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B&K sound Jubilee crossover ?'s


juniper

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I picked up a pair of Bob's crossovers after reading about how some preferred the passive method to the active method. The crossovers are described as having a bass boost, is this part of all of the passive crossover designs? or something Bob put together? I have a dx38 but haven't hooked it up yet. Has anyone compared this crossover to the dx38? or a similar crossover to the dx38? Thanks any info would be great!

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Roy did develop a bass boost circuit but it does not seem practical to build to me because it uses larger inductors than I have been able to find.  Interestingly the zobel incorporated in the design that Roy did seems to lift the LF a bit when doing acoustic testing on the crossover on a Jubilee bass bin.  May not be formally called a bass boost, but does seem to enhance the bass.

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On 3/20/2015 at 11:11 AM, BEC said:

Roy did develop a bass boost circuit but it does not seem practical to build to me because it uses larger inductors than I have been able to find.  Interestingly the zobel incorporated in the design that Roy did seems to lift the LF a bit when doing acoustic testing on the crossover on a Jubilee bass bin.  May not be formally called a bass boost, but does seem to enhance the bass.

 

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Roy's bass boost circuit calls for a 75mH inductor with DCR less than 0.6 ohms, and 1500uF of mylar caps.  That would give 3.5db of bass boost at 30hz.  The UT people do think such a thing could be built, but lots of money and probably delivered on a pallet.  Impedance of the Jub would go to about 3 ohms.  Another alternative is done with only 50mH at less than 0.6 ohms.  Only slightly more practical but that would put impedance down to 2.25 ohms.

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I used to build a 30.6hz  passive EQ for the Klipschorn that went ahead of the amplifier, used a 10H torroid inductor with a 2.7µF cap in a small plastic box. With a pot in parallel the Q may be adjusted over a wide range, at 2.7Ω the Q=1.4 (3dB of boost), at 4KΩ the Q=2 (6dB of boost), at 5KΩ the Q=2.6 (8.3dB of boost).

 

It should be pointed out that you can change the input coupling cap on your amplifier and add a grid-leak choke (instead of the grid-leak resistor).

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Thanks for all the info gentlemen!!! I Cant wait to hear these things.... I have had some clone bins in the garage for awhile sitting on the pallet they were shipped on.. I finally pulled them into the house yesterday, I cant get over the scale.... These are large, imposing and heavy. I like how they have an industrial almost machine age look to them. It took myself and a very large friend to carry them in.. He's about 6'7" and it was still a bit of  a struggle. This pair weights about 250lbs each. I always liked large speakers but these are almost ridiculous! Thanks again!!!!

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Roy's bass boost circuit calls for a 75mH inductor with DCR less than 0.6 ohms, and 1500uF of mylar caps.  That would give 3.5db of bass boost at 30hz.  The UT people do think such a thing could be built, but lots of money and probably delivered on a pallet.  Impedance of the Jub would go to about 3 ohms.  Another alternative is done with only 50mH at less than 0.6 ohms.  Only slightly more practical but that would put impedance down to 2.25 ohms.

 

LOL

 

Thanks for reminding me.

 

I'm going to be working on a custom line level crossover soon. Should be a fun experiment.

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I picked up a pair of Bob's crossovers after reading about how some preferred the passive method to the active method. The crossovers are described as having a bass boost, is this part of all of the passive crossover designs? or something Bob put together? I have a dx38 but haven't hooked it up yet. Has anyone compared this crossover to the dx38? or a similar crossover to the dx38? Thanks any info would be great!

 

I have listened to both passive (Roy's designs) and active (EV DX38, EV DC-One and Yamaha SP2060). My preference is the active system for several reasons but I honestly could be happy with any of them.

 

One of the most important things I would mention to anyone using an active crossover and not using the same amplifiers for all channels but instead using amplifiers of different gain/sensitivity for the system's channels is that it is essential that a proper gain balance be achieved between channels.

 

 

Have Fun,

miketn :)

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I must agree about the weight. What makes them difficult for me to move is the shape, a bit cumbersome. Getting them up stairs and thru doors is a pain but well worth the effort. I have also used passive and active. To my ears I like the passives.

 

Big D

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Regarding the bass 'boost'.....

I thought you could only cut signal with a passive and not 'boost' it?

??

With caps, inductors and resistors you can make a signal do just about anything...

 

 

 A digital processor with proper FIR filters can literally do anything you want. :D

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