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  • New Member - New Project - Seeking Feedback on Crossovers . . .

    Hello all!

    New member here but long time assembler/parts purchaser looking for some feedback.

    After reading and lurking for a very long time I have decided to try this combination of parts and desire the feedback of those far more knowledgeable/experienced than myself.

    I am attempting to construct a set of tower speakers for HT Mains and Stereo Music:

    Cabinet Volume = ~ 0.85 Cu Ft

    Ported - Front - NEED Port tube specs for this cabinet/speaker combo or your recommendations, please.

    Woofer = https://www.parts-express.com/goldwo...4-ohm--290-351

    Tweeter = https://www.parts-express.com/dayton...eeter--275-070

    Crossover = https://www.parts-express.com/dayton...00-hz--260-140


    Aside: I have looked at so many Mid Bass and Bass Woofer specs that I am going blind.
    They all have a nasty impedance spike between 30 ~ 60 Hz it seems and I am trying to understand why my selection of woofer is OK or not compared to more expensive drivers in my desired application.

    Have I chosen my components well or have I missed something?

    Thanks for any assistance and best wishes,

    Steve in Alabama . . .






  • #2
    Hello and welcome to the hobby and Forum!

    I'm sure more experienced and knowledgeable members will advise you, but regardless of which drivers you buy and how much you spend, a pre-made generic crossover won't work properly and you will most likely be disappointed in the sound: if nothing else, in this case the tweeter will play too loudly.

    A few questions to assist you, and PETT members, to help you:
    • have you already brought the drivers?
    • what's your budget, and does it include the cabinets?
    • what is your room size, what are your music preferences and listening level(s)?
    • will this be your first, and possibly only set of DIY speakers? If so, you will want to do it right and be happy with the result.
    • you're wanting to build tower speakers, I assume because you want the tweeters at ear level and not have to buy stands, is that right?

    I've built several sets of DIY speakers, all of which are others' proved designs. I thought I'd have a go at adapting (not designing) a crossover for an existing project and I have to say the end result was disappointing. Fun and a good learning experience, but disappointing.

    If you haven't brought the drivers, why not consider an existing, proved design which many people have built, is well-reviewed and for which there are build logs, photos etc. I rather like the feeling of knowing that what I've built sounds much better than retail speakers which cost heaps more! You won't get that feeling with generic crossovers.

    There are plenty of 6 - 6.5" two way designs which could suit; I couldn't find an existing design for your driver combination. I had a look at the Goldwood's supplied frequency response graph and it has a nasty looking spike at about 3,000 Hz which would need to be addressed in the crossover - another reason not to use a generic product.

    I can't help you with your questions on impedance spikes but I'm sure others will know the answers.

    HTH

    Geoff

    Comment


    • #3
      Hi Geoff!

      I've tried to answer your questions in detail but the server here keeps throwing a message stating that it is giving an invalid response.

      And then logging me out.

      OK, I will try one more time . . .

      To answer your questions in order"

      1. Yes, I have the drivers and the crossovers are showing up later today. These are all inside a JBL TLX-121 speaker cabinet but they lack the fullness I am seeking as mains. (tom-toms on drums have punch but no resonance like they should have (I'm a hobby drummer).
      2. Budget is not an issue - I have hobby shop and can do what I wish as long as the effort and expense is worth the cost - otherwise I would just purchase the Dayton Audio towers and be done with it - I want something better/more realistic sounding.
      3. Room is 12 X 20 X 8 with lots of furniture, wall art and openings into other rooms one end in closed-in and there are two passive subs under end-tables in there driven by a Crown 250 WPC amp from the Sub-out on the old Yamaha Surround receiver - I listen at moderately to somewhat loud levels.
      4. Far from my 1st and hardly my last attempt at this - it is a hobby and I like to tinker/experiment but yes, I'd like to get these speakers done right as I have plans for the enclosures that require a lot of woodworking and refined cabinetry in the shop.
      5. I want the tower speakers more for the additional cabinet volume so the speakers will deliver the full ranged of the audio signal sent to them more than anything else. Everything is currently mounted at ear level in the seating position currently, yet the rear vented speakers are caught in somewhat of a bass-trap behind the TV and under a shelf and not being reflected back into the listening area so I have been working with the sub-levels but there is still a hole in the perceived frequency response levels at the listening position which is almost at dead center of the room.

      Concerning your thoughts on purchasing an already available design, I have spent many hours going over all the kits and their specs and keep finding issues with them when combined with my existing center channel, and surrounds and their impedance and efficiencies.

      If I were to know now what I wish I had known in the past, I would have just bought all the BIC America matching speakers and been down the road already.

      :D

      Concerning the Goldwood woofers/Selected cross-over - I am crossing-over at 2KHz - I fail to see the spike issue at that point where you mention 3KHz.

      Thanks again and have a great day, sir - I really appreciate the time.

      Best!



      Steve.


