Flex Your PCD Mettle:

[dantheman]

No I haven't. I was thinking about doing some of that today. That was what I thought to be so interesting about the JBLs. The JBL enclosure also looks very good. The other ones that would be interesting in are the older Mackies. The new ones look like they've created diffraction issues just to differentiate them from the Behringers. Anyway, I need to do some more measuring of these Behringers.

Dan

[martyh]

Not sure if anyone has made this observation and I don't care to go through 22 pages to find out, but this thread has become the 'Dark Side of the Moon' of TT posts having been on the first page of the board for about six months now. The guys in the band would be proud.

[dantheman]

so here's vertical polars:
toward the woofer, on axis, the 11.25 degrees off axis, then 22.5 degrees off axis:


Now toward the tweeter, on axis, then 11.25, the 22.5, the 33.75, the 45:


What do you make of these Zilch? This is my first time ever doing them so I have nothing to compare to. I wish I had a better way to map it out, but the forward lobe is toward the tweeter and at least 22.5 degrees wide. I guess that's why I've had these so low and preferred them. It might be interesting to hang'em high and turn them upside down.

Dan

[Zilch]

What do you make of these Zilch? This is my first time ever doing them so I have nothing to compare to.

You've got it -- the forward axis and lobe are tilted upward toward the tweeter, and it looks like -6 dB in each direction would encompass -10° to +30°, quite good. That's the vertical nulls intruding on the response in your curves.

I am surprised the crossover frequency is so low, appearing to be ~1.8 kHz, which accounts for this performance despite the relatively wide separation of woofer and waveguide.

[Somebody did their homework with this design.... ]

[Zilch]

Not sure if anyone has made this observation and I don't care to go through 22 pages to find out, but this thread has become the 'Dark Side of the Moon' of TT posts having been on the first page of the board for about six months now. The guys in the band would be proud.

Yah, we're havin' plenty good speakergeek fun with PCD here.

The main thread on AudioKarma has been running a couple plus years, accrued 11,250 posts in 750 pages as of today, and is pushing towards three-quarter million views....

[dantheman]

Thanks for the analysis Zilch. I knew these things sounded better beneath my ear level. Tried them both ways and stuck with this one--midway between the drivers lower than my ear. Not bad for a buck fitty-two delivered. The impulse looks great and the build is rather robust as well. They made me give up on DIY. The measurements between the pair are also closer than anything I've built. I don't know how they've done it, but they've done it just the same.

My bet is that those JBLs will outperform these. I'd love to see some detailed 3rd party measurements of them.

Dan

[Dennis H]

The 2030P has also gotten good subjective reviews on this board with some simple cabinet mods -- dowels for bracing, stuffing on the walls. 75 bucks a piece, WTF?

And the 2031A active model is only 40 bucks more than the passive model. It has switches to dial in the bass response and BSC.

http://www.parts-express.com/wizards...omo=&srchAttr=

[dantheman]

I also found these measurements on the 2030p from http://www.linaeum.com:


There's a lot of reflections in them, but they look like they may be another budget champ. I'd call the 2031P a budget champ w/o hesitation. Doubly so after looking at the stereophile and soundstage measurements of other bookshelf and floorstanders. The active versions often have troubles with amps either breaking or picking up radio stations.

Anyway.... budgetphiles should enjoy the Behringers.

Dan

[bwaslo]

The 2030P has also gotten good subjective reviews on this board with some simple cabinet mods -- dowels for bracing, stuffing on the walls. 75 bucks a piece, WTF?

$65.50 ea, delivered, but who's counting. Like I need yet another pair of speakers, but geez.....

http://www.amazon.com/Truth-B2030P-S.../dp/B000QF2T1M

[dantheman]

Find the cheapest price you can and call zzounds. They'll beat it.

Dan

[dantheman]

Zilch, I am eagerly awaiting the measurements on the JBL WG. I know I liked what I heard in the shop, but had no music of my own and they were placed on a wall. I'm hoping to see something that can outperform the Behringers. It might bring me back to DIY as I think it's just in me. I need to see something that is awesome and available--especially now that I am single again.

Dan

Edit Dennis, Bill, you can get the 2031p for 152 matched pair delivered from zzounds after you tell them of the B&H Photo price. Shipping was fast and free.

[Zilch]

Note: The Dayton 6.8 uF is too long to fit the available spacing on the standard Econowave PC Boards; use Solen or Jantzen (shown) if building with these:

[Dennis H]

FWIW, here are WmAx's suggested mods for the B2030P.

1) Replace internal acoustic stuffing with more material and a higher grade material(ideally 4-8 lb/ft^3 density rockwool board or fiberglass board).

2) Fix vibrating metal can magnetic shield on woofer. Use liquid(NOT gel) super glue and squirt some generously around the seam where the can meets the driver - this will stop the vibration.

3) Fix air leak number 1. On the tweeter, where the tweeter motor connects to the tweeter faceplate, there is no seal between them. Use plain silicone sealant and squirt around the seam, being sure to also squirt around the base of the electrical leads.

4) Fix air leak number 2. On the plastic waveguide around the tweeter, there is no seal where the tweeter connects to the waveguide. Remove tweeter from the waveguide (4 screws on the back) and use bluetack, rope caulk or speaker gasket putty; flatten with your fingers and place small amounts on the ridges of the waveguide where it connects to tweeter. Re-mount tweeter and tighten screws. Scrape off excess putty on the front that squeezes out with fingernail.

[Skywave-Rider]

That looks like an excellent project, Zilch. As an early adopter of the economical D95HF-1 PT waveguide, I liked its potential, but did not have the skills to tweak the E-Wave circuit sufficiently. Thanks for doing this.

Is the woofer on the left an Eminence?

Note: The Dayton 6.8 uF is too long to fit the available spacing on the standard Econowave PC Boards; use Solen or Jantzen (shown) if building with these:

[dantheman]

Thanks Dennis, I'll look into it on the 2031. Maybe we start a new thread as not to muck up the econowave thread?

Dan

[Zilch]

As an early adopter of the economical D95HF-1 PT waveguide, I liked its potential, but did not have the skills to tweak the E-Wave circuit sufficiently. Thanks for doing this.

PCD is TRICK!

Is the woofer on the left an Eminence?

JBL 228H:

http://www.jblproservice.com/pdf/AE%.../AC1895-WH.pdf

[Another variant.... ]

[Skywave-Rider]

Oh yes. I remember.
Hard to keep all your variants in buffer memory.
Unobtanium woofers?

PCD is still gonna happen here.

PCD is TRICK!


JBL 228H:

http://www.jblproservice.com/pdf/AE%.../AC1895-WH.pdf

[Another variant.... ]

[Zilch]

Unobtanium woofers?

Worthy pursuits: copper-clad aluminum voice coil, SFG motor, copper-clad vented pole piece. Pro Parts can't sell these direct, but authorized JBL Pro dealers and service centers can get them.

http://www.jblpro.com/catalog/suppor...e=3&docid=1080

Not terribly expensive, as I recall, $118.

[Biggest magnet I've ever seen on an 8".... ]

[darrellh44]

At the risk of sounding like a complete blithering idiot, what the heck does PCD stand for? I hate TLAs.

Thanks,
Darrell

[Flacjunky]

At the risk of sounding like a complete blithering idiot, what the heck does PCD stand for? I hate TLAs.

Thanks,
Darrell

PCD = Passive Crossover Design