Zilch's AK Design Collaborative - Econowave Speaker

[KCM]

WinISD is a free downloadable box modeling program....

Thank you !

OK, maybe (or probably) I'm missing something, but venting this results in very little extension, and less even response. Seems like I should leave it sealed :headscrat

 

[Zilch]

OK, maybe (or probably) I'm missing something, but venting this results in very little extension, and less even response. Seems like I should leave it sealed :headscrat

BB6P suggests tuning 3 cuft to 30 Hz with one 4" diameter vent 9.17" long.

As you say, that generates a bit more extension and ~2.5 dB of boom at 60-70 Hz, not necessarily a bad thing. I like a bit of boom, myself.

What it DOES get you is significantly improved power handling. F6 is 31.5 Hz, and it'll handle the full rated 50W down to 27.75 Hz before falling off, and deliver 102 dB down there.

I'd tune lower, ~25 Hz, which reduces the boom to 2.0 dB. F6 rises a bit to 32 Hz, but it'll take full power down to 25 Hz. 4" vent length is 15.75", but I'd make that happen with an elbow.

Overall, we're talkin' ass-kicking performance in this alignment.

[According to the sims, anyway.... ]

 

[Clmrt]

Lessee here..this would be v4 by now for my pair.

Passive biamp, >95db hi-pass, no L-pad, optimized 123A-1 lo-pass.

 

[Zilch]

Lessee here..this would be v4 by now for my pair.

1) Is that working better for you?

2) Are you having speakergeek fun?

 

[Clmrt]

Getting the LP right was a major deal...well, all I had to do was buy and assemble the components...Of course without measurements it's all subjective, but it sounds better now than ever.

I'm still getting used to the HP, and should add a woofer load as discussed previously, as I'm runnung tubes. But it certainly does sound nice!

 

[KCM]

I'd tune lower, ~25 Hz, which reduces the boom to 2.0 dB. F6 rises a bit to 32 Hz, but it'll take full power down to 25 Hz. 4" vent length is 15.75", but I'd make that happen with an elbow.

Overall, we're talkin' ass-kicking performance in this alignment.

According to the sims, anyway....


I'll let you know ! Thanks again, Zilch

 

[Kegger]

Megawave!

Got through to JBL Pro Parts,

The 1" thread on version is $131.00 each, and I was told there were plenty in stock. :thmbsp:

Unfortunately I did not ask about the 1.5" bolt on version,

 

[Zilch]

Go, Kegger, GO! :tongue:

Edit: Got the invoice, and the 1.5" bolt-on version is $113 ea.

[Zilch, the cheapskate.... ]

 

[Russellc]

Wow, this thread CONTINUES to pick up momentum....it used to have the heaviest traffic only on weekends, now its prime time, 7 days a week, with more and more participants.

I dont know how this thread will grow in the future, or what directions it may go. While new people keep entering the fray, original members like myself and others are wondering about other drivers and horns. Not sure whether it will all happen under this thread, or if other "Mega Wave Collaberative" threads will pop up.

Either way, a very informative thread, with tons of participants and potential future participants. Absolutely no signs of slowing down as we go into 2009.
A speaker thread whose time has come in more than one way, as an information source on crossover compensation and design, RTA use, circuit board making, box building/scavenging, plus the design is so dam affordable,
it makes good "economic sense" in our troubled econonomic times. Top this off with a liberal dose of "ass kicking performance" ( another Zilch invention, along with "Imaginary gonadatrophic effect") and its easy to see why this thread has been so insanely successful. Weenies are we? Now the weenies have become the majority! How Orwellian!:yes:

Wave on dudes,

Russellc

 

[Russellc]

Go, Kegger, GO! :tongue:

Edit: Got the invoice, and the 1.5" bolt-on version is $113 ea.