      Comment


      • #4
        If you'd digested almost ANY "beginner" book (like SpeakerBuilding 201) you'd know that basically ALL drivers that employ a voice coil have an impedance plot that starts down low (typically referred to as the driver's "Re"), then rise to a peak at the driver's resonant freq. (Fs). This is VERY normally between 30-60Hz for a woofer (you've got no need to be concerned about this AT ALL) and maybe around 1k-3kHz for a tweeter.
        After that there's a fairly broad "valley" of low impedance (often near 200Hz for a woofer / 4k? for tweeters) with a consistent "rise" up to 20k. The distance up to 20k isn't that far away on tweeters (and is generally ignored) but it's a long way up there from 200Hz, so it's often beneficial to run a "Zobel" across a woofer's terminals (about $2?) to effectively flatten out the rise. (You can get by w/out this on the GW woofer - IF . . . )
        That woofer/tweeter combo should work well enough.

        Your "generic" 2k XO CAN be used effectively, BUT you need to add 3 components to it (2 resistors and a cap - to each XO).
        As Geoff pointed out, that woofer DOES have a bad peak at 3k (look at the FR plots to see it). You can snub that by paralleling the iron-core coil with a 4n(ohm) resistor in series w/a 2uF cap.
        The other noted problem (of the tweeter being too loud) can be remedied by adding a 4n resistor between the amp's "+" lead and the entrance side of the tweeter's 5uF cap. That should do it. (you do NOT want that resistor feeding the woofers coil - so you might have to do some surgery on the XO board)

        I'd tune the box to the low 40s (yielding an F3 below 40Hz - FINE for music!) by using either a 2" "Precision Port" that's 4" long, or make your own 3"id x 10" long port out of PVC or a cardboard tube.

        Hard to get a "tower" (usually w/the tweeter at LEAST 36" off the floor) from only 0.85 cu.ft. Either stands are in order, or a larger box w/a false bottom half (that's closed off).

        Comment


        • #5
          Chris, tried to send you a PM but the message limit has apparently been reached! I had that trouble with Paul Kittinger before, and he had to clear a lot out before anything would go through.

          Comment


          • #6
            (just cleaned house)

            thnx !

            Comment


            • #7
              Originally posted by Steve Lee View Post
              Hi Geoff!



              Concerning your thoughts on purchasing an already available design, I have spent many hours going over all the kits and their specs and keep finding issues with them when combined with my existing center channel, and surrounds and their impedance and efficiencies.

              If I were to know now what I wish I had known in the past, I would have just bought all the BIC America matching speakers and been down the road already.


              Welcome:

              In most proven designs (meaning successfully completed and enjoyed by many users) a lot of issues have been addressed and corrected by people a lot smarter than me. In my view, crossover design and fly fishing can only be done successfully after retirement. I have constructed a dozen or more proven designs resulting in immense pleasure and I don't feel cheated out of the experience of not personally designing the system. I also don't have a single poor sounding pair.

              As Chris pointed out, you'll find that some "issues" are crucial, audible and require a fix and others meaningless and a waste of time. You're not alone, I think most newer DIY folks for some reason come here for advice after they've already committed to their own concept and purchased the parts, without knowing if it will work.

              There are some really great folks on this site that can help design a system you will enjoy and maybe encourage you to continue with the hobbie. I would encourage you to build a proven design - in the process you'll get great advice from others who have built the system and possibly the designer. Worst case you'll end up with good speakers.

              There is a wealth of knowledge available in the sticky section of this forum. http://techtalk.parts-express.com/fo...building-bible

              This first thing I learned was that I didn't know how much I didn't know. start here:

              https://sites.google.com/site/undefinition/diy-mfaq

              https://sites.google.com/site/undefi...-provendesigns





              Comment


              • #8
                FWIW, I would advise you to take Chris R's advice. He is very familiar with that tweeter, and has gone to some effort to look up your woofer and XO. It is a few dollars worth of parts to greatly improve your results. You can see for yourself by trying your components with and without Chris' suggested mods. Make the cabs and run the wires out the port to the crossovers to access them to experiment. SOP for XO designing. Get some short alligator clipped test leads when you order the XO parts.


                That's what I would do.

                Comment


                • #9
                  Originally posted by djg View Post
                  FWIW, I would advise you to take Chris R's advice. He is very familiar with that tweeter, and has gone to some effort to look up your woofer and XO. It is a few dollars worth of parts to greatly improve your results. You can see for yourself by trying your components with and without Chris' suggested mods. Make the cabs and run the wires out the port to the crossovers to access them to experiment. SOP for XO designing. Get some short alligator clipped test leads when you order the XO parts.


                  That's what I would do.
                  +1

                  Geoff

                  Comment


                  • #10
                    Originally posted by Steve Lee View Post

                    To answer your questions in order"

                    1. Yes, I have the drivers and the crossovers are showing up later today. These are all inside a JBL TLX-121 speaker cabinet but they lack the fullness I am seeking as mains. (tom-toms on drums have punch but no resonance like they should have (I'm a hobby drummer).
                    Steve.

