I'm not entirely sure what you are referring to by 'design factor' I'm afraid Brian. All drive units can be horn loaded across some portion of their BW; that's just a matter of basic physics. How wide the practical horn loaded BW is and what the upper and lower corner frequencies are depends on the driver in question and to an extent, the amplifier powering it.
Regarding the pensils, Bob is quite correct; a nominally simple build was a major priority. With that said, performance wasn't secondary per se, but they have a different alignment to Bob's (excellent) MLTLs. They're generally tuned higher, with a pro-audio style FR, and TL levels of damping to flatten the impedance & keep cone deflection reasonably linear.
The exception to that ironically is the one for the 10.2. Ideally, to maintain the same style of alignment as the other pensils, it actually should be taller for the same total Vb; to maintain physical consistency, I accepted a deviation from the usual alignment I use & kept the box height the same as in the other boxes. Still works reasonably, but not quite the same, and not necessarily the most elegant proportions in this particular case.
The exception to that ironically is the one for the 10.2. Ideally, to maintain the same style of alignment as the other pensils, it actually should be taller for the same total Vb; to maintain physical consistency, I accepted a deviation from the usual alignment I use & kept the box height the same as in the other boxes. Still works reasonably, but not quite the same, and not necessarily the most elegant proportions in this particular case.
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IINM one of Scott's earlier (now orphaned) design series were a new take on the venerated Voigt pipe / TQWT - I'll let him "pipe in"
as to whether any were actually built? Certainly many similar designs would "work" well enough, but if I may, to describe the Pensil as "not optimal" (compared to what?) based on this thread, is a disservice to all.All kidding aside, I can heartily recommend the A10 M10
For interest, what most people call a TQWT is actually a conical horn, albeit one that (usually) isn't impedance matched down to the 1/4 wave cutoff frequency. Right Chris, I did do a few for the MA units. Beltane, Samhain & Solstice. Currently lurking in the electronic equivalent of my drawer of many things. A couple were built & they worked fine.
Re the pensil for the 10.2, I didn't say it's not optimal, I said it deviates from the usual pensil alignment. That may or may not be optimal depending on requirements. Unless a box is designed for a specific situation, it's always a compromise, and even then there are tradeoffs to make, since we don't live in a perfect world. Alas.
You could run a nice simple sealed floorstander; call it 29 litres, give you a critically damped Qtc; F3 around 80Hz & a good match to a couple of quality subs. If you want more output / LF extension, my suggestion of existing box designs that I know about would be for Bob's MLTL (which is certainly more pencil-like in appearance!) or the pensil if you don't mind its somewhat squat looks in 10.2 guise.
Re the pensil for the 10.2, I didn't say it's not optimal, I said it deviates from the usual pensil alignment. That may or may not be optimal depending on requirements. Unless a box is designed for a specific situation, it's always a compromise, and even then there are tradeoffs to make, since we don't live in a perfect world. Alas.
You could run a nice simple sealed floorstander; call it 29 litres, give you a critically damped Qtc; F3 around 80Hz & a good match to a couple of quality subs. If you want more output / LF extension, my suggestion of existing box designs that I know about would be for Bob's MLTL (which is certainly more pencil-like in appearance!) or the pensil if you don't mind its somewhat squat looks in 10.2 guise.
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I particularily liked the graphic that went with Beltane... after the last thread imagining dancing around the fire with Ms Shahi
An externally hosted image should be here but it was not working when we last tested it.
dave
For interest, what most people call a TQWT is actually a conical horn, albeit one that (usually) isn't impedance matched down to the 1/4 wave cutoff frequency. Right Chris, I did do a few for the MA units. Beltane, Samhain & Solstice. Currently lurking in the electronic equivalent of my drawer of many things. A couple were built & they worked fine.
Re the pensil for the 10.2, I didn't say it's not optimal, I said it deviates from the usual pensil alignment. That may or may not be optimal depending on requirements. Unless a box is designed for a specific situation, it's always a compromise, and even then there are tradeoffs to make, since we don't live in a perfect world. Alas.
You could run a nice simple sealed floorstander; call it 29 litres, give you a critically damped Qtc; F3 around 80Hz & a good match to a couple of quality subs. If you want more output / LF extension, my suggestion of existing box designs that I know about would be for Bob's MLTL (which is certainly more pencil-like in appearance!) or the pensil if you don't mind its somewhat squat looks in 10.2 guise.
For my case, sealed box maybe a good choice. How many stuff shall I put inside that 29L enclosure?
I was thinking a high output impedance amplifier might be in the mix somewhere, in which case the extra would be useful. Agreed though, with a high DF, smaller would be better once suitably stuffed.
Jim Griffin A10.2
Hello! What about these:http://http://www.diyaudio.com/forums/markaudio/192034-jim-griffin-a10-2-mltl-variation.html
http://http://www.diyaudio.com/forums/full-range/137585-mark-audio-alpair-10-mltl-design.html
How do they compare with the Pensil 10.2 and Bob's M10-A10?
Thanks,
Adel
Hello! What about these:http://http://www.diyaudio.com/forums/markaudio/192034-jim-griffin-a10-2-mltl-variation.html
http://http://www.diyaudio.com/forums/full-range/137585-mark-audio-alpair-10-mltl-design.html
How do they compare with the Pensil 10.2 and Bob's M10-A10?
Thanks,
Adel
which "who" exactly?
simulations are one thing, but has anyone actually listened to all the cited designs in the same room / system to formulate a real-world impression of their relative strengths ?
Having heard 2 different Pensils ( 7 and 12.P), and the 10.2 in several designs, of all these named, I'd be inclined towards Bob's, even if only for aesthetic reasons. But to extract even more from this driver, I'd probably wanna try the Woden Silbury. .
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