How to add a single subwoofer to my stereo system?

[drew3945]

Hello all,
Being on a very tight budget, and being a born experimenter, I've lashed together a system for listening to mp3 misic files and movies from a flatscreen TV with a SC card slot. The headphone output of the TV goes to a pair of active PC speakers to which I have added parallel outputs, going to a pair of hi-fi speakers. As the woofers are only 5" dia, and because I like experimenting, I'm planning to add a subwoofer. (I won't be annoying the neighbours, as my place is detached and I'm not into high volumes anyway. I just want to increase the fullness of my movie-viewing and music-listening experience.)

The question is, how best to wire it in. I have an extra amplifier which I can use, per my sketch, but am not sure the best way to wire it in. It's only a single 12" subwoofer, which ideally needs to pick up the signal from both channels of the amp. On my sketch, I have drawn what I think are three possible ways of wiring it in. Can anyone correct me if I'm wrong and/or tell me which of the three options to use? (Forgive the sketchiness of the sketch...). The disadvantage of option (3) is that it only outputs the sound from one channel.

Many thanks
Al (Drew)

[drew3945]

PS.. I seem to be having a problem with the Y-splitter. I thought that a simple headphones' Y-spitter would work well for splitting the signal petween two amps. Not so. The panning feature of the sound source doesn't work when I use a Y-splitter, and the sound quailty seems inferior too.

What component do I need to split the signal going to two amps?

TIA

[Firebottle]

Does your 25W stereo amp have a tape output. If so connect this to your 200W sub amplifier and switch it to mono so the single sub gets signal from both channels.

For option 3:
You will be better off using a much higher value of resistor on the unused channel of the sub amp, you will waste a lot less power and can use a smaller resistor. I would suggest 100 ohm, just to put a small load on the unused channel.

[bobbasrah]

Does the TV not have signal out as RCA ? Headphone circuits on TVs are not known for their high quality output...
It would be better to feed to amps at signal level...

[drew3945]

Does your 25W stereo amp have a tape output. If so connect this to your 200W sub amplifier and switch it to mono so the single sub gets signal from both channels.

Firebottle, Unfortunately, the amp has no such feature. Thank you for the tip about using a higher impedance resistor for an unused channel. I used a piezo tweeter the other day. I'm not sure if that was technically an okay thing to do, but it seemed to make sense, as I didn't have any resistors in my possession. I muffled the tweeter to make it inaudible.
Al

[drew3945]

Does the TV not have signal out as RCA ? Headphone circuits on TVs are not known for their high quality output...
It would be better to feed to amps at signal level...

Bob, Thanks for the suggestion. Unfortunately, none of the TV's RCA terminals appear to be audio outputs (see scan of TV handbook page below):