This is interesting. I wanted to come to this with my question. Today I will buy the wood, I'll make 10 liters sealed boxes, so there is room to bring reinforcements and padding. I have already bass reflex boxes I put together previously, then this is a matter of choosing which I like.
Hi,
This may be technically interesting, but I'm not remotely interested
in "optimum", i.e. Butterworth, vented boxes, I'm interested in what
is IMO the "optimum" way of using a particular driver for purpose.
Here I'd suggest detuning the vented boxes ports. Get some porous
foam, around ~ 8mm thick, cut into rectangles port length x 3 dia.
Insert into the ports, it will self support itself.
This IMO will be better than "optimum" sealed and vented.
Speaker design is the art of good compromises, not dogma.
rgds, sreten.
Attached is yellow = optimum sealed, green = optimum vented.
Driver = Qts - 0.35, Vas - 45L, Fs - 30Hz, ~ a good 8" driver.
I like the purple line at +8dB @ 20Hz over both the above.
Note the quasi first order slope of the purple line.
This gives quasi first order transient response, the best.
Look at F3, F6 and F10 for the green and purple lines.
Particularly note the slope of all of the lines at F6.
Compare the purple to the large/massive blue/red sealed box.
This may be technically interesting, but I'm not remotely interested
in "optimum", i.e. Butterworth, vented boxes, I'm interested in what
is IMO the "optimum" way of using a particular driver for purpose.
Here I'd suggest detuning the vented boxes ports. Get some porous
foam, around ~ 8mm thick, cut into rectangles port length x 3 dia.
Insert into the ports, it will self support itself.
This IMO will be better than "optimum" sealed and vented.
Speaker design is the art of good compromises, not dogma.
rgds, sreten.
Attached is yellow = optimum sealed, green = optimum vented.
Driver = Qts - 0.35, Vas - 45L, Fs - 30Hz, ~ a good 8" driver.
I like the purple line at +8dB @ 20Hz over both the above.
Note the quasi first order slope of the purple line.
This gives quasi first order transient response, the best.
Look at F3, F6 and F10 for the green and purple lines.
Particularly note the slope of all of the lines at F6.
Compare the purple to the large/massive blue/red sealed box.
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Hi,
That program is the basic WinISDbeta, WinISDpro is more advanced but
more difficult to use, neither are particularly accurate, though they both
reflect the basic mathematics, for a real design I'd cross check with
say Unibox, which is apparently very good, but not as quick, at all.
They are both good for playing with the numbers, the latter also
does maximum SPL and power handling stuff, quite illuminating.
(Also does active pre filters for 6th order designs).
They are free, The demo version of Basta! is also worth a look,
if for nothing else, the free technical info/manuals available.
rgds, sreten.
To play with WinISDbeta you only need Fs, Qts and Vas.
That program is the basic WinISDbeta, WinISDpro is more advanced but
more difficult to use, neither are particularly accurate, though they both
reflect the basic mathematics, for a real design I'd cross check with
say Unibox, which is apparently very good, but not as quick, at all.
They are both good for playing with the numbers, the latter also
does maximum SPL and power handling stuff, quite illuminating.
(Also does active pre filters for 6th order designs).
They are free, The demo version of Basta! is also worth a look,
if for nothing else, the free technical info/manuals available.
rgds, sreten.
To play with WinISDbeta you only need Fs, Qts and Vas.
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Today I bought the wood. I will make a sealed box about 9 liters, but there is also the option to open them to make it bass reflex, with the corresponding size for this application. Is a design that always used to be able to test so versatile. Tomorrow I'll start the assembly of the boxes. I estimate to complete them within ten days. As promised earlier, i´ll show you pictures
Hello,Good discussion of sealed boxes and bass reflex. Here is an effort at some of the reasoning or explanation with a stored energy bias.
Much of the discussion has been about driver Qtc and speaker (enclosure plus driver) total Q.
Pun included, it is a quality thing. Dampening is pretty much the reciprocal (1/Q) of Q. The higher the Q and the lower dampening the greater the stored energy and the more wobbly the bass gets. The trade off is greater dbs at lower Hz. The whole thing for extended Hz in a bass reflex box is stored acoustic energy compressed in the box and returned nearly 90 degrees out of phase as reinforcement. Sounds wobbly, fuzzy to me.
In my text book critically damped is Q=0.5.
DT
All just for fun!
I thnk youve maybe misinterpreted my meaning or my meaning wasnt clear.
i agree with your philosophy regards 'traditional' alignments, or at least the maximally flat butterworths. trouble is with stored energy. Chebychev is even worse. point being, all alignments are analagous to electrical filters (as we all know).
to the other poster, i have to agree, in a closed box system, provided power handling isnt too compromised, a total box Q of anywhere between 0.5 and 0.7 is where is aim, especially if i wanted seamless integration with a sub. thats just my personal opinion. plus it makes filters so much easier, and nicer phase wise-im sure even active has advantages using lower order filters-although to appease Sreten a little Weems book claims a cleaner upper bass from reflex designs than that of a closed box, but i cannot say i have noticed personally. having a reflex satellite crossed lower to a sub has its advantages, but the steeper filters needed, and the increased accuracy of their integration, are disadvantages. personally if i have a ported system with F3 = 45hz, i wouldnt even bother with a sub at all. maybe i have cloth in my ears
but i would like to see the group delay comparison with those curves Sreten, considering the gain between the HUGE closed box and the over damped vented box is due to the vent, coming with all the resonances, thru port reflections and phase issues that are inescapable. the vented alignment you show is interesting, I would use it for a main speaker system, but not for something to use with a subwoofer.
i essentially agree with you though. i would try and build a box suited for the vented alignment, with which you can tune the ports using foam, to varying degrees, to even aperiodic if needed. theres nothing wrong with playing around with stuffing or port sizes, or resisitive ports.
