Speaker sound damping

[raygreen]

I am rebuilding a pair of small speakers. This was on a previous post and the old cabinets I had made were not airtight and were too large (I have not done this before).

The new ones are smaller and are shaped to fit in a van. This is intended to be a very cheap build. The Gale Gold monitors were from a pair of old dented cabinets - drivers and tweeters in great condition.

My question concerns damping materials without buying expensive rolls of speaker material. I was thinking of initially lining the cabinets with a felt that I have used to line the van. I have also read about putting in different shapes at the back of the cabinet to deflect sound I was wondering whether sponge washing up pads cut to triangular shapes would do an effective job glued to the lining material at the back of the cabinet? It might seem like an odd question and actually seem rather funny but it is just trying to be a little novel with something that might work (plus its cheap and I have the materials to hand).

[walpurgis]

If you want to keep it really cheap and simple Ray. People may laugh when I say this, but an old towel actually damps rather well. I found this out by accident. I was decorating the bathroom and it echoed a lot while it was empty. When I hung one old towel up the echo died right down. I've tried a chopped up one in a pair of small old speakers and it worked a treat. I normally use the tried and tested damping materials for speakers, but for pennies a towel works. An old one is likely to work best as all the fibres have loosened and softened.

[Macca]

I see where you are coming from with that. B&W did something similar it was called PRISM or something. But they used a plastic moulding I think. It looked a bit like a scale model of Manhatten. The idea was not to absorb but to diffract the rear radiation from the bass mid. Like trying to simulate an open baffle mid I suppose. So your sponges will give a bit of HF absorption but no real damping or diffraction even if cut up into shapes. Is how I see it anyway. The best thing I found for this is Deflex panels but I've no idea if they still make them. Odd stuff. It looks wet and feels wet but is bone dry. And it is effective.

[awkwardbydesign]

If you are sticking with the ported cabinet, be careful where you put the damping. There could be quite a bit of air movement, especially between the bass drivers and the port, and you don't want to restrict that too much.

[raygreen]

If you are sticking with the ported cabinet, be careful where you put the damping. There could be quite a bit of air movement, especially between the bass drivers and the port, and you don't want to restrict that too much.

Would it make any difference if I go without the ports? I would probably prefer to leave them out!

[awkwardbydesign]

It would change the bass. Generally ported speakers provide more bass, but at the expense of a sudden cut off, and possibly a "one note" boom. A sealed box won't seem to go as low, but the bass will roll off more gradually, so actually go lower. And will be less prone to the one note effect, but it all depends on design and the room (or van; "cabin effect") where they are used. And the design of the drivers too. It's hard to generalise in a useful way. It would be better for you to google some of these questions, as at the moment the answers probably don't help you that much. And they are not really answers without a lot more detail!

[raygreen]

The latest in the Gale speaker saga...the quest continues.

Built new boxes shaped to fit above the barn doors of my VW van. These speakers are airtight to 28,000 feet I swear!! Removed the carpet around the cones and tweeter and all sealed with draught excluder. Sealed inside with silicone sealant. I used the old towel idea to line the insides with and I thought I would try some sponge shapes inside to diffract the vibration - not sure whether this has made any difference over leaving it out. Would like to compare with acoustic/ damping foam as a liner instead - I think it might add a little more bass and make them sound a little larger (they are a slightly smaller size now due to the cutaway at the rear shaped to the van - fit solid and secure though!).

Cut a long story short, they are 10 times better than they were. There is still a very slight distortion at a loud volume but the RCD200 may just not be up to the job at amplifying. A definite improvement in sound though.

Still a little tidying up to do to make a parcel shelf either side and in between the speakers. I will probably curse the first time I'm loading the van......'ouch'.

[awkwardbydesign]

Well done. You have learnt some basics too, such as sealing the cabinets. Now you can start to obsess over cables.

[raygreen]

Well done. You have learnt some basics too, such as sealing the cabinets. Now you can start to obsess over cables.
Dead right there...now I'm hearing every single imperfection...

[raygreen]

Here we go. Finally finished and sounding pretty good. Great response from the tweeters and no distortion in the bass. Just had to make sure the connections were all tightened up and replaced the link to the bi-wire ports with solder - seems to have worked a treat. I can't complain at the result with the materials I've used for the job. Even built in a few storage spots around the speakers.

[awkwardbydesign]

Nice looking job. Not sure about grey, though...........;)

[raygreen]

I would go for a darker colour next time but you pays your money and you takes your choice.