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Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

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  • Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

    I've currently got a soundcraftsmen PM860 which I dont know if it is a good amp for what I want but I've been pretty happy so far with it. I want to get an amp to drive four DVC385-88 subwoofers which are wired series/parallel to 8 ohm per channel. The subwoofers can give me quite reasonable bass at low frequencies so I want something that can do them justice (they are each in approx. 10cf tuned to 14Hz). I just tried a Crown XLS 1500 but I suspect it doesnt like to deliver power into frequencies below 20Hz. It sounds like its rolled off on the bottom or maybe at higher volume levels it falls flat or something.

    I've been considering the QSC RMX 2450 as a replacement. What else can I consider? How is the Crest CA6? I know all these are going to have somewhat noisy fans but they will be in a next room over so its not the end of the world. Getting good solid deep bass with a lot of control is what I'm really after.

    Any suggestions welcome and as far as price goes, I'd like to keep it under $1000 if possible.

  • #2
    Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

    Originally posted by contoursvt View Post
    I've currently got a soundcraftsmen PM860 which I dont know if it is a good amp for what I want but I've been pretty happy so far with it. I want to get an amp to drive four DVC385-88 subwoofers which are wired series/parallel to 8 ohm per channel. The subwoofers can give me quite reasonable bass at low frequencies so I want something that can do them justice (they are each in approx. 10cf tuned to 14Hz). I just tried a Crown XLS 1500 but I suspect it doesnt like to deliver power into frequencies below 20Hz. It sounds like its rolled off on the bottom or maybe at higher volume levels it falls flat or something.

    I've been considering the QSC RMX 2450 as a replacement. What else can I consider? How is the Crest CA6? I know all these are going to have somewhat noisy fans but they will be in a next room over so its not the end of the world. Getting good solid deep bass with a lot of control is what I'm really after.

    Any suggestions welcome and as far as price goes, I'd like to keep it under $1000 if possible.
    One suggestion: Crown XTi4000 or XTi4002. There's a few demo & used on eBay currently.

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    • #3
      Originally posted by Cuppa Joe View Post
      One suggestion: Crown XTi4000 or XTi4002. There's a few demo & used on eBay currently.
      Any reason why you suggest the xti series over the new drivecore models? Aren't they similar?

      By the way I am surprised to hear the xls 1500 couldn't keep up. From most of what I have read they are fine amps. I currently have a crown ps-400 and I plan on switching to an XLS1000 at some point.
      Salem

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      • #4
        Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

        Well the crown was fine, but it sounds a few db shy in the bass below 20Hz. Since my subwoofers are flat to 16Hz in room and can produce usable response in room to 12Hz, I kind of noticed that. I'm sure if I had a mini-dsp and EQ'd the bottom end back up, it would work, but I'd rather start with an amp that has some good weight on the low end

        Originally posted by eyekode View Post
        Any reason why you suggest the xti series over the new drivecore models? Aren't they similar?

        By the way I am surprised to hear the xls 1500 couldn't keep up. From most of what I have read they are fine amps. I currently have a crown ps-400 and I plan on switching to an XLS1000 at some point.
        Salem

        Comment


        • #5
          Originally posted by contoursvt View Post
          Well the crown was fine, but it sounds a few db shy in the bass below 20Hz. Since my subwoofers are flat to 16Hz in room and can produce usable response in room to 12Hz, I kind of noticed that. I'm sure if I had a mini-dsp and EQ'd the bottom end back up, it would work, but I'd rather start with an amp that has some good weight on the low end
          I did some searching and cannot find any reference to a high pass filter on this amp. Do you have the equipment to run a frequency response sweep?
          Thanks!
          Salem

          Comment


          • #6
            Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

            I've down some very basic test tones at 80db and plotted the response and its within a db of my soundcraftsmen in very low frequencies but I also found this link which tested the crown XTI which I believe is another of crown's class D amps (older model) and into a 4 ohm load, it made very poor power at 20Hz. Maybe something similar is happening here as well with the XLS 1500. I'm running 4 ohm stereo loads and at it just feels like there is no grunt when I'm watching movies. I tend to watch at a pretty decent volume so maybe higher power frequency response is not like what they publish for response.

            http://www.avsforum.com/t/855865/mea...#post_13869426



            Originally posted by eyekode View Post
            I did some searching and cannot find any reference to a high pass filter on this amp. Do you have the equipment to run a frequency response sweep?
            Thanks!
            Salem

            Comment


            • #7
              Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

              verified my findings with crown tech support. The XLS is rated 20-20K response. Below 20, it has a 12db / octave roll off I guess as a make shift subsonic or just to conserve power or something. I knew I felt a few db less weight LOL.

