Adding A Sub And Amp, But Keeping The Stock Headunit And Stock Amp..?

[matt-c]

I have the stock 6CD head unit in the car, with the stock amp and speakers, but I'm tempted to add a little self powered (active) sub in the boot, just to boost the low end a bit. What I don't want to do though is get into changing the headunit, or the stock amp and it's associated cabling.

I remembered this thread http://www.lexusownersclub.co.uk/forum/index.php?showtopic=78351 where sjrainsford fitted an ipod adapter into the CD changer port on the back, and said he already had a plug going into it for an external amp and sub.

I also have an ipod adapter (a Grom unit) using the cd changer port, but the Grom's have an extra plug on it so you can still use the CD Changer port for a CD changer, like a bypass or passthrough.

What I'm wondering is, can I simply get a cable that plugs into the CD Changer port (or in my case, the passthrough plug on the Grom harness) to feed an external active sub? I realise the amp on the sub will need wiring it for power, but I'm asking more if I can plug into the headunit CD changer port to supply the audio signal, without bypassing the stock amp - so that everything continues to work as it does now, but with the addition of a seperately powered sub. And if so, how does it get configured to only pass low freq signals to the sub and now full range (or is that filtered by the amp, assuming it has an active crossover built in.

I'm not going for anything big or powerful, possibly even just a little 10" bass tube, as I'm not looking for an SQ sound system (been there, done that) - with this I just want to add a ".1" to the system, much like a home 5.1 system; just a low end boost for a little thump. Standard speakers sound fine, but it just needs a little help with the bottom end I think.

Thoughts?

[jomo]

I,d just take a feed off the rear deck speakers ran through a high-rca filter and then to the amp input.

[matt-c]

Interesting. This high-rca filter - does it work like a crossover or something? Filtering out higher freqs and only passing the lower?

[jomo]

Not a filter just converts to RCA as far as i know matey.

[matt-c]

Wouldn't tapping into the speaker wire for one of the rear speakers change its impedance level load on the stock amp? Or would that not be a factor because the sub has its own amp?

[jomo]

No mate, the high to RCA just tap onto the cable, as in you dont cut the feed to the speaker and pass it through the high to RCA adapter.

If you just running a sub then you would only need to connect to one speaker, as a sub is mono only.

Looking at the pic i posted, you'd use the blue 2 wire's tapped on to the feed to one speaker + - and the black is grounded to the car body and then just connect to your amps RCA input and your away.

HTH...

[simonneve]

otherwise most amps have a "hi-level" input with you can feed to from the speekers as well as the converter there