proaudio dipole, tips/design?

[joecarrow]

Until I think it over a bit, I'll second what Dennis says. If you want assured success, build the Orion and tweak it. It would be easy to change one or more of the drivers for something more modern, and you wouldn't be the first to do so.

Seriously, Linkwitz is a smart guy and he put a lot of thought and effort into getting the Orion right. You may be able to surpass it with better drivers, but you can't dismiss the design process he's published as something to look at.

[thadman]

Thadman, we have a hard time answering your many questions because most of them have no good answer so most of us just keep quiet. We don't know any more about drivers we haven't used than you do. If you want guaranteed success, use a proven design with a published XO and bill of materials. If you want to go your own way, you're the test pilot. The old Y in DIY. Enjoy the ride and tell us how it goes. Maybe we'll all copy you.

I'd love to design my own speaker for various reasons. With the amount of technology available today and the ability to switch settings on the fly, the potentiality for failure is minimal. Designing a system doesnt seem difficult as long as you know what you're doing. With active crossovers, the ability to adjust EQ/Xover point on the fly makes it extremely difficult to screw up a design (if you know what you're doing). Open-Baffle designs also require very little carpentry skills, so beyond engineering the baffle to combine both waves in phase at the end of their passband and modeling in edge, there is very little you can screw up. The great potentiality for failure arises in driver choice, which must be researched thoroughly before hand (specifically where first breakup node is and crossing >3 octaves below it, among other things). Thanks to sites like Zaphaudio, I consider myself thoroughly learned in the HiFi driver realm (what drivers work best in a specific passband, what drivers excel at linear distortion, what drivers excel at non-linear distortion, among other things). Pro Audio drivers on the other hand have very little 3rd party reviews (that Im aware of)...This is what Im looking for. Does anybody know of a medley of HE paper cones reviewed?

[augerpro]

Thadman I *should* have measurments including THD and CSD for this: http://www.partsexpress.com/pe/pshow...number=290-382
and this: http://www.partsexpress.com/pe/pshow...=264-332&DID=7

by the end of the weekend. Not really top of the line I know but you may find them interesting. I'm finally comfortable enough with my measurment setup that I have a number of drivers I'll be posting here for those that are interested.

[thadman]

The RSS390HF may not be good to as high of a frequency as the 12" version. The 12" is good to 400 hz or so. With two of the 15"s, you're looking at 110 db at one meter for 50 hz, limited by excursion, so you want your midrange to be able to keep up with that at a reasonable crossover.

I don't know if it's reasonable to cross the 15" at 400 hz- but if you look here, you see that the PHL is starting to lose its edge at 400 hz:

http://www.markk.claub.net/Testing/PHL1120/PHL1120.htm

I've got to stop and think about this, how I would do it if it were my own. I'll try to get back to you later, after I imagine what it would be like having a larger dwelling.

Why wouldnt the 15 go as high as the 12? I've got both response curves in front of me, and the difference in breakup node peaks between the 12 and 15 is minimal at best. Besides efficiency, they look nearly identical (relative to first large amplitude peak). The first small amplitude peak for the 15 (1-2dB) doesnt begin until after >1200hz, slowly peaking around 1350-1400hz. The large amplitude peak (10dB) begins slightly after the first peak and sharply manifests itself completely around ~1600-1650hz. If I crossed 350-400hz I should be out of its main realm of ferocity (dodging even the low amplitude peak).

[thadman]

Thadman I *should* have measurments including THD and CSD for this: http://www.partsexpress.com/pe/pshow...number=290-382
and this: http://www.partsexpress.com/pe/pshow...=264-332&DID=7

by the end of the weekend. Not really top of the line I know but you may find them interesting. I'm finally comfortable enough with my measurment setup that I have a number of drivers I'll be posting here for those that are interested.

