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Crossover confusion

Hi All, 
  While I'm not a technical expert with stereo electronics and software, I do understand a lot of it. My problem is clipping on my woofers when playing the Stereophile test CD track 31 (20Hz 1/3 octave at -20db ). 
It would probably be best that I list my equipment from source to sound.
1.) Cambridge CXC transport
2.) Nad M51 DAC ( via fiber optic)
3.) Audio Research LS3B preamp ( all other interconnects are Kimber PBJ's ) 
4.) Bryston 10B Hi Lo crossover. ( Settings are 80 Hz for the low pass. 70 Hz for the high pass. High pass db is 0.)
5.) Low pass frequencies go to a pair of Audio Fathom F-113's which are active subwoofers
6.) Hi pass frequencies go to a Krell FPB 300 power amp
7.) Kimber T12 cables connect to PNB B741 speakers ( with two additional midranges) that have been fitted into a 
    pair of Dunlavy SC-IV's. The cables are Bi-wire that are common at the amp. The smaller conductors feed the midranges and tweeter. The larger conductors feed the woofers.
  My thoughts are that none of this 20Hz signal should  even be going to the Krell amp.  While I haven't heard any clipping when listening to music I am concerned. I was researching passive crossovers and came across Marchand Electronic's website. They make both active and passive crossover's. One of the diagrams show a hybrid setup that uses an active crossover with the hi pass going directly to the midranges and tweeter and the lo pass going to a passive crossover and then to the woofer. Before talking to Marchand Electronics I thought it would be a good idea to come here first since I've gotten a lot or good info here. If I have to use a hybrid setup, it would also be useful to know what the crossover Hz should be. The PNB B741 woofers bottom out at 25 Hz. Hope this is enough info for those that can help.
  Thanks to all concerned

















 
evelyn1
evelyn1 OP
55 posts
 
Me again,
  Screwed that part about the Marchand diagram. It actually showed the woofers getting a signal directly from the active crossover and the midrange and tweeter having a passive crossover between the active crossover and them. For me the low pass would be for the sub's and the hi pass for the rest. 
swampwalker's avatar
swampwalker
5,138 posts
 
Are you saying that the "clipping" (not sure if that is the right term) is heard on the JLs or the PBNs?
evelyn1 OP
55 posts
 
Hi,
  On the PBN's. I thought clipping was the correct term but it was a clicking sound coming from  what I thought were the woofers on the PBNs. I don't want to run the test CD again for fear of permanent damage. That was the lowest frequency on the test CD and all the other frequencies were ok. I don't think that the PBN crossover for the associated woofers have a shunt for frequencies lower than it can handle.
Please correct me if I'm wrong about the term clipping. I make an effort  to correct my ignorance. It could possibly be that my Bryston crossover isn't functioning properly. I don't have the test equipment to check it out. Having it tested and repaired if needed would have been my next step. I was thinking about just going with a passive crossover to separate the subwoofers from the PBNs. The Marchand Electronics passive crossovers only have a left and right channel in and a left and right channel out. That would serve to eliminate lower frequencies to the Krell amp. So I'm wondering why Marchand's passive crossover only has a single pair in and single out and why their hybrid schematic needs a passive and active crossover. Thanks for your reply.
erik_squires
16,407 posts
 
Crossovers are not absolute brick wall devices. they have a roll-off or slope, expressed in db/Octave. A 12dB/octave at 80 Hz would be down 12 dB at 40Hz , and 24 dB at 20 Hz.
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