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Multi-Way Conventional loudspeakers with crossovers

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Old 6th October 2012, 03:34 AM   #8211
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Truetone ... good find, thx. good find,thx. See you found my error in updated post.
There are lots of possibilities other than the spendy GPA 288's. I do have one 288K but useless except for mono. The main goal is to get below 800Hz crossover point. My new, soon to be turned standard Tractrix flare horn has Fc design of 240Hz so is usable from about 360Hz.

It's name: JAFtractrix horn.
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Old 6th October 2012, 01:06 PM   #8212
nuconz is offline nuconz  United States
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Originally Posted by Lynn Olson View Post

"In addition to the criteria of flat frequency response, I believe that the second biggest influence on the subjective quality of horns or waveguides is the unpleasant phenomenon known as “horn-honk”. This has been incorrectly attributed to a variety of causes, such as compression chamber and/or throat distortion, resonances in the horn cavity or walls, and even abrupt changes of DI between cone and horn transducers in a loudspeaker system. While the previously mentioned mechanisms can contribute to poor quality sound, the real culprit behind horn-honk is caused by poor mouth termination, and/or rapid flare rate changes within a horn or waveguide. In answer to Ian’s comment on subjectively poor performance of some CD horns, I note that many of the commercial devices on the market rely on diffraction slots and abrupt internal slope breaks (flare rate changes), while also displaying poor mouth to baffle impedance matching, all of which are responsible for imposing varying levels of horn-honk to the sonic character. Unfortunately, good CD does not guarantee good sonic performance."
i've jumped into this topic at page 112/822, so much lies ahead.

i've a pair of hedlunds that have some great sonic merits and one sonic flaw - horn honk. these were a "gift" and the builder made the wave guides smooth, so there is no stuffing. 2 drivers tried in these produce the same honk. poly fill behind the driver doesn't help.

a pair of harveys had the same flaw until i stuffed a good bit of poly fill in the upper mouth area of each. there was some egg crate stuffing in the harvey's chambers at the sides. don't know if this helped anything. my current belief is that is might not have helped at all.

any ideas as to what might improve the hedlunds?
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Old 6th October 2012, 05:19 PM   #8213
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Originally Posted by Truetone View Post
You can get an adapter to 1.4" at a reasonable price here:
You can get an adapter to 1.4" at a reasonable price here:
Altec Lansing GPA 21216 21216A Horn Adaptor NEW | eBay

I would think manifolding 2 x drivers really only achieves more power, which you don't need.

If you want to depart further from Lynn's spec and raise the cross over point JBL2420s sound great on 550Hz le Cleac'h horns - possibly 550 horns are more suitable for 1" drivers in general. That's my impression. Bear in mind the plot is with the mic at the horn mouth - purely to show horn/driver interaction - not a standard or comparable method. No flames please.

http://azurahorn.com/JBL2420_on_550.pdf

martin
The only reason manifolding was done "back in the day" was for more power - specifically, theaters with more than 1000 seats (70mm widescreen theaters were really big back then!). There in no improvement in fidelity; manifolds create reflections and roughen the response, so there is no reason at all to use them for home applications.

Compression drivers with 1" exits work fine with LeCleac'h horns, and Martin (Azurahorn) and other vendors sell them. The tradeoff, which is to be expected, is a higher crossover. I would suggest absolutely no lower than 1 kHz, with 1.4 kHz preferable. (Dr. Geddes gets away with 950 Hz, but he knows what he is doing.)

Metal-diaphragm drivers sound really bad if you try and cross them too low - you get the horrible garage-band PA sound if you try that. Plastic-diaphragm drivers tolerate this kind of abuse more gracefully, but I'd still not cross them any lower than 1 kHz - and if you go that low, I'd use a 3rd or 4th-order highpass filter.

The trick with any compression driver is to keep them well away from a too-low crossover - sound quality really deteriorates when you try and "push" them lower than they want to go. This SQ deterioration is much faster than equivalent direct-radiators, and there are a whole lot of PA speakers out there with badly chosen crossover points.

But you won't need a supertweeter, which is a plus.

Last edited by Lynn Olson; 6th October 2012 at 05:48 PM.
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Old 6th October 2012, 05:30 PM   #8214
Elias is offline Elias  Finland
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Old 6th October 2012, 05:32 PM   #8215
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As for the Hedlund horns, I have no clue where to start. I'm not a fan of full-range drivers, and particularly not whizzer cones, which have ugly mechanical crossovers in the 3~5 kHz range. A brute-force solution is a passive notch filter tuned to the worst breakups, but that has nothing to do with horn-honk, which is at lower frequencies and is typically a design defect in the horn itself.

The Hedlund looks like a folded horn; the folds create reflections, which in turn create comb-filtering in the frequency response as well ripples in the time domain. In a folded basshorn, a sharp (4th-order) lowpass filter can remove the trouble region, but this option is not present for a full-range system.

The best you can do is measure the system with a digital equalizer and notch-out the (multiple) peaks in the bass range; don't try and equalize the holes in the response, that'll just burn up the driver.

