Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 110 - diyAudio
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Old 9th August 2006, 07:38 PM   #1091
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Hi GM and Scott!
Thanks for the replies!
Well sort of expected it, regarding upward move. Nothing is free here in life except joy and happiness (well, that's gonna be taxed sooner or later)
Have been thinking about paper made eggcraters below driver with some acousta stuff behind the pyramids. The pyramids would be perforated and also the tops chopped off.

Instead of deflex pads it could also be done with silicone glue scraped out in circles with a rake. Similar to what one use when putting up tiles in bathrooms. Lots of thoughts, not enough time.

Cheers
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Old 9th August 2006, 07:44 PM   #1092
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Must clearify about the silicone, it should be the quality which is rubberlike when dried. The reference to bathroom tiles was about the rake. I don't know if it's the right name but it makes potatoe fields:

Cheers
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Old 9th August 2006, 08:36 PM   #1093
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SoudDomain is down, so I can't host on my website, but here is a picture of my BIBs with a little paint on them.

Thanks,

Josh

Click the image to open in full size.
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Old 9th August 2006, 10:52 PM   #1094
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Nice work. One for the pages, Jeff?
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Old 10th August 2006, 12:10 AM   #1095
GM is offline GM  United States
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Quote:
Originally posted by Scottmoose
You might want to try increasing the stuffing in the point above the driver, which should help kill some of the unwanted HF. Although in a positive tapered pipe / horn like the BIB, I'm not sure if the usual QWR rule applies: the point of maximum velocity for the LF occurs at the terminus, and closer to the sealed end with increasing frequency. Greg?
Greets!

Just as max loading (highest pressure) is at the closed end, it's where stuffing has the greatest impact on attenuating the widest BW, ergo at the terminus where it's at the lowest pressure (velocity maximum), it has the least effect, so it boils down to how much LF roll-off is acceptable to damp its harmonics. To ~'have your cake and eat it too' will require a BLH filter chamber. If nobody beats me to it, maybe one of these days I'll have time to work up a BIB BLH variant. In the meantime, in a previous post I discussed using low SAF damping filters above the terminus to 'trap' some of the unwanted mids/HF output.

GM
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Old 10th August 2006, 02:21 AM   #1096
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Default FE168 BIB

Quick question on damping.

My reading tells me you stuff the point above the driver and a 1" layer on the base with some felt behind the driver. What is the best stuffing material? I have some long haired wool (from ancient TL project), dacron and wool based house sound/heat insulation. For the base the wool based insulation would be easiest while the point would be easier with LHW - sound OK? The felt - in the past I have used carpet underfelt but this may be a bit thick (driver VERY close to internal baffle). Maybe a few layers of thin felt from a fabric suppliers? Not sure what would be best here.

TIA, Chris
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Old 10th August 2006, 08:06 AM   #1097
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Thanks for that Greg

Chris, what you propose re the stuffing sounds fine to me. There's very little difference between the respective damping properties of different materials, at least in audio applications, providing excessive quantities aren't used, so you should be fine. The layers of felt behind the driver might be a better bet than one thick one, if it puts said driver too close to the internal baffle.

Scott
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Old 10th August 2006, 09:39 PM   #1098
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Default FE168 BIB

Quick question on damping.

My reading tells me you stuff the point above the driver and a 1" layer on the base with some felt behind the driver. What is the best stuffing material? I have some long haired wool (from ancient TL project), dacron and wool based house sound/heat insulation. For the base the wool based insulation would be easiest while the point would be easier with LHW - sound OK? The felt - in the past I have used carpet underfelt but this may be a bit thick (driver VERY close to internal baffle). Maybe a few layers of thin felt from a fabric suppliers? Not sure what would be best here.

TIA, Chris
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Old 10th August 2006, 09:43 PM   #1099
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Default Huh?

Sorry about the extra post, seems to have happened as result of using the back and referesh keys???
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Old 10th August 2006, 11:34 PM   #1100
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Odd. Similar things have happened to me. Machines! You can delete though providing you get it in time (30 mins after posting) -go to edit, and have a look at the top: you'll see a delete post button.

Regards
Scott
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