Is hardboard effective for soundproofing a door?

[jamesnorton]

I want to soundproof a bedroom door against the sound from my stereo, which can be quite loud and bassy. I realise it can't be completely soundproofed but I would like lots of deadening. Unfortunately I'm as poor as can be and so it has to be cheap, and I can't afford to buy the wrong materials and start again. The door has a flat panel and I am not fussy about looks. I can't add more than 16mm thickness to the door or it won't open properly. I am thinking of hardboard - say 3 layers of 3mm. Is hardboard a decent sound insulator? Would it be better to put a gap with something less dense between layers - say cardboard? Heavy felt carpet underlay could be pinned to the door. Rubber seems a bit pricey. I have a couple of rubber car mats I can cut to overhang the edges for a sort of sealing. There aren't gaps though - the sound goes through the door more than round it, I think.
I would appreciate any knowledgeable suggestions.

[acsimpson]

If it's cheap and cheerful you're after the best way would be to use the volume control. Bass can travel very effectively through walls and floors so sound proofing the door may not make much difference.

[Perry525]

Noise travels as vibration. I've found that fitting a wood strip 6mm square round the edge of a door and then fitting 6mm plywood, that is only glued and nailed at the edges works fine.
The noise is absorbed into the thin plywood and doesn't cross the space, and doesn't come through the door.
My wife has all the usual kitchen toys, some a quite noisy, especially the TV and this system, means I don't hear them when sitting in the lounge only 10 feet away.

[jamesnorton]

Thanks for a practical suggestion, Perry525. I'm actually thinking of 2 layers of hardboard (cheap) slightly bigger than the door so it covers the door-frame gap with a sort of air gap between - either cardboard or polythene folded till it's at least 5mm, all as one panel, then just tacking that to the door. Comments on that?

[Perry525]

That should work fine. One trick you may like to try is, when you have glued the hardboard to the frame round the edge of the door, paint the hardboard with water, this will make the hardboard shrink to a tight drum skin fit.