OK, here's the rub..I'm getting some "stuff" from my brother-in-law who's traveling stateside, less than a month now. I've got this old (But still decent surround) driver, 6.5", Qts .749, Qes .959, Qms 3.42, Fs 57.8, RE 7.65, VAS 26.49L, Le .778, SPL 88.4, X +-4mm.
This will be my first ported....I've done sealed for a couple decades plus now. The point, is when I last did my sealed towers & had them "stuffed"...I was concerned the shape would tend to oscillate, I "hummed" scales loudly into the driver cut-outs...no resonances whatsoever, cool. So, wouldn't stuffing full a ported alignment damp out any resonances rendering the port non-functional??
Is the enclosure to be lightly damped & what determines "lightly" damped?
Using WinISD beta, I get 204.1 Liters, Fb 30.69 Hz. -3.01 Db@ 27.01 Hz......I'll deal with the "big box just fine & I don't need mega volume with my 4.5M by 5M "live room".
______________________________________________Rick..........
This will be my first ported....I've done sealed for a couple decades plus now. The point, is when I last did my sealed towers & had them "stuffed"...I was concerned the shape would tend to oscillate, I "hummed" scales loudly into the driver cut-outs...no resonances whatsoever, cool. So, wouldn't stuffing full a ported alignment damp out any resonances rendering the port non-functional??
Is the enclosure to be lightly damped & what determines "lightly" damped?
Using WinISD beta, I get 204.1 Liters, Fb 30.69 Hz. -3.01 Db@ 27.01 Hz......I'll deal with the "big box just fine & I don't need mega volume with my 4.5M by 5M "live room".
______________________________________________Rick..........
Well, WinISD defaulted towards Ported for the specs I supplied, reworking to use sealed I got -14Db plus @ 27 Hz, for a 500 Liter sealed enclosure. Ramping up & up the enclosure volume trying to push the Qtc towards the Qts....an "infinite" volume. My understanding is an EBP upwards of 50 "starts" to work best as in a ported alignment. Granted some 80+ works better.... Designers sometimes tend to split the difference making any one driver more flexible in a myriad of applications. I've found(Modeled) drivers running 30-70 EBP can get some really impressive low-end performance (Granted a really "Big-Box)""....as is this little 6 1/2 inch job.
___________________________________________________Rick.........
The issue is that such a high Qts already implies a peak in response in free air, when put in a box this only gets worse. When put in a ported box it ends up with a much bigger box than sensible and trying to push it into something smaller just results in poor boomy response.
The driver is suited to an open back speaker or maybe a transmission line.
The driver is suited to an open back speaker or maybe a transmission line.
Hi All,
FYI:
b
PS: BIL= Brother-IN-Law
OK, OK..........yikes all that data on one screen, I'd be tempted to print that out, grab my calculator, pencil & paper.
So the upshot is the ported alignment will just get me "sloppy", somewhat undefined bass?? OK, I will be running these with a Tri-Path 2020, so excursion limitations would have been a side issue.....My basic version of WinISD doesn't get me Qtc of the ported alignment....I thought 0.8 Qtc was within "acceptable" limits, not the case? If that IS the case & the bottom end will be MIA..I do have an alternative(addition) to fill in the bottom...I have a pair of these. 12" DVC Sub, Qts 0.52, Qes 0.58, Qms 4.58, Vas 496.7L, Fs 21.3, Re 7.0, Pe 60W, Le 1.75,SPL 90.7, X 12mm.
This should compliment my, (by now) satellites ..I do have physical room for this sub as I modeled it...frankly the two "large" first incarnation ported enclosures would have been difficult to locate.
Thoughts?
_____________________________________________________Rick.........
Hi,
That is a very large Vas and high senstivity for a 12" sub,
in reality more a bass unit suited to 250L sealed and well
stuffed. You could clamshell them and use isobaric, that
will get you to a more sensible 125L sealed and stuffed.
A peaking (say Q=2) highpass can boost the low bass,
if room gain doesn't come to the rescue, often does.
rgds, sreten.
That is a very large Vas and high senstivity for a 12" sub,
in reality more a bass unit suited to 250L sealed and well
stuffed. You could clamshell them and use isobaric, that
will get you to a more sensible 125L sealed and stuffed.
A peaking (say Q=2) highpass can boost the low bass,
if room gain doesn't come to the rescue, often does.
rgds, sreten.
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That's exactly how this pair was intended from the start(15+ yrs ago), however when I found out each coil was running at 3.5 Ohms per...I opted to set up just one...with the gigantic experimental enclosure. It performed quite well, however, the driver proper had not been stored properly & has developed a sag, some 2mm.....of which I had well documented & photographed(Didn't believe it!).....till I found out for myself..surrounds are just fine..but?
The other is NIB ready to go...I think I won't risk it...a surround failure or some sort after little use would leave me with a half size enclosure, Oh well, BIB?
__________________________________________________________Rick......
The other is NIB ready to go...I think I won't risk it...a surround failure or some sort after little use would leave me with a half size enclosure, Oh well, BIB?
__________________________________________________________Rick......
Hi,
Easy enough to wire as 4 ohm, series parallel, or parallel series.
I wouldn't worry about the sag much, clamshell will sort it out,
in the bigger picture, its not a problem at all, in any sense.
It will cause a mild increase in 2nd harmonic distortion,
and after that cause literally no effect at all in any sen
rgds, sreten.
Easy enough to wire as 4 ohm, series parallel, or parallel series.
I wouldn't worry about the sag much, clamshell will sort it out,
in the bigger picture, its not a problem at all, in any sense.
It will cause a mild increase in 2nd harmonic distortion,
and after that cause literally no effect at all in any sen
rgds, sreten.
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