BIB sub
This has been an amazing thread to follow. Before getting into fullrange BIBs, I've been thinking of building a single BIB sub for a mono system I'm trying to put together. I have a couple of older Dayton 6 1/2" woofers I thought might be just the ticket, putting both in a single cab. Not sure of how to build for this, though. I'd like it for say 90 to 100Hz on down, maybe starting even lower. It would be stuffed tightly into a corner, but I'm not sure yet about what ceiling height would be - I'm moving, but don't know where yet. At a minimum, the ceiling would be 8 feet though.
Specs are, for each Dayton woofer:
Fs = 33 Hz
Vas = .980 cu.ft.
Qts = .33
Sd = 21.2 sq. in.
Re = 6.7 ohms
Good idea? Bad idea? Any suggestions? Thanks
This has been an amazing thread to follow. Before getting into fullrange BIBs, I've been thinking of building a single BIB sub for a mono system I'm trying to put together. I have a couple of older Dayton 6 1/2" woofers I thought might be just the ticket, putting both in a single cab. Not sure of how to build for this, though. I'd like it for say 90 to 100Hz on down, maybe starting even lower. It would be stuffed tightly into a corner, but I'm not sure yet about what ceiling height would be - I'm moving, but don't know where yet. At a minimum, the ceiling would be 8 feet though.
Specs are, for each Dayton woofer:
Fs = 33 Hz
Vas = .980 cu.ft.
Qts = .33
Sd = 21.2 sq. in.
Re = 6.7 ohms
Good idea? Bad idea? Any suggestions? Thanks
Yup, good idea. 
Set length to 1/2 wavelength of whatever tuning frequency you want, then plug that, with the driver parameters into GM's BIB formula and you'll be fine. BTW, as it's for sub duties, I'd shift the driver position to 0.416 line length, rather than the 0.217 line length we use for FR BIBs.
Set length to 1/2 wavelength of whatever tuning frequency you want, then plug that, with the driver parameters into GM's BIB formula and you'll be fine. BTW, as it's for sub duties, I'd shift the driver position to 0.416 line length, rather than the 0.217 line length we use for FR BIBs.
Because almost all of those Zillaspeak boxes pre-date Greg's T/S Vb calculation, which usually (though not always) gives a greater volume. For the smaller box, I set line length to = 1/2 Fs, the slightly longer one is tuned a little lower. Zdriver position is 0.2 for that one, rather than 0.217 as it gives a smoother response in the smaller box.
Scottmoose said:
Greets!
Hmm, note that as the taper ratio increases, the driver needs to 'slide' down towards 'Sm' for max smoothness (something that's been mostly ignored in the various BIB high taper designs since I know of no simple way to calc it), so just that there's no confusion, 'smaller' here refers to taper ratio, not 'Sm' and/or net box volume (Vb). By the time you get down to ~ (0.4*L) though, it takes a big difference in the taper to make much audible difference in the driver location and why folks got what passed for excellent performance using this back in the days when TLs were 'designed' pretty much solely by making them 1/4 WL of the driver's published Fs.
GM
Hi!
I originally put this question in this thread. But got lost in the speed of replies. http://www.diyaudio.com/forums/showthread.php?postid=1290482#post1290482
Anyway, ask the same question in the right thread now.
When I built the Monacor BIB's, I made the "hand clap test" in the driver opening when they were undamped. Of course you get echo when undamped. But this got me thinking of my spare room that was unfurbished for a while. Hand clap effect prominent here. Now there's shelves for the childrens toys on one wall. Guess what, echo is gone, despite not much of soft material in the room.
In my naivity I ask, would it work in a BIB without change of other physical properties of the horn. Of course I'm talking of smaller sections of different lengths of shelves in the horn path.
Cheers
I originally put this question in this thread. But got lost in the speed of replies. http://www.diyaudio.com/forums/showthread.php?postid=1290482#post1290482
Anyway, ask the same question in the right thread now.
