Something for you to try out guys. I shamelessly plundered it from Dan's Dark Star. Should be particularly useful for those running smaller drivers, and having problems with HF leakage through the horn (interesting that the larger drivers seem to have less of a problem with this).
Get hold of some of that thin cork that's used for lining purposes, or that you see on the front of cork-boards etc., and line the front of the inner baffle with the stuff (this needs to be the thin cork -not the heavy-duty stuff used for flooring tiles. I tried those a year back, and they killed the dynamics stone cold).
You can also line the inside of the rear baffle with it too to pretty good effect. What you should get is an instant, dramatic reduction in HF leakage, and also of what I suspect are reflections from inside the pipe back up through the driver cone. At the very least, line the front panel -you can always add some to the rear later, if necessary (top building tip: make sure that when you build your BIB, the base is screwed, not glued on, with a sealing strip to prevent leakage). I tried this last night on my 165 boxes and it was a huge step forward. Much cleaner than before -they remind me of the ESL988s I heard a while back, without the lack of grunt in the LF. You should be able to find some cork sheeting fairly easily, and for little cash (mine originally came out of an old semi-permenant building nearby, so I got it for free), so it's well worth experimenting.
Have fun
Scott
Get hold of some of that thin cork that's used for lining purposes, or that you see on the front of cork-boards etc., and line the front of the inner baffle with the stuff (this needs to be the thin cork -not the heavy-duty stuff used for flooring tiles. I tried those a year back, and they killed the dynamics stone cold).
You can also line the inside of the rear baffle with it too to pretty good effect. What you should get is an instant, dramatic reduction in HF leakage, and also of what I suspect are reflections from inside the pipe back up through the driver cone. At the very least, line the front panel -you can always add some to the rear later, if necessary (top building tip: make sure that when you build your BIB, the base is screwed, not glued on, with a sealing strip to prevent leakage). I tried this last night on my 165 boxes and it was a huge step forward. Much cleaner than before -they remind me of the ESL988s I heard a while back, without the lack of grunt in the LF. You should be able to find some cork sheeting fairly easily, and for little cash (mine originally came out of an old semi-permenant building nearby, so I got it for free), so it's well worth experimenting.
Have fun
Scott
Ray
I have not. I have the basic Ray Collins Damping Technology applied, with the bit of stuffing and foam behind the driver, etc., and havent been in there for months. The cork comes from the open baffle diffraction issue, and there it works like a charm, particularly with the backwave, and looks the part too.
There doesnt seem to be much HF leakage with mine because of the foam I put onto the floor of the cabinet. I do like the idea of putting some on the front of the internal baffle though, but not enough to attempt it.
The more interesting thing is how much more real bass there is now with the BIB-168 hooked up to the Red Wine Signature 30 T amp of 30 watts, really grips the drivers and pushes LFR down quite abit. VERY fast, smooth, pretty flat to 30 I'd say, and pretty much perfect.
I have not. I have the basic Ray Collins Damping Technology applied, with the bit of stuffing and foam behind the driver, etc., and havent been in there for months. The cork comes from the open baffle diffraction issue, and there it works like a charm, particularly with the backwave, and looks the part too.
There doesnt seem to be much HF leakage with mine because of the foam I put onto the floor of the cabinet. I do like the idea of putting some on the front of the internal baffle though, but not enough to attempt it.
The more interesting thing is how much more real bass there is now with the BIB-168 hooked up to the Red Wine Signature 30 T amp of 30 watts, really grips the drivers and pushes LFR down quite abit. VERY fast, smooth, pretty flat to 30 I'd say, and pretty much perfect.
leonardc,
I didn't include the suprabaffles in my build.
I sent pictures of my 168's to Zilla for posting on the BIB site but they have not yet been posted. I had my attempts to post pictures here rejected due to excessive file size and I don't know how to comply. Perhaps Dan can post mine along with his?
Good luck with your build.....I assure you that you will not be disappointed.
Ray
I didn't include the suprabaffles in my build.
I sent pictures of my 168's to Zilla for posting on the BIB site but they have not yet been posted. I had my attempts to post pictures here rejected due to excessive file size and I don't know how to comply. Perhaps Dan can post mine along with his?
