Flex Your PCD Mettle:

[Zilch]

Re: Flex Your PCD Mettle:



Yikes! (See the images below.)

That's the system horizontal polars on the forward axis, which is 2.86° below the midpoint between woofer and waveguide, i.e., toward the woofer; the waveguide is operating at an oblique angle. Whatever anomaly is occurring at 2 kHz is clearly dominating this design.

[I'll do just the waveguide on its axis next.... :rolleyes: ]

[Zilch]

Re: Flex Your PCD Mettle:

It's clear why JBL crosses this waveguide at 2.4 kHz in AC16:





Abort? ;)

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Yikes indeed!!! :eek:

To get to 2.4KHz, a more capable woofer seems to be in order. Trying to get that one to reach that high seems doubtful. Even with the massive peaking you attempted with the transfer function doesn't push it high enough.



Perhaps the ScanSpeak Discovery 22W might do the trick.

[dantheman]

Re: Flex Your PCD Mettle:

I'd just scrap the idea of using that WG. I've seen smoother responses from an Eminence coax and that Selenium. I wonder how those small PE WGs would perform......... One small WG that has been shown to have good performance is the 6" one from MCM. Might be worth checking out.

http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-H-65-/54-580

Dan

[Zilch]

Re: Flex Your PCD Mettle:

Yikes indeed!!! :eek:

It's certainly instructive, illustrating my point at #329.

I ran the woofer to the limit of its natural rolloff at ~1.8 kHz. The waveguide does have a bit of pattern control at that frequency, but something nasty going on at 2 kHz. The distance to the cabinet edge overhang is 5", wrong frequency, and if it was a reflection, it would not be so well sustained off-axis, I don't believe. I'll remove those grill-mounting blocks to see what role they're playing in this. If Linkwitz, Elliott and Zaph are correct, this 90° waveguide should not be illuminating the cab edges enough to generate such a perturbation.

There remain other options; it's the woofer I'm dedicated to keeping here, vintage acoustic suspension bass available at yardsales and curbside for next to nothing, in the best EconoWave spirit.... :p

[Pete Schumacher]

Re: Flex Your PCD Mettle:

It's certainly instructive, illustrating my point at #329.

I ran the woofer to the limit of its natural rolloff at ~1.8 kHz. The waveguide does have a bit of pattern control at that frequency, but something nasty going on at 2 kHz. The distance to the cabinet edge overhang is 5", wrong frequency, and if it was a reflection, it would not be so well sustained off-axis, I don't believe. I'll remove those grill-mounting blocks to see what role they're playing in this. If Linkwitz, Elliott and Zaph are correct, this 90° waveguide should not be illuminating the cab edges enough to generate such a perturbation.

There remain other options; it's the woofer I'm dedicated to keeping here, vintage acoustic suspension bass available at yardsales and curbside for next to nothing, in the best EconoWave spirit.... :p

What we need is a WG that has loading to 1KHz . . . ;)

I believe you linked to a PE variant?

[donprice]

Re: Flex Your PCD Mettle:

[IMG]Yikes! (See the images below.)

That's the system horizontal polars on the forward axis, which is 2.86° below the midpoint between woofer and waveguide, i.e., toward the woofer; the waveguide is operating at an oblique angle. Whatever anomaly is occurring at 2 kHz is clearly dominating this design.

Is that the 6x6 JBL waveguide? Too bad...I've got them and they were probably going into a pair of rear surrounds (w/ Eminence Deltalite II 2510?). Oh well, another $13 goes into the spare parts pile. :o

[Zilch]

Re: Flex Your PCD Mettle:

What we need is a WG that has loading to 1KHz . . . ;)

Proving once again that size matters.

Is that the 6x6 JBL waveguide? Too bad...I've got them and they were probably going into a pair of rear surrounds (w/ Eminence Deltalite II 2510?). Oh well, another $13 goes into the spare parts pile. :o

Use with any woofer that'll cross at 2.4 kHz with 90° directivity. Skywave, for example, runs them successfully with vintage JBL LE8T-H woofers....

[donprice]

Re: Flex Your PCD Mettle:

I was hoping to recycle the eWave crossovers when I upgrade the mains to the QSC/DE250 combo. It will be 2011 so I have plenty of time shop for woofers and/or different waveguide.

[Zilch]

Re: Flex Your PCD Mettle:

I'd just scrap the idea of using that WG. I've seen smoother responses from an Eminence coax and that Selenium.

This will be next, if I can't come to a quick resolution here:

http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=179

The JBL 8" 90° x 50° will also fit.

[Maybe.... ;) ]

[Skywave-Rider]

Re: Flex Your PCD Mettle:

:D

[Zilch]

Re: Flex Your PCD Mettle:

1) Removed the grille blocks, and there was no measurable difference.

2) Tried crossing at 1.8 kHz with my "First Try" highpass - not high enough.

3) Installed XT120 w/bolt-on D220Ti - plays a bit lower, but not low enough.

4) Tried the 18-Sound HD125 driver it was made for - about the same

5) Tried B&C DE-10 - best of those; close, but still not good enough:



6) JBL 8" PT waveguide, presently in AR4x, looks like it'll get where we need to be:



I'll load it in for a restart.

Footnote: Stock crossover has no lowpass; they ran it full range, wart and all.

[Maybe it didn't have a wart originally.... ;) ]

[penngray]

Re: Flex Your PCD Mettle:

The Lambda TD10 series is likely to behave just like the TD12, with wider dispersion and smooth response.

I've got my eye on an upcoming project using a modified 122i waveguide profile to load the RS28F paired with the TD10S.

Should make for a heck of a two-way.

Very nice!!

Im going to be mating a waveguide with the SB29. Im waiting for the SB29/waveguide prototype from Mayhem.

I have many TD series woofers already in use so Im a HUGE fan. Best drivers I have owned. The new 6.5" TD series are out now too.

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Very nice!!

Im going to be mating a waveguide with the SB29. Im waiting for the SB29/waveguide prototype from Mayhem.

I have many TD series woofers already in use so Im a HUGE fan. Best drivers I have owned. The new 6.5" TD series are out now too.

Where are the 6.5" units? AE doesn't show them at their on-line store!!!

[Zilch]

Re: Flex Your PCD Mettle:

http://www.aespeakers.com/phpbb2/viewtopic.php?f=3&t=2493