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 Post subject: Dipole or Closed Box?
PostPosted: May 28th, 2022, 12:05 pm 
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I have a B&C 10MBX64 10 inch driver (data sheet attached). I plan to use it in the 100 Hz to 600 Hz band (mid bass driver). It's resonant frequency is 65 Hz. The system will use a four way dsp crossover. Opinions as to whether I should use it in a closed box or as a dipole radiator? The mid range is a horn and tweeter is a horn loaded air-motion radiator.


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PostPosted: May 28th, 2022, 1:01 pm 
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Dipole bass can be very effective below the Schroeder frequency which is somewhere between 100 to 200 Hz in most rooms. Since you are going to use it above 100 Hz there is not much benefit to a dipole configuration. Also, more importantly, the horn midrange and horn loaded tweeter are not dipoles and there will be a mismatch in radiation patterns if you use a dipole bass. Radiation pattern mismatches are especially damaging around the crossover points.

Tom


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PostPosted: May 28th, 2022, 1:12 pm 
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brombo wrote:
I have a B&C 10MBX64 10 inch driver (data sheet attached). I plan to use it in the 100 Hz to 600 Hz band (mid bass driver). It's resonant frequency is 65 Hz. The system will use a four way dsp crossover. Opinions as to whether I should use it in a closed box or as a dipole radiator? The mid range is a horn and tweeter is a horn loaded air-motion radiator.

To add to Tom's comments -- if you wish to use the woofer down to it's free-air resonance of 65-Hz. you need a large enclosure to serve as an infinite baffle. Additionally, the horn and AMT should be time aligned with the woofer. If you can tolarate a hard edgy sound then by all means use an electronic crossover -- otherwise go passive with the best possible parts your wallet will support.

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PostPosted: May 28th, 2022, 6:30 pm 
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baffle.jpg
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Speaker baffle construction so far. Per your comments I will build a box for the mid-bass driver I can bolt on to the back of the baffle sealing with a gasket. With regard to crossovers, in all my diy speaker systems the crossovers have all been electronic or dsp. In the early 70's my system had a home made electronic crossover using 741 op-amps. The power amplifiers were all Southwest Technical Product Kits. In this system I will use Ice power amps, Camilla dsp software, and a Essence STX II 7.1 sound card. Too bad the Essence STX II 7.1 sound card have become as rare as hen's teeth. I would like to get another one.


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PostPosted: May 28th, 2022, 10:07 pm 
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brombo wrote:
Attachment:
baffle.jpg


Speaker baffle construction so far. Per your comments I will build a box for the mid-bass driver I can bolt on to the back of the baffle sealing with a gasket. With regard to crossovers, in all my diy speaker systems the crossovers have all been electronic or dsp. In the early 70's my system had a home made electronic crossover using 741 op-amps. The power amplifiers were all Southwest Technical Product Kits. In this system I will use Ice power amps, Camilla dsp software, and a Essence STX II 7.1 sound card. Too bad the Essence STX II 7.1 sound card have become as rare as hen's teeth. I would like to get another one.

Horns + Solid-state electronics = PAIN! The more SS electronics in the signal path plus the extra interconnects (interconnects is another pain-in-the ass much less a pain in the ears with the wrong choices) the worst it gets.

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PostPosted: May 28th, 2022, 10:37 pm 
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The 70's system I mentioned had Altec 511B horns with 808A drivers, 3000H tweeters, and 411B woofers, and all solid state amps. The tweeter amp was a class A headphone amp from SWTP. Roscoe now has all the horns and drivers (mid-range and tweeter).


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