Problem with Pairing a passive sub-woofer from Sony in a box, with Yamaha RX440 AV

Hey Guys,

I'm in a crazy situation where i need to make use of the speakers sub from Sony HT in a box. I'm planning to power them with my Yamaha RX440 AV receiver and another DVD player.
Speaker outputs are matching Yamaha specs and RX440 able to drive the speakers, how ever i'm not able to drive the sub.
The sub is passive one and with a standard +/- speaker wire bindings behind. However the sub output from Yamaha is one single RCA jack.
So i connected a RCA pin to the standard speaker cable (1 RCA at source and two split ends at sub) - but there is no signal.

Can passive sub work with RX440?
Or am i missing anything with the cable?

Please help.

Not directly,but if you get a sub amp ,you can connect it to AVR subout.
You need to check spk impedence,power ratting if they match with AVR.

a simple solution is to connect +/- of ur left channel to your +/- of passive sub.
So, +/- of left channel would then be driving ur left speaker as well as sub. Low frequencies from ur sub doesnt have much of stereo effect..

Cheers !

Oh, i thought AVR is providing amplified sub out. If this is the case, can i get an active sub and connect it directly?

If you get an active sub, you can connect it directly. There will be no issues.

I dont know whether that would be a good idea. Yamaha website suggests usage of 440 with a sub-sat system since its only a 65 WPC AVR. However, I've used it with Jamo floorstanders and Yamaha sats for 6+ years with absolutely no trouble at sane volume levels but I suspect it would struggle to cope if asked to deliver low frequencies on a sustained basis to a passive sub.
The situation would get worse if the LFE signal is redirected to the fronts thru bass management. On the other hand, if the LFE is not redirected, it would continue to be output from the LFE RCA socket which is not connected to anything - so all LFE effects would be lost.

Hope my logic is not messed up. Please correct me someone, if I'm wrong.

hi demigod,

Avoid connecting the sony passive subwoofer to the yamahha AVR. Normally in the HTIB sony systems, the subwoofer or speakers are 3 ohms to 3.8 ohms in impedance. The yamaha AVR impedance ratings are from 4 ohms to 8 ohms or more. If you connect a speaker which has lesser impedance than 4 ohms, it will affect the yamaha AVR. Only the active subwoofers can be connected to the yamaha AVR.

Passive subwoofers can also be connected to the yamaha AVR, by using a seperate subwoofer amplifier. The subwoofer amp has speaker +/- outputs and rca inputs, volume control, frequency control, phase control etc.

Connect +/- of the subwoofer to the +/- output of the subwoofer amplifier and then connect the rca output from the yamaha AVR to the rca input of the subwoofer amplifier.

Thanks Jeeva,

That means not only Sub, and i can't connect any of the sat speakers from sony HTIB

When you say AVR will be impacted, can you please tell me exactly what would happen to the receiver? Sorry for my ignorance with impedance stuffs, but i'm already using the HTIB speakers with RX440 AVR.

I use Wharf 9.2 with Norge 1000 for stereo. Even WF9.2 impedance is 6ohm only where in Yamaha AVR output is 8ohm.
So i can't use WF9.2 also as front L/R.

That means i need to buy 5 more speakers

Is it really necessary to match amp/speaker impedance?
Until now i have been checking only the RMS output

hi demiogod,

The HTIB speakers will confirmly affect your yamah AVR by means of impedance matching factor. Lesser the impedance, harder the AVR to drive the speakers. Normally the amp will run hot when in use and when you use a lesser impedance speakers the will run much hotter due to high supply power used to drive the lesser impedance speakers, so the internal circuit parts will be affected in this regard. The life of the AVR will also be decreased. (sorry cant able to explain you technically)

All the yamaha AVR will support 4ohms, 6ohms and 8ohms impedance speakers. You can use wharfies withoput any problem and all the wharfedale speakers compatible with any 8omhs amplifier or AVR (Recommende by wharfedale company itself in thier catalogue as specified).

Yes, it necessary to match the impedance factor for amp/speaker and also the you should check about RMS output for both amp/speakers.

If the RMS output of the amp is higher, it is easy drive any speakers.