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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
ivan_nosnibor's avatar
ivan_nosnibor
1,047 posts
 
Yes, erik is quite right, they're not brickwall devices. At this point, I would venture to guess that you're now on the right track and that it's just a matter of experimenting and tracking down the right settings, on the digital side of things most likely. Hopefully no need for testing.

Good luck and let us know if the problem doesn't get worked out.

erik_squires
15,615 posts
 
For a high pass, I would suggest experimenting with the 12 or 18 dB/octave settings.

Correctly configuring a crossover is much easier with testing equipment. I use OmniMic, but Room EQ Wizard is free and has an active discussion group you can turn to for help.

Best,


Erik
evelyn1 OP
51 posts
 
Wow! That worked out great! Listening to the test CD again made realize that the 25Hz and31Hz signal were also having problems with dropout. They didn't click like the 20Hz signal but they weren't smooth like they are now. After warming up the equipment I went directly to the 12db setting and played the CD from the 1KHz tract on down. Thank you very much guys for solving my problem. I did a search on OmniMic and Room EQ Wizard and have decided that OmniMic might be the better choice for me. Parts Express is selling it for $298.00 and another bundled with DAT V2 speaker measurement for $348.00. I think I'll opt for the bundled version and let the real fun begin. You both have saved me the expense of testing my crossover and buying another crossover. I now can afford to buy the software and dial in everything correctly.
                Thanks again,
                                        Frank
erik_squires
15,615 posts
 
Not sure if you need DATS though. :) It is for impedance and Thiele-Small parameter measurements.

I have one, but I make my own loudspeakers. Otherwise only useful if you are hacking internal crossovers and want to measure parts precisely.

Best,


E
evelyn1 OP
51 posts
 
Thanks again Erik. You just me saved an additional $50.00. I'm sure I'll have questions in future about OmniMic.
                      Cheers,
                                F    
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