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it is good yes. not wanting to start a filler debate but in the end a composite of lots of materials is the best. foam fibre and felt....3 F's lol
OOOH,I´m using rockwool and polyfill.
Well, i´ll continue with the enclosures
Rock wool, read the MSDS. That stuff is as bad as asbestos. Every time the port pushes air out the fibers will be comming out too.
DT
Serious Stuff!
I was going to try rockwool on a sealed enclosure, and for an acoustic panel. Then you got me all scared. So I did some reading.
This pretty much sums up the reasearch (by world health organization, by the way).
I read all of page two, and many other pages. But page 2 is most important!
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-5.pdf
Use common sense when using it.
I would assume that you could use it in a ported enclosure if you put in inside, or cover with acoustic fabric. The fibers are NOT that similar to asbestos. Rockwool is similar to fiberglass, so don't be scared to use it.
From wikipidia, also...
The stuff I am going to be using is commonly used for hydroponics and is produced by europeans. Rockwool under brand name Grodan. I am in SoCal and there is a hydro place one block from me. And countless others Thanks, medical pot
I would try the woofer in different enclosures while measuring and recording results.
Post up on here so we can all see what happens
Hope this is not too off topic, as I am also thinking of trying different enclosures with different stuffing. The woofer I am going to play with is designed for sealed, but may play with some vented boxes....
Todd
This pretty much sums up the reasearch (by world health organization, by the way).
I read all of page two, and many other pages. But page 2 is most important!
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-5.pdf
Use common sense when using it.
I would assume that you could use it in a ported enclosure if you put in inside, or cover with acoustic fabric. The fibers are NOT that similar to asbestos. Rockwool is similar to fiberglass, so don't be scared to use it.
From wikipidia, also...
- R38 – Irritating to the skin
- R39 – Danger of very serious irreversible effects
- R40 – Possible risk of irreversible effects
- S36/37 – Wear suitable protective clothing and gloves.
The stuff I am going to be using is commonly used for hydroponics and is produced by europeans. Rockwool under brand name Grodan. I am in SoCal and there is a hydro place one block from me. And countless others
Thanks, medical pot I would try the woofer in different enclosures while measuring and recording results.
Post up on here so we can all see what happens
Hope this is not too off topic, as I am also thinking of trying different enclosures with different stuffing. The woofer I am going to play with is designed for sealed, but may play with some vented boxes....
Todd
I was looking for a definition in Spanish for carpet underlay (do not forget I am Argentinian, English is not my native language), but did not find much about it. What is it? Or what are their uses? Maybe then I can identify it.
On the other hand, in one hour I will finish the enclosures. Tomorrow I will do the bends in the edges of the fronts and I'll start with painting. I guess that'll end for next Monday or Tuesday. And I take another day to make cloth grilles, but that is a cosmetic issue, no big deal.
On the other hand, in one hour I will finish the enclosures. Tomorrow I will do the bends in the edges of the fronts and I'll start with painting. I guess that'll end for next Monday or Tuesday. And I take another day to make cloth grilles, but that is a cosmetic issue, no big deal.
Si tu quieres, yo puedo preguntar mis amigos que es el nombre de este material.
I speak enough spanish that I may be able to help
Mi amigo dice que es posible ellos usan la palabra "esponja".
Es para abajo la alfombra. Preguntas un trabajador de alfombra.
Carpet Padding - Carpet Underlay
I speak enough spanish that I may be able to help
Mi amigo dice que es posible ellos usan la palabra "esponja".
Es para abajo la alfombra. Preguntas un trabajador de alfombra.
Carpet Padding - Carpet Underlay
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Excelente, muchas gracias por tu amabilidad
I was asking, and is not a material used in my country for this purpose. As you said earlier, is something like a sponge.
I'll keep asking anyway, and if I can not get this material, I will use glass wool or rock wool. I have a outdoor space to work comfortably and without risk to those who live with me. And the wool in conjunction with the polyfill probably do a good job.
Thanks again, this time in English No need to speak in my language, I fully understand you. The only problem is that, as in this case, there are some materials that are not used here, or that are not easy to get.
I was asking, and is not a material used in my country for this purpose. As you said earlier, is something like a sponge.
I'll keep asking anyway, and if I can not get this material, I will use glass wool or rock wool. I have a outdoor space to work comfortably and without risk to those who live with me. And the wool in conjunction with the polyfill probably do a good job.
Thanks again, this time in English
No need to speak in my language, I fully understand you. The only problem is that, as in this case, there are some materials that are not used here, or that are not easy to get.- Status
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