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gmilitano 4th January 2006 05:11 AM

BD-Pipes with Radio Shack 40-1197
2 Attachment(s)
I can almost hear them. After about 2 years of planning, I am getting close to finishing up my first speaker project.

I finally figured out the secret, find someone with good carpentry skills to build the enclosure for you! ;)

Today I bought some ductseal and have dammped the driver frames. The duct seal was only $2.32 at Home Depot.

The only thing holding back the completion of these speakers now is the lack of suitable damping material. I have been told that what I need is wool or cotton felt. Can anyone point me to a source of suitable felt? I guess I can go hunt down some old speakers, but that can be hit and miss.

I have attached a photo of where I am so far. I can't wait to hear these.


rjb 4th January 2006 06:56 AM

Almost any loose fibrous material will do. Teased out wool is best, so is polyester fibre such as used in house insulation, and as the stuffing of pillows and cushions. You can usually buy small quantities in the local craft or furnishing shop, or at the local upholterer, or rip apart old pillows. (Don't use feathers or Kapok).
Even stuff used in sleeping bags is fine if teased out well.

Avoid fibreglass insulation, not because it does not work, but because it is a health hazard, and makes you itch, and gets into your speakers.
Avoid cotton wool, its too dense in its normal form.

I have also seen wood wool, as used in packing, installed, but the quantity will differ from poly. Again this best put into a cloth bag to avoid dust getting into the speakers. Alternatively, the speaker can be put in the bag.

gmilitano 5th January 2006 03:23 AM

Duct Seal
2 Attachment(s)
A furniture upholsterer sounds like a good bet.

Attached is a photo of the driver basket damped with duct seal.

I have put a little bit of duct seal on the webs. Is that ok?


gmilitano 6th January 2006 02:54 PM

Champfered Driver Cutout
In looking at Dave's and Pete's pages on the BD pipes, I see no mention of a champfered driver cutout to give the driver more space to breath.

The baffle thickness I am using is 19mm. Should the driver cutout be champfered?

I know that a champfered driver cutout is used with the W3-871S.

Scottmoose 6th January 2006 04:45 PM

It won't do it any harm, and might do some good, as far as I know. Bar advice to the contrary, I'd do it.

They look pretty good to me so far!


gmilitano 6th January 2006 06:51 PM


Originally posted by Scottmoose
It won't do it any harm, and might do some good, as far as I know. Bar advice to the contrary, I'd do it.

I really should have thought of this before so it could have been done with a router. I guess I will have to do it with a wood file! Now I know for next time!

SCD 6th January 2006 09:28 PM

Hello GG:

Yes chamfer the inside of the opening. It will definitely help to allow the back wave to develop. Be careful though because you need enough wood to hold the driver anchoring screws. A router would have been best but that is hind sight so use the exacto knife. The amount of duct seal you used looks fine. I wen tone stage further and encased the magnet with duct seal as well.
If yoou can figure out the right length it is advisable to try and put a re-enforcing dowel behind the driver. try to do the front driver at least.

I went to the craft shop and got a package of pillow stuffing. I weighted out about .25lbs/ft3 teased it out and in it went.

I did not build the BD pipe i made a TQWP as a bipole. I really like it and it got me going on bipole designs.

SCD 6th January 2006 09:32 PM

1197 driver
This is a great little driver. It is the driver that a lot of very skilled speaker designers "cut" there teeth on. It is very tweekable. Do a search and you will find some very inovative ideas for improving the sound. Phase plugs and "modge podge" make a nice difference. Good luck

gmilitano 7th January 2006 10:31 PM

2 Attachment(s)
I used a wood file and it did not take too long. I could not get to one side that great so I used a dremel on that side with little success.

SCD 9th January 2006 05:24 PM

That whittling looks pretty good.
Remember to add lots of bracing. Cabinet resonance sucks and needs to be reduced as much as possible.
Use single strands of CAT5 wire (24 gauge) it looks skinny but do not worry "Thin is in".
Good luck

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