To compliment my recent component-speaker install I'm planning a subwoofer, courtesy of Santa. I'm after something modest for me to listen to inside the car, rather than for other folks to hear outside, just to add some phatness

First thing I need to know is: will anything actually fit beneath the heated L & K seats?

The lowest-profile one on my shortlist is this In Phase which is just 69mm tall (http://www.ebay.co.uk/itm/260898995225?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

I could also fancy a Vibe to match my other stuff which is 80mm tall (http://www.ebay.co.uk/itm/VIBE-LiteAir-Optisound-Auto-8-compact-powered-subwoofer-/160652189958?pt=UK_In_Car_Technology&hash=item25679de106).

The Vibe is also available without an amp for £120 (which may be suitable for me), but both are in Santa's price range anyway.

So who's got one, heard one, tried to fit one? Am I just making things difficult trying to get it under the seat? Would I need a bigger one if it ends up in the boot? Is my shortlist total tosh?

As ever I'm grateful for any assistance

I think youll struggle, theres hardly any room with the shape of the seat runners. Measure it though and see. Chucked mine in the mesh pocket in the boot. Probably not as good but nowhere else to fit it.

you should consider this

http://www.focal.com/en/car-audio-sound/caissons-basse/subwoofers/bus-20.php

you should consider this

http://www.focal.com/en/car-audio-sound/caissons-basse/subwoofers/bus-20.php

I'd noticed that one but glanced past it due to the unimpressive look of the unit. Silly really when it's for listening to, not for looking at. I'll add it to my list, have you listened to one of these? Will it be effective if I end up installing it in the boot?

Lots of questions I know, but when I first ordered speakers I immediately got comments saying "you shouldn't have bought those!", and I cancelled the order and bought better. I'm just trying to cover that before I order this time

Edited 30 November, 201114 yr by ExHondaMan

No,have'nt listen it,but has good reviews on other forum.

Like you I want a sub under seat too,and my money will go for that Focal.

There are 2 versions of it,20 and 25 cm woofer diameter

And BTW ,is not that slim,76 mm high,is right between the 2 models in your first post.

It looks like this under the seat of an R32 MK5

Edited 30 November, 201114 yr by IulianE

Thanks for those pics, helps me gauge how it'd look. I work in packaging so I'll get a box made to the exact size of the unit, see how it fits in the car.

If it fits like the one in your pics that would be great. I rarely have more than 3 people in the car so it won't be in the way of a passenger's feet. I'd install it under my own seat, so I really feel da beets :p

Could you have a look over this one, seems to be a newer version of the 20cm one: http://www.focal.com/en/car-audio-sound/subwoofers/subwoofers/ibus-20.php

Yes,the driver side is the best choice,you don't want the rear passenger to put his feet on the sub.

I'm a bit worry about the rear heating ,the vents are blowing exactly in the sub.

Edited 30 November, 201114 yr by IulianE

I'll have to get under there and take a look. I have heated seats too so it could get very hot under there

Whats wrong with the boot ??

I got a smallish box in mine and still get a family of fours crap in there when we go away, it will miles better than those crappy under seat things

Some of us need every last inch of floor space in the boot. For instance, take my estate. My Marshall 4X12, and an amp head (plus a miniature spare I have) take up the entire boot space, and the cutaway on the right hand side, with just about enough room to sneak a couple of guitars on top and still pull the cover over to hide it all.

My only option is something like RobClubley's build over on the left hand side, since there's no way I'd give up floor space for one of those active tiddlers.

At the end of the day, there really is no substitute for cubic inches. When it comes to cone area, and more importantly, enclosure area. The throw (cone excursion) of those drivers on miniature active subs are usually very limited too due to the enclosure size, which is compromising them even further. I really ought to dig out my modelling software I had on a very old desktop and see if I can calculate something useable for an old Rockford Fosgate Punch 10 I still have kicking around in the garage somewhere, and do a custom enclosure like Rob's. It's been an awful long time since I messed around with ICE properly.

