Members Bro' FF Posted May 6, 2004 Members Share Posted May 6, 2004 Hi, I need your advice please... I have a pair of JBL SR4722x mains and SR4718x subs. I picked up a Behringer (I know) crossover which has a number of different controls on it. I have the crossover frequency set slightly above 100Hz. I am not really sure whether I am maximizing the system's potential here or not. I have a Crest CA9 powering the mains and a QSC RMX 1450 driving the subs. I had these reversed, but was not happy with the mains sound using the QSC. The sound quality has improved greatly simply by switching the amps. That being said, what is the "normal" frequency at which the sub signal is seperated? Also, there is a "low frequency delay" control for each channel. Should there be some delay on the subs, and if so, why? I have not played with those controls at all as of yet... I want the tone full and hard-hitting, but not "fast and furious" boomy. Thanks in advance for your help. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted May 6, 2004 Members Share Posted May 6, 2004 Originally posted by Bro' FF Hi, I need your advice please... I have a pair of JBL SR4722x mains and SR4718x subs. I picked up a Behringer (I know) crossover which has a number of different controls on it. I have the crossover frequency set slightly above 100Hz. I am not really sure whether I am maximizing the system's potential here or not. I have a Crest CA9 powering the mains and a QSC RMX 1450 driving the subs. I had these reversed, but was not happy with the mains sound using the QSC. The sound quality has improved greatly simply by switching the amps. That being said, what is the "normal" frequency at which the sub signal is seperated?Also, there is a "low frequency delay" control for each channel. Should there be some delay on the subs, and if so, why? I have not played with those controls at all as of yet...I want the tone full and hard-hitting, but not "fast and furious" boomy. Thanks in advance for your help. I cross over at about 90 hz,but I use e-horn subs. Use your ears but 90-100 hz is probably a good spot. What is the rolloff on that crossover? As for time delay,I don't think you want any if you're running a fairly normal stacked setup on your speakers. As for boomy bass,maybe you aren't operating your EQ correctly? A majority of boomy bass,from my experience,is caused by hot frequencies usually in the 90-140 hz range. Link to comment Share on other sites More sharing options...
Members Dookietwo Posted May 6, 2004 Members Share Posted May 6, 2004 Also, there is a "low frequency delay" control for each channel. Should there be some delay on the subs, and if so, why? I have not played with those controls at all as of yet... HelloThe low frequency delay is to time align the Subs to the Mids at the crossover point. The people who built your crossover had no idea what it may be used for. If you had Horn loaded midranges then the voice coils in the mids would be back more than the sub voice coils. Because both sub and mid are reproducing the same freq at the crossover point they would be out of alignment and cause cancelations and lobing. With the group delay in sub crossovers it is not uncommon for the subs to be back farther than the mids even though the drivers themselves seem to be the same distance front to back. You might want to check with the people who built your speakers.They may have settings for your sub to mid delay. Kindest Dookietwo Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted May 6, 2004 CMS Author Share Posted May 6, 2004 JBL recommends the 4718 be crossed between 80-100 Hz. Paired with the 4722's 12" driver you'll be good at somewhere closer to the upper end of that...95 to 100 Hz. This depends on your source material and room acoustics, so be prepared to adjust slightly in each venue. As both cabinets are front-loaded you may not need very much, if any, delay. Link to comment Share on other sites More sharing options...
Members Bro' FF Posted May 7, 2004 Author Members Share Posted May 7, 2004 Thank you all for your input. I will play around a bit with both the crossover freq and the delay and try to find what sounds best. I just wanted to make sure I was not "wasting my time" hovering around that frequency. I figured the crossover would occur somewhere in the same fequency vicinity as the low pass filter is shelved. I am unsure what the rolloff is, but I think it is around 12db/octave, if I recall correctly. Does that sound about right? I just got done jamming and singing a couple of tunes to CD through the PA at some fairly satisfying volume levels. To my ears, it sounds great. I think I could tighten up the bass just a bit, but it is full and balanced, and does not seem to be lacking in any area. Very pleased. Now to upgrade from the Mackie 1604 VLZ Pro to the Soundcraft Ghost console... Link to comment Share on other sites More sharing options...
Members tlbonehead Posted May 7, 2004 Members Share Posted May 7, 2004 Originally posted by Bro' FF I am unsure what the rolloff is, but I think it is around 12db/octave, if I recall correctly. Does that sound about right?I'm guessing it is 18 or 24. Link to comment Share on other sites More sharing options...
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