The Advent Loudspeaker
- Thread starter Zilch
- Start date
The waveguides are $14 apiece, Kegger; you probably have the rest already, or access to it. :thmbsp:
[BULA vs. ZLA. Heh, heh....
]
Paratima
E'Wavin'
The Bill o'Materials (except for different waveguide and included Dayton woofer) can be found in my KLH-17 thread HERE in the first post. PM Zilch on how to acquire the PCB.
Also, it should be noted that you'll need the JBL waveguide used in the original EconoWave thread if you have the Utility NLA, like I do. Not enough room in the 26" high cabinet, as shown in the Advent Speaker identification thread in the stickies.
Also, it should be noted that you'll need the JBL waveguide used in the original EconoWave thread if you have the Utility NLA, like I do. Not enough room in the 26" high cabinet, as shown in the Advent Speaker identification thread in the stickies.
I believe we have determined that the NLA utilities have wide enough baffles to accept the 12" standard E'Waveguide, so which option to use depends upon available baffle space, horizontal and vertical, and in some cases, either may be applicable.
Despite the bullnose NLAs not being quite wide enough, Wiredbecker's present plan is to go ahead and undercut them for the mod, and if he goes ahead with that, we'll be able to compare. These chamfered OLAs are also just a tad too narriow, but only the vinyl trim would have to be modified to accommodate the wider waveguide. I thought I'd use them to develop this alternative upgrade instead, since the Bauhausler was doing the standard.
Jury's still out on which lowpass is "better;" that may be more a matter of placement and preference, actually. Clearly, I have come close to the original alignment's bass response in these, and they sound fine in freespace, but I can also appreciate that it might be excessive with boundary reinforcement. I'm just going to have to do similar measurements with the standard E'Wave lowpass that the Bauhausler used for comparison. My determinations earlier in this thread also indicated that replacing the stock foam damping with fiberglass mitigates a bit of what some might perceive as "boominess" in the originals.
Measurements are getting us more answers about Advents here; we're not done yet.... :thmbsp:
Paratima
E'Wavin'
My New Utilities are the sort that are 14.25 x 26 x 11.5. So I'm committed to the original waveguides ("horns" according to the Doctor). According to my measurestick, that comes to about 2874 inches on the inside (not allowing for the internal brace) or 1.6 cubic feets. I've done the carving and was about to start on the crossover. Oh well, I can wait. I've got these great ZLH's I can listen to while you work it out. 
Any parts I don't use here will probably work in the Indignias I plan to build sooner or later.
But seriously, if there's anything I can do to help, let me know. Build it both ways & tell ya which I like better? Well, maybe...
Any parts I don't use here will probably work in the Indignias I plan to build sooner or later.But seriously, if there's anything I can do to help, let me know. Build it both ways & tell ya which I like better? Well, maybe...
Do it.
It'll cost an extra $15, and you can make the same determinations I am working through here.... :thmbsp:
skywave-rider
Slumming in Akihabara
Zilch,
I read you determined the acoustic center w/ 8x8 as being 2" below the waveguide. I assume you are moving the measurement mic up/down to determine best vertical response?
I'd think this is a good outcome for this speaker because it could be tilted back on a riser or raised further in large bookshelf fashion.
I read you determined the acoustic center w/ 8x8 as being 2" below the waveguide. I assume you are moving the measurement mic up/down to determine best vertical response?
I'd think this is a good outcome for this speaker because it could be tilted back on a riser or raised further in large bookshelf fashion.
In this instance, it's 2" below the waveguide CENTER, which is still within the waveguide.
To make the determination, I invert the HF driver phase and move the mic up and down vertically, while remaining on-axis horizontally, to generate the deepest notch. I post it with 1/6 octave smoothing, but have actually refined it looking at the unsmoothed response, where I can get it within +/- 1/16". It's very sensitive, and where the drivers totally cancel at the acoustic crossover frequency, seems like it dips all the way to China, sometimes. That also tells me the crossover frequency very precisely, or what I'm gonna call it, at least.... :thmbsp:
Hi Zilch,
I found this thread after having read and re-read most of the econo-wave story and ordering all the x-over components, wave guides and selenium 220ti's for my old bullnose Advents. I see you've mentioned 3.5mh inductors and a 10uf caps here, vs the 1.5mh and 12uf ala econo-wave. Should I reorder coils and caps or is your impression that it's a minor difference?
