The coils seem okay... I had a speaker a while back with damaged voice coils and it was immediately obvious what the problem was. Extremely distorted sound when playing and obvious scraping when pushing the cone in. The ones I have now spring right back when pushed in and don't actually sound too distorted, they're just missing an awful lot down low because of the Fs.
I considered using a decent woofer, Moondog... thanks. Might still do that, and in the short term I might just cross my sub over a little higher, but that's obviously not a good idea in the long term. There were a pair of M22's on eBay yesterday, probably should have put a bid in.
Hmm, wonder where I've read that recently..........
Anyway, ignoring Vas, the measured specs yield a 'close enough' F3 to the old published specs, but assuming the same Vas it will take a ~7.91x larger cab for a too under-damped (if not converted to TL loading) T/S max flat alignment due to the high average Qts.
Bottom line, unless you can find a reason for the poor specs, then from what you've posted it seems that an OB or ~aperiodic alignment to keep size semi-acceptable plus 'sub' system will yield the best overall results.
Skeet practice, anyone?
GM
Anyway, ignoring Vas, the measured specs yield a 'close enough' F3 to the old published specs, but assuming the same Vas it will take a ~7.91x larger cab for a too under-damped (if not converted to TL loading) T/S max flat alignment due to the high average Qts.
Bottom line, unless you can find a reason for the poor specs, then from what you've posted it seems that an OB or ~aperiodic alignment to keep size semi-acceptable plus 'sub' system will yield the best overall results.
Skeet practice, anyone?
GM
""There were a pair of M22's on eBay yesterday, probably should have put a bid in. ""
What we need is a group buy of 1000+units, so we can get an OEM price.
I do thank-you for not driving the price up, although I would not have gone over $120- the pair anyway.
Do you have spouse approval to use 15 inch woofers in a 3-way??
What we need is a group buy of 1000+units, so we can get an OEM price.
I do thank-you for not driving the price up, although I would not have gone over $120- the pair anyway.
Do you have spouse approval to use 15 inch woofers in a 3-way??
Hmm, wonder where I've read that recently..........
Anyway, ignoring Vas, the measured specs yield a 'close enough' F3 to the old published specs, but assuming the same Vas it will take a ~7.91x larger cab for a too under-damped (if not converted to TL loading) T/S max flat alignment due to the high average Qts.
Forgive me if my understanding of the theory is wrong, but shouldn't the Vas change? I thought it was only dependent on the dimensions of the driver and the compliance... and the compliance clearly has changed if the Fs is off by so much (the only other possibility is that the moving mass has changed, which I find unlikely).
In fact, I should be able to infer the Vas if the dimensions of the driver and the moving mass haven't changed, right?
Doing so gives me about 4 L for the Vas, down from the spec of 35. Which actually simulates okay in my cabinets of 20 or so litres if I seal the box. 3dB down at 110 Hz, which is a lot worse than I designed for but not dreadful since I have a sub to help out at the bottom.
Okay... might be usable, but I'm not sure what else the stiff compliance would affect (e.g. efficiency, roll-off). Still worth a quick redesign based on what I've measured the specs to be rather than what I've assumed them to be all along.
Fs = ((1/Pi)/2)*((1000/(Mms*Cms)^0.5)
So with no Vas measurement we can juggle mass and compliance numbers till the cows come home and still not be right and why I arbitrarily kept Vas constant as one example and not meant to imply this would be the case.
In retrospect though, with such a drop in motor strength (big increase in Qes) and steep rise in Fs it seems reasonable to me that mass took the brunt of the change (if not all of it) with a different VC since Qms didn't change enough to matter:
Qe = (2pi*Fs*Mms*Re)/Bl^2
Qms = 1/(2pi*Fs*Cms*Rms)
GM
So with no Vas measurement we can juggle mass and compliance numbers till the cows come home and still not be right and why I arbitrarily kept Vas constant as one example and not meant to imply this would be the case.
In retrospect though, with such a drop in motor strength (big increase in Qes) and steep rise in Fs it seems reasonable to me that mass took the brunt of the change (if not all of it) with a different VC since Qms didn't change enough to matter:
Qe = (2pi*Fs*Mms*Re)/Bl^2
Qms = 1/(2pi*Fs*Cms*Rms)
GM
Not sure it is the magnet - I got around to measuring Vas using the added mass method and it looks like the moving mass is what it should be (14 grams). For each driver, Qes and Fs were off by the same amount and therefore (if my maths is right) the equation for Qes given above suggests that BL is where it should be.
Argh... too much maths.
On the other hand, I did manage to drop the Fs of the worst driver by about 30 Hz by physically trying to loosen the spider and surround by giving them a little "tough love". I'm trying to loosen them a bit more by driving them close to xmax for an hour or so.
Thanks for the help, everyone. I really appreciate it.
Argh... too much maths.
On the other hand, I did manage to drop the Fs of the worst driver by about 30 Hz by physically trying to loosen the spider and surround by giving them a little "tough love". I'm trying to loosen them a bit more by driving them close to xmax for an hour or so.
Thanks for the help, everyone. I really appreciate it.
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