Uprating the Harman Kardon subwoofer speakers?

[Jakg]

Originally Posted by Avulon

Yep, as illustrated by duotone's photo, the rear of the cones is open to the boot space, making the boot space the enclosure and the inside of the 'sub' the front of the speaker baffle - the path to the central hole to the car cabin is a port - where the length and cross section determine tuning - see here - http://www.colomar.com/Shavano/subs.html

Which shows the arrangement is very similar to a bandpass enclosure. as illustrated below. The HK sub is the bit in front of the driver - the box behind is provided by the car's boot space (not sealed - but that's probably not important given it's size when empty). This will be why you can get decent bass out of such a small cone.

It's an interesting idea, and I think the maths suggest you might be correct. It would mean it was highly dependant on the quantity of stuff in the boot though - e.g. how much stuff was in there, if the ski-hatch was open etc.

[Avulon]

Originally Posted by Jakg

It's an interesting idea, and I think the maths suggest you might be correct. It would mean it was highly dependant on the quantity of stuff in the boot though - e.g. how much stuff was in there, if the ski-hatch was open etc.

Only to a small degree I would think - i.e. you'd notice if the boot was rammed full of hard boxes. You'd probably also notice if the ski hatch was open. Otherwise I think it pretty much counts as an infinite baffle with the empty boot space not only not sealed but so large as to make no difference - filling it with soft stuff wouldn't make much difference either as it's already carpeted inside the box: which largely takes the box enclosing the rear of the driver out of the equation. There is a another thing I notice about the HK sub - and that is that it is assymetric not only with reinforcing shapes to prevent flexing but that each side is different: that must be deliberate.

[Phil63]

What about the tourer?

[Rick-sta]

I fitted the rainbow speakers to my dads hk sub today and wow its a big improvement from the standard speakers. There is very good bass and the sound is crystal clear. No vibration or bad noises at all even at high volumes. You can really hear the bass coming from the rear sub now.

Okay it doesn't provide the massive bass i get from my 12inch sub in my ZT (never expected to anyway given the size of the speakers) but the bass from these speakers fitted to the hk sub is perfectly adequate cant comment on how well this would work with the oem hk amp, but this set up works well with the alpine v power 250w amp i have it wired to

The upgrade is worth doing from my experience thanks again to tony for looking into this and originally trying it out on his 75

[awvc1]

Originally Posted by Avulon

Only to a small degree I would think - i.e. you'd notice if the boot was rammed full of hard boxes. You'd probably also notice if the ski hatch was open. Otherwise I think it pretty much counts as an infinite baffle with the empty boot space not only not sealed but so large as to make no difference - filling it with soft stuff wouldn't make much difference either as it's already carpeted inside the box: which largely takes the box enclosing the rear of the driver out of the equation. There is a another thing I notice about the HK sub - and that is that it is assymetric not only with reinforcing shapes to prevent flexing but that each side is different: that must be deliberate.

This makes a lot of sense - I think I'd agree, the asymmetry of the enclosure indicates maybe bandpass style design. As you say, open your boot or empty your boot and the bass increases, I believe many have commented on that in the past.

It certainly makes me think stuffing the hk box with pillow foam will be useless in that case, and the lack of vibration I've experienced means I can't see any benefit in sound dampening materials, or mdf pieces where the speakers join. So, I think we can say the best way to get the best out of this sub is:

1) drive indirectly from the HeadUnit with a pre amped out going into a 2 channel amplifier first.
2) replace bass drivers with Rainbow EL-W5.

Like Rick says, don't expect to get a 12" sub competitor, you won't, but what you should have is a decent SQ setup, with nice rich bass that does a wide range of music types justice.

[Phil th Barrow]

Hi Tony, (AWVC1)

Managed to fit th Rainbows today. Tested with Yello cd How How. Nice....

Mine are driven by th normal Rover radio so not got th advantages of your set up. But yes for th money iv noticed a tighter slightly bigger bass with a lot more power handling. When they've done a few hours they be even better ..

So for th out lay of 40 odd quid I'm happy. Thanks for th head's up.

Phil

[awvc1]

Originally Posted by Phil th Barrow

Hi Tony, (AWVC1)

Managed to fit th Rainbows today. Tested with Yello cd How How. Nice....

Mine are driven by th normal Rover radio so not got th advantages of your set up. But yes for th money iv noticed a tighter slightly bigger bass with a lot more power handling. When they've done a few hours they be even better ..

So for th out lay of 40 odd quid I'm happy. Thanks for th head's up.

Phil

hi Phil, sorry when I got your pm's i was in and out of a hospital a lot- hope i answered you as well as I could.

Good to hear you are happy too, its nice to have some independent validation of this mod too.

thanks

Tony