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Just finished a pair of subs and they suck. Why?

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  • #46
    Re: Just finished a pair of subs and they suck. Why?

    This issue has me intrigued, so here are my thoughts.

    From what little I could tell from the video (which was made using some thumping music and not pure tones or a sweep), it sounds like the crossover is just set too high and midbass is making it through to the woofer on the 'thumps'. The adjustable crossover is still not a very high-order filter (only 12 dB/octave), so if the crossover frequency is set above 50 Hz and the level is high enough, then material above 100 Hz would still be audible, which you normally don't want from a subwoofer. You probably want to err on the side of using a lower crossover frequency than you're using.

    The RSS210-8 is a very competent driver, and can work well even as a woofer in a three-way configuration, so if it is receiving midbass information then it will not be filtering it out by any means. That being said, 70 watts is fairly light for this driver and certainly won't provide a lot of headroom, so amp clipping on the peaks is a definite possibility even if the "average" level the system can achieve is acceptable. The combination of the RSS210-8's upper frequency extension and amplifier clipping would result in clipping being more clearly audible (garbage in, garbage out).

    Run a slow bass sweep (like the 40-0 Hz sweep on a Bass Mekanik CD) and see if you still notice the distortion or any mechanical noise. The only noise you might hear if everything is working properly is wind noise from the port. If you hear a "grumbling" sound then you're just underpowered and should upgrade to a larger amp (like an SPA250). If you hear a metallic, grating noise, then that's the only time when I'd suspect something is mechanically wrong with the driver. This type of noise would be loud and very distinctive.
    Best Regards,

    Rory Buszka
    Product Manager, Dayton Audio

    The best way to predict the future is to create it.

    Comment


    • #47
      Re: Just finished a pair of subs and they suck. Why?

      So the noise went away in free air, provided the pole piece vent remained unobstructed? In some testing I have done, a vented pole piece is extremely important for clean operation.

      Since you have ruled out the amplifiers and the source, as you say that leaves box and driver. You were able to duplicate the sound in free air by obstructing the pole piece vent. Next step, if possible, mount the driver firing into the cabinet and see if the brace is actually too close to the pole piece...
      Don't listen to me - I have not sold any $150,000 speakers.

      Comment


      • #48
        Re: Just finished a pair of subs and they suck. Why?

        I can only guess that PE sell 100's of these per year, I think that we all feel that they are well made, etc. I would add if you want that pounding bass, yes get some extra power.
        If the goal was a pounder with 60 - 70 watts, you would need a more effeicient driver in a large box (maybe huge).

        Comment


        • #49
          Re: Just finished a pair of subs and they suck. Why?

          I don't see a problem with the brace 2" behind the pole piece. That's not obstructing airflow to a significant degree. It could be the problem is caused by pressure buildup under the dustcap. The driver in a vented box will still pressurize the air, maybe enough to cause a weak dustcap glue joint to flab, or a badly aligned pole piece to rub, or who knows what.

          All this talk about letting in higher frequencies causing your amp to run out of gas doesn't sit well with me. Try this: Set the crossover high enough to cause the noise, then back it down to 50Hz again. Turn the volume up about 3dB. Still no noise? It ain't the amp. Next?

          I second the notion to use sine sweeps and tones. Download a generator if you don't have one. (If you have WinISD, you have one.) The noise didn't sound to me like midbass content, but it could be I guess.

          My money's on a bad batch of drivers. We'll see.

          Comment


          • #50
            Re: Just finished a pair of subs and they suck. Why?

            I meant to spend this weekend further diagnosing the subs, but instead I accidentally formatted over 1.5TB of data during a Windows XP install and have been stressing over trying to recover it. I've recovered deleted data in the past, but so far no luck with this.

            Anyways, my next plan of attack is as follows.

            One sub is already reverse-mounted in the box. I'm going to leave the box outside my car (to avoid hearing resonations) and run some wire to my car sub's amp. It's a JL Class AB w/ 340W into 4 ohms, and a 24db/Oct LPF. I will also have a 0-24db/Oct crossover and parametric EQ on my Alpine deck. They are both proven components. I've even read that someone measured the same deck with an Oscilliscope, and could NOT get it to clip. It won't let you turn it up to that point, I've experienced this myself. The deck will stop increasing the RCA voltage at a certain point even if you keep turning up the volume.

            I hope to do this after work today and will post my results.

            As for the comments about the sub not being able to handle power at the higher frequencies, I'm not exactly trying to run them full range. I just want to raise the crossovers above 40hz on the amp and 50hz on my sound card. I just don't buy it that, given these woofers have been used in a 3-way speaker crossed at 800hz (Wolf's Attitudes), I can't cross them at 80 or 100hz at a reasonable volume.

