From Post #52... Sorry, it was Widget who asked.Originally Posted by Giskard
From Post #52... Sorry, it was Widget who asked.
- You've recently pointed out that there is a variable pad between the .5mH inductor and your 1 uf cap which modifies the interactions.
- "All" these passive elements interact with each other / and therefore need to be treated as a whole / hence Giskards advice ( as I understand it ) aimed at helping you obtain an insight to these realities .
Of course you are right. As I noted before, at this point the 1 mfd not on the board but is hanging on the tweeter so is after the pad.
But as I also noted, if it stays, ultimately it would be before the pad and the simulation shows this so it is also of interest.
- You've recently pointed out that there is a variable pad between the .5mH inductor and your 1 uf cap which modifies the interactions.
- "All" these passive elements interact with each other / and therefore need to be treated as a whole / hence Giskards advice ( as I understand it ) aimed at helping you obtain an insight to these realities .
Viewed in the context of Mr. Widget's measurements of actual driver response, I ask, rhetorically, if there is some rationale for shaping the UHF drive like that?
Certainly not the "above 10 kHz" portion, where the uncompensated response is basically flat out to driver rolloff.
My point is, this has all got to work together, and an additional significant factor is how it meshes with what the MF driver is doing in the 5 - 10 kHz range in combination with ITS filter.
I'd say it's better to rely on "The book," i.e., what has worked successfully in the past, for starters. Innovation is great, and I have plenty good fun myself trying stuff out, but without measurement tools to asess how it's all playing together with the requisite accuracy and resolution, I have to advocate in favor of staying on the well-traveled path:
Leave out the additional cap for now....
The steeper slope keeps the 075 from adding to the already high 2-8K band from the horn. At least that's what my analyzer indicated, for what its worth.Certainly I don't want the peak, and to attain a steeper slope using just the cap coil may be nice and preclude this incidence. But that would require more $$$ that may not prove audibly beneficial. The slope for the simple cap/coil does look nice and smooth and will probably be employed in the final, as is.
But it's not the 500 Hz we were looking at in the woofer nearfield.
Here with LE85 mid, same with both of two known good ones.
Not enough overlap between the HP and LP filters, apparently, and the midrange looks right.
So, I'll work with the Zobel tomorrow as Giskard suggests.
And the LE175's.
UHF plays WAY hot; gotta dial it almost off to balance like this. Connecting its filter direct to the input wasn't a very good idea, looks like.
I'll try rearranging that, too....
Based on the octave resolution of my analyzer, the hole appears at about 500 Hz. Also, based on my analyzer, the tweeter is not that hot even turned up pretty high, but my mic/equipment probably has more high frequency roll-off.
Just for kicks, what does the spectrum look like with 16 ohms in series with the woofer?
1) O.K., here's the 16 Ohms in series with the woofer. All it does is attenuate, and all the bad stuff we've already discussed, of course.
2) The tweeter wide open runs 15 dB too hot. These are NIB 2402H.
3) Before anybody yells at me about the lens, here's the midrange only without the lens.
4) And here with the lens.
5) I ain't makin' this up.
Yeah, I'm doin' CONSTRUCTIVE stuff, too, but I don't have any answers yet....
We're chasin' room/measurement stuff at the lower frequencies (<1 kHz) here, apparently. With two-ways, I'm usually ignoring all that.
1) If I pull back to 2M, it's all good. See D'Appolito.
2) LE175 on DLH potato masher. To borrow a JBL engineering term: sounds "Dreadful." Playin' in a coffee can, like. S/N 7242, the foilcal says "8 Ohms," DCR is 6.5 Ohms.
3) Move it to HL91, and it's a decidedly different picture.
4) At 1M, the same "problem" as LE85. The 630 Hz notch is in the woofer response measurement, in fact.
5) At 2M, all's well. Note the hump at 500 Hz. This illustrates the difficulty of system measurement. Need a "bigger flashlight."
These sound very nice. The rising response through the upper midrange confers a "crispness" to their voice. I've kept all of the settings the same for this comparative testing. I'd probably dial these down some to suit my own listening taste. A bit too much midrange, as I'm hearing them now.
I did play with the Zobel. Taking it out bumps up the response in the 800 - 1 kHz region, where the curves do overlap. The system could be fine tuned that way, but it's not bad with the existing values.
I'll look more at the UHF connection thing. It's of concern that we're not getting at all the same behavior.
Other than that, I'd say you're good with these. Let your AutoEQ tell you what's needed. The basic performance is there....
I recently read where that didn't work so well with L212.Just go bury it in the ground face up and suspend your mic over it.
[Heh....]
Interesting difference between the HL87 and HL91. Do you think this is more attributable to the difference in shape or length?
The potato masher in my center cabinet is very old (has the old decal on it), has a different number (not HL87, but don't recall what it is..., 4-digits I believe), and is the same length as an HL91 (1" longer than a typical HL87..., and yes, I held them up side-by-side-by-side).
Also, based on your analyzer, when used with the UHF, there really isn't that much difference between the LE175 and LE85 when used on the same horn and both are pretty comparable in the 1K-7K range.
The more you look, the more you notice.
I know zip about horn theory, but there's an article on lenses in the site Library. I think it's the lens. Lookin' through it, it's a wonder anything passes.
So it seems. Remember, though, we shouldn't generalize from just this one sample of unknown history here. I yanked it from a C56 cabinet. There should be another here, somewhere. Hamilton wants to know how they play on CD horns, so I need to find it for a Q&D "Somethin'-'r-other."
Sure, whenever YOU get around to doin' that little inquest....
[Zilch does CD, not lenses. You know the drill....]
It's here, waitin' for me to solve the second computer problem, or drill some holes through the wall.
Mr. Widget suggests I set up a separate testing lab AND a listening room....
[I ain't doin' no billion-dollar anechoic doo-dah here. Nope.]
I've only bugged 'em about:
1) Whether 1.5" OA horns like 2352 are operationally compatible with 243x drivers (they are,) and,
2) Gettin' 1.5" PT-F waveguides, which I KNOW they have because they've published pictures of them, recommended them, and gave 'em a part number....
[If they sent me a pair, it might shut me up for a coupla days evaluatin'....
Found the second LE175. The horns are 1217-1290. The performance is the same. Call it the "Ski-boot" curve.
In the full system, as Todd observes, the overall frequency response looks good:
I tried the crossover and drivers (LE175 and 2402) with a bunch of different horns here. Surprisingly, many of the CD horns are "plug 'n' play" with the appropriate adapters, since they aren't being asked to do VHF.
1) $10 PT-F95
2) PT-H1010
3) PT-H1010 mounting
4) Front view
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