Maybe you can use Nelson's Trans line , starting here:
http://www.diyaudio.com/forums/showthread.php?postid=749237#post749237
A couple of posts below he shows the path dimensions. Obviously you will have to redraw it to accomodate the thickness of the material, and put the driver in the top.
If you keep the cross section abd the distances the same, then you could change it to fit your multisided design..
that thread is probably the place to discuss your idea...
http://www.diyaudio.com/forums/showthread.php?postid=749237#post749237
A couple of posts below he shows the path dimensions. Obviously you will have to redraw it to accomodate the thickness of the material, and put the driver in the top.
If you keep the cross section abd the distances the same, then you could change it to fit your multisided design..
that thread is probably the place to discuss your idea...
GCDOB (Garage cabinet door open baffle) up and running!
This is my first attempt at an open baffle - I am impressed! For a couple of hours work, the results are really compelling. Not a lot of bass, but a wonderfully clear and involving sound.
The surrounding environment is not in the least music-friendly, but these little speakers have massively improved the experience of listening to music in the garage. I was planning to move on to a BIB - now I'm not so sure...
Thanks so much, Mr. Pass! And thanks also to the organizers and participants at the Burning Amp who made it all happen!
This is my first attempt at an open baffle - I am impressed! For a couple of hours work, the results are really compelling. Not a lot of bass, but a wonderfully clear and involving sound.
The surrounding environment is not in the least music-friendly, but these little speakers have massively improved the experience of listening to music in the garage. I was planning to move on to a BIB - now I'm not so sure...
Thanks so much, Mr. Pass! And thanks also to the organizers and participants at the Burning Amp who made it all happen!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
At the moment there are too many wires hanging about for the doors to close.
The metal grills PE sells fit perfectly over the B20 but dull the sound quite a bit. They will protect the front of the drivers tho.
I would protect the back of the speakers with something too. Maybe a mesh wire box from Staples like this:
http://www.staples.com/webapp/wcs/s...catalogId=10051&productId=12001&cmArea=SEARCH
or just a simple curved piece of sheet metal curved across the back of the driver leaving the top and bottom open.
Otherwise, cool.
I would protect the back of the speakers with something too. Maybe a mesh wire box from Staples like this:
http://www.staples.com/webapp/wcs/s...catalogId=10051&productId=12001&cmArea=SEARCH
or just a simple curved piece of sheet metal curved across the back of the driver leaving the top and bottom open.
Otherwise, cool.
The good news is that I'm pretty much the sole user of the garage, so I can control what goes in the cupboards. I would rather use something very transparent like a very sparse wire structure - perhaps I have to DIY something 
.
Actually my biggest concern is sawdust getting into the works - perhaps I need a removable grille and speaker cloth?
I have acquired one of those air cleaner things (Jet) that hangs up in the roof and sucks all the dust through a couple of filters - since putting that in the difference is night and day - I can now breathe properly, and I imagine it will help the speakers too.
tim
. Actually my biggest concern is sawdust getting into the works - perhaps I need a removable grille and speaker cloth?
I have acquired one of those air cleaner things (Jet) that hangs up in the roof and sucks all the dust through a couple of filters - since putting that in the difference is night and day - I can now breathe properly, and I imagine it will help the speakers too.
tim
That's the best way to mount them, regardless of your work space . . .
Bet you have better stereo separation than I do, though
Kensai
An externally hosted image should be here but it was not working when we last tested it.
Bet you have better stereo separation than I do, though
Kensai
Kensai said:That's the best way to mount them, regardless of your work space . . .
http://12southstudios.com/OfficeRig.jpg
Bet you have better stereo separation than I do, though
Kensai
They may be a little bit too high. I don't think your head is all that far up while you are looking at your monitor. I assume that you also have a nice vintage receiver hooked up to your computer too, correct?
Nelson:
Sorry - I realize that you wrote "Thus ends my micro Bu20Fu20 article" but I have a couple of questions:
1. How far down is the B20 in the TL? If your diagram is to scale it looks like it is about 8.5 in (from the inside).
2. Did you find the need to add a BSC? When I simulated the TL using Martin King's TL Sections worksheet it appears that a BSC is needed. Something like 5 ohms and 3 mH seems to be right.
Sorry - I realize that you wrote "Thus ends my micro Bu20Fu20 article" but I have a couple of questions:
1. How far down is the B20 in the TL? If your diagram is to scale it looks like it is about 8.5 in (from the inside).
2. Did you find the need to add a BSC? When I simulated the TL using Martin King's TL Sections worksheet it appears that a BSC is needed. Something like 5 ohms and 3 mH seems to be right.
Hey, Kensai - your OBs are much better looking than mine! Do you have any plans for bass?
I haven't done anything yet, but I can clearly hear a need for a BSC and/or subwoofer that reaches fairly high. I tried tone controls, but they were a bit too drastic. The good news is that my ultra-sophisticated electronics (car radio) has a subwoofer line out, so I can do some testing without building a dedicated crossover.
tim
I haven't done anything yet, but I can clearly hear a need for a BSC and/or subwoofer that reaches fairly high. I tried tone controls, but they were a bit too drastic. The good news is that my ultra-sophisticated electronics (car radio) has a subwoofer line out, so I can do some testing without building a dedicated crossover.
tim
John,
I can never figure you guys when you're all saying that driver positions of 30"-38" are "ear height". I'm only 6'2", and when I sit up in that chair, my ear height is around 46". The driver centers there are about 43", so even when I slouch a bit, they're not much above ear height. I'm all leg, too. I mean my wife is 5'3" and when we're sitting on the same surface she's only maybe 5"-6" shorter than me.
That rig is in the newly finished basement now, though still in a corner. In fact, other than the window there and the wainscoating, the setup doesn't look much different at all. I have, however, gotten that rack below the top shelf of my desk moved back enough that I can let the monitor extend as far up as its stand will allow so that now the top edge of the monitor is just above driver center height there, which is much more ergonomic for me.
And actually their running of the core of little JVC shelf system, one with an older Hybrid Feedback digital amp in it. Sounds much more lively, not to mention has much stronger bass, than an original SI T-Amp, and several orders of magnitude more clean and detailed than a Pioneer VSX-D411 5.1 receiver.
Tim,
Thanks, but you have to know that they're just a pair of Farberware bamboo cutting boards, $10 each at walmart, mounted with a couple of $.60 hinges to a couple lengths of 1"x2" that I have wedged in there.
I'm mulling about several different options for bass, though with no budget and no time, I'm having a hard time getting started. Besides, I use an E-Mu 0404 sound card as my source, and it allows for nearly unlimited EQ control, in the digital domain before the signal hits the DACs, and with that I am able to get these B20s on these 12"x18" baffles to be solid to 60Hz or so, with audible response down into the lower 50s all the way up to a touch over 16kHz. As far as I can hear since no matter what I'm testing, including a pair of Grado headphones or a 2-way monitor using a B&G Neo3PDR tweeter that's supposed to be good way up over 20kHz, that's as far as I can reliably pick out a test tone from the harmonics. However I do find that a stiff shot of EQ boost in the top frequencies does produce alot more audible "air", if you know what I mean.
Anyway, I guess the goal here is to build something that can do without any EQ at all. Running these things flat in a normal 44.1/48kHz mode (CD and DVD), they're pretty dull and lifeless, and certainly aren't getting me much below maybe 100-120Hz. Running them in a 176.4kHz mode (a nice x4, whole number multiple of the original sample frequency) really does make them come alive, with tons more detail. When I test the frequency response, it doesn't actually get better when upsampling, but somehow it sounds like it has when you listen to actual music, so that's what I want to be able to do.
I've gotten a pair of the Dayton 5/8" dome tweeters that everyone's been talking about with the Chang DBVRs and other B20 enclosures. Just got a bit for drilling the appropriate sized hole over the weekend, so I haven't had the chance yet to actually install them. On the bass side, I'm still wallowing in a mass of ideas, constrained by the fact that I have no real budget for purchasing drivers. I'm also constrained by the fact that I want to keep the bass OB as well.
I'm in the middle of building a pair of BiB variants for the Pioneer A11 that are meant for a buddy of mine who currently has television speakers and a 2.1 set of Creative Labs multimedia crap. They're pretty impressive, getting down solid to 55Hz or so with no EQ and with it you can at least make out a clean 20Hz test tone. However, they instantly sound boxy to me, and I can easily detect where the bass is actually coming from (the bottom rear of the cabinet; they're like an inverted BiB except they are rear firing instead of firing straight down). IMO, this is okay for boombox or party duties, but I've been well beyond that level of sound quality for some time now, so with this experience, I'm convinced that I'm not going to like, let alone be satisfied with any sort of enclosure style bass.
I've kinda gotten the Dayton 8" DVC subwoofer driver stuck in my mind as a fun option. Its cheap, flexible, pretty low Fs, specs look like it would match nicely, and more importantly, how cool would 4 of them look in a line array with a B20, eh? Anyway, just with those, the options are pretty boundless. There's the line array I just mentioned (not likely hinge mounted like the current baffles, but you never know). Perhaps just WFW (and MTM with a B20 as the tweeter) would be enough.
I'm also interested in perhaps trying an SDA alignment. This is a Polk technology that they've basically let out of the bag with the advent of their Surround Bar product since that uses SDA and then a ton of passive filters to get a surround effect. What the SDA does is supposedly create a wider sound stage and the implementation is dead simple. You get two drivers on each side, their centers about the same distance apart, horizontally, as a human's ears (so for these, they would just be lined up edge to edge), with one driver being wired normally and the other wired with an inverted version of the signal from the other side. I've tried this with matched sets of Kenwood 6"x9" drivers (which I thought were pretty good sounding until I got a pair of B20s for Christmas and learned the error of my ways), and the soundstage did indeed sound wider and the bass response was, if not much lower, quite a bit more authoritative down to the point where it fell off a cliff.
