Uprating the Harman Kardon subwoofer speakers?

[Canonite]

The HK is ok, and has much more mid and high tone detail than the standard set up but even with the BM24 (Rover) in my Highline I think its pretty poor. Even with the levels flat, turning it up enough to hear on a motorway is just awful.
There's virtually no low end which I enjoy, so i'm looking at swapping the two speakers in the saloon HK sub enclosure for better driver units.

Has anyone done this, i'm worried that basically the plastic box the speakers fire into isn't gonna handle any higher pressure from a more powerful driver?

[dadragon]

Hi Alan,

This is something I will be looking to do myself, I will be picking up a set of 13cm woofers and swapping them over as the existing speakers in the HK sub ones are paper cones and pretty poor.

I cant see any issues if you change your speakers as it should improve the bass but as you are running the original HK amp I don't think you will get the full benefit from any improved speakers. Still it should be better than nothing so give it ago!

[Jakg]

The box will handle it - but don't do it.

A ported enclosure has a specific volume and port length specifically tuned to the electro-mechanical properties of the driver - different speakers require different box designs.

If you change the speaker, you've got the wrong size box, wrong size port and now tuned to the wrong frequency. It may still sound better - but nowhere near as good as it could do. Or it may even sound worse...

EDIT - For example I know this looks like a random bit of wood, but thats actually the port in my subwoofer - the width, volume and length is all tuned to mm accuracy (it took ages - I have no life) to match the speaker. Another drive, that moves more air, would lead to air going too fast through the port and would introduce port noise for example.

[Canonite]

Originally Posted by Jakg

The box will handle it - but don't do it.

A ported enclosure has a specific volume and port length specifically tuned to the electro-mechanical properties of the driver - different speakers require different box designs.

If you change the speaker, you've got the wrong size box, wrong size port and now tuned to the wrong frequency. It may still sound better - but nowhere near as good as it could do. Or it may even sound worse...

EDIT - For example I know this looks like a random bit of wood, but thats actually the port in my subwoofer - the width, volume and length is all tuned to mm accuracy (it took ages - I have no life) to match the speaker. Another drive, that moves more air, would lead to air going too fast through the port and would introduce port noise for example.

This is precisely the kind of thing I was apprehensive of happening.
Basically, all I want to do is add more weight to the low end....make it a bit thicker as at the minute it is very poor.

I'm going to check the cones themselves as I suspect they may be damaged.

Any pointers towards decent small subs would be nice, i'm more than handy with the MDF to make a box for it.

[awvc1]

just out of interest - what is the volume of the hk enclosure? Presumably if known, it is only a case of finding matching sized bass drivers that between them added together have the same enclosure volume isn't it? When you buy them, most bass drivers quote what they require in terms of enclosure volume with ported and sealed figuires given after all?

[Avulon]

Just a query, why leave the levels flat? Turn the Bass up! if that doesn't get enough then turn the treble down and the volume up. It seems people think that amp/speaker setups should sound how they expect them to with the levels flat. Even when they adjust the tone controls I often hear of people that 'run out of bass boost' not realising that turning up the volume will give them more as will turning down the treble alter the bass/treble balance. (I blame having separate controls for Bass and treble, it's easier to adjust correctly with a single tone balance control or if you want mid control as well then two controls one for bass/treble balance and one for mid cut/boost - then use the volume to compensate for any drop in overall volume. If that doesn't get you where you want to be then I suspect that the HK sub box isn't going to do it with the small drivers it uses anyway. There is a good reason that Bass guitar amps use 15" drivers!

[awvc1]

since there has never been a satisfactory public answer on this one, I'm going to take one for the team.

Courtesy of Cyber monday deals, I got - at a price that I can afford to take the hit on if I'm wrong - a pair of 130mm Rainbow EL-W5's - damn good speakers for their size which should fit the HK enclosure. I'd never settle until I knew, and once it arrives, I will make sure all of you do too.

A better use of my money might be made, but i like projects that no one else does, and hate an unanswered question, what can I say.

I will be watching for better, palpable bass response, maybe different volume, and any induced port noise caused by this. I will report back.

[Rick-sta]

Originally Posted by awvc1

since there has never been a satisfactory public answer on this one, I'm going to take one for the team.

Courtesy of Cyber monday deals, I got - at a price that I can afford to take the hit on if I'm wrong - a pair of 130mm Rainbow EL-W5's - damn good speakers for their size which should fit the HK enclosure. I'd never settle until I knew, and once it arrives, I will make sure all of you do too.

A better use of my money might be made, but i like projects that no one else does, and hate an unanswered question, what can I say.

I will be watching for better, palpable bass response, maybe different volume, and any induced port noise caused by this. I will report back.

Will be interested in how you get on Tony


Not sure what the factory fitted HK system sounds like, but myself and Tony have fitted Alpine amps to our retrofitted HK subs, and have found the HK sub to be pretty good this way. Not massive bass, but still makes a big difference and my dad loves it in his 75

[awvc1]

Thanks Rick. I think, if people feel the HK sub is a charity case, and not worth the money spent on it, then fine, they can do things another way.

Myself I'm curious, and want to see what happens. I know it can produce a reasonable amount of bass when driven correctly, so armed with the knowledge of what the rainbow front component drivers did for my overall sound, I am hopeful there will be some noticeable improvement.

I know it might go south, and sound worse, or at best sound better than it did, but not sound as good as it should, but none of us will actually know until I try it and see is how i see it.

If anyone else has any other ideas about improvements let me know - my ideas were as follows:

• Wadding inside the HK enclosure to 'trick' it to make it think it is bigger - is that appropriate with a ported bass reflex enclosure or does that just work on sealed subs?
  
• 2 small mdf rings inserted before the speaker screws into the plastic sub enclosure to decouple the speaker from it
  
• Sound deadening materials applied

if you have any other ideas of what might be good, please chip in - but also please remember this is just a 'for fun' project, so raining on my chips and saying 'just buy a good 12" sub' is both known and not required please!

[Jakg]

Originally Posted by awvc1

]Wadding inside the HK enclosure to 'trick' it to make it think it is bigger - is that appropriate with a ported bass reflex enclosure or does that just work on sealed subs?

It will depend massively on what it's tuned to, in terms of volume (of the enclosure) vs port size and factoring in speaker specs to work out whether that will help or hinder. But I don't think the first two pieces of information are out there.