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  • 7in woofer out to 3kHz?

    Since killing one of my ribbon tweeters in my Jasmine design, I've been longing for a nice true ribbon speaker again. One of the design rules I try to follow is avoiding beaming on large woofers, so when I use a 6.5-7in woofer, I usually try not to cross above ~2.2kHz or so. And if I'm running a ribbon that won't go lower than 3kHz, I use a smaller 5in-ish class woofer. However, I've seen lot of both commercial and DIY designs mating 7in woofers with tweeters that I know can't go lower than 3kHz (namely ribbons), so they must be running the woofers up to near 3kHz. Many of these designs use shallow filter slopes and the measurements of ones I could find (few) don't seem to show adequate suppression of breakup, but they all get good reviews from either the commercial crowd (yes, I know those reviewers are not well liked or respected here) and the DIY crowd. Even if I ignore designs (be it commercial or DIY) that either don't seem to adequate address breakup or questionable whether it's adequate, there's still designs that I'm sure are done properly for breakup but still appear to have the beaming issue that still get rave reviews.

    I purchased a pair of 830991 HDS 5.25in woofers to mate with a ribbon for a new TM design. But I already have a 7in HDS that I always thought was too big for a ribbon that only goes to 3kHz, even though I could make the response stretch high enough to meet it. I figure there'd be polar radiation issues and power response issues, along with having to address breakup. But if I can use the 7in, that saves me cost (which is important right now) for this new design.

    The ER18 MTM with Fountek CD3.0 ribbon is one of the ones I'm sure is done properly to address breakup since Mr. Murphy designed the XO, but I don't see how it gets around the beaming issue running the 7in woofers to meet up with the ribbon.

    So I'm trying to decide if I should just use the 7in HDS Nomex woofers I have now with the new ribbon since it appears beaming issues may not really be an issue, or use the 830991 5.25" HDS woofer instead.
    What are your thoughts on this?

    If I choose to just use my 7in woofers, anyone interested in a pair of Peerless 830991 GFC woofers for the Deal of the Day price of $69 + sh? I haven't even received the 830991 yet.

    Thanks.
    Nichikuros - Peerless 831735 Nomex + Vifa NE25VTA
    Digger8 - Small compact 8" sub with F3 = 20Hz
    Madison-D and Madison-R - Tang Band W4-1720 + Vifa BC25SC06 or Beston RT003C (TM and MTM)
    Jeffrey - Tang Band W5-704D + Beston RT003C
    Jasmine - Fountek FW146 + Fountek NeoCD3.0 Ribbon in Pioneer BS21 Cabinet

  • #2
    Re: 7in woofer out to 3kHz?

    Glad you posted this as its also something I'm looking at

    two 6.5" midwoofers to think about are the SB Satori and also the new Alpair 12PW (madisound)

    I've read that the Satori's start to beam above 2.5khz or so - the alpair might be better behaved at 3khz due to the shallow cone

    There are a few ribbons that can cross at 2 -2.5khz ok

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    • #3
      Re: 7in woofer out to 3kHz?

      I've already got the ribbon selected. The ones that can go below 3k tend to be out of my budget. I'm more asking what others feel about the beaming of a 7in woofer in the 3k-ish range since there are many commercial and DIY offerings that do it and the ER18 MTM Ribbon does it likely also since it uses a ribbon that doesn't work well below 3k. If I can save the cost of not buying smaller woofers for the design and take advantage if the sensitivity and bass response if the larger woofer, it'd be nice. I think the Peerless woofer had a fairly low beaming frequency since it's decently deep. I would love to use the Satori though.
      Nichikuros - Peerless 831735 Nomex + Vifa NE25VTA
      Digger8 - Small compact 8" sub with F3 = 20Hz
      Madison-D and Madison-R - Tang Band W4-1720 + Vifa BC25SC06 or Beston RT003C (TM and MTM)
      Jeffrey - Tang Band W5-704D + Beston RT003C
      Jasmine - Fountek FW146 + Fountek NeoCD3.0 Ribbon in Pioneer BS21 Cabinet

      Comment


      • #4
        Re: 7in woofer out to 3kHz?

        At the crossover point half of the system output is coming from the tweeter and half from the woofer. If the tweeter has very wide dispersion at this point it can compensate for quite a bit of the woofer's beaming. The woofer's directivity takes over below the crossover point, but this isn't a hard transition, it occurs somewhat gradually. So, the off-axis response may not be a bad as we might think if we only push a woofer a little higher than optimum. Besides, having a small off-axis dip around 3 khz is usually not a bad thing in most rooms.

        Jeff B.
        Click here for Jeff Bagby's Loudspeaker Design Software

        Comment


        • #5
          Re: 7in woofer out to 3kHz?

          Johnny, the other thing to consider is a small 3-way to accommodate the ribbon. Higher cost, but if you like the ribbon sound that much...
          Some people are addicted to Vicodin. I'm addicted to speaker building.

          The Chorales - Usher 8945A/Vifa XT25TG Build
          ESP Project 101 Lateral MOSFET Amplifier
          LM4780 Parallel Chipamp
          Sonata Soundbar Project
          The Renditions - Active/Passive Towers

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          • #6
            Re: 7in woofer out to 3kHz?

            Thanks Jeff. I knew it wss a progressive transition for dispersionnarrowing but didn't think of the tweeter covering for the woofer.