Actual boot space isn't much of a priority for me, we have a people-carrier for big loads / holidays anyway. The most I regularly carry is 2 MTBs and I just lift the rear seat bases and stand them up there, wrapped in tarpaulins of course. I do like having my audio hidden away though, so I'd go for a stealthy 'hidden box' approach for that reason too.

My basic idea for putting the sub inside the cabin is that I really don't want the music loud, I just want to add some bass that's missing. Everything I listen to has a sub-woofer (including the Mac Pro I'm using at work right now), and I really miss that deep sound when I get in the car. :'(

I also thought that by having a smallish sub inside the cabin I'd get this bass at modest volumes, that can be heard crisply and cleanly from the driver's seat. Perhaps I could have a look & listen to yours fatty, as you're local? That way I could get a better impression of the installation size / sound I can expect before I buy. Have you got pics of your installation? What sub is it?

The other issue with these compact subwoofers is that they're not really 'sub'-woofers at all. Look at the response specs of all of them.

My little 5 1/4" home made bookshelf speakers have a more impressive response than most of them (but then I did design and tune them very carefully to the drivers fitted, both the crossovers and the cabinet design)

The other issue with these compact subwoofers is that they're not really 'sub'-woofers at all. Look at the response specs of all of them.

My little 5 1/4" home made bookshelf speakers have a more impressive response than most of them (but then I did design and tune them very carefully to the drivers fitted, both the crossovers and the cabinet design)

Interesting stuff, exactly what specs are good for a real sub-woofer? I'm new to this stuff and keen to learn if you have patience to explain it me

Well, the flat subwoofers are a compromise really. The best bang for buck would be a proper box to allow the speaker to breathe.

Interesting stuff, exactly what specs are good for a real sub-woofer? I'm new to this stuff and keen to learn if you have patience to explain it me

Not much to explain really. Below 100Hz is regarded as sub-bass. But 100Hz isn't a very deep tone at all if your hear it directly from a frequency generator, and it doesn't give you much of a kick if you set up 100Hz as a momentary pulse. Many of those little boxes rarely go below 50Hz. 50Hz is quite easy to achieve from a quality normal woofer, in a well designed cabinet, using cones even as small as 5 1/4". Even 50Hz doesn't actually feel that low in reality, and won't give you much of a kick in the kidneys. It's deep, but not what I'd call sub-depth.

Personally, if a sub-woofer failed to go below even 35Hz at more than -3dB, I wouldn't be interested in it at all.

Here's an interesting factor when looking at the specs. Most things are quoted between a certain range at + or - 3dB, that is the frequency response should be within 3dB either side of the "flat" line. Now it takes double the wattage to make an increase of 3dB volume at any given frequency. 3dB is quite noticeable, and anything in excess of that sticks out like a sore thumb, both in the peaks and the troughs of the response curve, if you REALLY know the material that you're listening too.

Personally I just wish I had room in the car for an open-reel tape deck (since my turntable probably wouldn't work so well in the car ), some dipole subs, and a couple of nice valve amp monoblocks. But I'll save that for the living room. (Actually, in reality, in the study. The wife would go ape-**** if I had all my hi-fi gear in the living room.)

Well, the flat subwoofers are a compromise really. The best bang for buck would be a proper box to allow the speaker to breathe.

But then there are boxes, and there are boxes. You've really got to match the enclosure carefully to the drive unit itself. Too big and the sub will sound slow, pondering, and rather boomy as the speaker will be underdamped and out of control.

Too small and the sub will be tight, punchy, but not that deep, and may have a rather high resonant frequency, that is to say a not very deep note that will seem louder than all the others.

Porting is another issue and should be calculated VERY carefully based on the thiele small parameters of the drive unit and a given cabinet size, since that has a real habit of tuning the cab to one particular boomy note, if not fully understood.

But yes, small flat subs are a massive compromise, and don't really do what they claim to.

TBH I have an 8 inch flat sub in the boot (ally enclosure) and while it wont rattle your teeth out definitely does add a fair bit of low end clout.

Edited 4 December, 201114 yr by Liverpool-Lad

Teeth rattling was never my style anyway. Or clout for that matter. I prefer things to sound natural and flat (I'm an audiophile at heart, hence why I've gone to such great lengths to design cabinets carefully in the past) and would rather tap myself in the head than listen to bass heavy dance tunes. The only reason I've ever added subs in cars is because of the massive compromise that the main speakers are under. Nowadays I can't afford to lose the room though. Too much gear and family to lug around.

Thanks guys, lots for me to think about there. I"ll pop a shortlist up when I've decided on some options

It does kind of depend on how much this evening's eBay sales go!

Don't bother with anything below 30hz as it just sounds like 'woofle'... you get a crisper sound if you can cut anything below 30. With a sub make sure your components can have a high pass filter at around 120hz engaged. This will help eliminate any potential vibration from your components!

As you know Vlad, I'm currently running my components directly from the head unit, using the crossovers to limit the high-end sounds to the tweeter. Vibe said this was fine, and that adding a sub-woofer would prevent the deepest bass sounds being passed to the woofers and lost or worse: sounding gash.

Once I have a subwoofer I'll achieved that sub-bass AND a better sound from the woofers, so I think I'll be happy for a while. I may just want to install an amp to drive those woofers eventually, which would hopefully be an end to it!

I can buy a sub anytime after December 10th, so serious shopping / thinking to be done this weekend if I'm to install it in time for Santa to listen to

As you know Vlad, I'm currently running my components directly from the head unit, using the crossovers to limit the high-end sounds to the tweeter. Vibe said this was fine, and that adding a sub-woofer would prevent the deepest bass sounds being passed to the woofers and lost or worse: sounding gash.

Adding a subwoofer won't prevent ANYTHING from being passed to the woofers in this case. Unless you run either a seperate simple crossover in front of the front speakers as a hi-pass filter, or run them off a seperate amp limiting the frequencies with an active crossover. All a sub is doing in the way you are running it is simply adding bass. It does not affect the front speakers in any way, shape or form.

Just adding a sub will not affect the way the front woofers work at all without a hi-pass filter.

Still, I'm not surprised that advice like this came from Vibe. They're not exactly well designed stuff, or quality components by any stretch of imagination. More a case of, this looks nice, we'll put this unit in it, 'cause it also looks nice!

Don't bother with anything below 30hz as it just sounds like 'woofle'... you get a crisper sound if you can cut anything below 30.

Not with a well designed enclosure properly matched to a decent drive unit it won't, but if we're talking bass on a budget, then yes. And of course you need a decent amp and clean power supply to go really low without sounding flabby.

I was actually thinking that connecting a sub to my (http://www.kenwood-electronics.co.uk/products/car/cd_receivers/cd/KDC-BT61U/) head unit's subwoofer pre-out would mean that the bass frequencies go there instead, filtered from the source. I believe my head unit has a low-pass filter but I can't access that sub-menu without actually plugging one in. Here's what the manuel has to say on the subject:

Although my eyes lose focus when I try to absorb the details, it seems to be saying that I can select the filtering frequency for the sub anywhere between 30 and 250Hz, with 250Hz being the default. Does that seem correct?

I was actually thinking that connecting a sub to my (http://www.kenwood-electronics.co.uk/products/car/cd_receivers/cd/KDC-BT61U/) head unit's subwoofer pre-out would mean that the bass frequencies go there instead, filtered from the source. I believe my head unit has a low-pass filter but I can't access that sub-menu without actually plugging one in. Here's what the manuel has to say on the subject:

Although my eyes lose focus when I try to absorb the details, it seems to be saying that I can select the filtering frequency for the sub anywhere between 30 and 250Hz, with 250Hz being the default. Does that seem correct?

No, you still need to set the high-pass filter from the front. Setting both sub and fronts centred around 100Hz with an -18dB slope would be reasonable. Are you still running rears from the head unit? If so, you might want to set the high-pass on those too.

The head unit uses a network of active crossovers that affect ONLY those particular outputs.