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Multi-Way Conventional loudspeakers with crossovers

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Old 21st March 2013, 02:33 AM   #8451
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I guess I just don't think about tube amps anymore but that would make sense. At a 100db output I wouldn't think the distortion should be enough to warrant a second 15" driver but if that is something you want to worry about,,,,,,,
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Old 21st March 2013, 03:50 AM   #8452
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There are three versions of the speaker that I've considered (in the last couple of years): single 15" driver, two 15" drivers, or single driver with front-horn loading. The gotcha with the horn-loaded version is that horns that go down to 60 Hz are BIG ... and even bigger if you want the horn not to have any folds in it. (Folds make it very difficult to reach the 700 Hz crossover of the AH425 horn - and if the horn goes lower, say 500 Hz, it has to be bigger as well.)

So it's a question of dynamics: is 15" enough, or am I willing to live with a cabinet twice as big? I'm hoping to build my own prototype this year, so I'll find out.

I've listened to the first prototypes built in Dallas, and the dynamics from the Radian 745Neo & Azurahorn are stupendous. The direct-radiator 416 was impressive too, but not quite in the same league as the horn system. Plenty of old-school studio monitors have been built with twin 15" drivers, so that's definitely a consideration.

I've been down this single versus twin-driver road before, with the Ariel. I'd heard a predecessor that was built with a single 5.5" Vifa midbass, and it just didn't have enough dynamic range. Pretty-sounding, smooth and attractive, but very petite in character. The improvement going to twin drivers was really substantial, taking the speaker from the minimonitor category to a decent full-range speaker, and efficient enough to be used with moderate-power triode amplifiers (which was a design goal).

There's a reasonable possibility, based on the difference I heard with the Ariel, that the 6 dB jump in headroom would transform the speaker from a pretty good 15" direct-radiator to a system that is more comparable to a all-horn system ... but without the size and issues with horn-folding.

Last edited by Lynn Olson; 21st March 2013 at 03:59 AM.
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Old 21st March 2013, 05:44 AM   #8453
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Another option would be the use of a short straight horn, similar to Dr. Edgar's 80Hz straight or Volvotreter's 70Hz conical. Since this type horn will only load down to the mid-bass frequencies, anything bellow will need to be augmented by sub(s). This could have the possible advantage of locating the subs at their optimum positions which most of the time is different from that which is optimum for the mains.

http://www.volvotreter.de/pics/conic...n_setup_14.jpg

The GPA 515-16G would be a shoe-in for such a horn.

Last edited by musical noise; 21st March 2013 at 06:09 AM.
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Old 21st March 2013, 06:03 AM   #8454
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The gotcha with the horn-loaded version is that horns that go down to 60 Hz are BIG ... and even bigger if you want the horn not to have any folds in it. (Folds make it very difficult to reach the 700 Hz crossover of the AH425 horn - and if the horn goes lower, say 500 Hz, it has to be bigger as well.)
Yes, just what I found. I made 160Hz Le Cleac'h horns for LM555 drivers crossed over at about 300hz and this works just great with my Vitavox K15/40 bass horns. (and can even get somthing close to time alignmernt with them hanging over the back). A pair of Onkens with TD15M drivers came up and have been setting these up for my son with 420 horns / JA6188B drivers . This seems a much more natural combination. Hard to imagine one could possibly want 2 x 15" drivers per side - already awesome in the bass compared to the bass horns. Why bother with bass horns at all? Just that what bass there is comes from nowhere - it makes music.

Click the image to open in full size.

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Old 21st March 2013, 06:07 AM   #8455
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Forgot to add, that by horn loading the mid-bass driver it will definitely match the dynamics of the compression driver/Azura horn combo and it will also raise the sensitivity of the speaker to the 104-5 dB/w level. This might have the side benefit of simplifying the crossover high-pass for the RAAL tweeter. I am basing this (and I could be wrong) on the rising response of this ribbon, that happens to put it at around 104dB at 7KHz which if I remember correctly is the crossover point.
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Old 22nd March 2013, 05:00 AM   #8456
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Originally Posted by Truetone View Post
Yes, just what I found. I made 160Hz Le Cleac'h horns for LM555 drivers crossed over at about 300hz and this works just great with my Vitavox K15/40 bass horns. (and can even get somthing close to time alignmernt with them hanging over the back). A pair of Onkens with TD15M drivers came up and have been setting these up for my son with 420 horns / JA6188B drivers . This seems a much more natural combination. Hard to imagine one could possibly want 2 x 15" drivers per side - already awesome in the bass compared to the bass horns. Why bother with bass horns at all? Just that what bass there is comes from nowhere - it makes music.

martin
Well, Martin, I take your comments very seriously, since you're the first person in the world to have heard the AH425! I didn't get to actually hear the AH425's until I heard the prototypes in Dallas, which was more than a year later.

