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Thread: Stargate Aurora Reference System

  1. #1
    Mike Bates
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    Stargate Aurora Reference System

    Almost all JBL drivers--

    This is a five-way fully horn loaded system.

    My Webpage

    For the deep bass it used three eighteen inch woofers (2 EVX180 and the center has a JBL 2242H) loaded in three seperate MGA subhorns. They have powerful low distortion response well below 20 cycles and are operating in mono below 35 cycles. The subs are behind the screen and take up the front wall.

    The bass is handled by the two side wall placed bass horns. Each horn is loaded with two JBL 2220 Alnico 15" woofers operated in dipole isobaric (the back of the rear woofer is open to the room) for ultra low distortion and realistic impact. They cover the 35 to 160 cycle range.

    The midrange horns are modified Sierra Brooks tractrix horns loaded with a JBL 2123J 10" drivers that has been specially treated. The back chamber is tuned with a tiny one liter enclosure for the best sound/response. These horns cover from 160 cycles to 1000 cycles. These are the soul of the system reproducing most fundementals. Sensitivity is 107 db with a watt.

    The upper range horns Sierra Brooks tractrix horns loaded with JBL 2440 compression drivers. Thir range is 1000 cycles to 8000 cycles. Very refined and sweet sounding!

    The ultra high treble is covered with a pair of fully charged JBL 2405 Alnico slot tweeters. They blend in just perfect with the rest.

    Overall I find this system to be as close to perfect I have heard. it is triamped with an amp for the subs, another for the bass, and another for the 160 cycle up range. All the horns are alligned within 1/4 wavelength at the crossover frequency and require no sound degrading digital crossover. It REALLY gets the midrange right and has damn near heart stopping dynamics.


  2. #2
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    Re: Stargate Aurora Reference System

    Very impressive!

  3. #3
    Senior Member JuniorJBL's Avatar
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    Talking Looks like fun!!

    That must be fun to play with!!
    Great job!!
    Shane

  4. #4
    TimG
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    So I see you have switched away from the BMS compression driver that you were previously using. Have you tried the BMS 4590 in your current configuration? Also do you have any system response measurements you could share? How are you dealing with the time delay in the horn subwoofer transition? I have a design for a horn midbass that will cover 40-250 using a JBL 2226H, but I have never had time to build it. I was waiting until I could afford a crossover that incorporated digital time delay before attempting a full horn system.

  5. #5
    Mike Bates
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    Originally posted by TimG
    So I see you have switched away from the BMS compression driver that you were previously using. Have you tried the BMS 4590 in your current configuration? Also do you have any system response measurements you could share? How are you dealing with the time delay in the horn subwoofer transition? I have a design for a horn midbass that will cover 40-250 using a JBL 2226H, but I have never had time to build it. I was waiting until I could afford a crossover that incorporated digital time delay before attempting a full horn system.
    I had the 4591 never had the coax 4590 but did have the little 1" neo driver here to try as a tweeter.

    In room response at my listening couch is +- 3 db 10 Hz to 15K smoothed to 1/20th octave using LMS. I can send you a file if you wish. Move the microphone a foot and it looks quite different -- unless you go to 1/10 octave or higher..

    I crossover at 35 cycles between the bass and subs 3rd order with a variable phase control. These horns are within 1/4 wavelength at the crossover frequency and the others are with 1/8th. I did this so I didn't have to use a sound degrading digital crossover. Never tried the BSS that is supposed to be OK but why bother if you can build a system without it?

    Last edited by Mike Bates; 04-05-2004 at 10:56 PM.

  6. #6
    Mike Bates
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    Re: Looks like fun!!

    Originally posted by JuniorJBL
    That must be fun to play with!!
    Great job!!
    Shane
    Thanks , it's FUN but it can be lethal in the wrong hands.

  7. #7
    Mike Bates
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    Re: Re: Stargate Aurora Reference System

    Originally posted by Giskard
    Very impressive!
    Thanks you.

  8. #8
    Super Moderator Hofmannhp's Avatar
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    BMS

    Originally posted by Mike Bates
    I had the 4591 never had the coax 4590 but did have the little 1" neo driver here to try as a tweeter.