Other options include finding/using a single 10"-15" driver (I think I can corral a 15"er and the B20 into the space I have, somehow) onto a new, more beefy baffle, or possibly making something a bit more "subwoofer-y" arrangement setup behind the desk, which could be anything from a single large driver on a simple baffle to maybe a dual line of the Dayton 8"ers.
Anyway, I'm trying to take my cues from MJK's new article (and the attendant thread here discussing it) about passive fullrange+bass helper OB. I figure as long as I can get the bass helper system, whatever it ends up being, to be at least 6dB more efficient than the B20 (which is 88-91dB, depending on who you believe), then I should be able to hack something together with a pleasant combined response.
Oh, and don't forget the phase plugs. Got mine from P10, and they totally make a new driver out of the B20s (which were already an order of magnitude better than my old Kenwoods when they were stock).
Kensai
I can never figure you guys when you're all saying that driver positions of 30"-38" are "ear height". I'm only 6'2", and when I sit up in that chair, my ear height is around 46". The driver centers there are about 43", so even when I slouch a bit, they're not much above ear height. I'm all leg, too. I mean my wife is 5'3" and when we're sitting on the same surface she's only maybe 5"-6" shorter than me.
That rig is in the newly finished basement now, though still in a corner. In fact, other than the window there and the wainscoating, the setup doesn't look much different at all. I have, however, gotten that rack below the top shelf of my desk moved back enough that I can let the monitor extend as far up as its stand will allow so that now the top edge of the monitor is just above driver center height there, which is much more ergonomic for me.
And actually their running of the core of little JVC shelf system, one with an older Hybrid Feedback digital amp in it. Sounds much more lively, not to mention has much stronger bass, than an original SI T-Amp, and several orders of magnitude more clean and detailed than a Pioneer VSX-D411 5.1 receiver.
Tim,
Thanks, but you have to know that they're just a pair of Farberware bamboo cutting boards, $10 each at walmart, mounted with a couple of $.60 hinges to a couple lengths of 1"x2" that I have wedged in there.
I'm mulling about several different options for bass, though with no budget and no time, I'm having a hard time getting started. Besides, I use an E-Mu 0404 sound card as my source, and it allows for nearly unlimited EQ control, in the digital domain before the signal hits the DACs, and with that I am able to get these B20s on these 12"x18" baffles to be solid to 60Hz or so, with audible response down into the lower 50s all the way up to a touch over 16kHz. As far as I can hear since no matter what I'm testing, including a pair of Grado headphones or a 2-way monitor using a B&G Neo3PDR tweeter that's supposed to be good way up over 20kHz, that's as far as I can reliably pick out a test tone from the harmonics. However I do find that a stiff shot of EQ boost in the top frequencies does produce alot more audible "air", if you know what I mean.
Anyway, I guess the goal here is to build something that can do without any EQ at all. Running these things flat in a normal 44.1/48kHz mode (CD and DVD), they're pretty dull and lifeless, and certainly aren't getting me much below maybe 100-120Hz. Running them in a 176.4kHz mode (a nice x4, whole number multiple of the original sample frequency) really does make them come alive, with tons more detail. When I test the frequency response, it doesn't actually get better when upsampling, but somehow it sounds like it has when you listen to actual music, so that's what I want to be able to do.
I've gotten a pair of the Dayton 5/8" dome tweeters that everyone's been talking about with the Chang DBVRs and other B20 enclosures. Just got a bit for drilling the appropriate sized hole over the weekend, so I haven't had the chance yet to actually install them. On the bass side, I'm still wallowing in a mass of ideas, constrained by the fact that I have no real budget for purchasing drivers. I'm also constrained by the fact that I want to keep the bass OB as well.
I'm in the middle of building a pair of BiB variants for the Pioneer A11 that are meant for a buddy of mine who currently has television speakers and a 2.1 set of Creative Labs multimedia crap. They're pretty impressive, getting down solid to 55Hz or so with no EQ and with it you can at least make out a clean 20Hz test tone. However, they instantly sound boxy to me, and I can easily detect where the bass is actually coming from (the bottom rear of the cabinet; they're like an inverted BiB except they are rear firing instead of firing straight down). IMO, this is okay for boombox or party duties, but I've been well beyond that level of sound quality for some time now, so with this experience, I'm convinced that I'm not going to like, let alone be satisfied with any sort of enclosure style bass.
