Car subwoofer?

[tomgarth]

Hello.

Was wondering if it is possible to connect a car subwoofer up to my sherwood RD-6103R amp and if so how best to go about it?

Tom

 

[Nimby]

Hi Tom

Most car subwoofers are designed to take advantage of so called "cabin gain" in order to produce much bass. The small volume of the car's cabin space greatly increases the bass from speakers and subwoofers. You get much the same effect from small rooms but don't get nearly as much free bass. So the subwoofer has to work much harder to play loud bass in a larger space. In a normal room the results are likely to be very disappointing.

Running any subwoofer on a full range speaker signal is likely to disappoint too. You can't use the Sub-out (or LFE) connection because this is a low level signal of a fraction of a volt and needs an active (amplified) subwoofer to make any noise at all.

If you connect the subwoofer in parallel with a speaker on a speaker channel the car subwoofer will play all the notes from high to low. This will probably sound very bad.

You will also run the risk of burning out that channel on a stereo amp or AVR because of the very low impedance load placed on the amplifier by the two units working together. (speaker + subwoofer) Usually placing two units in parallel halves the impedance seen by the amplifier. Some car audio drive units have 2 Ohm voice coils which results in a very nasty load indeed on any amplifier not specially designed for it. That means you can't use most AVRs, stereo amps and pro power amps.

Many car audio subwoofer speakers (drive units) have a very low spec compared with home audio and HT drive units. They suffer from lots of chrome and bright colours to attract the innocent buyer. They might work fine in car but not in a home system.

In summary: Probably not a good idea at all.

 

[Import racer]

Have to disagree somewhat on the car audio subs.

I was in the trade of awhile and have seen the massive improvements in car audio subwoofers over the last 15 years.
Yes some are pretty rubbish, but some are truly amazing over engineered speakers much better than most HC subwoofer drivers.

The JL fathom's / Gotham's for example are essentially slightly reworked car audio speakers.

Most big name brand names and some not so well known subwoofers from around £125 are very, very good these days, but obviously still require the right amp/crossovers and boxes to work very well in the home.

 

[k13 wjd]

id have to agree.......having heard a "car" subwoofer in a full on HC setup..

It was a dual coil 12" pioneer subwoofer, with 4 inch cone excursion, and 2000WRMS power " handling"...mounted in a 1.5 cubic ft box........,meter showed it going down to 15 HZ...my eyes saw it opening the door, and my ears heard nothing for about a week afterwards !


It all changed when kicker came out with the square subwoofer !

 

[Nimby]

Thanks guys. I can only speak from personal experience. When I was looking for 12" ,15" or 18" drivers for my IB I found nothing in the car audio range with remotely enough Xmax or a low enough Fs for domestic subwoofer use. There are a number of excellent US drivers of course but I found nothing in the specialist car audio shops or online here in Europe.

When Tom asked about a subwoofer I imagined a ready-made, passive box or tube designed for placing in a car boot. My observations above still hold true for their domestic use. They are voiced for cabin gain. They also need separate amplification and an active crossover. None of which will be likely to end in real satisfaction. An active, domestic subwoofer would probably be cheaper in the long run and provide a lot more fun.

If Tom owns a JL or Fi subwoofer driver I'm almost certain he would have mentioned it in his post.

 

[tony brazao]

Agree that car audio subs can be brutal.

There's loads to choose from too.

 

[majorwedgy]

Im with Nimby on this one - no because a car sub couldnt cut the mustard but because the sherwood amp wouldnt. You cannot connect a pair of 2k floor standers to a £50 eltax amp and expect deep bass, the same applies here, to get a decent rumble you are going to need a seperate amp akin to what a HC sub would have. Also connecting the sub direct to the speaker output will sound awful without some form of crossover and enclosure. If you fancy disecting an old HC sub and replacing the drive unit with a car sub it may sound better than the original but you are essentially asking for a miracle by adding a car sub to a cheap amp without an enclosure (assuming you are not using an enclosure) and even if you are you will still need a meaty amp - not the sub pre-out that may be fitted to your amp or even the sub output that your amp may have

 

[Import racer]

JL and FI are most certainly not the only company's making amazing car/home subs if the OP now wishes to build a decent sub, hopefully the opinions here may help to decide on whether it is possible,

With care and effort yes it's possible to rival SVS.
But agree and should have wrote in first post not with a sherwood amp or any old sub.

 

[Nimby]

JL and FI are most certainly not the only company's making amazing car/home subs if the OP now wishes to build a decent sub, hopefully the opinions here may help to decide on whether it is possible,

With care and effort yes it's possible to rival SVS .

It might be helpful at this point if you name some suitable subwoofer drivers.

I could do with some tips on decent drive units for future research.

 

[Import racer]

It might be helpful at this point if you name some suitable subwoofer drivers.

I could do with some tips on decent drive units for future research.

There is masses of information available on the internet,
but if anyone is genuinely interested they can always PM me and as always will be glad to help.