Using a car subwoofer with home system.

[Kawi]

Hi, I recently got a new denon avs S700W to go with my tv. I have 4 good size speakers that I hooked up in all 4 corners of the room, a centre channel and a sub, both of which are pretty weak. The sub is small and can barely be heard. If I put too much sub power it just starts popping. I have a couple of sub boxes from back in the day when I was into that sort of thing, a 12 and a 10. Very powerful subs in tip top condition. Can I not somehow use these? I know they are 4ohm but I'm pretty sure the denon operates on 6, plus I think I saw two different watt/channel values in the spec sheet, one for 4 and one for 6 or 8 ohms. Does that mean that the system would just sense the different resistance and adjust? Would there be a setting I would have to change? I'd really like to use one of these subs in place of the current one. Anyone know more about doing this?

 

[WaynePflughaupt]

It doesn’t matter if the two car sub’s impedance are a proper match for the Denon. The great majority of home theater subs are not powered directly by the receiver but have built-in amplifiers of their own. In your case you would need an outboard amplifier to drive the two subs.

Regards,
Wayne A. Pflughaupt

 

[Kawi]

I just crawled back behind the unit to check the sub I currently have hooked up to the denon and you are right, it is self powered. I never realized. It has its own dial and is plugged in to power and has an on/off light. I obviously know jack $#!t about home theatre. :/
(None of these speakers nor the sub came with the receiver, I had them already.)
So basically the denon powers up to 7 speakers since it's a 7.2, but provides no power to the sub? It has 2 sub ports in the back, they're both just signal ports with no power?

 

[KEW]

That's correct. the Sub-outs are "line-level" while the speaker terminals are "high level" outputs.

Did you try turning up the volume on the sub?
It sounds like a simple case of damaged (or very crappy) sub, but being optimistic, there is a chance that the subs volume is low and you are running the pre-amp too hot when you turn it up and it starts popping.

This would do the job for $125 if 233 Watts is enough for your car sub:
http://www.parts-express.com/refurbished-dayton-audio-sa230-230w-subwoofer-amplifier--88-300-813

 

[Kawi]

I will try that, but it is likely just a crappy sub ;( its a small Phillips that came included with an old home theatre. The cone is 4 or 5 inches, my phone is wider. It works, it's just meant to work with those palm sized speakers that come with surround systems. It's not making real base. So I guess I need a sub that is self powered, which I'm guessing is why home theatre subs are more expensive than car subs lol.

 

[KEW]

Yeah, 4 or 5 inch drivers does not a sub make. If your receiver is crossing over at 80Hz, that is probably pushing the subs low end extension.

 

[Kawi]

I do believe I saw it at 80hz, I can't seem to find that setting anymore no matter how much I search, this receiver is not very intuitive for newbs. I think for now I'll just get the base from the speakers which are producing way more base than the sub anyway. Thanks for the input.

 

[KEW]

Not all home subs are self powered and they certainly don't have to be.
However, because the power requirements for a sub can vary from very low (humongous ported sub - not an option for a car) to tremendous (1500watts for high quality sealed sub), it made sense for the receiver manufacturer to not guess and let the sub manufacturer select amplification suitable for their own design.
The biggest problem of adapting a car sub to a home is that they often don't have enough output to pressurize the room. Any normal room will have many times the interior volume of your car. Add to that the greater demands of HT content (war scene with continuous gunfire, bombs, etc) and they are typically not designed to do that. However, a good car sub would probably work decent with music, and I have seen car subs that easily beat many cheaper home subs.

But realistically, something like this will probably give you the most satisfaction on a tight budget (since an amp for your sub will cost this much). I should have thought of that sooner.
http://www.parts-express.com/dayton-audio-sub-1200-12-120-watt-powered-subwoofer--300-629
http://www.hometheatershack.com/forums/speaker-subwoofer-reviews/71766-dayton-audio-sub-1200-subwoofer-review.html

 

[Kawi]

Yes I never thought of that, you are right, my car sub is 400w and it would pound the earth in my car, but in an empty room it would indeed sound like simply vibration noise from a washing machine in the next room.
As for that link, am I missing something? Those are a little too cheap, no? 12" powered sub for under 200$? I know I'm new to this but shouldn't that be like at least triple that?

 

[KEW]

Yes I never thought of that, you are right, my car sub is 400w and it would pound the earth in my car, but in an empty room it would indeed sound like simply vibration noise from a washing machine in the next room.
As for that link, am I missing something? Those are a little too cheap, no? 12" powered sub for under 200$? I know I'm new to this but shouldn't that be like at least triple that?

They are an incredible bargain. The second link is a review by Jman. He has reviewed a couple dozen or more subs so has a good perspective on what you should expect for a price and these are great over-achievers. Not the lowest sub, nor the loudest, but within their limitations they are well behaved.
I am very comfortable saying you will love one for your HT and suspect you would end up using it for music as well (depends on the speakers you have and what type of music you listen to). I used the SUB-1200 in a system I put together for my girlfriend. They do a great job. We use a pair for music and HT in her large living room (open into kitchen and dining room).
I wrote it up here:
http://forums.audioholics.com/forums/threads/my-take-600-budget-for-avr-speakers-and-subs.92915/#post-1062757

I do agree with your statement, three times the price would be reasonable. In a way, they might do better at $390, people are pretty quick to assume they can't be good for much at $130!

Too many subs at the $200 and below price point exhibit "one note bloat". These do not.

 

[Kawi]

It would do the trick for me that's for sure. 95 percent tv and 5 percent movie. No music. Thanks for the link!

 

[KEW]

Happy to help.
Let us know what you think when/if you get one!