    Hi Mike,

    I'm courious about your experiances with the BMS driver and the tweeter (4540ND ??)
    What's about a comparision to the JBLs.

    HP

    Last week I heard a big horn system with the BMS coax driver 4594ND . This driver has a frequ. resp. like a line. It sounds great.....but I think my 2441 is ready to compete.
    Hope to place some pics of the horn I heard....

    HP
    Please help us save more info about the vintage systems. Let us register your speakers and drivers.

  9. #9
    jandregg
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    Sounds like it sounds wonderful. Is the special treatment of the 2123 something you did yourself? And can you elaborate?

    John

  10. #10
    Senior Seņor boputnam's Avatar
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    Stargate Aurora Reference System

    Hey, Mike...

    That is beauty! Quite an intriguing design, and assemblage.

    Tell me more about the pre-amps, mains and are you using any EQ at all?
    bo

    "Indeed, not!!"

  11. #11
    Mike Bates
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    Re: BMS

    The JBL 2440 sounds better than the BMS 4591 in all ways to me when used above 500 cycles. The BMS loads a little better below that in big horns otherwise no contest. I also prefer the 2440 to 2441. The smaller BMS driver would be OK for a small two way or as a HF tweeter although it does roll off more than the BMS graphs indicate. The 2405's win here again, more extended and linear above 10K.

    Not bad for 30 + year old technology!!


    Originally posted by Hofmannhp
    Hi Mike,

    I'm courious about your experiances with the BMS driver and the tweeter (4540ND ??)
    What's about a comparision to the JBLs.

    HP

    Last week I heard a big horn system with the BMS coax driver 4594ND . This driver has a frequ. resp. like a line. It sounds great.....but I think my 2441 is ready to compete.
    Hope to place some pics of the horn I heard....

    HP

  12. #12
    Mike Bates
    Guest

    Re: Stargate Aurora Reference System

    Originally posted by boputnam
    Hey, Mike...

    That is beauty! Quite an intriguing design, and assemblage.

    Tell me more about the pre-amps, mains and are you using any EQ at all?
    Hello, I use a simple transformer volume control preamp (TVC) made by Antique Sound Labs. It's dual mono and has lots of inputs and two line outputs. With it matching in and out impedence as well as output levels is critical. It's purely passive and sounds excellent. I use a seperate phono preamp with high gain 6922's for my moving coil cartridge. For the satellites I use a line level passive 2nd order network built into the front end of Audio Mirror 40 watt 6C33C SET mono amps. (have some other amps but these are the best) The bass horns are fed by a Crown PSA2 with a 4th order low pass Marchand electronic crossover XM1 module (kit), the Subhorns are driven With another PSA2 through a Paradigm X30 electronic crossover with a 3rd order lowpass set at 35 cycles.

    No eq needed. I have both a digital eq and a pair of White parametrics but don't need them. The attenuators on the Crown amps allow me to countour the sound and match levels with the satellites/tube amps. It's all pretty simple considering it'a a triamped 5 way.

  13. #13
    Mike Bates
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    Originally posted by jandregg
    Sounds like it sounds wonderful. Is the special treatment of the 2123 something you did yourself? And can you elaborate?

    John
    They have 3 coatings of violin varnish on them and the entire frames and magnets have a thick coating og Mortite rope caulk.

  14. #14
    Senior Seņor boputnam's Avatar
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    Re: Re: Stargate Aurora Reference System

    Originally posted by Mike Bates
    It's all pretty simple considering it'a a triamped 5 way.
    Ha! That, is what I expected. With that degree of parsing of the signal, and your detailed crossovers, you have great control, indeed...

    Since you're not making good use of that crummy old obsolete (credits to John Nebel... ) White, let me know any tracking info when you ship it out this way!
    bo

    "Indeed, not!!"

  15. #15
    Mike Bates
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    Re: Re: Re: Stargate Aurora Reference System

    Originally posted by boputnam

    Since you're not making good use of that crummy old obsolete (credits to John Nebel... ) White, let me know any tracking info when you ship it out this way!
    http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3092166076

    They're up for auction!


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