Do you mean this one?
http://www.diyaudio.com/forums/attachment.php?s=&postid=526880&stamp=1102221644
I was trying to figure out what the physical measurements of the line and CSA were. At first glance the line appears too long. Pretty darn close for gosh and golly though. Can that line be shortened up any? Something like L=32, CSA=24?
That may be a tough one. I think we can do a little better and have a simpler design. I've not tested the Fostex design but my guess is efficiency is less and power handling is higher in their design than a TL would be.
http://www.diyaudio.com/forums/attachment.php?s=&postid=526880&stamp=1102221644
I was trying to figure out what the physical measurements of the line and CSA were. At first glance the line appears too long. Pretty darn close for gosh and golly though. Can that line be shortened up any? Something like L=32, CSA=24?
That may be a tough one. I think we can do a little better and have a simpler design. I've not tested the Fostex design but my guess is efficiency is less and power handling is higher in their design than a TL would be.
About the "quality" of the other reference project.... And what I meant about not setting our sights high enough:
That project initially aimed for a speaker that might be described as good quality 2-way, useful for A/B comparisons to our other projects and using drivers that would show potential for tweaking or redesigning for other/better applications. Perhaps it was the second part of that criteria or maybe the way it was presented that pushed it more toward the simplest, newbie/first DIY speaker of decent quality.
At any rate what we didn't end up with, was a project worthy of interest to veteran builders who already have more hi-end reference speakers and realized the P13/D27 combo in a small cab would have its limitations. Namely that no matter how clear the mids and highs, this simple 2way needs a sub and would never have the presence a larger woofer/cab combination would have.
In retrospect, at $200, or twice that for the TLb, (in order to get decent midbass presence), looks to me that this price has too much competition for experts with too many projects already on their wishlist. Even in the DIY Frugalphile (thanks Dave) world, there seems to be a price/performance ratio albeit with different compromises.
This fullrange project, OTOH should cost half of that one and (hopefully) the compromise is in maximum SPL's, with the gain being the imaging of single-point-source, surprising bass from TL's and the quality reputation benchmark of Fostex. Those of us who persue frugal as a starting point will likely learn something yet again. For myself, I've learned to have great faith in the advice of the posters who've moved this project along, and hope it continues.
Thanks for your efforts.
I like the designs with the narrow front cabs, I'll be building both, knowing that whichever becomes my reference, the others will find a home. My drivers are on the way.
That project initially aimed for a speaker that might be described as good quality 2-way, useful for A/B comparisons to our other projects and using drivers that would show potential for tweaking or redesigning for other/better applications. Perhaps it was the second part of that criteria or maybe the way it was presented that pushed it more toward the simplest, newbie/first DIY speaker of decent quality.
At any rate what we didn't end up with, was a project worthy of interest to veteran builders who already have more hi-end reference speakers and realized the P13/D27 combo in a small cab would have its limitations. Namely that no matter how clear the mids and highs, this simple 2way needs a sub and would never have the presence a larger woofer/cab combination would have.
In retrospect, at $200, or twice that for the TLb, (in order to get decent midbass presence), looks to me that this price has too much competition for experts with too many projects already on their wishlist. Even in the DIY Frugalphile (thanks Dave) world, there seems to be a price/performance ratio albeit with different compromises.
This fullrange project, OTOH should cost half of that one and (hopefully) the compromise is in maximum SPL's, with the gain being the imaging of single-point-source, surprising bass from TL's and the quality reputation benchmark of Fostex. Those of us who persue frugal as a starting point will likely learn something yet again. For myself, I've learned to have great faith in the advice of the posters who've moved this project along, and hope it continues.
Thanks for your efforts.
I like the designs with the narrow front cabs, I'll be building both, knowing that whichever becomes my reference, the others will find a home. My drivers are on the way.
Back on track
Well said x. onasis:
It looks like we got stalled a bit. Perhaps we should get back to the design details of either the bipole or the mono with BSC. Is it safe to assume the published T/S specs from fostex are close enough to conclude our designs.
