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Zilch's AK Design Collaborative - Econowave Speaker

Giskard said:
Then you just use an LE10H instead which handles a ton more input and has significantly better performance in every way. I see no point whatsoever in using an 8-inch in a box for a 10-inch.

My recommendation stands. They are very old and very antiquated, Q too high and suspension too loose. I would personally use them sealed in the 1.0 to 1.2 cu ft box because they sound a ton better but I know alot of people wouldn't.
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Spot on the issues Jack is wrestling with for his center channel; he's working with LE10H primarily.

Skywave and I are revisiting LE8T-H in smaller cab sizes.

Thank you again for this insight, Giskard.... :yes:
 
jackgiff said:
So Giskard thinks the 116H is a better woofer? Do you concur?
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IMHO, the L19/4301 (with the 116A first, then the 116H) was the best-sounding speakers of any kind that JBL made with 8" woofers, at least in the vintage days. Others may have done little things better here and there... but for a whole system, it was just RIGHT...

As for my experience with the LE8T- my personal best with those, was in about 1.75 cubic feet (any larger, and it unloaded, any smaller and it boomed), with a PR10 passive radiator, modified with larger weight. IIRC, it was with one of those JVC ribbon tweeters (like the ones sold by Radio Shack), as a supertweeter (above 8KHz or so). Just did it because I had the parts available at the same time. That's the best low-bass output (combination of power and extension) I've personally ever heard from an LE8 of any sort... and it was pretty jaw-droppingly coherent too.

IIRC, these were the longer-coil version of the LE8- some of those only had about 1/4" long windings... these were somewhere closer to 7/16" voice coil winding length...

Regards,
Gordon.
 
GordonW said:
IMHO, the L19/4301 (with the 116A first, then the 116H) was the best-sounding speakers of any kind that JBL made with 8" woofers, at least in the vintage days. Others may have done little things better here and there... but for a whole system, it was just RIGHT...
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I think that opinion is shared by a good many.
GordonW said:
Just did it because I had the parts available at the same time.
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Well, that drives alot of DIY projects for sure...
 
8 Inch question

While you are on the 8inch woofer discussion, please allow me to ask your opinions about the D123. I have a couple of 16ohms sitting in my closet. It will be a waste to leave them there to rot. Some are using them as fullrange in open baffle. I tried it as a fullrange, not as an open baffle, but it sounded as though something was missing. I would love to hear your comments. I just know so little about them. Yet, I know that they are valued by JBL collectors.

Thanks
 
Thank you Zilch, Giskard and Gordon.

I am currently trying the box with Zilchplugz, though I should get some fill for it.

It makes sense that the LE8TH was a ceiling speaker design; and it is working as part of a very good nearfield monitor here in conjunction with the 8x8 waveguide.

I am evaluating building a slightly bigger (1.2cu ft) box which would allow waveguide on the baffle.

My impression of the 8x8 waveguide in my current setup: Imaging (phantom image) is not as stable and solid as with Econoguide. However I like the sound a bit better.

Thanks again.
 
mrTT said:
While you are on the 8inch woofer discussion, please allow me to ask your opinions about the D123.
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They're 12", and "Extended range," not full range. Use "Search" to find our previous discussions about them here.

Bottom line: they're midbass drivers, basically.... :yes:
 
I'm guessing a whole new crossover would be in order?

That may make a more than this simple mind could handle.
 
Thanks, T. IIRC, you're using a dynamic mic?
Probably not very flat, and usually not able to make the upper reaches.
That may account for your curve.



mrTT said:
Hi Skywave

Here is the graph you've asked to post. Again, it's a disclaimer. Cheap microphone+freeware. But looks very consistent with what Zilch has been posting. I am following Wayne's recommendation. R1=16ohms R2=50 ohms and C1 at .33uf. I like this much better. I feel like the high is much more extended. Personal pref, of course.

My crossover has some switches and what not. Following some advices, I have designed it for first order, first order with zobel, second order, and second order with zobel. Each has different cat. I like gadgets. That's all! :D

Sounds really good.
Click to expand...
 
ejfud said:
Does the inductor go in between the two woofers? How expensive are we talking?

So Zilch, want to help a moron like me make these a reality?
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Skywave used 20 mH with his 16-Ohm Altec 414 pairs. For 8-Ohm woofs try 10 mH, PE# 266-946:

http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=266-946

The woofers are wired in parallel, and the inductor goes in series with the "Helper" one, comprising a 1st-order lowpass at an appropriate frequency. Depending upon the actual impedance down there, PE chart says that'll kick it in somewhere around 100 - 150 Hz.

