Flex Your PCD Mettle:

[Zilch]

Econowave Delite 10e:

[penngray]

Re: Flex Your PCD Mettle:

Hi, Penn,

Don't know how many have picked up on it yet, but I've done all of these with basically the same woofer/waveguide center-to-center distance, so the primary variable in establishing the height of the forward vertical lobe is the crossover frequency, and we can see that, even with its 12" woofer, Deluxe achieves a more relaxed alignment. Delite 10e uses the 122i waveguide, which imposes additional constraints due to its pattern control limitations. A substantial proportion of its 10" diameter is dedicated to roundover, and if my data is correct, operatively, it is a "small" waveguide not suited for use at so low a crossover frequency as some may have presumed.

Somebody's going to have to mount 122i on a flat baffle with a bigger motor than CDX1-1425 to obtain more definitive data with respect to its capabilities than this build has demonstrated. Usable within these limits? Yes, but not much more, until proven otherwise. I'll be working up the summary for Delite 10e this weekend and posting it. A remeasure of Deluxe horizontal polars should appear here soon, as well, now that I am better set up with a rotary table to do that....

Thanks! Im mounting the 122i with the bigger 1745 CD for a set of speakers soon so I will be doing my own. The woofer isnt choosen yet but I probably will use the Faital Pro 12" woofers I have in my garage unless I try the new low cost Parts express pro audio woofers


Do you have any pics or could you explain your "rotary table", I need to make something better because Im not very accurate in my off axis measurement degrees right now.

[Zilch]

Re: Flex Your PCD Mettle:

http://www.rockler.com/product.cfm?page=2273&filter=18531&pn=18531

Plus a large drafting protractor.

Ideally, it rotates about the acoustic center, which is a crap shoot, if you don't know where that is, which I typically don't.

I have a motorized one as well, but that's going to take some work to get running. Once that's done, I'll take the data automatically.... :D

[Duffinator]

Re: Flex Your PCD Mettle:

Looking good Zilch. So what's the vintage update all about?

[Zilch]

Re: Flex Your PCD Mettle:

Hi, Duff, and welcome to Tech Talk!

There are two of them on deck, actually. I need to take a few measurements to be sure they are viable candidates first, tho. Should be ready to start something later tonight or tomorrow....

[Zilch]

Directivity:

Deluxe was still on the test stand, so I ran it out to 90°. Its deep overhang shadows the direct field above ~75°:








And normalized per Stereophile's Atkinson:

[dantheman]

Re: Flex Your PCD Mettle:

Cool Zilch! Out to 90 is where the action is. It let's you see how the break up is effecting everything and requires notching. You haven't by chance tried any further have you or doing some notch filters? I just got the measurement rig up again and I'm going to have a look around later this week.

Good on you man! Nice to see others doing it.

Dan

[Pete Schumacher]

Re: Flex Your PCD Mettle:

It would be interesting to try a "semi-omni" approach to this, like the way Dan Neubecker worked his Soundrounds or HOSS.

Upfire the woofer at the top of the cabinet, with the waveguide mounted below firing forward, always listening 90 deg off axis from the woofer.

Baffle step would be eliminated entirely and response side to side would be totally uniform for the woofer.

[Zilch]

Toggles:

And now for the Speakergeek Curve Junkie Nutjob Fun Stuff!

Open each member of a pair in a separate tab, then click between them:

1) Horizontal Polar Map:
Deluxe
Delite 10e

2) Conventional Horizontal Polar Plot:
Deluxe
Delite 10e

3) Horizontal Directivity Waterfall:
Deluxe
Delite 10e

4) Horizontal Polar Directivity Map:
Deluxe
Delite 10e

5) Vertical Polar Map:
Deluxe
Delite 10e

6) Wavelet Transform:
Deluxe
Delite 10e

7) Vertical Listening Window:
Deluxe
Delite 10e

[Zilch]

Re: Flex Your PCD Mettle:

It would be interesting to try a "semi-omni" approach to this, like the way Dan Neubecker worked his Soundrounds or HOSS.

Upfire the woofer at the top of the cabinet, with the waveguide mounted below firing forward, always listening 90 deg off axis from the woofer.

Baffle step would be eliminated entirely and response side to side would be totally uniform for the woofer.

Practitioners of constant directivity typically strive to push the controlled window as low in frequency as possible, some resorting to 3-way designs using midrange waveguides to limit dispersion, in either case emphasizing the importance of smooth transitions in directivity.

As shown in these Deluxe plots, it's holding a 90° beamwidth to below the 1.55 kHz crossover and gradually widening below there, in conformity with this objective:

http://www.gedlee.com/downloads/directivity.pdf

Cool Zilch! Out to 90 is where the action is. It let's you see how the break up is effecting everything and requires notching. You haven't by chance tried any further have you or doing some notch filters? I just got the measurement rig up again and I'm going to have a look around later this week.

As earlier noted, Deluxe would benefit from a notch at ~2 kHz. The breakup of Delite 10e's 2510 woofer is clearly affecting the off-axis response, but if we mitigated that, it doesn't look like the HF has the requisite wherewithal to make up for the deficit it would generate.... :(

[Pete Schumacher]

Re: Flex Your PCD Mettle:

As earlier noted, Deluxe would benefit from a notch at ~2 kHz. (

Looking at the tweeter/wg response for the Deluxe, I'm not so sure the notch should be on the tweeter as much as it should be on the woofer.

I did model one up with a notch on the woofer to take care of that peak at 2KHz in the response of the 3012. It does help keep everything within 1dB of the 90dB sensitivity line.

[Zilch]

Re: Flex Your PCD Mettle:

Looking at the tweeter/wg response for the Deluxe, I'm not so sure the notch should be on the tweeter as much as it should be on the woofer.

I did model one up with a notch on the woofer to take care of that peak at 2KHz in the response of the 3012. It does help keep everything within 1dB of the 90dB sensitivity line.

Thanks, Pete, I'll try that next time I open one up; I do see the knee there. The crossovers are no longer exposed, so I'll need to bring the woofer leads out one of the ports to tweak it further.

[We're talkin' 1 - 2 dB max here.... ;) ]

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Thanks, Pete, I'll try that next time I open one up; I do see the knee there. The crossovers are no longer exposed, so I'll need to bring the woofer leads out one of the ports to tweak it further.

[We're talkin' 1 - 2 dB max here.... ;) ]

I will agree that adding a notch on both the woofer AND tweeter can smooth the area between 1KHz and 3KHz to nearly flat.

[dantheman]

Re: Flex Your PCD Mettle:

As earlier noted, Deluxe would benefit from a notch at ~2 kHz. The breakup of Delite 10e's 2510 woofer is clearly affecting the off-axis response, but if we mitigated that, it doesn't look like the HF has the requisite wherewithal to make up for the deficit it would generate.... :(

Sorry I missed that. Still don't read it, but no matter. Have you done the out to 90 on the woofer and tweeter separately? I wouldn't build a filter prior to doing that. I'm sure you know you'll need a smaller or stiffer woofer.

Dan

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Sorry I missed that. Still don't read it, but no matter. Have you done the out to 90 on the woofer and tweeter separately? I wouldn't build a filter prior to doing that. I'm sure you know you'll need a smaller or stiffer woofer.

Dan

Or a woofer with better linearity in that region, like the AE Lambda TD12 series. More money, but also smoother response above 1KHz.