            Hey Hong. The design started out as a 3way actually. A pair of 4in Peerless 830992 GFCs flanking the ribbon in MTM and either a set of 4x 5-7in woofers (XO ~750-800Hz) or a single 8in at the very bottom of the cab (XO ~150-300Hz) for the low end. But the cost of all the drivers, the cab and crossover components along with not having space for another set of towers made me look for more compact designs. So it went down to just the MTM section thinking I'd use a sub to cover the bottom. But 4x 830992s still weren't very cheap, and the day I was looking for a larger woofer alternative, the 830991 was deal of the day. Then browsing the web this weekend i found a bunch of yet larger woofer options (mix of well done and not-so-well done designs I'm sure) lead to now. Cant beat the cost of free woofers I already have. I thought about a compact 3way too but the component cost pushes my budget still. Thought about the FE85 for the compact 3way. Too many ideas...sucks to have no budget. But now I have to ship the 5.25in 830991 woofers back...argh.
            Nichikuros - Peerless 831735 Nomex + Vifa NE25VTA
            Digger8 - Small compact 8" sub with F3 = 20Hz
            Madison-D and Madison-R - Tang Band W4-1720 + Vifa BC25SC06 or Beston RT003C (TM and MTM)
            Jeffrey - Tang Band W5-704D + Beston RT003C
            Jasmine - Fountek FW146 + Fountek NeoCD3.0 Ribbon in Pioneer BS21 Cabinet

            Comment


            • #7
              Re: 7in woofer out to 3kHz?

              Originally posted by Jeff B. View Post
              having a small off-axis dip around 3 khz is usually not a bad thing Jeff B.
              there are several speaker companies that actually design their crossovers so there is an off axis dip in this range.
              craigk

              " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

              Comment


              • #8
                Re: 7in woofer out to 3kHz?

                Today's Deal Of The Day is a Vifa 6.5" woofer that is rated 40 to 4,000 Hz. That might allow for a 3,000 Hz crossover.

                http://www.parts-express.com/vifa-ne...ofer--264-1096

                I own a couple of Focal Chorus sets with a 6.5" midrange/woofer and they have a 3k Hz crossover point for their tweeters.
                1: Sony DVP-S7000 | Denon DVD-2900 | Laptop > Parasound Zdac > Denon AVR-5700 > Focal 826V | Def Tech BP2000 | (2) DIY 15" Subs powered by Crown XLS2500
                2: Computer > Schiit ‹bered Bifrost > Emotiva RCA Control Freak > Crown XLS 1500 > Focal 706V | Def Tech SM450 | Velodyne F-1000B Sub

                Comment


                • #9
                  Re: 7in woofer out to 3kHz?

                  I tried to cross a tweeter quite a bit higher than I should of (4k) with a woofer that had a bit of a nasty breakup peak. I tried all kinds of notch filters and steep slopes to try and get rid of it but that acidic, grainy sound still showed through, so my advice is to make sure you pick a woofer that has a smooth, controlled breakup if you're going to cross higher than you should be.
                  The interesting thing about the breakup was that I got used to it in the end and it was only when I went back to a speaker that didn't have it, that I really noticed it. It's surprising how our ears adjust.
                  Crossing the same woofer at around 2.5k was much, much better...

                  Comment


                  • #10
                    Re: 7in woofer out to 3kHz?

                    The 7" HDS has break up at around 4khz so I would imagine its a bit tight, crossed at 3.
                    What ribbon are you using?

                    Comment


                    • #11
                      Re: 7in woofer out to 3kHz?

                      I've tried and tried to do what you propose and have come to the subjective conclusion that the radiation pattern of smaller, 4-5" midrange drivers just sounds soooo much better than larger drivers in the 1-4khz range. It's lead me to conclude ribbons are only suitable in three way systems, and unfortunate and expensive conclusion none the less.

                      Comment


                      • #12
                        Re: 7in woofer out to 3kHz?

                        I think the Eclipse W6520R at Meniscus maybe capable of crossing that high. I am working with one now and will be taking off-axis measurements soon. It does extend well up to around 8k with a small peak at about 3k. Click image for larger version

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                        • #13
                          Re: 7in woofer out to 3kHz?

                          Consider the SEAS U18 or CA18RLY. I've crossed them up around 2800-3000 and they work well.

                          Comment


                          • #14
                            Re: 7in woofer out to 3kHz?

                            I'm using the 831735. The breakup looks about the same as the ER18. The U18 and CA18 are smoother though with no real breakup. But if the ER18 can do it successfully, the 831735 should too. HD between the 2 are also very similar.
                            I get a smoother FR with the 830991s but then I have the additional cost of the drivers and crossover along with yet another speaker that I don't know where to put as my wife gets mad at me for having too many speakers. I'd love to make a while new speaker but cost and space limitations prevail.
                            Nichikuros - Peerless 831735 Nomex + Vifa NE25VTA
                            Digger8 - Small compact 8" sub with F3 = 20Hz
                            Madison-D and Madison-R - Tang Band W4-1720 + Vifa BC25SC06 or Beston RT003C (TM and MTM)
                            Jeffrey - Tang Band W5-704D + Beston RT003C
                            Jasmine - Fountek FW146 + Fountek NeoCD3.0 Ribbon in Pioneer BS21 Cabinet

                            Comment


                            • #15
                              Re: 7in woofer out to 3kHz?

                              Originally posted by maynardg View Post
                              Consider the SEAS U18 or CA18RLY. I've crossed them up around 2800-3000 and they work well.
                              It's been a while now, but when I did the HTS series for Salksound I crossed the CA18RLY over to AC G2 ribbon at 2.8 kHz with no problems. Jim and I were both very happy with the sound and there have been no ribbon failures in the field.
                              Click here for Jeff Bagby's Loudspeaker Design Software

                              Comment

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