# HT subwoofer replacecent help please



## Golden Ear (Oct 14, 2012)

Hi guys. I have a Harmon Kardon ht-14 subwoofer that sounded great until last night. I think the sub itself is blown and I'd like to replace it. It's a bass reflex (ported) enclosure about 2-2.2 cubic feet with a 12" sub. The amp is 200 watts rms. I'd like to know if I need to put an 8ohm sub back in or if the built-in amp will run a 4 ohm sub. I also need a sub recommendation.

Thank you in advance for all the help!


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## asoggysponge (May 14, 2013)

The amp is stable down to 3.5ohms, so your final impedance wired can be 4 ohms. If the sub you took out was an 8ohm, the wiring already exists to take it recommended impedance and I would use an 8ohm driver. Check parts-express, all the suggested enclosure information is available per sub.

Before you go about buying a new sub, are you sure it's the sub and not the amp? Can you try testing the sub on a different amp?


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## Golden Ear (Oct 14, 2012)

asoggysponge said:


> The amp is stable down to 3.5ohms, so your final impedance wired can be 4 ohms. If the sub you took out was an 8ohm, the wiring already exists to take it recommended impedance and I would use an 8ohm driver. Check parts-express, all the suggested enclosure information is available per sub.
> 
> Before you go about buying a new sub, are you sure it's the sub and not the amp? Can you try testing the sub on a different amp?


Thanks for the help! Do you know if I install a 4ohm sub if it'll double the power output of the amp to 400watts or at least more than the 200 watts @ 8ohms?

I checked PE but all the subs say the ideal enclosures are from 4-8 cubic feet. Who the heck has an 8 cubic foot sub in their house??? I did see a morel that was close to the specs of my enclosure but it was around $250. 

It's definitely the sub and not the amp, it has a blown sub sound.


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## asoggysponge (May 14, 2013)

The amp is only stable to 3.5ohms, you cannot take the final load below that. You could go with a 4ohm dvc sub and wire it in series to get an 8ohm load.

You don't have to use a home sub, you could pick up any 12" subwoofer. Shop around, there are plenty. Recommended is just that, as long as the dimensions are close you won't have a big problem.


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## Golden Ear (Oct 14, 2012)

asoggysponge said:


> The amp is only stable to 3.5ohms, you cannot take the final load below that. You could go with a 4ohm dvc sub and wire it in series to get an 8ohm load.
> 
> You don't have to use a home sub, you could pick up any 12" subwoofer. Shop around, there are plenty. Recommended is just that, as long as the dimensions are close you won't have a big problem.


So if the amp is stable to 3.5ohms why couldn't I put a svc 4ohm sub in? Is it because ohms vary constantly and will drop below 3.5? Pardon my ignorance, its just that I have a couple 4ohm subs in my garage that I could use if the amp allowed. Thanks again!


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## legend94 (Mar 15, 2006)

Have you looked at madisound?


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## asoggysponge (May 14, 2013)

Golden Ear said:


> So if the amp is stable to 3.5ohms why couldn't I put a svc 4ohm sub in? Is it because ohms vary constantly and will drop below 3.5? Pardon my ignorance, its just that I have a couple 4ohm subs in my garage that I could use if the amp allowed. Thanks again!


It's all a matter of how it is wired. If the original driver was 8ohm, then it was wired to produce around 4ohms at the amp. I'm assuming the original driver was a single voice coil and the impedance was taken down at the amp and not the driver.

If you take a 4ohm dual voice coil sub and wire it in series it will produce the desired final load at the amp. If you use a 4ohm single voice coil sub and use the existing wiring the final load will be below what the amp can tolerate and it will fry. 

If the original driver was 8ohm that's what I would suggest using. If you have a 4ohm dvc and you wire it in series the load would be 8ohm. As long as it's 8ohm it won't be a problem.


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## Golden Ear (Oct 14, 2012)

I haven't checked Madisound yet, actually, I didn't even think of it. Good idea!

The sub I was thinking about using is a Kenwood KFC-W3005. It's a cheap 4ohm svc sub with high sensitivity. 

I'd rather not fry the amp so I'll find an 8ohm or dvc 4ohm sub to use. I'm hoping to find something ideal for my enclosure but I might have to settle for something that's "close enough".

Thanks for the help guys!


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## legend94 (Mar 15, 2006)

What is your budget for the new sub?

If you want used I bet a wtb in the for sale section here would work.


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## Golden Ear (Oct 14, 2012)

So I pulled the sub out of the enclosure and found a toy car, a pair of socks, and a Spider-Man glove :/ I think the car was bouncing around on the sub and causing the noise...unbelievable. Thanks for the help guys.


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## legend94 (Mar 15, 2006)

That is hilarious! That should be a thread in off topic.


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## msmith (Nov 27, 2007)

Most powered home subs use a LOT of EQ to extend low bass. Many also employ limiters to protect the driver. You can't apply conventional box design formulas without accounting for the EQ curve.


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## asoggysponge (May 14, 2013)

Golden Ear said:


> So I pulled the sub out of the enclosure and found a toy car, a pair of socks, and a Spider-Man glove :/ I think the car was bouncing around on the sub and causing the noise...unbelievable. Thanks for the help guys.


Fantastic news, hopefully it won't need replaced.


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## ousooner2 (Jan 6, 2011)

Golden Ear said:


> So I pulled the sub out of the enclosure and found a toy car, a pair of socks, and a Spider-Man glove :/ I think the car was bouncing around on the sub and causing the noise...unbelievable. Thanks for the help guys.


Hahahah


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## Golden Ear (Oct 14, 2012)

asoggysponge said:


> Fantastic news, hopefully it won't need replaced.


Thanks bud. Fortunately, I put it back together and it's back to normal.

I should start a thread on why and how wife's and kids hate on our ht. Good idea!


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