Tim have you checked the numbers from a set of drivers that have been broken in?
some common design concepts to start things off:
Birch plywood or solid wood is very good
Use 1/4" concrete board to line the inside of the enclosure
Try to get non-parralel insides.
Brace the panels to eliminate enclosure resonance
Use cat 5 wire inside the enclosure
Use duct seal to reduce driver basket resonance
That should get things going again
Well said x. onasis:
It looks like we got stalled a bit. Perhaps we should get back to the design details of either the bipole or the mono with BSC. Is it safe to assume the published T/S specs from fostex are close enough to conclude our designs.
Tim have you checked the numbers from a set of drivers that have been broken in?
some common design concepts to start things off:
Birch plywood or solid wood is very good
Use 1/4" concrete board to line the inside of the enclosure
Try to get non-parralel insides.
Brace the panels to eliminate enclosure resonance
Use cat 5 wire inside the enclosure
Use duct seal to reduce driver basket resonance
That should get things going again
Re: Back on track
I have not personally, however, others have and the variances are minimal.
I like working with those materials although by the time you add concrete board and braces the external material becomes less consequential IMHO. Non-parallel sides can be beneficial but I wonder if less experienced builders would be put off by it. Basket damping is definitely recommended as is adding felt to the magnet back. I also like lining surfaces close to the back of the driver with felt or poly-batting. I had put up a FR graph for the monopole but I apparently deleted it when I edited my comments.
At L=32" and CSA at 24"^2 it looked pretty good.
SCD said:
I have not personally, however, others have and the variances are minimal.
SCD said:
I like working with those materials although by the time you add concrete board and braces the external material becomes less consequential IMHO. Non-parallel sides can be beneficial but I wonder if less experienced builders would be put off by it. Basket damping is definitely recommended as is adding felt to the magnet back. I also like lining surfaces close to the back of the driver with felt or poly-batting. I had put up a FR graph for the monopole but I apparently deleted it when I edited my comments.
At L=32" and CSA at 24"^2 it looked pretty good.
Not being a big fan of BR in general -- i have heard some that are OK -- i'd stay way-way away from the double bass reflex... and from the tuning on the BR i'd say we are already achieving a lower F3 (due to the support of the quarter wave resonance). All the BR gains you is some cabinet size savings (10 litre vrs about 14 litres)... the ML-TL is also inherently better braced (and if you routed off that top-front void would give you a little bit of un-rectangular flair to the box.
dave
Attachments
Re: Back on track
we can specify this as standard (pick 1 -- ply would be my choice) but with people out looking for shelving to cut up to make boxes we should leave it clear there is some flexibility.
Also, what is standard -- if you go into home despot what widths can you buy (so i can tailor a design to standard widths)
I'd move towards 1/2" ply with extra hardwood bracing before i mass-loaded with concrete (matter of fact i'd do alot of other things before i added concrete board which is antithetical to my concepts of cabinet building)
Always a laudable goal, but hard to acheive in a box if you don't have Scott-Dunn-like woodworking skills... the easiest way to achieve a large portion of this requirement is to build a tapered line instead of a straight one -- we have one ML-Voigt on the table already... what can we get out of a tapered line? with or without ML?
The largest expanses are not all that wide... but this is never a bad idea.
a very good base
There are a number of driver mods that i considered required minimum, and this is one of them.
For the reference design we should keep things fairly simple -- the addition of enhancements can then give people an idea of the veracity of those enhancements.
dave
SCD said:
we can specify this as standard (pick 1 -- ply would be my choice) but with people out looking for shelving to cut up to make boxes we should leave it clear there is some flexibility.
Also, what is standard -- if you go into home despot what widths can you buy (so i can tailor a design to standard widths)
I'd move towards 1/2" ply with extra hardwood bracing before i mass-loaded with concrete (matter of fact i'd do alot of other things before i added concrete board which is antithetical to my concepts of cabinet building)
Always a laudable goal, but hard to acheive in a box if you don't have Scott-Dunn-like woodworking skills... the easiest way to achieve a large portion of this requirement is to build a tapered line instead of a straight one -- we have one ML-Voigt on the table already... what can we get out of a tapered line? with or without ML?