              Comment


              • #8
                Thanks for the info. That is the first time I have heard confirmation if a high pass filter on the drivecore xls amps. I personally am not going to try to reproduce sub 20hz with a subwoofer but if that is your thing the behringer ep and epx series have been used reliably for a long time and their cutoff is closer to 5hz. Good luck!
                Salem

                Comment


                • #9
                  Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

                  Thanks! Its so funny you should say this because I had just decided to pick up two EP4000 for the same price as one QSC 2450, thinking that at least each amp will be working less and I might have more headroom and if an amp ever dies, at least I can still enjoy my movies while getting a replacement I didnt know about the 5Hz thing but I knew they do go pretty low being copies of the RMX



                  Originally posted by eyekode View Post
                  Thanks for the info. That is the first time I have heard confirmation if a high pass filter on the drivecore xls amps. I personally am not going to try to reproduce sub 20hz with a subwoofer but if that is your thing the behringer ep and epx series have been used reliably for a long time and their cutoff is closer to 5hz. Good luck!
                  Salem

                  Comment


                  • #10
                    Wow, that is a ton more power . The only negative I have heard about these is the fan may be loud but they are apparently pretty easy to replace.

                    Good luck!
                    Salem

                    Comment


                    • #11
                      Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

                      Damn I just picked up one, and the fan is pretty damn loud but I drove the subs as hard as I could without fearing damage for at least a couple minutes (longer than any scene in any movie) and the amp was still blowing stone cold air so I'm sure I could at least cut the airflow in half and be safe. It might still be audible then but it will be easily drowned out by anything playing in a movie or be silenced in a cabinet.

                      The EP4000 has very similar bass to my Soundcraftsmen amp which is what I wanted. I will pick up a second because I'm happy with the bass quality. This way each amp is doing half the work. They should hopefully last a long time and be reliable.

                      Originally posted by eyekode View Post
                      Wow, that is a ton more power . The only negative I have heard about these is the fan may be loud but they are apparently pretty easy to replace.

                      Good luck!
                      Salem

                      Comment


                      • #12
                        Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

                        The QSC RMX HD's will stomp the digital amps on Subs. They will also outperform the Behringers, as the Behringers use smaller transformers. We did an A/B test with a QSC RMX 1850HD bridged on a 2x18" Pro Sub, compared with a QSC PLX3602, at twice the rated power. The RMX hit noticeably harder. The 4050 and the 5050 are also beasts.

                        Comment


                        • #13
                          Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

                          About the Behringer having smaller transformers, is that mostly an issue if I'm trying to get a lot of power because I'm probably only going to want to push a couple hundred watts into each of my Dayton DVC385 15" drivers so it will be running 8 ohm stereo. I think it will probably not even be flinching at this low load. I do find the amound of deep bass and low frequency response of the behringers to be very good - well being sort of a cheap clone fo the RMX line. Way better low end than the class D for deep bass.

                          Originally posted by jarvissound View Post
                          The QSC RMX HD's will stomp the digital amps on Subs. They will also outperform the Behringers, as the Behringers use smaller transformers. We did an A/B test with a QSC RMX 1850HD bridged on a 2x18" Pro Sub, compared with a QSC PLX3602, at twice the rated power. The RMX hit noticeably harder. The 4050 and the 5050 are also beasts.

                          Comment


                          • #14
                            Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

                            The smaller trafo is probably undersized for 2 ohm operation, and marginal for 4 ohms. At 8 ohm, it probably puts out a few watts less than the RMX, but with the same reservoir capacitance there won't be much difference. This makes more difference than the size of the transformer at 20 Hz. You may be tempted by the GX5 because it's the same price as an EP4000, but it really struggles at heavy load - they cheaped out a little too much so it's not a good contender for sub duty. I bought one for monitoring, but it eventually found its home in my medium rig driving the HF horns above 800 Hz.

                            Those RMX5050's *are* beasts. It beats anything I have except the CA18's, which is a real (but dated, 75 pound) touring amp. Stereo 5050 beats two bridged PLX's driving horn subs - especially at the end of a 100' #10 extension cord.

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                            • #15
                              Re: Good power amp that can deliver lots of power at low frequencies (ie below 20Hz)

                              I wonder if people upgrade the caps on these amps to see if they can bolster low end... say if the caps are 10,000uf each, to replace them say with 15,000 each. I suspect you cant go too large because something has to fill the caps when they are empty and maybe that rush of current would blow something up but would be an interesting mod maybe

                              Originally posted by wg_ski View Post
                              The smaller trafo is probably undersized for 2 ohm operation, and marginal for 4 ohms. At 8 ohm, it probably puts out a few watts less than the RMX, but with the same reservoir capacitance there won't be much difference. This makes more difference than the size of the transformer at 20 Hz. You may be tempted by the GX5 because it's the same price as an EP4000, but it really struggles at heavy load - they cheaped out a little too much so it's not a good contender for sub duty. I bought one for monitoring, but it eventually found its home in my medium rig driving the HF horns above 800 Hz.

                              Those RMX5050's *are* beasts. It beats anything I have except the CA18's, which is a real (but dated, 75 pound) touring amp. Stereo 5050 beats two bridged PLX's driving horn subs - especially at the end of a 100' #10 extension cord.

                              Comment

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