Good luck with your build.....I assure you that you will not be disappointed.
Ray
Nope, I did mean up the front of the sloping internal baffle, and the front of the rear baffle.
If your enclosures are half as well-built as I suspect Dan, I'm not surprised you don't fancy opening them up -especially the way you use them too, where it likely wouldn't make much of a difference.
I reckon this will work at it's best with the smaller drivers, which obviously have more of a problem in this respect than the larger ones, but it was a big step forward with my boxes. 3mm is the stuff to use. One of those occasions where you don't know you have a problem until it's gone, and you wonder just how you lived with it before. Just to reitterate what Dan mentioned though: please, please make sure you have that floor layer of stuffing or foam guys: it makes a big difference.
My impression is that the cork is particularly good at eating any remaining HF leakage, and of killing reflections inside the horn. Most of us use something directly behind the driver, but this seems to work better, to my ears at least, probably due to the greater coverage preventing off-axis reflections through the driver cone for example. Cheap and easy, and plenty of room to experiment! I might try some on a side wall, and on the rear of the internal baffle as well, out of interest.
If your enclosures are half as well-built as I suspect Dan, I'm not surprised you don't fancy opening them up -especially the way you use them too, where it likely wouldn't make much of a difference.
I reckon this will work at it's best with the smaller drivers, which obviously have more of a problem in this respect than the larger ones, but it was a big step forward with my boxes. 3mm is the stuff to use. One of those occasions where you don't know you have a problem until it's gone, and you wonder just how you lived with it before. Just to reitterate what Dan mentioned though: please, please make sure you have that floor layer of stuffing or foam guys: it makes a big difference.
My impression is that the cork is particularly good at eating any remaining HF leakage, and of killing reflections inside the horn. Most of us use something directly behind the driver, but this seems to work better, to my ears at least, probably due to the greater coverage preventing off-axis reflections through the driver cone for example. Cheap and easy, and plenty of room to experiment! I might try some on a side wall, and on the rear of the internal baffle as well, out of interest.
Greets!
You can post pics via Image Venue which has a resizing feature for images <1.5 mb, or for sites that allow posting from your computer, Snagit 5 allows you to screen capture and save it to a folder in a much smaller file size.
http://www.imagevenue.com/
http://www.addget.com/technote/main...pds&command=down_load&d=&filename=snagit5.exe
GM
You can post pics via Image Venue which has a resizing feature for images <1.5 mb, or for sites that allow posting from your computer, Snagit 5 allows you to screen capture and save it to a folder in a much smaller file size.
http://www.imagevenue.com/
http://www.addget.com/technote/main...pds&command=down_load&d=&filename=snagit5.exe
GM
Greets!
You're welcome!
'Thin' acoustic rated cork (0.5 - 0.875" thick) typically has a peak in its noise reduction response curve centered in the upper mids/lower treble with a lower Q (wider BW) up to a point of diminishing returns with increasing thickness. Really thin cork such as drawer liner only damps upper treble BW, which is high enough to get attenuated in the pipe folds if no reflectors are used, so it seems to me that covering large areas such as the angled baffle board with it would mainly damp the spurious panel resonances that strong pipe action can generate.
Anyway, IMO parallel surfaces and low incident angles are the main problems in a BIB, so lining one wall all the way through the bends and on the bottom with whatever density material that doesn't overdamp the transients (dynamics) is what I've done, then adjust in-room pipe Q with stuffing at the point. Never having used cork inside a speaker though, I don't know how it 'sounds' compared to the various felt/fiberglass densities I've used, only that it can work well on its exterior and room first reflections if the decor (SAF) allows it.
GM
You're welcome!
'Thin' acoustic rated cork (0.5 - 0.875" thick) typically has a peak in its noise reduction response curve centered in the upper mids/lower treble with a lower Q (wider BW) up to a point of diminishing returns with increasing thickness. Really thin cork such as drawer liner only damps upper treble BW, which is high enough to get attenuated in the pipe folds if no reflectors are used, so it seems to me that covering large areas such as the angled baffle board with it would mainly damp the spurious panel resonances that strong pipe action can generate.
