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.
Regards,
Gio.
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.
Regards,
Gio.
Attachments
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.
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.
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.
http://www.t-linespeakers.org/FALL/bd-pipes.html
http://www.pmillett.com/tqwp.htm
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.
http://www.vikash.info/audio/W3-871S/build.asp
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.
http://www.t-linespeakers.org/FALL/bd-pipes.html
http://www.pmillett.com/tqwp.htm
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.
http://www.vikash.info/audio/W3-871S/build.asp
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.
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.
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
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
I'm a little late to this thread. Our BD-pipes have a champher on the back of the cutout... your freestyle effort probably has additional benefits in not being regular.
The best source of cotton felt in Canada is out of vintage Noresco speakers -- the ones with a "tweed" grill and the backs held on by Robertson screws. (as a side benefit they come with some nice isophons (sold on eBay a good source of funding towards the next project) or some Philips 5 or 7" whizzer cone drivers.
dave
The best source of cotton felt in Canada is out of vintage Noresco speakers -- the ones with a "tweed" grill and the backs held on by Robertson screws. (as a side benefit they come with some nice isophons (sold on eBay a good source of funding towards the next project) or some Philips 5 or 7" whizzer cone drivers.
dave
Cotton Felt
I bought some felt from a furniture upholsterer. I posted a picture below.
The front drivers are still breaking in (the rear ones were used and already broken in). Once that is done, I will take a good listen. After I am use to the sound, I will drop in phase plugs.
So far, I am very pleased with the sound.
Cheers,
Gio.
I bought some felt from a furniture upholsterer. I posted a picture below.
The front drivers are still breaking in (the rear ones were used and already broken in). Once that is done, I will take a good listen. After I am use to the sound, I will drop in phase plugs.
So far, I am very pleased with the sound.
Cheers,
Gio.
Attachments
Bracing
Due to the almost full length tapered divider, and the use of plywood, this enclosure is already very well braced side to side and stiff. If you haven't already permanently attached the side panel, all that's needed to complete the bracing would be a pair of vertically oriented 75mm or so wide pieces wedged between the center and front and back.
SCD said:
Due to the almost full length tapered divider, and the use of plywood, this enclosure is already very well braced side to side and stiff. If you haven't already permanently attached the side panel, all that's needed to complete the bracing would be a pair of vertically oriented 75mm or so wide pieces wedged between the center and front and back.
I got a webpage up for this project
http://ca.geocities.com/gmilitano/Speakers/BD-Pipes/BD-Pipes.htm
I purchased some phase plugs from Planet_10 and will try them out in a while when the speakers are fully broken in. I'll report back with the results.
Cheers,
Gio.
http://ca.geocities.com/gmilitano/Speakers/BD-Pipes/BD-Pipes.htm
I purchased some phase plugs from Planet_10 and will try them out in a while when the speakers are fully broken in. I'll report back with the results.
Cheers,
Gio.
GG said:
Gio,
I couldn't help noticing that on your webpage that you stated that the upper midrange was a little forward. If you haven't installed the phase plugs you may find that this problem will disappear after you do. Your description seems to match what I heard on my 1197 "Black Box" speakers until Dave gave the drivers 2 thin coats of Puzzel Coat and installed his phase plugs. I might add that he was only too happy to do this for me (I had his car blocked in the driveway
). Seriously though, I thought they sounded pretty good before, but the improvement afterwards was very dramatic, even to these old ears.Best Regards,
TerryO
Measured Response of BD-Pipes
I have been playing around with an SPL meter and I came up with the following measurements of the BD-Pipes.
The attached plot shows measurements at 1 m so I have cut off readings below 1000Hz as I can't imagine they would be meaningfull. The measurements were made in a lightly furnished room 3.6 m X 6 m. The speaker was 1.2 m from the back wall and 1.8 m from the side walls.
The response seems very good with the exception of the spikes between 6 and 7kHz.
Response is very extended, dropping off slowly after 16kHz and dropping off very fast after 18kHz. These measurements are with the Planet_10 phase plugs. The plugs helped tame some, but not all of the upper mid-range brightness. To my surprise, the phase plugs extended the response by about 2kHz!
Other peoples measurements of the 40-1197 have not shown the peaks I recorded between 6-7kHz. I can't imagine the room would have any affect at that high a frequency and I don't think I did anything wrong. Any comments?
I have been playing around with an SPL meter and I came up with the following measurements of the BD-Pipes.
The attached plot shows measurements at 1 m so I have cut off readings below 1000Hz as I can't imagine they would be meaningfull. The measurements were made in a lightly furnished room 3.6 m X 6 m. The speaker was 1.2 m from the back wall and 1.8 m from the side walls.
The response seems very good with the exception of the spikes between 6 and 7kHz.
Response is very extended, dropping off slowly after 16kHz and dropping off very fast after 18kHz. These measurements are with the Planet_10 phase plugs. The plugs helped tame some, but not all of the upper mid-range brightness. To my surprise, the phase plugs extended the response by about 2kHz!
Other peoples measurements of the 40-1197 have not shown the peaks I recorded between 6-7kHz. I can't imagine the room would have any affect at that high a frequency and I don't think I did anything wrong. Any comments?
Attachments
Re: Measured Response of BD-Pipes
OK. Now this is the one I need help with. This is the 20-1000Hz response at 3.5 m. I assume that a distance of 3.5 m is far enough away to pick up the port.
What is going on between 45 and 70Hz? Is that suck out of bass caused by the room? What about between 90 and 100Hz, is that also a room mode?
What about the drop after 250 Hz .. what does that mean? Is the enclosure too big for the drivers?
I have no idea on what is going on at 900Hz. I checked that reading several times.
Should I be looking to add more stuffing?
As always, comments are appreciated.
Cheers,
Gio.
OK. Now this is the one I need help with. This is the 20-1000Hz response at 3.5 m. I assume that a distance of 3.5 m is far enough away to pick up the port.
What is going on between 45 and 70Hz? Is that suck out of bass caused by the room? What about between 90 and 100Hz, is that also a room mode?
What about the drop after 250 Hz .. what does that mean? Is the enclosure too big for the drivers?
I have no idea on what is going on at 900Hz. I checked that reading several times.
Should I be looking to add more stuffing?
As always, comments are appreciated.
Cheers,
Gio.
Attachments
- Status
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