The largest expanses are not all that wide... but this is never a bad idea.
a very good base
There are a number of driver mods that i considered required minimum, and this is one of them.
For the reference design we should keep things fairly simple -- the addition of enhancements can then give people an idea of the veracity of those enhancements.
dave
Timn8ter said:
A bump also probably means a bit less desirable group delay thou...
Here is V0.2 which is an inch taller to make the line 2 " longer. The driver also moved up an inch to keep it in the middle. (keep in mind that tho deflectors are probably more important as braces than they are as reflectors, ie the woodwork challenged could leave them out to simplify things).
dave
Attachments
A tapered TL can be created by getting some 2" thick rigid foam insulation at Home Depot while picking up the wood type material.
You cut it to size, taper the thickness along the length (from 2" to zero) then put this on one wall of the box.
The only tricky part is tapering the foam. The best way is using a hot wire cutter- which is pretty easy to make with nichrome wire and a transformer. BUT if you just cut it with a bread knife and a sawing motion you can do it. This leaves a rougher surface which his probably better actually. AND you end up with 2 pieces from one cut. Easy to make deflectors this way too....
Yes, let's also make the design buildable using shelving from there too. I'll try to do research - someone else do it too- the crowds are packing the place this close to Christmas.
You cut it to size, taper the thickness along the length (from 2" to zero) then put this on one wall of the box.
The only tricky part is tapering the foam. The best way is using a hot wire cutter- which is pretty easy to make with nichrome wire and a transformer. BUT if you just cut it with a bread knife and a sawing motion you can do it. This leaves a rougher surface which his probably better actually. AND you end up with 2 pieces from one cut. Easy to make deflectors this way too....
Yes, let's also make the design buildable using shelving from there too. I'll try to do research - someone else do it too- the crowds are packing the place this close to Christmas.
Actual board measures can be found here: http://www.arnoldlumber.com/size.html
This applies to solid wood boards (generaly spruce or pine). All of the board sizes should be readily available (with the possible exception of 1x10 in some areas).
Home Depot also carries MDF in 3/4 thickness in 12 and 16 inch widths. I believe the 16" width is available in 48" lenghts, and the 12" in 96" lengths.
Hope this helps.
This applies to solid wood boards (generaly spruce or pine). All of the board sizes should be readily available (with the possible exception of 1x10 in some areas).
Home Depot also carries MDF in 3/4 thickness in 12 and 16 inch widths. I believe the 16" width is available in 48" lenghts, and the 12" in 96" lengths.
Hope this helps.
) is if shelving is in the same widths.I tend to agree with Timn8ter on the monopole. Although the bipole will produce more LFs, even with the rear driver inductored, it still wont point-source as well as the monopole. If we are building a "reference" speaker for the Fostex, we should concentrate on making the virtues of a single driver shine. And bass response isnt really one of them. The simplier monopole will really show the drivers qualities best and would probably be built by far more people than the bipole. Adding a sub can be easily done to round out the sound. Now we have a speaker that can be used in a satalite/sub system, office/bedroom/dorm etc. More flexibility lower cost and ease of construction. The cost savings from the extra drivers can go towards woofers or proper stands.
amt
amt
Actually, the 1"x** boards are used as shelving material. Most often the 1x12. The only other shelving material that I am aware of is the MDF shelving, common particle board, and the various pre-finished-vinyl-coated ones.
Also, most home centers will have these boards available in different species and grades of wood, including red oak in most sizes - which may make a very nice finished cabinet. The oak, however, may be expensive for many.
Also, most home centers will have these boards available in different species and grades of wood, including red oak in most sizes - which may make a very nice finished cabinet. The oak, however, may be expensive for many.
As has been pointed out, the monopole and dipole are pretty much the same thing. For simplicities sake we could focus on the monopole, but I certainly hope that people also make the dipole and that we can also discuss good/bad points and tweaking tips for the dipoles in this thread. After all, if you are willing to assume that bass is expendible and a sub is needed, then we might have to consider other approaches instead, such as open baffle.
Also in some rooms isn't it posible that the bipole would point source better?
Also in some rooms isn't it posible that the bipole would point source better?