            If nothing comes of this, I will still probably be able to use them crossed at the lowest possible point with my ported overnight sensations. However, if I had some sealed speakers that rolled off at a higher point, I don't think I'd be able to get them to integrate with these subs the way they are now.

            HiFi guy: Yes, I did buy these new. I actually bought three of them, all at separate (but similar) times, but one of them I accidentally left at the shipping-receiving company and someone walked off with it. D'oh!

            To the person who mentioned the rubber surround looking 'distorted': You are correct. I ran out of smaller screws on and had to use a couple with heads that were slightly too big, and that barely caused the surround to indent at a couple spots. I've since replaced those screws with smaller-headed ones, but they weren't an issue.

            Comment


            • #51
              Re: Just finished a pair of subs and they suck. Why?

              Ouch dude! Sorry to hear about the drive... That's going to be tough to fix. Normally, once the MFT is overwritten (assuming NTFS?) the only way back is to use a tool that recognizes directory entries and file types by whatever headers they might have. Not fun. Best of luck man...

              Comment


              • #52
                Re: Just finished a pair of subs and they suck. Why?

                I'm with Rory on this. It sounds like exagerated HF gak coming through as the crossover frequency is increased. I could clearly be wrong and it was hard to tell on the video exactly what was going on to me at least. But Rory's suggestion to try a sine wave sweep from say 20 or 30 hz up to 150 hz and listen for mechanical sounds seems like the way to go in my book. It takes a lot of other stuff out of the equation.

                If you played the subs integrated into the system with the OS's could you hear the noise problem? I would bet perhaps that you couldn't. Again just my $.02.

                Originally posted by RoryB@daytonaudio.com View Post
                This issue has me intrigued, so here are my thoughts.

                From what little I could tell from the video (which was made using some thumping music and not pure tones or a sweep), it sounds like the crossover is just set too high and midbass is making it through to the woofer on the 'thumps'. The adjustable crossover is still not a very high-order filter (only 12 dB/octave), so if the crossover frequency is set above 50 Hz and the level is high enough, then material above 100 Hz would still be audible, which you normally don't want from a subwoofer. You probably want to err on the side of using a lower crossover frequency than you're using.

                The RSS210-8 is a very competent driver, and can work well even as a woofer in a three-way configuration, so if it is receiving midbass information then it will not be filtering it out by any means. That being said, 70 watts is fairly light for this driver and certainly won't provide a lot of headroom, so amp clipping on the peaks is a definite possibility even if the "average" level the system can achieve is acceptable. The combination of the RSS210-8's upper frequency extension and amplifier clipping would result in clipping being more clearly audible (garbage in, garbage out).

                Run a slow bass sweep (like the 40-0 Hz sweep on a Bass Mekanik CD) and see if you still notice the distortion or any mechanical noise. The only noise you might hear if everything is working properly is wind noise from the port. If you hear a "grumbling" sound then you're just underpowered and should upgrade to a larger amp (like an SPA250). If you hear a metallic, grating noise, then that's the only time when I'd suspect something is mechanically wrong with the driver. This type of noise would be loud and very distinctive.
                Loren Jones

                http://techtalk.parts-express.com/sh...-sound-drivers

                http://techtalk.parts-express.com/sh...for-live-sound

                Comment


                • #53
                  Re: Just finished a pair of subs and they suck. Why?

                  I don't buy it... Mine are fine to 810Hz and no issues. I have stuffing right behind the driver. My guess is a cabinet issue, but both drivers do this?

                  I am at a loss for sure- don't know the cause.
                  Good luck,
                  Wolf
                  "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                  "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                  "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                  "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                  *InDIYana event website*

                  Photobucket pages:
                  http://photobucket.com/Wolf-Speakers_and_more

                  My blog/writeups/thoughts here at PE:
                  http://techtalk.parts-express.com/blog.php?u=4102

                  Comment


                  • #54
                    Re: Just finished a pair of subs and they suck. Why?

                    Don't buy what?
                    Don't listen to me - I have not sold any $150,000 speakers.

                    Comment


                    • #55
                      Re: Just finished a pair of subs and they suck. Why?

                      I don't know if it means anything but the surround is distorted at a minimum of one screw hole... upper left on the video. Could the basket be distorted just enough to be causing the VC to rub but only at certain frequencies as other distortions increase? Can't VC movement become slightly nonlinear at some frequencies?
                      "We are just statistics, born to consume resources."
                      ~Horace~, 65-8 BC

                      Comment


                      • #56
                        Re: Just finished a pair of subs and they suck. Why?