Project concept idea using the standard E'Wave with dual woofs:

http://manuals.harman.com/JBL/HOM/Technical Sheet/SK2-1000 Hercules ts.pdf

See L2 there?

OR, stack 8" woofs vertical-in-line as towers with the 8" square E'Waveguide.


ejfud said:
So Zilch, want to help a moron like me make these a reality?
Click to expand...

PM Jackgiff regarding the potential availability of E'Wave crossover boards.

He's working up a biampable version, last I heard.... :thmbsp:
 
Thanks, T. IIRC
Click to expand...
, You're very welcome Skywave.
you're using a dynamic mic?
Probably not very flat, and usually not able to make the upper reaches.
That may account for your curve.
Click to expand...
Correct. It's an el cheapo mic. So, it is not accurate. But that's the best I can do for now.

I have a question for everyone. What's driving your awesome econowave. And what kind of speaker wire are you using? I am just curious.
 
Last time I did an x.5 type setup I brought the 2nd woofer in where the baffle step would occur based on baffle width. It worked out really well in that application.

Ray
 
I've been keeping an eye out for woofer/enclosures as being possible candidates for Econowaves but have no confidence in choosing the right candidate that can handle 1500hz as most drivers seem to be crossed over below 6-700hz. Are most LF drivers in a 2-way system capable up to 1500hz? Thanks
 
tubed said:
Are most LF drivers in a 2-way system capable up to 1500hz? Thanks
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Yes, generally, as are most of those used in 3-ways, but crossed lower.

15", you've got to look harder at the specs, or measure, but just about everything else except sub drivers is suitable.... :yes:
 
Zilch said:
We're WAITING...! ;)

Tell us how to figure that, Ray, please.... :yes:
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Find the frequency where the wavelength of the sound wave is equal to the smallest dimension (usually the width) of the baffle. That will be the point where the center of the woofer (if centered on the baffle) will be 1/2 wave away from the outside edge of the cabinet. At any frequency lower than this, the wavelength will be BIGGER than the baffle dimension, and the sound waves will no longer be "supported" by the baffle... they will 'wrap around' the cabinet, which will reduce the effective output to the front of the speaker.

In scientific terms, we call this the "2-pi to 4-pi radiation transition frequency". In layman's terms, it the frequency where the bass drops in level because of the loss of baffle support. In short, it's known as the "baffle step frequency"... because, if you graph it, it looks like a "step" in the response curve at that frequency.

Fortunately, it's about a 6 dB step, in theory... pretty much equivalent to the output of a second woofer added in parallel to the first. So, if you pick a crossover frequency for the second woofer EQUIVALENT to the frequency where the baffle is 1 wavelength wide... you will be in the ballpark.

IME, I've had good luck with a sort of modified approach. Tune both woofers to an EBS vented (long-tail rolloff vented box) or low-Q (near Qtc of .5 or so) sealed alignment, and use a lower frequency lowpass crossover on the .5 woofer (about 1 octave below baffle-step). This makes for a more subtle baffle-step compensation... more like 2-3 dB rather than the full 6 dB. I find this works better for speakers in real rooms... where the speaker is still somewhat "supported" below the baffle step by proximity to a wall behind the speaker cabinet (which "restores" to an extent, the 2-pi baffling effect below the nominal baffle step frequency of the cabinet)...

In short... there's no hard-and-fast rules on what will sound best in your particular ".5 woofer" setup... but these will give some good guidelines on where to start. For larger enclosures, you need less compensation (bring the woofer in at a lower frequency relative to the theoretical model above), for smaller ones, you probably need a bit more (closer to the theoretical frequency).

BTW: the speaker in my avatar (Seeburg DDS1 mod) is a good example of this approach. Two 15" woofers, nominal baffle step frequency of around 330 Hz. Tuned to EBS alignment (normal B4 port tuning would be around 35 Hz- these are tuned to around 25 Hz) with the second woofer brought in at a relatively low frequency (in this case, around 80-90 Hz- almost two octaves below baffle-step). But, the second woofer added JUST enough support...to make a system that would normally have a baffle step and only go down to 40 Hz or so (with a single woofer) flat down to 30 Hz (with both woofers)...

Regards,
Gordon.
 
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