[Zilch, the cheapskate.... ]

Lord, I hope there will be a little play from those of you with RTAS with the 1" version. You are right Zilch, my eyes did go up a little when I saw mention of the JBL model using it, but when I clicked the link, I had trouble figuring out what is going on there with the crossover. Couldnt determine what the compensation/notch/tank filter if any, was? It particularly interested me as it used 2426H, very similar to my 2425H on hand. Can you tell what is compensation on that contraption, Zilch, or anyone?
I've been waiting for some 2425H/2426H play here for a while......
Thanks,

Russellc

 

[Zilch]

Another link for the E'Wave database, courtesy member Onplane:

http://sound.westhost.com/articles/waveguides1.htm

It particularly interested me as it used 2426H, very similar to my 2425H on hand. Can you tell what is compensation on that contraption, Zilch, or anyone?

It actually uses 2425HS, the "snooted" version of 2425H, same as 2426H with the thread adapter removed:

http://www.jblproservice.com/pdf/Theatre Series/4632M-HF.pdf

SPICE tells me that R1 and C2 values as published in the schematic are wrong. Somebody'll have to buy the actual factory network to know for sure, but here's my corrected version. I can check it out using a throat adapter, maybe, assuming I have one:

 

[Russellc]

Appears to be 24 db L-R crossover? Not sure what R-1 is...
and C3,R2 and C3 are a notch filter?

Russellc

 

[Zilch]

Appears to be 24 db L-R crossover? Not sure what R-1 is ... and C3,R2 and C3 are a notch filter?

"Quasi-" something.

Notch filter makes the dip at ~3.5 kHz, yes.

We don't know the inductor DCRs, so consider the transfer curve "representative" of the topology only.... :yes:

 

[Russellc]

"Quasi-" something.

Notch filter makes the dip at ~3.5 kHz, yes.

We don't know the inductor DCRs, so consider the transfer curve "representative" of the topology only.... :yes:

Hmmmmmmmm maybe somethings going on with the 2425H at 3.5 khz, or maybe some interaction with the mids? Seems a little high for that to be the case. Never noticed anything funny with the response of that unit. What does Zilch think they are notching out of there?

Russellc

 

[Zilch]

That's what's doing the HF comp above there, by yanking down a curve that would approach 0 dB at 20 kHz more slowly. Compare to Wayne's "ideal" curve.

This approach is more typical of how JBL accomplishes the same purpose.... :yes:

 

[Russellc]

That's what's doing the HF comp above there, by yanking down a curve that would approach 0 dB at 20 kHz more slowly. Compare to Wayne's "ideal" curve.

This approach is more typical of how JBL accomplishes the same purpose.... :yes:

Ahhhhh, so removing a notch at a certain place along the frequency response results in a lifting of the higher frequencies? Boy after all these years I still have PLENTY (and that's being kind) to learn about this stuff. I understood how the cap jumps some energy past the resistor in the Econowave crossover, but it'll take some more 'splainin for me to understand how making a notch filter at 3.5 raises the high frequency response.:headscrat:headscrat:scratch2::scratch2: Am I missing the boat or does it do this because the notch does not "remove" the energy where the filter is, just pushes it away from 3.5 and it pops up higher on the frequency response? ( Nothing like exposing the depth of my own stupidity on the world wide web!)

The only use of filters like these I have ever been involved with were to remove resonant spikes in dome tweeters which were not ferro fluid dampened, and it was a little close to the crossover frequency.

Russellc

 

[dnewma04]

I think what is more likely happening here isn't that it's lifting the high frequency, it's picking a point at the approximate center of the high output area of the CD horn response and using a very low Q notch filter to lower the response on either side of that point rather than shelving the high frequency above a certain frequency.

 

[Zilch]

Taming MegaWave VHF:

Transparent shade courtesy member Wiredbecker selectively attenuates 2384 VHF on axis:

This one has flattened the response above 5 kHz generally, and knocked down the 18-20 kHz peak by 40%; it's now merely +5 dB.

Just need to determine the correct transparency ratio to replicate that of a theater screen, and we'll have the "remarkable" response shown in the tech note. :thmbsp:

[OH, and the obligatory LED light organ in behind there for Simi.... :tongue: ]

 

[skywave-rider]

Excellent results, Zilch.
Have you found any variance in attenuation at changes in distance from waveguide to the shade?

 

[Zilch]

I'll think about how I might test that, Skywave, but for now, I'm gonna listen. :yes:

[And figure out how to set up the pair here now.... ]