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Old 23rd July 2006, 10:37 PM   #1
colinB is offline colinB  United Kingdom
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Default FE167 BR Speakers - Best damping material (1st Post here)

Hi,

I'm a newbie to DIY loudspeakers and I was wonder if anyone out there could offer advice regarding damping materials for use with a FE167e BR cabinet that I have recently put together. The loudspeaker cabinets were based on the design on the Fostex datasheet that came with the drivers (the one with a built in stand if you are familar with this design).

So, after much hard work (with hand tools) I finally got the speakers together this weekend. After hooking them up to my DIY tube system (5698 pre + EL34 SE power) I was very pleased with the sound even though the drivers were new.
But at the moment I have no damping material in the boxes (nor sand in the stand). So what is the best (cheap) material to use? I know this is probably a difficult and contentious question to answer but I have no idea what would be the best to start with e.g. is it fibreglass, carpet underlay, synthetic wool, etc.

Also, can you give me an idea of the quantities required so that I can start tweaking!

Thanks
Colin
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Old 24th July 2006, 12:36 AM   #2
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How does it sound with nothing in there?


I'm running an MLTL using Fostex 127e with
nothing inside at all. I tried a few pieces of this and
that and wound up yanking all the pillow stuffing out.
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Old 24th July 2006, 02:06 AM   #3
JandG is offline JandG  United States
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In my fe167e BR's there is a small amount of white fiberglass directly behind port on back of cab & a little on the R side of 1 & on the left of the driver on the other. Don't ask me why cuz I don't know...does it sound good.OHHHHHHHHH YES... but with shout, that I will get rid of!!!!!!!!
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Old 24th July 2006, 02:15 AM   #4
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I'm hardly an expert, but following on from loninappleton's idea, in my limited experience any sort of soft damping material had a negative impact on the sound my speakers.

I built a pair of double bass reflex enclosures for the FE127E. I tried wool and polyester of various thickness and density. The speakers lost what I would call their openness and detail, and sounded much like a pair of low-end commercial bass reflex speakers.

I liked the sound with no damping material but I thought it could do with some improvement. And in theory standing waves and reflections through the driver could have had a negative impact.

I noticed on the Japanese version of the plans it showed HP-reflectors in various places in the enclosure, so I decided to try them (see the Fostex accessories on the madisound website).

I tried very hard to assess changes in sound with an open mind, and not just claim an improvement because I spent money on these! I definitely think they were worth the money. Bass increased considerably while still sounding natural. Imaging improved (probably due to breaking up of internal reflections), and a strange "honky" sound I had complained about in other threads was resolved. This was also probably due to internal reflections.

I have not measured the changes, to me speaker building is just for fun and I just do what sounds good to my ears.

I'm sure other enclosures built by more experienced people sound great with soft damping materials. But, if you have the Japanese version of the enclosure plans, and if they show HP-reflectors perhaps you should try them!
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Old 24th July 2006, 05:36 PM   #5
Dumbass is offline Dumbass  British Antarctic Territory
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Zaphaudio has some ideas on this topic:
http://zaphaudio.com/whispermat.html

What about the cheap stuff?

Egg crate foam is the worst there is. It's almost like using nothing. One potentially good cheaper material is 1/2" thick carpet padding. The thick felt kind is almost always good, and you can double it up if you need more damping. The chopped foam type can be good also, although the acoustic properties of this can vary. You will have to test it. You can almost tell how well it's going to do by just putting close to your ear while listening to pink noise.

I hear that "Miraflex" brand fiberglass is pretty good although I've never tried it. The good part is that it does not itch or get in your lungs like fiberglass, it's much easier and safer to work with. Now if I can only find a place that sells it...

For sealed enclosures, most of the time Acousti-stuff damping material will be fine. It's a little better than the Dacron pillow stuffing found in craft stores. Fill up the enclosure while keeping the damping away from the immediate area behind cones.
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Old 25th July 2006, 07:01 AM   #6
zBuff is offline zBuff  New Zealand
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On the subject of the Foxtex HP reflectors, has anyone tried cobbling up a DIY alternative/copy?

I've always liked the sound of enclosures without damping(internally that is), but the cost of the HP reflectors has always put me off.
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Old 25th July 2006, 07:33 AM   #7
colinB is offline colinB  United Kingdom
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Thanks everybody for the suggestions. Plenty of ideas to think about.

Yes, I built the enclosures for the FE167e based on the Japanese version of the plans. I could see the reflector on the photo's but couldn't make out what the exactly it was (can't read Japanese of course!) Thanks arjscott for suggesting a source of these - I'll probably go ahead and order a pair from Madisound as a first attempt at tweaking the sound unless someone suggests a DIY alternative/copy as zBuff asked for.

Colin
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Old 29th July 2006, 06:16 PM   #8
Jeb-D. is offline Jeb-D.  United States
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I used this on my last project and was very impressed.

http://www.partsexpress.com/pe/showd...number=260-520

There isn't a hint of anything above bass frequencies coming out of the port, when I put my ear up to it. And it has adhesive already on it. Just peel the back off it like a sticker.
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