Anyway, IMO parallel surfaces and low incident angles are the main problems in a BIB, so lining one wall all the way through the bends and on the bottom with whatever density material that doesn't overdamp the transients (dynamics) is what I've done, then adjust in-room pipe Q with stuffing at the point. Never having used cork inside a speaker though, I don't know how it 'sounds' compared to the various felt/fiberglass densities I've used, only that it can work well on its exterior and room first reflections if the decor (SAF) allows it.
GM
Is anyone reading this thread considering building the Jumbo GM Hempsters? If so, if this accelerates your decision making process, I just added phase plugs to the Hemp 8.0 V.20 drivers last night and can tell you they became a whole nother animal, with the usual spectacular improvements in treble dispersion, beaming, etc.
These are ValueKing drivers at least on the level of the Visaton B200. I love that big BIB. Or, perhaps, BAB. Bad-A$$ BIB.
Someone please build one. Not me, I'm on Project Lockdown presently.
These are ValueKing drivers at least on the level of the Visaton B200. I love that big BIB. Or, perhaps, BAB. Bad-A$$ BIB.
Someone please build one. Not me, I'm on Project Lockdown presently.
Jumbo GM hempsters
Hi, I couldn't get the jumbos past my wife but built the smaller 200 sq. inch mouth model on the BIB site. They are in (near) corners. I also have the Visaton B200 on open baffle. My wife and I both much prefer the BIB Hemp8.0 and this is primarily because of the mid range. These are incredible in the bass dept. as well. The hemp driver is really something special. Better in my opinion than the Visiton B200. When my wife first saw these she had no enthusiasm at all. After the 1st couple hrs of listening she said we have to keep these. I don't have pics ( just as well -Haven't veneered or otherwise prettied them yet) Jim G
P.S. I have been thinking about phase plug too (sometning I usually do) Thanks for the recommendation.
Hi, I couldn't get the jumbos past my wife but built the smaller 200 sq. inch mouth model on the BIB site. They are in (near) corners. I also have the Visaton B200 on open baffle. My wife and I both much prefer the BIB Hemp8.0 and this is primarily because of the mid range. These are incredible in the bass dept. as well. The hemp driver is really something special. Better in my opinion than the Visiton B200. When my wife first saw these she had no enthusiasm at all. After the 1st couple hrs of listening she said we have to keep these. I don't have pics ( just as well -Haven't veneered or otherwise prettied them yet) Jim G
P.S. I have been thinking about phase plug too (sometning I usually do) Thanks for the recommendation.
JimG
Thanks for that, it never occurred to me to sell the idea of the 200^2" job. Did you use Scott's DIM's or your own? More info please, as possibly I could take another swipe at the idea armed with scissors and cardboard, and make another 'sales' presentation...
Glad you like the Hempsters. I also prefer them to the B200, which sound too hi fi in comparison, IMHO, the warmth of the midrange, especially the lower midband right down to 200Hz is to die for in my book. It combines warmth, with resolution, and TONE is out the window. And now someone whom has built some Hemp BIB's.
Thanks for that, it never occurred to me to sell the idea of the 200^2" job. Did you use Scott's DIM's or your own? More info please, as possibly I could take another swipe at the idea armed with scissors and cardboard, and make another 'sales' presentation...
Glad you like the Hempsters. I also prefer them to the B200, which sound too hi fi in comparison, IMHO, the warmth of the midrange, especially the lower midband right down to 200Hz is to die for in my book. It combines warmth, with resolution, and TONE is out the window. And now someone whom has built some Hemp BIB's.
Another one falls prey! And if 'she who must be obeyed' likes them too, bonus! (big bonus). Hemp FR8 BIBs. I would like to hear those.
Dan -judging from the responses in MathCad at least, I don't think there's going to be a massive difference between the Monolith and the 200in^2 version, providing you can corner load them (not that I need to tell you that). Although the curve looks like it rolls off more than some others at first glance, check out the SPL levels at 30Hz: 91db. And that's before you factor in room-gain. Gulp. By contrast, the FE168ESigma is 82db at 30Hz.