Axiom Home Page Forums General Discussion Home Theater need help with passive subwoofer

Hi all, I've just got an old passive subwoofer. It is from Design Acoustics. I have problem with how to connect it with my HK 525 receiver. I have a M22 as my from main speaker, a definitive center but no surrounds. The sub can only be connected to receiver's front main speaker output then to front main speakers. I am worried about this put too much burden to the front main channels of the receiver. my question is can I use the two rear surround or surround channels to connect the sub. Then how should I set the crossover. I also have a retired sony GTS 700ES receiver. Can I use it as an amplifier for the sub. How should I connect them with HK525. the 700ES does not have a LFE out connector. If it can not be used as an amplifier, can I use it in any other way in my system? Or may be I should just get rid of it.
Any suggestion is appreciated. Thanks.

Do you currently have or are you planning to have a surround-sound setup? A passive sub will not work with surround sound because your receiver will not know a sub is connected, and will therefore not know where to send the bass signal.

If, on the other hand, you have a stereo-only setup, then I'd suggest putting the sub in-line with the front L and R speakers. Speaker wires should run from the receiver to the sub, and then from the sub to the speakers. Your H/K amp shouldn't have a problem with it.

No problem!
Connect the sub out on the HK to your retired Sony with an RCA cable. Connect the sub to the Sony's speaker output, using the same (right or left) side that you used from the HK. Sony's volume control sets the relative amount of subwoofer volume, which you would calibrate using the trusty SPL meter. Set the crossover on the sub to where it integrates with your M22s (most likely setting them to small on the HK and match the frequencies). Now mark that volume and leave it there. The HK does all the work, the Sony is just an amplifier.

Thanks for the help. One thing I am not clear is that sub out from HK525 should goto which part/connector of Sony receiver. The sony does not have a low level direct input. Please suggest.
Henry

Wow. I missed the part about the other receiver altogether. Oops!

Henry, any low-level input can be used. For example, use the right channel CD input and then connect the speaker wire from the right channel main terminals to the sub's terminals.

Yes, I am planning to have a surround-sound setup. I was thinking of using HK525's no.6 or no.7 channels to drive the passive sub. speaker since HK525 has 7.1 channels, and relieve the burden from the two front channels. Thanks for your suggestion anyway.

That would work except for the fact that there's no way to tell the 525 to send the LFE signal (low frequency effects, separate from the other channels) to the 6 and 7 front speakers (ie, your sub). I'd go with the sub (LFE) out to the Sony, using that as the sub amp.

Henry, if my reply wasn't clear, I was of course speaking of using the Sony, not the HK, to drive the sub. Assuming that the 700 is in good condition, there's no reason to look for a way to put an extra load onto the 525 to drive a sub.

Thanks JohnK, I tried the connection you suggested during the weekend, but the volume of sub was very low, even I turn the sony's volume dial to very high level(85%). I used to turn sony's volume at very low level(15%)before it was retired and still got enough output. I wonder if the LFE output from HK525 is low or the sub need more power. Any suggestion? I have adjusted the HK525 sub level to +10dB. The Sony STR-GX700ES is rated at 300W and can drive 4/8 ohm speakers. The sub is supposed to connect to the left and right main output of the amplifier, but I can only get power from the right channel of CD input through the right main speaker output. Does this have anything to do with the low volume problem?