Yes I can see that one. Curious about why have you opted for a 5 sided midrange enclosure?
Inspired by but as the speakers not very deep i might not taper it off as it might restrict the air space for the mid ?
TBH, i've not worked out how many litres i need for the mid or how many litres the enclosure will work out to be.
I'm thinking i'm going to make a test box and see how it sounds/measures.
I've not seen any builds/designs using this mid to get an idea what works for this driver.
The more sides the closer the box approaches to a circle. 4 sides has the issue of parallel sides, 3 is best i’d think (i typically use a heavily tapered midTL out the back).
dave
That might be useful. Did the people you are being inspired by do this? Are you intending to add stuffing to absorb the sound from the rear of the midrange?
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1st pass, 300 litres F6 aboutt 40, F10 in the low 30s. Possibly not the driver you want for a “small” box.
Sad that we no longer have the SDX7, you can get near 25 hz sealed and only need about 40 litres.
2,3 litre (plus) undamped for a Q = 0.707, F3 = 126 Hz (if you want to use the sealed corner as 2 poles in your XO).
Given those numbers probably a gross volume in the vicinity of some 320 litres or so...
dave
I was thinking 3 or 5 sided to avoid parallel sides, i thought a 5 would keep more space between the mid and the enclosure wall rather than 3 ?
I will probably line the inside walls with fleece and get some natural wool to lightly stuff the rest of the enclosure. The outside of the enclosure will have some bitumen sheet applied to it.
That works against the plywood and the bracing, it is counterproductive.
Now on the outside of the mid enclosure to lower its resonance below (say at least an octave) below the XO point, allthou any radiated box energy will radiate into the bass enclosure to one has to ask the question, how much will a midEnclosure wall resonance affect the midrange.
I’d go for a low pressure aperiodic midTL out the back ideally with only one panel needed to separate it from the bass enclosure. It should be noted that that topology lends itself to “2” boxes with isolation between them (if you want to get anal).
dave
dave
That's looking more and more attractive as time goes on, do away with the box too, hey presto...a naked dipole 😉
Every OB i have heard has had the same kinds of problem. I stil have one more in me (gotta use up 8 10” OB woofers).
dave
dave
Thanks for crunching those numbers.
I thought i was OK volume wise for the Visaton based on some enclosure examples on their website. Natural roll off isn't going to be the deepest even if i had the space for a bigger enclosure but i should be able to make it sound nice with some modest EQ. Again, it looks like i will have to do a test enclosure before committing to a full build. They're on there way from Germany at the moment.
TIW 250 XS - 8 Ohm | Visaton
I might end up doing a tapered dagger if it only needs 2.3L for the mid, plus i was only going to use it down to about 400-500hz.
Nice to know, i'll not use it on the mid enclosure. Is it good to use it on the insides of the rest of the speaker ?
Why do you believe parallel sides are an issue particularly if you are going to stuff the box? If you are not sure and getting conflicting information off the web (who would have expected that) then performing an experiment on a prototype as suggested above is likely to be a pretty good idea.
The air velocity is zero at the walls and at a peak value a quarter of a wavelength away (varies with frequency). Given sound is dissipated by squeezing air rapidly through tiny holes how useful is stuffing next to the walls compared to the middle of the enclosure? Which is likely to be better heavily stuffed and which lightly?
Damping is necessary for the resonances in the midrange enclosure but not for the main enclosure if you get the resonances above the woofer passband and isolate it from the midrange enclosure.
andy19191 asks good questions ime..
damping has proven to work better in the middle of the enclosure vs the sides. afaict
damping has proven to work better in the middle of the enclosure vs the sides. afaict
You might well have to go to an aperiodic enclosure — as opposed to EQing — to help with the big peak.
Way too small for a vented box. Sealed a Q of near 1.3, F3 = 90 Hz, F6=80, F10=62ish. You have to be very concerned with the extra excursion and power required to get this woofer even down to … i’d have to look up the figures, but there is some quadrupling in there.
dave