When I built the Monacor BIB's, I made the "hand clap test" in the driver opening when they were undamped. Of course you get echo when undamped. But this got me thinking of my spare room that was unfurbished for a while. Hand clap effect prominent here. Now there's shelves for the childrens toys on one wall. Guess what, echo is gone, despite not much of soft material in the room.
In my naivity I ask, would it work in a BIB without change of other physical properties of the horn. Of course I'm talking of smaller sections of different lengths of shelves in the horn path.
Cheers
Hmm. You're basically disrupting the airflow & altering the expansion rate by doing this, so interesting things might happen to the response. Efficiency would drop, & you'd probably get reflections back along the line that wouldn't do the response any favours. Better IMO to use that triangle of material hanging down the 2nd half of the horn path GM suggests, which should solve the echo problem without adding the problems.
Hmm. You're basically disrupting the airflow & altering the expansion rate by doing this, so interesting things might happen to the response. Efficiency would drop, & you'd probably get reflections back along the line that wouldn't do the response any favours. Better IMO to use that triangle of material hanging down the 2nd half of the horn path GM suggests, which should solve the echo problem without adding the problems.
Thanks Scott!
As always, most ideas are crap in the end
Well, at least my ideas!
I use a soft divider in the last section of the pipe. These shelves were intended to reduce damping material. Oh well..
BTW, Scott. Did you recieve the plans? Have had some problems with attachment recently.
Cheers
As always, most ideas are crap in the end
Well, at least my ideas! I use a soft divider in the last section of the pipe. These shelves were intended to reduce damping material. Oh well..
BTW, Scott. Did you recieve the plans? Have had some problems with attachment recently.
Cheers
Greets!
While both are half WL resonators, one's fundamentally a horn and the other a closed pipe, so shelves filled with a variety of absorbent and/or diffusive objects can be used to damp a room's higher order modes (Earl Geddes' HOMs), but a horn's is generated at the throat, so damp them here and there's not much left till you get to a bend or the mouth where new ones are generated and why these are the three places to concentrate damping, with the most being at the throat, etc..
Bottom line, 'shelves' in a horn's path-length big enough to work will probably disrupt the BIB's horn action too much, but both BLHs and TLs have been built in straight pipes using staggered 'shelves' which roll-off the HF pretty quick, so if you're up for some experimenting with slats angled towards the mouth to approximate a screw thread............
GM
While both are half WL resonators, one's fundamentally a horn and the other a closed pipe, so shelves filled with a variety of absorbent and/or diffusive objects can be used to damp a room's higher order modes (Earl Geddes' HOMs), but a horn's is generated at the throat, so damp them here and there's not much left till you get to a bend or the mouth where new ones are generated and why these are the three places to concentrate damping, with the most being at the throat, etc..
Bottom line, 'shelves' in a horn's path-length big enough to work will probably disrupt the BIB's horn action too much, but both BLHs and TLs have been built in straight pipes using staggered 'shelves' which roll-off the HF pretty quick, so if you're up for some experimenting with slats angled towards the mouth to approximate a screw thread............
GM
Hi Greg!
Makes me think of these..
http://www3.ocn.ne.jp/~hanbei/eng-angular.html
I will see if I can try two shelves angled towards the bend, under the driver if it makes a difference. More shelves and it will be difficult to attach them, as new boxes are glued and missing only base plate. (And drivers, lacquer, connections, cables..)
Thanks!
BTW, I just marvel over your patience regarding all the questions from people! I salute you, Scott, Dave and others not mentioned!
Cheers!
Makes me think of these..
http://www3.ocn.ne.jp/~hanbei/eng-angular.html
I will see if I can try two shelves angled towards the bend, under the driver if it makes a difference. More shelves and it will be difficult to attach them, as new boxes are glued and missing only base plate. (And drivers, lacquer, connections, cables..
)Thanks!
BTW, I just marvel over your patience regarding all the questions from people! I salute you, Scott, Dave and others not mentioned!
Cheers!
They are BIG!
Just completed my FE208ESig/T90A BIBs so here are some pics.
Bit early for any real impressions or comparrisons with my beloved 168BIBs but clearly large scale sound and those T90As sound sweet.
