Is it possible for yamaha receiver to amplify passive subwoofer somehow?

[oarabacioglu]

I have a spare passive subwoofer from previous home theater (sony bdv e4100) system.
Its mainboard failed to run after years of operation.
Then purchased a receiver unit(yamaha rxv685) but realized that there are no amplified subwoofer output.
Thought may be I can use a channel on receiver(zone1 or zone2) somehow to amplify.
Are there any risk to burn the system? And if there is not how could it be done in settings of receiver?

 

[scene]

Hmm. Unless your sub had specific inputs for standard l/r channels, and then outputs for l/r speakers I'd be loathe to connect it to you yamaha directly. If nothing else, because it would probably be tricky to configure on the receiver. You could possibly try to set it up as the base speaker of a bi-amped front pair, with the high-end going to a front (small) speaker and the low-end going to the sub. However, you could only route one of the two front low ends (bass) to the sub - which could give some oddities with the bass.... And there would be no way of setting any cross-overs. You'd basically set the system up as 5.0, with the front pair bi-amped (the 685 is a 7.2 system), and the low end of one front speaker would go to the sub...

System would probably/might be OK - that is probably/might not damage it.., bass would probably suck. If you're dead set on it, you'd be better to get a separate power amp for the sub and attach the sub via the sub pre out. Given that a subwoofer amp is going to set you back about £100 - you might be better to get a cheap sub for £100 - or cheaper 2nd hand? Are you using the other speakers from the Sony system with the yamaha?