Another reason why a new design shouldnt be frightening. We have the ability to measure FR, non-linear distortion, and linear distortion, among other things. I can objectively observe the results of higher/lower Xover points/EQ. I dont want to limit myself by building a compromised design (relative to my goals and environment), something tailored specifically for me is much more enthralling. Im not saying all preconceived designs are bad...not by any means (specifically Linkwitz' designs, they are fantastic), but they seem to be focused on meeting the goals of a multitude of individuals and focus around a central theme. I can slightly improve (go with cheaper parts in some cases, The Orion uses older parts which may be surpassed by significantly cheaper and better performing drivers) the design and make it specifically suited for me, not having to worry about driver availability or construction difficulties :B

Also, having been a member of diymobileaudio.com for quite some time, I've grown akin to the moderators (npdangs) habit of objectively measuring drivers (with some subjective opinions) that are mailed in to him. I dont understand why something like this couldnt work over here. We could setup a review section (sub-thread off mission possible DIY) where objective data for the drivers was collected, we could have our drivers (if the person is willing) shipped to a trustworthy/honorable leading forum member and have all the drivers measured in an identical manner. In this way, we could make the data available for all and choosing between drivers becomes much less of a hassle :B Maybe Im just a dreamer...

[joecarrow]

Why wouldnt the 15 go as high as the 12? I've got both response curves in front of me, and the difference in breakup node peaks between the 12 and 15 is minimal at best. Besides efficiency, they look nearly identical (relative to first large amplitude peak). The first small amplitude peak for the 15 (1-2dB) doesnt begin until after >1200hz, slowly peaking around 1350-1400hz. The large amplitude peak (10dB) begins slightly after the first peak and sharply manifests itself completely around ~1600-1650hz. If I crossed 350-400hz I should be out of its main realm of ferocity (dodging even the low amplitude peak).

Sorry, it's just an assumption I made. It just seems intuitive that a 15" driver based on the same construction method as a 12" driver would not be able to play cleanly as high as the 12". I guess I need to remember, "When you assume, you make an ass out of you and me". I just hadn't heard confirmation that the 15" version held with the 12's unusually good performance to 400 hz.

I guess this case could be a lot like the Hi-Vi M6a and M8a. These drivers are usable to essentially the same point.

Regarding the Selenium driver Augerpro mentioned, I'd be very interested to see how it performs at different drive levels, as compared to a more traditional hi-fi driver. This is another one of my assumptions, but I would be surprised if it can hit 110 db more cleanly than a lot of the drivers in Zaph's 7" comparison. For lower levels I'm guessing it will have moderately good THD and mediocre CSD. Anyway, that's enough guessing and generalizing about drivers I've only read about.

[joecarrow]

Another reason why a new design shouldnt be frightening. We have the ability to measure FR, non-linear distortion, and linear distortion, among other things. I can objectively observe the results of higher/lower Xover points/EQ. I dont want to limit myself by building a compromised design (relative to my goals and environment), something tailored specifically for me is much more enthralling. Im not saying all preconceived designs are bad...not by any means (specifically Linkwitz' designs, they are fantastic), but they seem to be focused on meeting the goals of a multitude of individuals and focus around a central theme. I can slightly improve (go with cheaper parts in some cases, The Orion uses older parts which may be surpassed by significantly cheaper and better performing drivers) the design and make it specifically suited for me, not having to worry about driver availability or construction difficulties :B

Also, having been a member of diymobileaudio.com for quite some time, I've grown akin to the moderators (npdangs) habit of objectively measuring drivers (with some subjective opinions) that are mailed in to him. I dont understand why something like this couldnt work over here. We could setup a review section (sub-thread off mission possible DIY) where objective data for the drivers was collected, we could have our drivers (if the person is willing) shipped to a trustworthy/honorable leading forum member and have all the drivers measured in an identical manner. In this way, we could make the data available for all and choosing between drivers becomes much less of a hassle :B Maybe Im just a dreamer...

This is in the archive of reference threads:

https://www.htguide.com/forum/showthread.php?t=11700

"Testing, 1... 2... 3..."

[Paul W]

Thad,
Here are the results of a quick test session with the 10NDA520...

For a fairly well known "reference" I included the Seas W26...besides I have another use for it coming up. Both drivers are centered on very similar 19" wide baffles, closed across the top, but open to the sides and back...so the baffles influence the low end and likely introduce a little diffraction on the top end. No smoothing, no baffle extensions, basically "un-fooled-around-with" driver measurements at 500mm.

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First, the W26:

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Violent breakup at 4k which is why I like to stay below 800Hz with these guys. However, good correlation with the Seas factory curves which have a reputation for brutal honesty.

Now the 10NDA520:

Images not available

Again, good correlation with the 18Sound factory curves. Bottom line is that the 18Sound factory curves seem trustworthy.