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How to tune a crossover please?

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  • #16
    That link is indeed a very detailed account [thanks] but in all honesty a little too technical for me to grasp all of its concepts, right now at least. So would one be able to set separate slopes on a digital crossover for high pass and low pass or only one slope setting allowed?


    • #17
      With most digital processors you can set all parameters differently for each filter if you want, but they also allow settings to be mirrored to a second channel if you are doing a stereo setup for example.

      Steeper filters offer more protection but also add more phase shift.. that is the catch with all of this, and phase shift is difficult to deal with as it tends to not behave linearly... it varies with frequency. Digital processors often can adjust for phase shift at the crossover frequency but that doesn't fix the problem everywhere so often a compromise is made and we use a medium filter slope like 4th order(24db/oct) to get good out of band rejection without too much phase shift. An added benefit is that even order filters sum flat and a generally flat response is the target anyway.
      Paul O


      • #18
        Ok so from what I have learned so far it appears that a Digital crossover has advantages over an analog, I will get to this in a a few. Meantime, if I wanted to hear specific instruments highlighted "in a horn" in particular, like violin, hi pitched cymbal or wind chimes, how might I go about getting those results please?


        • #19
          To highlight certain items in a recording is difficult, if the recording engineer wanted that instrument to be prominent at that time he would have raised the instruments level in the recording. The best you can do with a finished recording is boost the frequency range of the instrument with a parametric EQ, but if there are other instruments or sounds in the same range they will get boosted too so it doesn't work quite as well.
          Paul O


          • #20
            FWIW most of the pros who regularly post on my forum use 48dB slope if their crossovers allow it. They can do so because a good DSP employs linear phase filters that eliminate phase shift issues.


            • #21
              Thanks guys. Next, I have asked a few people who have used both digital and Analog crossovers and I had asked specifically about the Driverack 260 and a BSS FDS388 and was told the DBX does not even come close to the BSS, that one will get better quality sound with the bss or the more expensive crossovers like Lake, RCF e.t.c.

              Thing is, I have heard one bass tuned with both a BSS FDS388 and an Ashly XR1001 and I could not tell the different between the two so I don't know about the higher end digital crossovers giving better quality sound, what's the opinions of both situations above for you guys here please?

              I gad also asked a DBX Tech the question of the DBX 260 vs the BSS 388 and these were his words

              "Most people running the DriveRack 260 are pretty impressed with the quality. I have not heard one complaint. I’ve never really done a shootout between those two models, I mean some people swear by the old BSS Signal Processing equipment and of course it has some benefits like the multiband compressor for example we discussed earlier.

              I guess what you get with the 260 is that it is a still serviceable product that is in production still, that is another benefit. At it does, loudspeaker management, you can’t really go wrong tbh.


              • #22
                I've never seen a complaint from a Drive Rack 260 owner, nor PA2 for that matter.


                • #23
                  Originally posted by frustrated View Post
                  Next, I have asked a few people who have used both digital and Analog crossovers and I had asked specifically about the Driverack 260 and a BSS FDS388 and was told the DBX does not even come close to the BSS, that one will get better quality sound with the bss or the more expensive crossovers like Lake, RCF e.t.c.
                  Compared to the speakers in use the electronics and processing is tens of thousands of times less significant in determining overall sound quality. A very high spec fullrange audio system can be very revealing of subtle details which can then lead to subtle but noticable differences in gear with critical listening, but claims of "massive" differences in electronics is overblown IMO.

                  Originally posted by frustrated View Post
                  Thing is, I have heard one bass tuned with both a BSS FDS388 and an Ashly XR1001 and I could not tell the different between the two
                  A bass as in a bass guitar? If so you're not going to hear much if any difference at low frequencies, all the detail is in the mid and high frequencies.

                  The DR260 is generally accepted as a very good piece of gear with good flexibility and sound quality, the DRPA boxes on the other hand are not as well liked, they have limited routing options and many users report poorer sound quality. The Behringer DCX is generally considered to be superior to the DRPA in SQ and it has the same routing flexibility as the DR260... all at a fraction of the price.

