Flex Your PCD Mettle:

[Zilch]

Re: Flex Your PCD Mettle:

Well, I reset the targets and took another shot at it. I still have more components than you, mainly to take care of that resonance and give the woofer a smoother roll off. 4 on the woofer, 5 on the tweeter to do some shaping as well.[/IMG]

We are very close, and have arrived at the same topology, looks like, as I'm 5 on the tweeter, not 4. I have PM'd you my values.

The speaker is upside-down in the pic for convenience in measuring, though it should work either way. When I said forward axis "above" the midpoint between drivers, I meant between there and the waveguide, actually. Sorry for that confusion.

Interestingly, there's a current thread about speakers for a HS bandroom. In that installation, they'd be mounted as in the pic, up high, with the forward axis aimed slightly downward.

http://techtalk.parts-express.com/sh...d.php?t=215547

If we can tame it, DC300-8 appears to be a capable low-cost performer:

http://techtalk.parts-express.com/sh...34#post1600434

[Pete Schumacher]

Re: Flex Your PCD Mettle:

We are very close, and have arrived at the same topology, looks like, as I'm 5 on the tweeter, not 4. I have PM'd you my values.

The speaker is upside-down in the pic for convenience in measuring, though it should work either way. When I said forward axis "above" the midpoint between drivers, I meant between there and the waveguide, actually. Sorry for that confusion.

Interestingly, there's a current thread about speakers for a HS bandroom. In that installation, they'd be mounted as in the pic, up high, with the forward axis aimed slightly downward.

http://techtalk.parts-express.com/sh...d.php?t=215547

If we can tame it, DC300-8 appears to be a capable low-cost performer:

http://techtalk.parts-express.com/sh...34#post1600434

Why not go for the gusto and use a 12" pro woofer? This beast can handle the range nicely, and it's 6dB more sensitive. :D

[Zilch]

Re: Flex Your PCD Mettle:

Why not go for the gusto and use a 12" pro woofer? This beast can handle the range nicely, and it's 6dB more sensitive. :D

I have Kappalite 3012LFs coming for another variant. Is that what you're showing above?

With assist, those'll do 114 dB @ 30 Hz in these cabs.

[Better use Gorilla Glue to build 'em tho.... :p ]

[Zilch]

Re: Flex Your PCD Mettle:

Augerpro's measurements of this waveguide are posted here:

http://sites.google.com/site/driverv...-jbl-knock-off

The polars were taken using DE250 and a throat adapter with no highpass filter:

Horizontal:

http://493531664873718246-a-18027447...attredirects=0

Vertical:

http://493531664873718246-a-18027447...attredirects=0

It's beginning to lose vertical pattern control at 3 kHz, still usable at 2 kHz, but below that, we're relying upon the vertical nulls to augment the pattern per the teachings of Pi-Speakers' Wayne Parham. The horizontals reach nearly an octave lower with equivalent control. Load in separate tabs and click between them to view the difference in directivity....

[Zilch]

Here's mine:

[Zilch]

Driver Alignments in KD Trap Cab:

DC300 rear mount & D2500Ti on standard eWaveguide front mounted:

Kappalite 3012LF rear mount & DE250 on QSC waveguide front mounted:

[Please excuse the dust.... ;) ]

[Zilch]

Flex It, Round Two:

KappaLite 3012LF and B&C DE250 on QSC 152i waveguide:

I have provided an FRD of both drivers concurrently from the midpoint between them (10.5" c/c distance) for finding the acoustic offsets per the method of Ralph:

http://www.speakerdesign.net/sbarticle.html

See driver alignment pic in previous post.

What I've got:

[Pete Schumacher]

Re: Flex It, Round Two:

KappaLite 3012LF and DE250 on QSC 152i waveguide:

I have provided an FRD of both drivers concurrently from the midpoint between them (10.5" c/c distance) for finding the acoustic offsets per the method of Ralph:

http://www.speakerdesign.net/sbarticle.html

See driver alignment pic in previous post.

What I've got:

Looks a little "hot" around 1-2KHz. Can you begin the tweeter roll off just a tad sooner to help bring down that peaking?

[Zilch]

http://www.avsforum.com/avs-vb/showt...3#post18127203

The wavelength at 1.5 kHz is 9.04" by my calc, so we're operating in the region between 1 and 1.5 lambda there....

[Zilch]

Re: Flex Your PCD Mettle:

Regenerated FRDs from one axis, midpoint between the woofer and waveguide, @ 44" measuring distance.

[WHAT, no dancing banana...? :p ]

[Zilch]

Re: Flex Your PCD Mettle:

Reworking the crossover from the new data, I was able to eliminate a couple of parts, but it still has some excess energy at 2 kHz:

Key to the vertical polar map:

Red = Forward Axis
Up toward waveguide = Org, Yel, Gry, Lt. Gry
Down toward woofer = Grn, Blu, Vio, Cyn

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Reworking the crossover from the new data, I was able to eliminate a couple of parts, but it still has some excess energy at 2 kHz:

I'd like to play with them. Do your FRD files already include relative acoustic offset?

[Zilch]

Re: Flex Your PCD Mettle:

I'd like to play with them. Do your FRD files already include relative acoustic offset?

The new set of FRDs was taken from a single point in space, at the midpoint between the drivers and on axis horizontally, so the responses would include the relative offsets.

They include minimum phase. I don't know how CLIO calcs that, but I did not alter the time window.

I also provided the same measurement for the two drivers combined, from which the relative offsets may be derived by matching the response with no filters.

I did that, and came up with a crossover having a beautiful response curve and phase behavior. I built it up, measured the response, and it had a perfect inverse notch at the design axis, which I take to mean that the correct offsets should be derived with the HF polarity inverted.... :p

[Pete Schumacher]

Re: Flex Your PCD Mettle:

The new set of FRDs was taken from a single point in space, at the midpoint between the drivers and on the horizontal axis, so the responses would include the relative offsets.

They include minimum phase. I don't know how CLIO calcs that, but I did not alter the time window.

I also provided the same measurement for the two drivers combined, from which the relative offsets may be derived by matching the response with no filters.

I did that, and came up with a crossover having a beautiful response curve and phase behavior. I built it up, measured the response, and it had a perfect inverse notch at the design axis, which I take to mean that the correct offsets should be derived with the HF polarity inverted.... :p

If it includes minimum phase, then relative offsets are not included, but could be derived by adjusting the individual offsets until the summed response matches the measured combined response. From what I can see, the tweeter is behind the woofer about 2.5" in order to get the result you measured for the raw combined response.

[Zilch]

Re: Flex Your PCD Mettle:

If it includes minimum phase, then relative offsets are not included, but could be derived by adjusting the individual offsets until the summed response matches the measured combined response. From what I can see, the tweeter is behind the woofer about 2.5" in order to get the result you measured for the raw combined response.

Yes, and I got the same result, ~60 mm, which is consistent with the actual physical alignment: