Axiom Home Page Forums General Discussion Stereo Connecting Integrated Amp to Sub

I have a tube integrated amp and a Polk PSW505 sub. I've connected the left amp O/P to the left main speaker & the right amp O/P to the right main speaker.

I've connected the left pre-amp O/P to the left Line In of the sub, and the right pre-amp O/P to the right Line In of the sub.

I get no sound out of the sub, except a low level rumble.

I have connected the polarities correctly.

Any ideas?

Well, thoughts are, can this amp be a unit that disables the pre-outs when the speaker outputs are in use, or does it have a setting that's required to be turned on to activate the pre-outs? Besides checking the manual for some obscure setting requirement, try things one at a time. Run the sub from the pre-outs without the speakers connected; if no result, connect it with the speaker wires to the speaker level inputs to see if it's even working correctly.

Try disconnecting one of the pre-amp outputs to the sub.

Manarex, are you trying to use the pre-out of the main speakers to the sub or the "subwoofer" pre-out?

Also, what are you using to determine that sound is coming out or not? Most material don't have enough low frequencies to be drive a sub loudly.

I should have told everyone that the sub is a Polk PSW505 (rear-slotted vent, with 12" driver, and DSP circuitry). I'm playing Bach & Widor organ music. I've taken off the sub's grill so I can watch the diaphram move, and put my hand in front of the rear slotted port to feel air movement.

I can barely see the diaphram move, and there is no air coming out of the rear-slotted vent. Volume is set at 12 o'clock, and the low pass filter to 60 degrees.

I should also told everyone that this is an integrated tube amp. There is a connection for CD, SACD, DVD, and tuner, all of which are controlled from one multi-position switch. There are also two pre-amp O/Ps, which are not dedicated to anything. I am using one of the pre-amp O/Ps to drive the sub. I'm feeding the positive wire into the Line In+ terminal, and the negative wire into the Line In- terminal.

The main speakers are connected to the amp speaker O/P. The sub low pass knob is set to 60 degrees, the phase to 0 degrees, and volume is at 12 o'clock.

The integrated amp is just a plain-Jane integrated amp, with no processing.

The sub has two pairs of "Speaker Level O/P", and two pairs of "Speaker Level Input". I assume they are for home theatre stuff. I'm using Line In R and Line In L.

The integrated amp has two pre-amp outputs, which I presume were meant to feed two amps. The are no sub O/Ps from this amp.

Ok, I don't know enough these type of connections to be of any help to you since I am not convinced this can work at all. Hopefully, someone more knowledgeable will come along soon make sure of the additional info you provided.