                  But all that said, if you're just starting out with PA systems any of these processors including the DRPA would be a great option, as I mentioned above the speakers are going to have a far greater influence on the final results so spend most of your time and money there instead.

                  Paul O


                  • #24
                    The DBX Venue 360 is very flexible in set up and and routing and the latest Drive Rack PA2 is much better than the original DR PA versions.
                    Both of those also have very good set up and control apps, you do need to put the 360 or the PA2 on a WIFI router to control them.
                    With the 360 app you can download it and run it with out being connected to an actual 360 if you wanted to get the feel of.

                    I use many 360's in my sound systems and have installed quite a few 360's and PA2's in other systems.

                    Mike Caldwell


                    • #25
                      Well that should explain why I heard no noticeable difference in the bass from the speaker when tuned with either the Ashly or BSS but you guys would agree that for mids/highs the digital processor would be better than an Analog crossover I'm guessing?

                      Moving on, when I look at the graphs of all horn drivers, I am seeing the roll off going downwards usually after 2khz, if you wanted to choose a driver for a horn which would produce enough highs for the Hi-hats so I am guessing around 20khz, is there any horn driver which would maintain 20khz please?


                      • #26
                        Don't get too obsessed on reaching 20khz and even more so if we're talking about PA system components here, getting out to 16khz or so some what flat is fine.

                        Humidity in the air will attenuate 20khz at most distances a PA system would be trying to cover and not to mention very few middle aged people are even going to be able to hear out to 20khz, loud music aside just daily noise. driving in the car with the windows down, factory work, lawn mowing, city street noise, ect all takes it's toll
                        as well as just the aging process of the ear itself, I wear ear plugs a lot!!!

                        In a full active system some horns require what's called CD horn eq (constant directivity) to help flatten the response of the horn. It varies from horn to horn but it's
                        something like a gentle high shelf boost starting around 3khz.
                        Some passive crossover have the EQ as part of the crossover.

                        What system speakers and amps are you using?

                        As for hi hats about 15khz is where they are going to top out at, most of the fundamentals are in the 500hz to around 4khz.

                        Mike Caldwell


                        • #27
                          Where concert sound is concerned 12kHz is sufficient. I've got over a hundred RTAs I took when I worked the FOH at a major venue with million dollar systems, none show much content above that.


                          • #28
                            I actually low pass filter my high frequency out on the DSP's at 16.5khz with a 18db BW filter.
                            There's nothing out there worth wasting the power on that's not going to get reproduced anyway.
                            Mike Caldwell


                            • #29
                              These Frequency Response numbers in the the attached image is confusing me taken from this driver's page:


                              can you guys tell me what they mean or how that info should be applied please?

                              Click image for larger version

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                              Mike C
                              That 1st pic on your site:

                              Is that Stevie Nicks? it looks like a pic from the video of her concert in Chicago I believe which is one of my very fav videos and best version of her tune "Edge of seventeen".


                              • #30
                                Unfortunately I have never worked with Stevie Nicks, that picture is from a show with a Fleetwood Mac tribute band! They were really good to the point you started to forget they were a tribute band.

                                The Peavey driver spec means that in the frequency range from 500hz to 3,200hz the the peaks and dip in the response only vary by 2db, the range from
                                3200hz on out to 8000hz the response is dropping in level by 3db, beyond 8000hz the response is dropping at a rate of 6db per octave. An octave equals doubling
                                of a frequency so that would mean say if at 8000hz the level was 106db at 16,000hz it would be down to 100db.

                                The response graph on the spec sheet you linked to kind of follows the numbers in the spec.

                                In theory and going by the numbers on the spec you can see that you would need to apply upwards to 20db
                                of boost towards the top end of that driver to get to a somewhat flat to 20,000hz response, not something you really want to do.

                                The response spec of newer one inch drivers are better but they still start getting peaky and dropping off around
                                16,000hz look at some B&C drivers for example.

                                Different diaphragm materials, shapes and sizes all play into a drivers response as well as the the drivers exit throat and phase plug.
                                standing waves/reflections can build up in the driver throat causing cancellation at different frequencies.
                                Mike Caldwell