I also ordered a pair of selenium HM25-25 horns for fun and see they would be a better fit in my OLA's. Have you ever measured them with 220ti's or 210ti's? Would you like to? I could send them your way when they arrive...
http://www.seleniumloudspeakers.com/site2004/catalogo/pdf/pro_corneta_hm25-25_new.pdf
Jim
I'd be happy to send them your way for evaluation when they arrive.
I found this thread after having read and re-read most of the econo-wave story and ordering all the x-over components, wave guides and selenium 220ti's for my old bullnose Advents. I see you've mentioned 3.5mh inductors and a 10uf caps here, vs the 1.5mh and 12uf ala econo-wave. Should I reorder coils and caps or is your impression that it's a minor difference?
I also ordered a pair of selenium HM25-25 horns for fun and see they would be a better fit in my OLA's. Have you ever measured them with 220ti's or 210ti's? Would you like to? I could send them your way when they arrive...
http://www.seleniumloudspeakers.com/site2004/catalogo/pdf/pro_corneta_hm25-25_new.pdf
Jim
I'd be happy to send them your way for evaluation when they arrive.
In theory, it should be a major difference with respect to how much bass the Advents deliver, but I don't know yet for certain. With the standard E'Wave lowpass, you'll be building what the Bauhausler is hearing. If you're going to use the speakers with boundary reinforcement, that may be the preferred response.
There's certainly no harm in trying both variants, so having components for both will allow you to make your own determination.
That Selenium horn is an exponential, as I recall, and if so, will not deliver E'Wave's constant directivity. Let us know how that works out, as well. The HF compensation will be different using it; you may get away with none, actually, from examining the curves.... :yes:
Interesting, as I know little to nothing about horns/waveguides apart from what I've read here, what is it about this exponential horn and "the curves" that you lead you to that supposition? Are you referring to the response curves while using the JBL waveguide?
Is it likely that it will roll off VHF? Beaming issues? Higher distortion?
Thanks!
Jim
That's the horn Selenium uses to generate the response curves shown in the D220ti data sheet, right?
It's a deception. The only way to compare the native response of various compression drivers is to measure them on a Plane-Wave Tube. Any horn or waveguide will produce a different result, unless its a true constant directivity one, which gives the same as PWT. The requisite HF comp to yield flat response is the conjugate of that curve.
By virtue of its flare geometry, an exponential horn will produce a flatter curve; it does the requisite HF comp mechanically, well, acousticaly, actually, by beaming the high frequencies.
Does D220ti play as shown? Well, "Yes," but only on-axis.... :yes:
From what I could find googling, it appears they used the HM14-25 horn for the 220ti. I guess that's irrelevant based on your comments though. I'll soon have both to play with so we'll see. Thanks again Zilch, I greatly enjoy lurking your threads and appreciate all of your work with Jack on the econowave!
Jim
http://www.seleniumloudspeakers.com/site2004/catalogo/pdf/D220Ti.pdf
Jim
http://www.seleniumloudspeakers.com/site2004/catalogo/pdf/D220Ti.pdf
Thanks for the datasheet on HM25-25.
While they call it an exponential, it's not behaving as one above 10 kHz, and will require HF comp in that highest octave, ~12 dB, perhaps, to play flat out to 20 kHz w/D210ti.... :yes:
I'll be trying it with the 220ti/HM25-25 and standard JBL waveguide when all the parts arrive. I'd like to understand the effects of your crossover changes for the 8" waveguide, does it augment the VHF response, the amplitude or the off-axis response? Or a sum of all these?
The 8" PT Waveguide requires different HF compensation to play flat.
Further, if we change the lowpass for different bass response, that alters the attenuation required to balance the HF at midpoint on the L-pad, so we have have to adjust that, as well.
Midpoint is a convenient repeatable setting point, but also, arbitrary, and itself subject to adjustment.... :yes:
Further, if we change the lowpass for different bass response, that alters the attenuation required to balance the HF at midpoint on the L-pad, so we have have to adjust that, as well.
Midpoint is a convenient repeatable setting point, but also, arbitrary, and itself subject to adjustment.... :yes:
Other than a cursory look at the polar response, and listening for any anomalies, I accept the dispersion characteristics of the particular PT waveguide as published by JBL. A different compression driver is unlikely to alter what's going on behind the curtain in this respect, as that is established by the flare contours.... :yes:
