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MarkAudio 12P and 12PW question

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#3
Jeff,

The 10.X models had awful cone break-up, particularly on brass instruments. Completely unlistenable. And that was AFTER over 300 hours of slow, gentle breakin. I sent back the 10.2 drivers but thought that just maybe it would be different with the 10.3 model. Wrong. It was actually worse. (Fool me once, shame on you. Fool me twice.... I'll do what I can to prevent a third time.)

Would like to try the 12P or 12PW, but don't want to waste more money on a driver that has cone break-up. Again.

By "distortion peak" do you mean cone break-up?

BTW, never had a problem with the 7.3's.

Bill
 
#4
silverhairbp said:
By "distortion peak" do you mean cone break-up?
Click to expand...

I guess you could call it that. When the cone is producing harmonic content at a certain frequency that isn't in the signal being fed to it.

Were the 10's running full range? What is your implementation, as mids?

silverhairbp said:
BTW, never had a problem with the 7.3's.
Click to expand...

Horns generally sound pretty good with the A7's.

jeff
 
#5
Jeff,

The 10.X's were running full range. The 10.2 pair was running in 10.2 Pensils. The 10.3 in 10.3 Pensils.

Yes, the A7.3s in Pensils are pretty decent. For the cost of a pair of drivers and a sheet of 3/4" Baltic Birch, it's possible to construct a very nice pair of speakers that most people could live with. At least live with if they don't push them too hard.

I have a design for a large system that uses CSS FR125SR full range drivers as mids. I was able to get a few pairs when they went out of production. But I am selling the last pair of speakers that use those drivers and there are no more FR125SR's available. So I'm looking for a better driver as a substitute.
 
#7
Zman - Thnx for the CSS link. Been looking at that for a little while, hoping Bob will eventually post the frequency response graph for the raw driver.

I won't touch another Alpair 10 m driver. Cone breakup in the two different pairs I bought (10.2 and 10.3) was unacceptable.
 
#8
Indeed the new CSS driver could be thought of as a direct descendant of the FR125- we built a very successful MTM BLH with them and a low cost buy-out tweeter- also from Bob-a year or so ago. As those enclosures where essentially a stacked/inverted pair of FH3, they weren't particularly compact
 
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#11
As far as I understand it, all drivers will exhibit cone breakup when standing waves develop across the cone. The only question is how well-controlled the breakup is. Larger cone -> lower frequency for the onset of breakup. You can usually tell from the data sheet when this happens as the directivity will start to suffer. This means the various SPL curves for, say, 15º, 30º, 45º, etc. will start to diverge. This is all physics in action. The speaker driver designer is up against a pretty hard wall on that one.

Tom
 
#13
tomchr said:
As far as I understand it, all drivers will exhibit cone breakup when standing waves develop across the cone. The only question is how well-controlled the breakup is. Larger cone -> lower frequency for the onset of breakup. You can usually tell from the data sheet when this happens as the directivity will start to suffer. This means the various SPL curves for, say, 15º, 30º, 45º, etc. will start to diverge. This is all physics in action. The speaker driver designer is up against a pretty hard wall on that one.

Tom
Click to expand...

Yes. The question is audibility.
 
#15
tomchr said:
As far as I understand it, all drivers will exhibit cone breakup when standing waves develop across the cone. The only question is how well-controlled the breakup is. Larger cone -> lower frequency for the onset of breakup. You can usually tell from the data sheet when this happens as the directivity will start to suffer. This means the various SPL curves for, say, 15º, 30º, 45º, etc. will start to diverge. This is all physics in action. The speaker driver designer is up against a pretty hard wall on that one.

Tom
Click to expand...

Not sure I completely agree with you statements. Directivity is a matter of cone size vs. frequency. As the wavelength approaches the cone diameter, the driver will start to beam. As the frequency increases, beaming gets worse. It can be used to an advantage in certain designs.

I did not experience a beaming problem with the A10.2 or A10.3, but the cone breakup was "very evident" in both. I'm guessing breakup was around 400hz - 500hz, well below the 2Khz to 3khz point where beaming should start to kick in.

And some of the larger SEAS metal-cone drivers break up over 3K. That's well above the point where they start beaming.

Cone breakup and its severity seems to me to be more based on cone material. Beaming is generally cone diameter vs frequency. Two different animals.
 
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#17
Tried the A7.3 last evening as a midrange / upper midrange. I've been generally satisfied with the driver in a 7.3 Pensil at low levels in a nearfield arrangement and was hoping that it would perform well at higher levels in a large system. But the ringing was evident, particularly on vocals. No a lot, but at an audible level.

If once I hear it, it will become an annoying distraction.
 
#20
I tried an open baffle isobaric years ago, when a buddy gave me 3 weeks with 4 scanspeak revelators to play with.
What struck me was the unexpected lack of deeper bass, and the much improved detail throughout the midrange.
So I've wondered if that sealed cushion of air between the 2 drivers was cushiony (is that a word?) enough to maintain a cones wide pressure against the cones, damping resonances from their breakups.
 
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