Flex Your PCD Mettle:

[Starkiller4299]

Re: Flex Your PCD Mettle:

Well, finally getting ready to start on my own Ewaves tommorrow.:D I'll be using the super budget XD120 and the Eminence Deltalight 2510 in a sealed 1cuft enclosure.

Hey Mayhem--what crossover did you eventually decide on, if any?

[Mayhem13]

Re: Flex Your PCD Mettle:

Hey Mayhem--what crossover did you eventually decide on, if any?

I haven't actually.....at least not yet. I have started on the active bass bins though. I'll be pulling my RSS315HF's from their sealed homes and installing them in 3.3cuft ported bins tuned to 22hz and fed 400w each. In order to keep port length managable, i'll be doing a POLK POWERPORT once i locate the spreadsheet.(Lost mine in the crash).

Zilch has shown us that 2.2khz is about as low as the XD120 should go and 2510 Juuuuussssst make it there with a notch.

I'm also waiting for Zaph to post some measurements on those Klipsch 6.5's for a side by side pair under 152/220i for an old school monitor. That's the $200 per pair system to beat IMO as we know 152i can go to 1.6khz and the 6.5's are a good directional match at that FR. That top end on a 15" sub bin would be killer.

[Zilch]

Measured Horizontal Directivity of 12" Woofer

Altec 414-8B rear-mounted in Dayton KDT kit cabinet:

[edlafontaine]

Re: Flex Your PCD Mettle:

Zilch,

What is the likelyhood that the dip in the polars ocurring just below 700 Hz and/or the accompanying bump above that are diffraction artifacts?

[Zilch]

Re: Flex Your PCD Mettle:

It is rock stable consistent across all angles, and thus disappears when normalized. Looking back, the 16-Ohm vintage Altec 414 has it also, but not the front-mounted JBL 2262H:

http://techtalk.parts-express.com/showthread.php?p=1664327#post1664327

I'd expect a diffraction effect to vary with off-axis angle, and it does not appear to be an artifact of the measurement setup like a reflection off the mic stand. A resonance, perhaps? I'd call it an Altec 414 response characteristic in this cab until otherwise determined....

[Zilch]

Flex It Round #7.1 - EconoWave Altec 414-8B

The 8-Ohm Linn Altec 414-8B gets mated with a diminutive BMS 4552nd on the QSC 152i in Dayton KDT cab w/ the baffle moved full forward:

[Zilch]

Re: Flex Your PCD Mettle:

The files:

[Zilch]

Re: Flex Your PCD Mettle:

Directivity:




Compare with 1.5" BMS 4555 on PT-F95HF waveguide:

http://techtalk.parts-express.com/attachment.php?attachmentid=11801&d=1288312336

http://techtalk.parts-express.com/attachment.php?attachmentid=11045&d=1284623314

The 1" compression driver/waveguide combination pushes directivity control well into the top octave, and it looks like a roundover on the woofer opening would widen the pattern below crossover for an even smoother directivity transition.

[Zilch]

Re: Flex Your PCD Mettle:

Here, showing the crossover transition region:




Compare with woofer only:

http://techtalk.parts-express.com/attachment.php?attachmentid=11781&d=1288240417

http://techtalk.parts-express.com/attachment.php?attachmentid=11802&stc=1&d=1288313026

[Edit: The links are correct now.]


How does the ferrite BMS 4550 play with the same crossover?



No spike killer required with 4552nd.

[Nobody but us knows that.... ;) ]

[Pete Schumacher]

Re: Flex It Round #7.1 - EconoWave Altec 414-8B

The 8-Ohm Linn Altec 414-8B gets mated with a diminutive BMS 4552nd on the QSC 152i in Dayton KDT cab w/ the baffle moved full forward:

WOW!!! Nice one Zilch!!!

[Zilch]

Re: Flex Your PCD Mettle:

THANKS, Pete -- PCD is certainly nailing these, now!

[Looks like we've got a good handle on the directivity thing, too.... ]

[Skywave-Rider]

Re: Flex Your PCD Mettle:

That's great, Zilch!
I was operating under the assumption that the 4550 and 4552ND were equivalent. But now we know that's not so.

Forward axis of 4552ND on QSC is 0º midway between drivers?
(+4.55º midway between drivers with 4550?)

I think 0º is ideal. Point it where you want it, good on stands or short tilt back risers.

[Zilch]

Re: Flex Your PCD Mettle:

Forward axis of 4552ND on QSC is 0º midway between drivers? (+4.55º midway between drivers with 4550?)

Yes, 4550's acoustic center is further back.

Regarding the frequency response, I'd have to measure a bunch before I'd call this example definitive.

It's easy enough to adjust 4550 VHF response flat in PCD.

[And add a spike killer.... ]

[Mayhem13]

Re: Flex Your PCD Mettle:

With the PA310 on sale for $66, those on the fence about building an Ewave need to jump in, the water's fine.;)



P.S. For those that wish to build this as a tower with about 4cuft of volume at 4ft tall, you can get some nice bass extension in this alignment without a sub. Should match up with room gain nicely.

[Brian Steele]

Re: Flex Your PCD Mettle:

With the PA310 on sale for $66, those on the fence about building an Ewave need to jump in, the water's fine.;)

That's an amazing price, considering that PE has 12" PRs that cost more than that...