doesn't work that way.
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