                        Originally posted by Wolf View Post
                        I don't buy it... Mine are fine to 810Hz and no issues. I have stuffing right behind the driver. My guess is a cabinet issue, but both drivers do this?

                        I am at a loss for sure- don't know the cause.
                        Good luck,
                        Wolf
                        Do sub amps have higher distortion in the non sub frequencies? Also did ypu have to put a notch in the xo? My 10'' HO sub dust cap caused a very audible ringing. Almost like a speaker mounted in a soda can.

                        Comment


                        • #57
                          Re: Just finished a pair of subs and they suck. Why?

                          I've also used these in the same size enclosure and tuning as Ben though crossed at 80hz and 24db/octave cross. If the basket is tweaked that could cause an issue but1) this is occurring on both drivers and 2) would be more likely to occur at lower frequencies. My suspicion is with Rory.


                          can you varify the enclosure size and tuning for us? port location?
                          https://www.facebook.com/Mosaic-Audi...7373763888294/

                          Comment


                          • #58
                            Re: Just finished a pair of subs and they suck. Why?

                            Sorry guys for the lack of updates, I've been busy this week. I plan on running a bunch of tests with my car equipment as I mentioned previously; I should have those results by tonight.

                            Comment


                            • #59
                              Re: Just finished a pair of subs and they suck. Why?

                              Ugh. Just finished testing the sub outside of my car using the car's deck and sub amp, and I'm more confused than ever. I didn't learn anything new about my sub, but I did learn some weird stuff about my Alpine Head Unit. As I was running through the test tones, I noticed the voltage from my deck went UP as I increased the frequency towards the 200hz LPF (Yes, it WAS the sub out RCAs). So the amp was getting a way larger signal at 120 vs 50, 50 vs 30 etc. This explains why I've never been able to get the same kind of bass as I did with the same sub & amp running off my old pioneer head unit, no matter what settings I used.

                              Anyways, that's a tangent; back to the issue.
                              While playing the test tones, I tried to keep the amp's output voltage around 16.7V (70 Watts). I had both the sub amp and head unit set to 200hz 24db low-pass, and everything set to flat (No boost/eq etc)

                              I played 20, 25, 31.5, 40, 50, 63, 80, 100, 120, 160hz, and a 20-160hz sweep, and everything sounded fine. There was some outdoor noise so If something was really quiet I may have missed it, but I don't think I did.

                              I attempted covering the pole piece vent in each of the frequencies to see what effect it had. At 20 & 25hz, no audible effect. Starting at 31.5hz, it added a "wind noise", kinda like port chuffing. As the tone freq increase, the wind noise increased in speed, becoming a sort of buzzing until it got to the point where covering the vent hole just changed the pitch of the sub's sound. All of this sounded like stuff I should expect; I was not able to recreate the "bad" sound.

                              I also covered the box port. At the lower frequency this induced chuffing, which went away as the frequency increased. Nothing to see here.

                              Then I went on to playing a variety of music Some FLAC, some mp3. Immediately the bad sound presented itself, even though at this time I had the volume turned slightly below what I had it at during the test tones. I played around with the volume and crossover settings on the deck and amp, with no aha! moments. Pretty much the same results as when I used my sound card + SA70 plate amp or sound card + Emotiva UPA-500.

                              Some questions answered:

                              I don't know if it means anything but the surround is distorted at a minimum of one screw hole... upper left on the video. Could the basket be distorted just enough to be causing the VC to rub but only at certain frequencies as other distortions increase? Can't VC movement become slightly nonlinear at some frequencies?
                              A couple screws had heads that were slightly too large, but they were replaced. Regardless, my most recent tests were with the sub reverse-mounted, in which case the screw heads don't come anywhere near the surround or anything else.

                              can you varify the enclosure size and tuning for us? port location?
                              The enclosure is 30L after displacements with a 2" precision port that tunes the box to 26hz. The port is mounted horizontally in the top half of the box. The driver and amp are in the bottom.

                              If you played the subs integrated into the system with the OS's could you hear the noise problem? I would bet perhaps that you couldn't. Again just my $.02.
                              Yes. Perhaps I couldn't precisely pick out what was wrong, but I knew something didn't sound right with the subs, which prompted this whole investigation.


                              ---

                              One thing I want to emphasize is that I do not think I am asking too much of these. I've never been dissapointed in audio projects or purchases before. I'm kinda resigning myself to using these subs to provide low-level, sub-40hz sound only.

                              Comment


                              • #60
                                Re: Just finished a pair of subs and they suck. Why?

                                Try rolling up a t-shirt and stuffing the port. See if you can hear any ugly noises coming from the box.

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