When ready for a listen to broken in stock driver (probably next weekend) , we'll likely use the FH3 - very compliant with a range of drivers, and will allow a rough comparison to the 10Ps in the XLs. Note that we don't have a stock pair of 10Ps, so it'll only be a very rough taste test of overall tonal balance - extension at both ends of the spectrum, macro-dynamics, etc. The polka dots make enough of a difference in the micro-dynamics, sense of depth of image, etc that direct comparison would be misleading at best.
Hopefully Mark OK's the UK group buy; I'll use a pair of 7P's with two pairs of other brand woofers I have (will swap between two designs until funds allow)
If I can stretch to a pair of 12PW's, I'll match these with ribbons
I imagine the 7P will sound v different to the 10P, at the top end at least
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Late to the party as usual but when I saw the values of the xo components, I couldn't help but think that seems like a high xo point. Mr. Moose, can you let on what lead to that please?
Ta.
I also had the same thought. Would I be correct in assuming it has something to do with keeping things simple and affordable?
No less, I'm sure it will still deliver the goods!
Yes, quite simply Mark preferred a higher crossover frequency to be used for this particular speaker. He feels lower is a waste of the 12s BW potential. 1KHz gives a reasonable compromise given the low order filters for level padding, adjustments for step-loss &c.
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Here is my dilemma. The basic mantra of full-range is no XO 300-3kHz. An XO of 1kHz, while ideal by multi-way standards, it prohibited by full-range standards. The A7x is not a tweeter. It seems that there would be better choices for a tweeter with a 3-5kHz XO. Perhaps when the 4 and 5cm Alpairs show up. Also, using a single driver for 35-3kHz raises the issue of IM/phase/Doppler (whatever you want to call it) distortion -- THE major issue with single driver speakers.
On the other end, is the A12PW sufficiently better than my current sub to warrant limiting use of the A12PW to 35-200Hz? I will still need the sub for the bottom octave, making the system three-way active, requiring yet another DAC and amp. Is is worth $300 plus design time plus prototype materials to find out?
I am very much on the fence here. I will probably bit the bullet and get a pair of A12PW's. First, I have to settle a revised design for the A7P. Design work is finished, but the drivers are still in the boxes. I had a bit of out-patient surgery Monday that will keep me out of the shop until next week.
Bob
Hello Bob,
Interesting points, glad you raised them but they appear to be based on the "standard driver" premise. I did expect this type of thinking would make its appearance at some point.
I have some sympathy with the basic "stay out of the telephonic band" mantra where inclined coned LF drivers are teamed with domed diaphragm or flat emitting surface tweeters are concerned. Such is the acoustic operational differences between these driver types, the cross over point is, where possible, best tuned either side of the telephonic band. However, you might recall that I dropped to fairly large hint in Post No. 1 paragraph 2., regarding fundamentals that would apply when twinning the 12PW with the 7P. Hence all the back-room work that went on to get the efficiency of these drivers into close proximity.
I'm not quite sure why you've dismissed the role of a 7P to emit into the HF range when twinned with the 12PW (or another LF unit). Its perfectly capable of operating to 25kHz which for many is a range that would be considered reasonable tweeter territory. Granted driver matching does apply but there's no technical reason to not consider the Alpair 7P (or 7M) for these roles. Given their cone acreage based on an ultra shallow cone profile, they provide a dispersion pattern well suited the delivering the goods in the mid and high ranges.
There appears to be some confusion regarding "doppler" (etal.). I notice a sprouting of angst on the subject from time to time. Depending on driver size, mechanical oscillations of the size and type that might cause audible shunting are rare. Providing the driver and box alignment is optimal, LF loads should be generated with relatively limited length oscillations (excursion). Granted for some end-users with a very particular need (I recollect you have a passion for loud organ music), in which event there's no physical way to avoid some audible shunting from any source in such cases. Essentially, there's no technical reason to exclude the Markaudio long-throw driver from the mix on these grounds.
The limiting factor is power handling. For those end-users who have a particular need for more power, then lighter load drivers, including Markaudio units shouldn't be their first choice.
As regards needing s Sub, I'd recommend experimenting with the 12PW first. You may yet be surprised by what LF can be extracted from a 12PW(s) in an optimised box.
The key is not to get too stuck in convention. Markaudio drivers aren't "conventional", thats why they attract an alternative diy and end-user audience. Be prepared to experiment.
Hope you recover well!
Thanks
Mark.
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Similar here.
I will be crossing our 1st effort in the <350 Hz range
We may try the A12pw by itself with a similarly sensitive ribbon i have on the shelf.
dave
Mark's comments are noted.
If I decide to mate the A12PW and A7X in the middle of their respective ranges, I will probably try a series XO. Seems like good candidates. Crossing the A7 that high would mean that it could be put is a small sealed box, whereas if crossed low, a larger aperiodic enclosure may be required.
With regard to bass modulating the midrange, I have no intention of conducting proper experiments to prove the point, but I hear it. Bass to me is not beating on a kick drum, it is petal organ and a half dozen double bassists sawing away on their extended C strings with vigor. My current favorite test track for bass is Bela Fleck's "Flight of the Cosmic Hippo". If you think your system has good bass, give this track a try. It features a 6-string electric bass at the bottom of the B string. Anyway, there was a substantial difference in the midrange with A10P's in a MLTL when they were crossed to a sub at 200Hz.
Bob
If I decide to mate the A12PW and A7X in the middle of their respective ranges, I will probably try a series XO. Seems like good candidates. Crossing the A7 that high would mean that it could be put is a small sealed box, whereas if crossed low, a larger aperiodic enclosure may be required.
With regard to bass modulating the midrange, I have no intention of conducting proper experiments to prove the point, but I hear it. Bass to me is not beating on a kick drum, it is petal organ and a half dozen double bassists sawing away on their extended C strings with vigor. My current favorite test track for bass is Bela Fleck's "Flight of the Cosmic Hippo". If you think your system has good bass, give this track a try. It features a 6-string electric bass at the bottom of the B string. Anyway, there was a substantial difference in the midrange with A10P's in a MLTL when they were crossed to a sub at 200Hz.
Bob
If the A12pw is in a box that gets to <30 Hz, then that middlepoint is in the neighborhood of 700 Hz.
First guess series XO of 3mH/15uF
dave
Bob - personally, I rather prefer the shorter reprise version of "Hippo" musically, but Victor does dig pretty deep on the full length track .
My other two favorite tests for both bass extension & "slam", as well as articulation, imaging and depth are "Duende" by Bozzio, Levin, Stevens, and "Post Modern Blues" - Patricia Barber.
My other two favorite tests for both bass extension & "slam", as well as articulation, imaging and depth are "Duende" by Bozzio, Levin, Stevens, and "Post Modern Blues" - Patricia Barber.
Guys, mind if I ask... (many missed it). Based on Mark's measurements of 12P, why would you need to pair it to 7p. It should be a nice driver, but nature is nature, you will have some beaming on the top and not that great off-axis response. In my opinion all you need for 12p is a ribbon tweeter. Pair it with smth like Fountek CD3 and you good.
There is the 12P (paper) and the 12PW (PaperWoofer), guessing you mean the latter
"The 12PW is primarily designed to be partnered with the Alpair 7P yet will also be a excellent partner for many tweeters. The marriage between 7P and 12PW promises much in the way of deep rich bass and fine mid-high range detail." Madisound.
"The 12PW is primarily designed to be partnered with the Alpair 7P yet will also be a excellent partner for many tweeters. The marriage between 7P and 12PW promises much in the way of deep rich bass and fine mid-high range detail." Madisound.