Last edited by Lynn Olson; 6th October 2012 at 05:40 PM.
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Old 6th October 2012, 06:39 PM   #8216
nuconz is offline nuconz  United States
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horns rule if you can "get them right". i don't like the typical "make your ears bleed" type of midrange horn sound. i do like the jbl cd horns. awesome outdoors. need a bit of equalization to get the "life like" midrange sound.

the hedlunds have their moments. but if the source has a lot of "husky" vocals, they amplify this significantly.

i bought the harvey enclosures for $75 from a chap that hated the sound. said they sounded like PA speakers. well after putting a dayton PA130 in them and stuffing the top they sound good. no horn - honk.

hedlunds don't have a top and bottom. this is the disadvantage. "adjusting" the sound with poly foam might not work. i'd prefer a low-tech solution like this but might wind up having to do as you suggest. i do have a frequency counter and an audio generator. a little more "bargain rate" gear and i'm there.
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Old 6th October 2012, 09:07 PM   #8217
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Quote:
Originally Posted by Lynn Olson View Post

The Hedlund looks like a folded horn; the folds create reflections, which in turn create comb-filtering in the frequency response as well ripples in the time domain. In a folded basshorn, a sharp (4th-order) lowpass filter can remove the trouble region, but this option is not present for a full-range system.
update from the earlier post.

2 of the CSS WR125ST speakers were mounted today. previously i had 1 in each horn ~ 16 ohm load. amp didn't like. so the response wasn't quite authentic.

anyway w/ 8 ohm load and some stuffing at the bottom of the chamber and some behind the drivers, the sound is improved and not really objectionable.

the hedlund is a good cab and these sound better than the BOFU which is too much for the cab, but plays really loud!
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Old 7th October 2012, 07:17 PM   #8218
DougL is offline DougL  United States
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Lynn,
I was wondering if you happened to try the B&C DE 5 or De 7 in the same horn profile (scaled down) that you have the mid-range horn on. My thoughts are that horn profiles are good for about a decade. If a 1" will go to about 1200 Hz comfortably, it may struggle above 12Khz or so, which may be a good compromise for a two way, but not if that's the only range its being ask to reproduce.
It might be better to have a half inch (or three quarter )throat driver if it doesn't have to play below 8 k or so. Advantages are simular time domain behavior, simular dispersion, simular efficiency, much lower cost. Probably just as hard to integrate.

Random thought.

Doug
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Old 8th October 2012, 07:23 AM   #8219
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The old-timers were right about the one-decade range for horns. When you try and "stretch" the frequency range, you lose many of virtues of horns and are left with the faults. When a horn is working too low, the effortless dynamics and vivid tone colors go away, replaced by some pretty ugly artifacts - harshness and gritty sound. All of the stereotypes of bad PA systems - now that "waveguides" are getting popular for home-theater speakers, we're starting to hear that kind of sound in home speakers, too.

A 1" exit compression driver is taking it really easy above 2 kHz - assuming the horn has competent diaphragm loading through the working range.

1.4 kHz - well, now we're needing to be more careful about the crossover, but still do-able if you're willing to mess around with the crossover and do a lot of subjective listening. (Are vocals harsh? Is the midrange congested-sounding on complex recordings? Raise the crossover and see if it goes away.)

1 kHz with 1" exit drivers is only for experts. I wouldn't even try it, and I've been doing crossovers for a while now.

Set aside the economics and look at the physics of the situation. Large-format compression drivers comfortably handle 500 Hz if the horn is large enough (at least 1.4X the size of the AH425, and preferably larger). That makes using 15" drivers very easy, with the efficiency advantages of 15" drivers and resulting increase in headroom in the bass range. If you're bold enough and have enough room, a pair of 15" drivers will truly satisfy - the audio equivalent of a V8 with twin turbos. All the power you could ever want.

Small-format drivers want to be crossed an octave or more higher. That's pretty much what you'd expect based on the differences in size of the diaphragm itself - it's like comparing a 15" bass driver to a 8" bass driver. The dynamic capabilities are very different.

With a crossover falling in the 1.4~2 kHz range, it's kind of the outer limit of what 15" drivers can do. Most 15" drivers have a broad peak around 1.5 kHz, which easily equalized, but the directivity may be getting a little weird around that peak, which is not so easily equalized. There are a handful of 15" drivers which sound OK in the 1~2 kHz range - probably the Altec/GPA 416B (which will need EQ) and the Acoustic Elegance TD15M.

10~12" drivers are the obvious alternative, but then the efficiency is typically 2~3 dB lower. One way around that is using a pair of 10~12" drivers, which gets back to the desired efficiency target. The MTM layout works well for small drivers like the 5.5" drivers in the Ariel, but I have not been pleased with the sound of large MTM systems - however, that's a purely subjective opinion. You may like them just fine.

At one time, I was considering the layout used in the Altec monitoring loudspeaker, with twin 12" bass drivers side-by-side and below the horn. I think with the drivers directly next to each other (which they certainly won't be in a MTM system), the midbass will be fuller and more satisfying. For that matter, if I go ahead with twin 15" drivers, I most certainly will use a side-by-side layout with the free-space horn above.

Last edited by Lynn Olson; 8th October 2012 at 07:40 AM.
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Old 8th October 2012, 07:46 AM   #8220
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