Just saw this design http://www.t-linespeakers.org/FALL/bd-pipes.html
What are they? Bi-poles? Di-poles? what is the difference between these designs?
Then on the same page, there is a pipe built around FE 103, two drivers per box, one in front, one at the back. Why??
http://members.shaw.ca/t-linespeakers/FALL/images/BD-Pipes-FE103A.jpg
Are there specific advantages to that use?
What are they? Bi-poles? Di-poles? what is the difference between these designs?
Then on the same page, there is a pipe built around FE 103, two drivers per box, one in front, one at the back. Why??
http://members.shaw.ca/t-linespeakers/FALL/images/BD-Pipes-FE103A.jpg
Are there specific advantages to that use?
Very true, and no question is daft! Both of these speakers are basically the same classic Bert Doppenberg design. Strictly, they're neither bi, nor dipolar, though they're much closer to being bipoles.
The best way of describing a DIpole speaker is to think of an open baffle type design. The driver mounted to the baffle radiate energy both forward and backward into free space.
A BIpole speaker technically requires two drivers, facing directly away (or directly toward, though I've never seen that!) from each other on opposite sides of a normal cabinet -it doesn't matter what type -sealed, BR, TL etc. So, the BD pipes you've noticed are obviously closer to a bipole, though strictly speaking I wouldn't describe them as such. Probably pedantic of me.
What's the rear driver for in this design, and bipoles in general? It has a similar effect to a dipole open-baffle design (now there's a surprise!). A normal speaker radiates energy in a conical, or better, a globular fashion forward of the driver. Bi and dipolar types radiate energy rather differently. I can best describe the pattern like this: think of two snooker balls connected together. This has quite a few advantages, not least of which being that it eliminates baffle-step problems, and, energises room modes far less than conventional speaker types -the exact reverse of what many people suppose.
How to wire a bipole speaker? In parallel, and in phase. If the rear driver is mounted directly behind the front (as, stricktly speaking, it should be), you can also apparantly get some real advantages by having a mechanical connection between the drivers -a length of dowel-rod for example, so they work in push-push configuration against each other. Cuts down on cabinet stresses.
Here are some larger bipole designs, also from Dave's page:
http://www.t-linespeakers.org/FALL/bipolar/index.html
I'm in the process of modifying the dimensions of designs number1 to and 3 to use the Fostex FE167E and FE127E respectively.
For more information on dipoles, and speaker radiation behaviour in general, I cannot reccommend reading the articles here highly enough:
http://www.linkwitzlab.com/
Look in the Concepts section at the articles there.
Hope this helps
Best
Scott
Oh, by the way, these BD pipes are supposed to be quite good with the FE103E -even TNT-Audio built and reviewed a pair:
http://www.tnt-audio.com/casse/tqwp_e.html
I take all reviews with a ton of salt, but it's always nice to have another oppinion!
The best way of describing a DIpole speaker is to think of an open baffle type design. The driver
A BIpole speaker technically requires two drivers, facing directly away (or directly toward, though I've never seen that!) from each other on opposite sides of a normal cabinet -it doesn't matter what type -sealed, BR, TL etc. So, the BD pipes you've noticed are obviously closer to a bipole, though strictly speaking I wouldn't describe them as such. Probably pedantic of me.
What's the rear driver for in this design, and bipoles in general? It has a similar effect to a dipole open-baffle design (now there's a surprise!). A normal speaker radiates energy in a conical, or better, a globular fashion forward of the driver. Bi and dipolar types radiate energy rather differently. I can best describe the pattern like this: think of two snooker balls connected together. This has quite a few advantages, not least of which being that it eliminates baffle-step problems, and, energises room modes far less than conventional speaker types -the exact reverse of what many people suppose.
How to wire a bipole speaker? In parallel, and in phase. If the rear driver is mounted directly behind the front (as, stricktly speaking, it should be), you can also apparantly get some real advantages by having a mechanical connection between the drivers -a length of dowel-rod for example, so they work in push-push configuration against each other. Cuts down on cabinet stresses.
