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Zilch's AK Design Collaborative - Econowave Speaker

Kegger said:
So Geddes calls it a "Foam Phase Plug" but it's in the whole horn surface area?
Anyone have a pic of one of these things?

No I have not had a chance to listen, just turned the system on, will in a few.
Click to expand...

It's just a foam plug stuffed into the mouth of the horn. It extends all the way down into the throat and nearly flush with the mouth. Geddes tends to curve it slightly at the mouth, so that it bulges at the center ever so slightly. I suspect this is partially to come closer to matching the distance travelled for sound on-axis to that off-axis (within the pattern), but also partially for aesthetics.

The same open cell foam used for speaker grilles can be used. You want something that acts like an acoustical resistance, but not like a filter. You want it to attenuate the sound equally at all frequencies above 1kHz or so, not a lot of attenuation, but some.

As Zilch said, the idea is to attenuate traverse waves bouncing off horn walls more than those traveling withing the coverage angle. The way it works is sound traveling at angles greater than the wall grazing angle must pass through more foam so more attenuation is provided.
 
Thanks Wayne, I was doing a search on "Foam Phase Plug" when I came across Geddes
Patent deals, but it doesn't go into detail of exactly what it was and I didn't find a pic.

A picture is worth a thousand words, anyone happen to have a picture of one of these?
 
Here's a photo of Geddes' Summa, with Earl Geddes and Duke LeJeune:

AudioKinesis_Geddes_Room.jpg


More photos:

I did that write-up, by the way. One thing I didn't mention is that I became convinced that John Malkovich is actually Earl Geddes working under an assumed name. :scratch2: Seriously, Both Earl and Duke are great guys. I really enjoyed being with them. Sometimes we don't agree, but on the vast majority of things, we do. One day, they'll start using the right coverage pattern tweeter horns and we'll agree on everything. :D
 
Kegger said:
Yay or Nay?

Just got the idea to try this, I'll listen tomorrow and see if it does anything. :scratch2:

(If anything else I think it looks kinda cool)

EDIT: OK I did some research and this is something Geddes has been talking about, Humm....
Click to expand...
The ones I got from Earl with the shabby waveguides were much larger. For the 10" diameter WG they would have been about 4" deep and looked as though they were cut from the section of a sphere; conical to fit into the WG throat and spherical on the face you'd see.

Attached is the best photo I have.
 

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OK I SEE now, thanks guy's!

The "Phase Plug" name was throwing me, as it's a piece of foam that fills the whole
horn not what would look like your typical type phase plug that is used by Geddes.

That is more like what I thought Dave was talking about earlier in the thread, just the
whole "Phase Plug" name was throwing me when I went searching for the darn things.

I'm using some foam that came from Parts-Express for internal dampening, it's the egg
crate type looking stuff that looks "open cell" to me but I have no idea it's properties.
 
OK well it didn't work. :( (but read on, please)

Put em in and it dropped the level to far that even turning the L-Pad's all the way up would
not compensate, I recently changed amps from the sweep amps to a conventional setup of
push pull UL that does not have quite the high frequency content of the sweeps and those
pads are set just a hair past halfway now. (with the sweeps I woulda gotten closer)

Well I chopped the Plug in half got closer but still not there, chopped it down to just a puck
that is roughly a 1/4" thick an just fits into the throat of the horn, now with pads a hair less
then the full setting I can get a propper level. (now my 8-16k is down a bit more, about 3db)

I'm going to increase my RC cap size now back to .47uf an see if the 8-16k comes back up
but what I'm getting now is a more even soundstage/imaging that has moved away from the
speakers, it is a fuller presentation that goes more away from the "center/speakers" image
to an image that fills the entire space between the speakers better than before.

The upper frequencies hold together better at higher SPL's as well and are less aggressive
sounding, now is that imparted by the lower 8-16K range I'm not sure, but it does seem to
sound better to me as far as smoothness goes, we'll see once/if I get the larger caps back
in there and it raises those upper frequencies back up some. (Dammit more Xover tweaking)

Overall the "pucks" drop output down roughly 4-5 db, probably not the correct type of foam
and I'd like to experiment with some others but if I get that UHF with this foam and still find
it improves things I may just leave it.

