Altec 902 / Edgarhorns: compensation experiments [message #17671] |
Thu, 24 March 2005 17:13 ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Floyd Andrews
Messages: 31 Registered: May 2009
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Baron |
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I've just gotten a pair of Edgarhorn 650 hz round horns to use with Altec 902 drivers. These have replaced a pair of JBL 2345 horns with Selenium 205 1" drivers. The new setup sounds fabulous; I couldn't be more pleased. After waiting about a week to get used to the new gear, I started playing with compensation components. My system has an active crossover, so the 902's are driven directly from a small tube amp. I wasn't sure that I even needed more high end, but I wanted to try it out. 50 ohms in parallel with .47 mfd was way too hot. So was 25 ohms and .47 mfd. Right now I'm using 8 ohms and .47, but I think that this still may be too much. Does anyone out there have any experience with this driver/horn combination? What is the effect if I go to a smaller capacitor, say .33 or .22? All suggestions appreciated. thanks.
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Re: Series and Shunt Resistance [message #17681 is a reply to message #17675] |
Sun, 27 March 2005 11:07 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
spkrman57
Messages: 522 Registered: May 2009
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Illuminati (1st Degree) |
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I would use the 14 ohm shunt with a 30 ohm series(paralleled with .33 ufd) like the 4 pi crossover. By the way, I am getting ready to try a comparison between the JBL 2426 and the Altec 902 on the 650hz round tractix(Edgar) and the 650hz wooden tractix(Martinelli). Two different drivers and 2 different horns to mix and match and see which I like best. By the way, I still prefer passive crossover on my JBL/Altec systems. Makes life easier. Ron
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Uniform DI verses Collapsing DI [message #17682 is a reply to message #17681] |
Sun, 27 March 2005 15:34 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18756 Registered: January 2001
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Illuminati (33rd Degree) |
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I would suggest that you compare a system with uniform or matched directionality to another with axisymmetric horns having collapsing DI. More specifically, you would be comparing a loudspeaker system that uses tractrix round horns with another that uses 90x40 horns. That involves using matched mids and bass systems and, in the case of the uniform DI speaker, you'll also want a crossover that minimizes comb filtering between adjacent subsystems. In my opinion, the type of system you are making determines the horn you should use.It's not just a matter of comparing one particular horn with another, that's kind of like comparing a car's tires without discussing suspension. Unless they are of the same general type, a comparison isn't really appropriate. Some things can be quantified but overall performance cannot. Some tires are more suited for one kind of vehicle or another, like tall, bouncy slicks for a drag car or short, rigid tires for a road race. Both are designed to maximize traction, but one is optimized for straight-line launch and the other for lateral hold. Either way, the tuner has to optimize properly or the car isn't setup right. Put a drag slick on an indy car and you can out-corner it in a mini-cooper. Put a Formula I tire on a top fueler and you'll melt it to the rim without even leaving the lights. So the long story short is that I don't think it is going to really work comparing an individual round horn to a 90x40. The system optimizations are different. One is optimized when power response is uniform, the other when on-axis response is uniform. A nice experiment might be to compare a loudspeaker system with all round horns to another with all 90x40 radial horns. If you like the tractrix curve, you could use round tractrix horns for one system and for the other, use radial horns having a tractrix expansion in the vertical plane and uniform 90° in the horizontal plane. But whatever the flare profile, I suggest the 90x40 horn be used in a system that has a DI matched midwoofer or a cornerhorn that uses all 90° flares. I'd use the round horn in a system that has all axisymmetric horns. Then you can compare systems, because I think that makes a lot more sense.
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Wish i understood everthing you said... [message #17691 is a reply to message #17682] |
Tue, 29 March 2005 12:32 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to previous message](/forum/theme/AudioRoundTable/images/down.png) |
spkrman57
Messages: 522 Registered: May 2009
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Illuminati (1st Degree) |
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Wayne, The "DI" factor loses me. I know I just tried out my 1st JBL compression driver(2426J). I used the 4 Pi-pro figures(15 ohm shunt and 33 ohm series/.33 ufd cap). I also used .68 ufd bypass caps on the PE 1.6 khz hi-pass crossover. So far I think the caps are still new and not smoothed out(less than 2 hrs time on them). I find the JBL to be rather bright in the upper midrange/lower treble area used on the Martinelli horn. I know that the 2426J is a 16 ohm driver, but I have used Altec 8 ohm and 16 ohm drivers without changing up the crossover with little difference of sound. I think the JBL with titanium diaphram is more brittle sounding than the aluminum of the Altec drivers I have used. I set up the crossover this time with easy "connect/disconnect" terminals to swap out the horns quickly. I have my Altec 902B on my 650hz Edgar horn and will be trying it out tonight. I think the JBL needs less HF compensation than the Altec 1" drivers. Ron
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