Initially dissapointed with constricted sound and lack of bass but I had not done any break in on the 208s before the went in the BIB cabs whereas the 168s had 100 hours before I listened to them. Getting better tho and droping the cap on the T90 from 1uf to .68uf was definitely a help to reduce mid band dominance.
Build is regulation BIB and peretty much as I built the 168s (family resemblance obvious!)
Anyhow - the pics
Just completed my FE208ESig/T90A BIBs so here are some pics.
Bit early for any real impressions or comparrisons with my beloved 168BIBs but clearly large scale sound and those T90As sound sweet.
Initially dissapointed with constricted sound and lack of bass but I had not done any break in on the 208s before the went in the BIB cabs whereas the 168s had 100 hours before I listened to them. Getting better tho and droping the cap on the T90 from 1uf to .68uf was definitely a help to reduce mid band dominance.
Build is regulation BIB and peretty much as I built the 168s (family resemblance obvious!)
Anyhow - the pics
Attachments
Thanks.
The timber on the 168 is marine ply but I don't know the type of timber, simple polyurethane finish . For the 208s its similar ply but not marine adhesive, in fact I was quite disappointed with the quality of the ply for the 208 tho the grain of the outer ply was really nice. I used a stain which brought out the grain and merged the end ply well before applying the poly. Both use MDF supra baffles with a redwood stain brushed on to look somewhat like wood grain.
Th 168s are awesome speakers - I wouldn't have gone for th 208s if it wasn't for that DIY urge to build bigger and better
You will find plenty of comments around the sound of 168 BIBs on the thread including plenty of my own!
The timber on the 168 is marine ply but I don't know the type of timber, simple polyurethane finish . For the 208s its similar ply but not marine adhesive, in fact I was quite disappointed with the quality of the ply for the 208 tho the grain of the outer ply was really nice. I used a stain which brought out the grain and merged the end ply well before applying the poly. Both use MDF supra baffles with a redwood stain brushed on to look somewhat like wood grain.
Th 168s are awesome speakers - I wouldn't have gone for th 208s if it wasn't for that DIY urge to build bigger and better
You will find plenty of comments around the sound of 168 BIBs on the thread including plenty of my own!
About those thin wire hookups for the BIBs:
I need some advice first on the application and how good it is for the FE127e and second how to do the connection to a solid state receiver.
The problem is the connection at the receiver I use. It has those
tabbed connectors in which you put the bare wire through a hole and
clamp the stranded wire with the tab.
What kind of 'pigtail' or other wire connect tips can you give to get the
thin wire into this awkward connection?
Also attaching the wire to the FE127e without soldering. I will not solder onto those delicate terminals. The preferred method would be
a mechanical connection using a fine screw.
I need some advice first on the application and how good it is for the FE127e and second how to do the connection to a solid state receiver.
The problem is the connection at the receiver I use. It has those
tabbed connectors in which you put the bare wire through a hole and
clamp the stranded wire with the tab.
What kind of 'pigtail' or other wire connect tips can you give to get the
thin wire into this awkward connection?
Also attaching the wire to the FE127e without soldering. I will not solder onto those delicate terminals. The preferred method would be
a mechanical connection using a fine screw.
loninappleton said:
I have put 24 gauge wire into spring clips on my receivers with no trouble. But if you are worried that the clip willl snip the wire: you could strip a longer piece, then bend it back over on itself a couple times; maybe even fold it back over the insulation before putting it in the clip.
When I connected to my FE108Es I used crimp on 1/4" quick disconnects. Much safer than trying to solder on the driver.
CHeers, Jim
loninappleton said:
I use the same technique as Jim when i find the amp terminals can't clamp the thing wire.
As to soldering the FE127 terminals... delicate? We swap 127s (& 126s & 108s) in and out, and out and in over & over again, with no issues, And i use a Weller soldering gun for this (aka welder). I have never had any problems with the terminals, Even thou it would be helpful to have 3 hands to do it, i also do not bend the wire going into the terminal, but lever it throu the hole to get as much mechanical contact with the terminal as possible.
dave