If others have foam to try on there's I certainly would be interested in there findings with the
EconoWave setups they are runing. After I make the cap changes I'll update the outcome.
 
There are exchanges regarding the correct foam and sources local to you earlier in this thread. Use "Search this Thread" to find them. Ross was wanting some, as I recall.... :yes:

[Where IS Ross with his E'Wave Advents, anyway? Were they a flop? :dunno: ]
 
Wayne Parham said:
...

It is also worth noting that delay from physical offset is not the same as crossover delay. Physical spacing creates a fixed delay, where the band-splitting filters in a crossover produce a delay proportional to frequency. So it is best to space the drivers appropriately or at least "in the ballpark" to begin with. But as long as the overlap band is not large, i.e. crossover slope is not too low, then the crossover delay can be used to ones advantage, fine-tuning the phase between drivers and shifting the null angles to put them where you want them to be.
Click to expand...

Dickason shows 2 ways are a stretch because you get into the inductance rise of the midwoofer. Would it then be reasonable to assume that a higher order filter is better for 2 ways because it allows you to get closer to that limit but remain in a predictable range for crossover components and delay?

I find him a tough read.:boring:
Your x-over paper helped me get a little closer but I might be a hopeless case.:smoke: Ask Zilch.
 
Zilch said:
There are exchanges regarding the correct foam and sources local to you earlier in this thread. Use "Search this Thread" to find them. Ross was wanting some, as I recall.... :yes:

[Where IS Ross with his E'Wave Advents, anyway? Were they a flop? :dunno: ]
Click to expand...

Yah I hear yu Zilch, but sometimes you just grab what you have and go to town with it. :D

But yes I would like to try the "correct" stuff.
 
Weekend fun! There was a package waiting for me when I got home from work tonight! Too bad the Pyles did not make it,:no: but I'm glad I ordered the elliptical WGs so I can play with these over the weekend. :yes: I need to search through the posts to see how you guys laid out your crossovers. I'm just going to tack things together on some terminal strips for now. Now where are those L-pads I have stashed away??

Tom
 

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OK I AM DOOOOOOONNNEE!!!!!!!!!!!!!!!!!!!!
(need a beer, or 9) :)

These things are frickin rockin!

I clip leaded in a .1 uf cap in with the .33 C3 stage and my 8K came back up flat, upped
the zobel resistor to 12.5 from 10 to splash in a bit more midrange and I'm rockin on out!
 
http://www.diyaudio.com/forums/showthread.php?postid=1238120#post1238120

********

Seems Kegger's been "DONE" a dozen times, already.

[It has something to do with celebratory libations, perhaps.... :p: ]

TomSc said:
Weekend fun! There was a package waiting for me when I got home from work tonight!
Click to expand...
I've just linked my KLH 17 upgrade thread over here and suggested what you're working with might be suitable for that purpose.

[You're being watched.... :thmbsp: ]

http://audiokarma.org/forums/showthread.php?p=2188568#post2188568
 
Zilch said:
Seems Kegger's been "DONE" a dozen times, already.

[It has something to do with celebratory libations, perhaps.... :p:
Click to expand...

Nah I've been close a few times and it has sounded good to very good at times,
but for me it has never been outstanding! It is at that point now! While I'd hate
to say I'm never going to tweak it again I do feel I'M THERE!:smoke:

Others have listened to this system and thought it was great, but I still left a
few reservatioins for myself until now, it is really quite that good at this point.

---

Now where did I put those beers?
 
[You're being watched.... ]
Click to expand...

So....you mean I'm going to have to drag the RTA gear out of the the road cases in the garage. Well...if it must be done:D

I just found the Speaker Workshop site. Quite a bit more advanced that TrueRTA! So now I'm learning new software at work AND at home now:nerd:
 
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