Here are some larger bipole designs, also from Dave's page:
http://www.t-linespeakers.org/FALL/bipolar/index.html
I'm in the process of modifying the dimensions of designs number1 to and 3 to use the Fostex FE167E and FE127E respectively.
For more information on dipoles, and speaker radiation behaviour in general, I cannot reccommend reading the articles here highly enough:
http://www.linkwitzlab.com/
Look in the Concepts section at the articles there.
Hope this helps
Best
Scott
Oh, by the way, these BD pipes are supposed to be quite good with the FE103E -even TNT-Audio built and reviewed a pair:
http://www.tnt-audio.com/casse/tqwp_e.html
I take all reviews with a ton of salt, but it's always nice to have another oppinion!
Scottmoose said:
Hi Scott,
You are throwing some light here, for sure. Thanks for that.
I swear that I'll read all the theory links you have sent. Now, if I could understand a little bit more about the calculations and drivers specs behing TQWT designs.. Well, it will come.
Can't wait to enjoy the Zigmas first. And yes, I find those BD pipes quite appealing.. but summer is here, and it will have to wait 'til fall. First things first..
And I'm leaving for Ogunquit (holidays) in July!
If you are interested in Taper Quarter Wave designs have look at the wonderful work done by Martin King. Bob Brines also has some very good stuff to look at as well. You will also find a lot of discussion here on this forum.
I have built a few TQWPipes and heard the speakers that Dave made and they sound very good.
Welcome to a new world, It is quite nice.
I have built a few TQWPipes and heard the speakers that Dave made and they sound very good.
Welcome to a new world, It is quite nice.
SCD said:
SCOTT: sorry for tooting my own horn, but while the inspiration (and drivers) came from Dave, the material and sweat was by yours truly.
Sylver300B: Bert's design was orginally for a kit to be marketed with a custom labelled ( ACR) version of the Fostex FE103E. Apparently that supply line dried up, and he decided to pull the design from his site.
I've built at least 6 or so pairs of these, best results with the vintage Fosters ( as dubbed FE103A by Dave); with phase plugs on front drivers & the tweeter is optional.
IINM, this design could be classified as a folded TQWP, and the exact dimensions may not be optimal for some of the newer FR drivers (i.e the VERY interesting CSS WR or FR125) The WR125 is available in 16ohm version intended for MTM designs, and would be very interesing to try in this enclosure.
FWIW, one or two of the early pairs of these were built in MDF, all others in 13ply baltic birch with superior results to our ears.
If using just 8ohm FR drivers, there's no reason you couldn't wire them in series for 16ohm load that some tubed amps might prefer. Until I recently had and accident with utility knife trying to "improve" on Dave's dust cap circumcision for phase plugs, I was running a pair of bipole MLTL FE127E in series. While some weight in the lower octaves is sacrificed, the bass is cleaner and more articulate on my little EL84RH parafeed amps
And why not toot ones' own horn (perhaps I should re-phrase that... ?
I should have mentioned series wiring shouldn't I? Agreed wholeheartedly -very useful in some cases. Do you have any design info / dimensions for the bipole MLTLs with the FE127E you could share by the way? Perhaps we could swap notes once my ML TQWTs are completed. Did you couple the drivers together at all, or were they just firing in opposite directions?
Best
Scott
?I should have mentioned series wiring shouldn't I? Agreed wholeheartedly -very useful in some cases. Do you have any design info / dimensions for the bipole MLTLs with the FE127E you could share by the way? Perhaps we could swap notes once my ML TQWTs are completed. Did you couple the drivers together at all, or were they just firing in opposite directions?
Best
Scott
chrisb said:
Hi Chris,
The pair of drivers I am using right now, are Fosters. Too bad I don't have 2 pairs. I am building Zigmahornets. As well, I intend to experiment by making them "bipoles" after I have had some experience with them in original form..
About MDF. I always have felt that MDF had its particular sound signature, and I don't like it. And as well, baltic birch is not much more expensive, and so much easier to work with, to cut etc.. Perfect for the novice like me.
About "weight" I'm over 200
oops. . about amps, I have a some nice ss amps at hand, but always prefer the musicality of my SE-300B (I built it after Fi Primer's plan) and I am about building an SE-45 parafeed, but that's another story. Too many projects, too little time. I read it somewhere..As for the BD pipes, I would apreciate if you could share your plans. The ones for the Foster drivers interests me a great deal, and I can't wait to chase and recycle a few more of these drivers.
Thanks for sharing all of this, same applies to folks here.
CSS FR125 BP
As designed by Tim Foreman, and sketched by dld; after hearing the new FR125 at Al Wooley's last week, I'll be making these without tweeters. And just for fun, 2 identical pairs in MDF and 13 ply Baltic Birch.
http://www.diyaudio.com/forums/showthread.php?postid=641317#post641317
As designed by Tim Foreman, and sketched by dld; after hearing the new FR125 at Al Wooley's last week, I'll be making these without tweeters. And just for fun, 2 identical pairs in MDF and 13 ply Baltic Birch.
http://www.diyaudio.com/forums/showthread.php?postid=641317#post641317
CHRIS:
Of course I knew you constructed the cabinets and did a very fine job as well. I inadvetently forgot to give proper credit. I guess I was a little too quick in my reply. Accept my apolgy, yet you and Dave are connected as one, a compliment to one should be felt by both.
Regarding the FR125: Are the T/S parameters the same as the WR125 or similar enough to use the same cabinet.
Of course I knew you constructed the cabinets and did a very fine job as well. I inadvetently forgot to give proper credit. I guess I was a little too quick in my reply. Accept my apolgy, yet you and Dave are connected as one, a compliment to one should be felt by both.
Regarding the FR125: Are the T/S parameters the same as the WR125 or similar enough to use the same cabinet.
Re: CSS FR125 BP
Hi Chris,
Thanks for the link, but the design seems different than what I had in mind: http://members.shaw.ca/t-linespeakers/FALL/images/BD-Pipes-FE103A.jpg
Does someone has a plan for this one?
I think you are quite brave to build one pair of each material
I'm impressed
And I'm curious to see what the results will be.
I would lean toward thinking that the bigger the cabinet, the more it should make a difference in sound, since the resonance patterns of different materials should be more prominent. I'd think it would make less of a difference on the diminutive Zigmahornets.. and no! I won't build a second pair!
chrisb said:
Hi Chris,
Thanks for the link, but the design seems different than what I had in mind: http://members.shaw.ca/t-linespeakers/FALL/images/BD-Pipes-FE103A.jpg
Does someone has a plan for this one?
I think you are quite brave to build one pair of each material
I'm impressed
And I'm curious to see what the results will be.
I would lean toward thinking that the bigger the cabinet, the more it should make a difference in sound, since the resonance patterns of different materials should be more prominent. I'd think it would make less of a difference on the diminutive Zigmahornets.. and no! I won't build a second pair!
variant only
Sylvain:
The differences in the medium brown 2-way BD pipes are:
1) tweeter (some paper cone alnico magnet specials from Dave's stash)
2) front bafffle stepped back 1/2" for "time alignment" of the tweeter - this was easier to achieve than rear mounting with a routed "wave guide" as in the maroon painted MDF pipes.
Once I get started in the woodworking part of the project, I rarely take time to get pictures, so I'm relying on memory; there was some minor reworking required to angled deflector/brace above the front driver to accomodate the tweeter.
Sylvain:
The differences in the medium brown 2-way BD pipes are:
1) tweeter (some paper cone alnico magnet specials from Dave's stash)
2) front bafffle stepped back 1/2" for "time alignment" of the tweeter - this was easier to achieve than rear mounting with a routed "wave guide" as in the maroon painted MDF pipes.
Once I get started in the woodworking part of the project, I rarely take time to get pictures, so I'm relying on memory; there was some minor reworking required to angled deflector/brace above the front driver to accomodate the tweeter.
Hmmm. I have 2 pair of WR125ST.
I'd be prepared to build a variant of the BD Pipes using these if I can get advice on the dimensional changes required to accommodate the FS params of those drivers.
cheers
Doug
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