I find your bass horn vs TD15M comment especially interesting. You've been listening to your bass horn setup for many years; subjectively, how does it compare to the single TD15M in the Onken cabinet? I can imagine integration with the AH425 might be better with the TD15M, since the direct-radiator effortlessly goes up to 700 Hz. Time-alignment is also a lot easier; just move the AH425 back and forth a few inches.

But I'm surprised to hear a single TD15M might be better in the bass range than a well-engineered bass horn; bass horns can have truly stupendous bass when done right. My main reservation about them is the sheer size; they won't fit into my living room, which kind of limits my interest.

P.S. I found that optimum time-alignment of the AH425, at least with the crossovers I was using, was with the outer edge of the AH425 about 1/2" in front of the front panel of the bass cabinet, and about 2" to 3" of vertical clearance between the lower edge of the horn and the top of the bass cabinet. The imaging was surprisingly sensitive to front-back alignment; 1/4" movements were easily audible, as well as measurable.

One of the great virtues of a free-standing horn is the ease and precision of time-alignment. Also really spacious sound with very deep images ... frankly, the best I've heard from a high-efficiency system. You probably heard that too.

Last edited by Lynn Olson; 22nd March 2013 at 05:10 AM.
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Old 22nd March 2013, 07:47 AM   #8457
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subjectively, how does it compare to the single TD15M in the Onken cabinet? ......

But I'm surprised to hear a single TD15M might be better in the bass range than a well-engineered bass horn; bass horns can have truly stupendous bass when done right.
The Onken cabinets came available when the guy who had them decided he wanted bass horns like mine (1/4 WL 50Hz T=60) for his GoTo system. We compared TD15M and also his GoTo SG38WN 15" drivers on the bass horns and in the Onken cabs. We both preferred the horns for natural presentation - the Onken cabs went deeper and had more power, but at the expense of some overhang. I had thought I would do him a swap (I wanted more bass and to follow along with this thread), but in the end I couldn't bring myself to let the horns go. The guy built himself some bass horns to my design, and I took the cabs for my son. Unfortunately not enough room to bring them here to play with the set up, and have not yet had the chance to do this at my son's place.

It's an interesting question if adding more direct radiator drivers to bring up the sensitivity to horn levels will emulate the bass horn control (that's a laugh - they measure dreadfully), while keeping the bandwidth advantage. And as you say, it is particularly the upward extension you need: you can get flat looking rta response with a 420 horn and 600Hz 12dB cross over - but subjectively I find the low mid range LM555 horn sounds a lot more richly satisfying. My friend with GoTo mid range drivers finds the same thing. Even Lowthers sound better (in low mids). Unfortunately bass horns just don't go high enough. Or low enough. But what they do do is very very good.

martin
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Old 22nd March 2013, 05:07 PM   #8458
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Originally Posted by Lynn Olson View Post
Well, Martin, I take your comments very seriously, since you're the first person in the world to have heard the AH425! I didn't get to actually hear the AH425's until I heard the prototypes in Dallas, which was more than a year later.

I find your bass horn vs TD15M comment especially interesting. You've been listening to your bass horn setup for many years; subjectively, how does it compare to the single TD15M in the Onken cabinet? I can imagine integration with the AH425 might be better with the TD15M, since the direct-radiator effortlessly goes up to 700 Hz. Time-alignment is also a lot easier; just move the AH425 back and forth a few inches.

But I'm surprised to hear a single TD15M might be better in the bass range than a well-engineered bass horn; bass horns can have truly stupendous bass when done right. My main reservation about them is the sheer size; they won't fit into my living room, which kind of limits my interest.

P.S. I found that optimum time-alignment of the AH425, at least with the crossovers I was using, was with the outer edge of the AH425 about 1/2" in front of the front panel of the bass cabinet, and about 2" to 3" of vertical clearance between the lower edge of the horn and the top of the bass cabinet. The imaging was surprisingly sensitive to front-back alignment; 1/4" movements were easily audible, as well as measurable.

One of the great virtues of a free-standing horn is the ease and precision of time-alignment. Also really spacious sound with very deep images ... frankly, the best I've heard from a high-efficiency system. You probably heard that too.
Richard Heyser used to say that one quarter inch of time alignment was critical.
It is good to see someone else confirming this.
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Old 22nd March 2013, 05:13 PM   #8459
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I just remembered that with a digital cross over (dbx driverack pa) the 420 horn actually worked very well with the bass horn, and I had it set up like this for a long time (mainly with a Lowther on a long 2.3m bass horn that also had good upward extension) - but when I abandoned multi amping, a simple 12dB best guess passive cross over and no time alignment really had problems. I guess a wideband mid range horn is a lot more fogiving and takes away the need to know what you are doing with cross over design.

martin
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Old 22nd March 2013, 05:15 PM   #8460
limono is offline limono  United States
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..Richard Heyser used to say that one quarter inch of time alignment was critical.
It is good to see someone else confirming this..

And Paul W. Klipsch said it was all bollocks ..
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