I've kinda gotten the Dayton 8" DVC subwoofer driver stuck in my mind as a fun option. Its cheap, flexible, pretty low Fs, specs look like it would match nicely, and more importantly, how cool would 4 of them look in a line array with a B20, eh? Anyway, just with those, the options are pretty boundless. There's the line array I just mentioned (not likely hinge mounted like the current baffles, but you never know). Perhaps just WFW (and MTM with a B20 as the tweeter) would be enough.
I'm also interested in perhaps trying an SDA alignment. This is a Polk technology that they've basically let out of the bag with the advent of their Surround Bar product since that uses SDA and then a ton of passive filters to get a surround effect. What the SDA does is supposedly create a wider sound stage and the implementation is dead simple. You get two drivers on each side, their centers about the same distance apart, horizontally, as a human's ears (so for these, they would just be lined up edge to edge), with one driver being wired normally and the other wired with an inverted version of the signal from the other side. I've tried this with matched sets of Kenwood 6"x9" drivers (which I thought were pretty good sounding until I got a pair of B20s for Christmas and learned the error of my ways), and the soundstage did indeed sound wider and the bass response was, if not much lower, quite a bit more authoritative down to the point where it fell off a cliff.
Other options include finding/using a single 10"-15" driver (I think I can corral a 15"er and the B20 into the space I have, somehow) onto a new, more beefy baffle, or possibly making something a bit more "subwoofer-y" arrangement setup behind the desk, which could be anything from a single large driver on a simple baffle to maybe a dual line of the Dayton 8"ers.
Anyway, I'm trying to take my cues from MJK's new article (and the attendant thread here discussing it) about passive fullrange+bass helper OB. I figure as long as I can get the bass helper system, whatever it ends up being, to be at least 6dB more efficient than the B20 (which is 88-91dB, depending on who you believe), then I should be able to hack something together with a pleasant combined response.
Oh, and don't forget the phase plugs. Got mine from P10, and they totally make a new driver out of the B20s (which were already an order of magnitude better than my old Kenwoods when they were stock).
An externally hosted image should be here but it was not working when we last tested it.
Kensai
That's my kind of speaker! Re-purposing and finding new configurations is half the fun.Kensai said:
EQ is certainly one solution, and at least with the PC you can work out what you want electronically before building (and it's a cheap solution as you already have it...
Let me know how that goes - at present I'm running without a tweeter, but if I strengthen the bass I'm sure I'll want to try to do something with the top end.
I'm looking forward to hearing more about your experiments.
I don't know anything about phase plugs - what's the effect you hear?
...and thanks for the detailed description...
tim
The phase plug really clears up the mids and treble, and possibly extends the high end response by 500Hz or so (which isn't really noticeable unless you're running manual test tone sweeps). As I understand it, a phase plug is supposed to move distortion/cancellation up an octave, virtually halving the space from one side of the cone to the other, pushing it up to where its either less audible, or not at all. In practice, it removes a bit of cupped hand sound that seems to be common for FR drivers, especially those with whizzers. It also provided more sense of air and detail.
Another effect the mod caused comes from having removed the dust cover to mount the phase plug. The missing mass doesn't seem to have done much to the sound, but not having the trapped air mass between the pole piece and the dust cap has given the driver more apparent motor strength as its night fighting that air compression force. This has given it more authority on the bottom end. In close testing, I was only able to discern 2-3Hz greater extension, but it was able to hit that far down with less rolloff. The absolute bottom attainable frequency didn't change much if at all, but the spl getting down to that point was greater before that final, sharp rolloff.
Of course, the phase plugs change the B20 from a $25 driver to a $50 driver, unless you can DIY your own, but I can't, and I'd been living with them for a good while already and was itchy to tweak.
I think you've gotten in at a good spot with the B20. What little experience I've had with the smaller FR drivers has me equating them to yippy little lap dogs, while the B20 is more like my folks old greyhound. He's pretty laid back and relaxed, but he's got the legs to really run when he its necessary.
Kensai
Another effect the mod caused comes from having removed the dust cover to mount the phase plug. The missing mass doesn't seem to have done much to the sound, but not having the trapped air mass between the pole piece and the dust cap has given the driver more apparent motor strength as its night fighting that air compression force. This has given it more authority on the bottom end. In close testing, I was only able to discern 2-3Hz greater extension, but it was able to hit that far down with less rolloff. The absolute bottom attainable frequency didn't change much if at all, but the spl getting down to that point was greater before that final, sharp rolloff.
Of course, the phase plugs change the B20 from a $25 driver to a $50 driver, unless you can DIY your own, but I can't, and I'd been living with them for a good while already and was itchy to tweak.
I think you've gotten in at a good spot with the B20. What little experience I've had with the smaller FR drivers has me equating them to yippy little lap dogs, while the B20 is more like my folks old greyhound. He's pretty laid back and relaxed, but he's got the legs to really run when he its necessary.
Kensai
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