juniper Posted March 20, 2015 Share Posted March 20, 2015 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! Quote Link to comment Share on other sites More sharing options...
Deang Posted March 20, 2015 Share Posted March 20, 2015 The bass boost circuit was developed by Roy Delgado. Bob uses Roy's low pass design in conjunction with simple high pass, since he uses a driver that doesn't need much if anything in the way of correction. Quote Link to comment Share on other sites More sharing options...
BEC Posted March 20, 2015 Share Posted March 20, 2015 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. Quote Link to comment Share on other sites More sharing options...
OO1 Posted March 20, 2015 Share Posted March 20, 2015 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. Mr Crites - I am reading over your writing - were you able to find the larger inductors or not -thank you Quote Link to comment Share on other sites More sharing options...
seti Posted March 20, 2015 Share Posted March 20, 2015 I use Bob's passives and have tried DX38. I prefer the passives. Hey Bob what value inductor would that be and could it be added later?? Quote Link to comment Share on other sites More sharing options...
Deang Posted March 20, 2015 Share Posted March 20, 2015 Could run a pair in series to get the required inductance, but that kind of copper starts to get pretty expensive. Quote Link to comment Share on other sites More sharing options...
BEC Posted March 21, 2015 Share Posted March 21, 2015 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. Quote Link to comment Share on other sites More sharing options...
djk Posted March 21, 2015 Share Posted March 21, 2015 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). Quote Link to comment Share on other sites More sharing options...
juniper Posted March 21, 2015 Author Share Posted March 21, 2015 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!!!! Quote Link to comment Share on other sites More sharing options...
seti Posted March 21, 2015 Share Posted March 21, 2015 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. Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted March 21, 2015 Share Posted March 21, 2015 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 Quote Link to comment Share on other sites More sharing options...
Bigdnfay1 Posted March 21, 2015 Share Posted March 21, 2015 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 Quote Link to comment Share on other sites More sharing options...
Coytee Posted March 22, 2015 Share Posted March 22, 2015 Regarding the bass 'boost'..... I thought you could only cut signal with a passive and not 'boost' it? ?? Quote Link to comment Share on other sites More sharing options...
djk Posted March 22, 2015 Share Posted March 22, 2015 "I thought you could only cut signal with a passive and not 'boost' it?" The input impedance drops at the boost frequency (no such thing as a free lunch). Quote Link to comment Share on other sites More sharing options...
seti Posted March 22, 2015 Share Posted March 22, 2015 "I thought you could only cut signal with a passive and not 'boost' it?" The input impedance drops at the boost frequency (no such thing as a free lunch). Comprende. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 23, 2015 Share Posted March 23, 2015 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... Quote Link to comment Share on other sites More sharing options...
Don Richard Posted March 23, 2015 Share Posted March 23, 2015 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. Quote Link to comment Share on other sites More sharing options...
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