                    Why am I thinking drummer who wants realistic, in a sense tactile reproduction of drums, might be interested in something like the Trump Tower build?
                    http://techtalk.parts-express.com/fo...khanspires-but
                    http://techtalk.parts-express.com/fo...pico-neo-build
                    http://techtalk.parts-express.com/fo...ensation-build

                    Comment


                    • #11
                      He's not going to get it with that woofer, unless it's used in a set of mains along with a good sub or two.
                      www.billfitzmaurice.com
                      www.billfitzmaurice.info/forum

                      Comment


                      • #12
                        Originally posted by Chris Roemer View Post
                        If you'd digested almost ANY "beginner" book (like SpeakerBuilding 201) you'd know that basically ALL drivers that employ a voice coil have an impedance plot that starts down low (typically referred to as the driver's "Re"), then rise to a peak at the driver's resonant freq. (Fs). This is VERY normally between 30-60Hz for a woofer (you've got no need to be concerned about this AT ALL) and maybe around 1k-3kHz for a tweeter.
                        After that there's a fairly broad "valley" of low impedance (often near 200Hz for a woofer / 4k? for tweeters) with a consistent "rise" up to 20k. The distance up to 20k isn't that far away on tweeters (and is generally ignored) but it's a long way up there from 200Hz, so it's often beneficial to run a "Zobel" across a woofer's terminals (about $2?) to effectively flatten out the rise. (You can get by w/out this on the GW woofer - IF . . . )
                        That woofer/tweeter combo should work well enough.

                        Your "generic" 2k XO CAN be used effectively, BUT you need to add 3 components to it (2 resistors and a cap - to each XO).
                        As Geoff pointed out, that woofer DOES have a bad peak at 3k (look at the FR plots to see it). You can snub that by paralleling the iron-core coil with a 4n(ohm) resistor in series w/a 2uF cap.
                        The other noted problem (of the tweeter being too loud) can be remedied by adding a 4n resistor between the amp's "+" lead and the entrance side of the tweeter's 5uF cap. That should do it. (you do NOT want that resistor feeding the woofers coil - so you might have to do some surgery on the XO board)

                        I'd tune the box to the low 40s (yielding an F3 below 40Hz - FINE for music!) by using either a 2" "Precision Port" that's 4" long, or make your own 3"id x 10" long port out of PVC or a cardboard tube.

                        Hard to get a "tower" (usually w/the tweeter at LEAST 36" off the floor) from only 0.85 cu.ft. Either stands are in order, or a larger box w/a false bottom half (that's closed off).
                        Chris!

                        Man, thanks for your excellent direction and assistance - I didn't really expect to get this level of technical help at all so I am quite impressed. Thanks - seriously.

                        I will take heed of your advice and put those components in my next order here from PE.

                        Wow. What a community you guys have here . . .

                        Thanks again Mr. Wizard!




                        Steve.

                        Comment


                        • #13
                          Originally posted by dwigle View Post

                          Welcome:

                          In most proven designs (meaning successfully completed and enjoyed by many users) a lot of issues have been addressed and corrected by people a lot smarter than me. In my view, crossover design and fly fishing can only be done successfully after retirement. I have constructed a dozen or more proven designs resulting in immense pleasure and I don't feel cheated out of the experience of not personally designing the system. I also don't have a single poor sounding pair.

                          As Chris pointed out, you'll find that some "issues" are crucial, audible and require a fix and others meaningless and a waste of time. You're not alone, I think most newer DIY folks for some reason come here for advice after they've already committed to their own concept and purchased the parts, without knowing if it will work.

                          There are some really great folks on this site that can help design a system you will enjoy and maybe encourage you to continue with the hobbie. I would encourage you to build a proven design - in the process you'll get great advice from others who have built the system and possibly the designer. Worst case you'll end up with good speakers.

                          There is a wealth of knowledge available in the sticky section of this forum. http://techtalk.parts-express.com/fo...building-bible

                          This first thing I learned was that I didn't know how much I didn't know. start here:

                          https://sites.google.com/site/undefinition/diy-mfaq

                          https://sites.google.com/site/undefi...-provendesigns




                          Dwigle!

                          Thanks for your feedback - I looked through your links and they are eye-openers.

                          The 2 kits offerred here at PE that I keep coming back to are:

                          Samba (reconfigured with a front port) --> https://www.parts-express.com/samba-...only--300-7119

                          Amiga (modified for height requirements of 30" tall, front port as well) --> https://www.parts-express.com/amiga-...inet--300-7124


                          I may well just put these generic crossovers-in the existing cabinets and modify them as Chris suggested as a learning experience and then go build a kit later when I have the extra time to spend on it all.
                          Again,

                          Thanks for the feedback - I am learning . . .



                          Steve.

                          Comment


                          • #14
                            Originally posted by djg View Post
                            FWIW, I would advise you to take Chris R's advice. He is very familiar with that tweeter, and has gone to some effort to look up your woofer and XO. It is a few dollars worth of parts to greatly improve your results. You can see for yourself by trying your components with and without Chris' suggested mods. Make the cabs and run the wires out the port to the crossovers to access them to experiment. SOP for XO designing. Get some short alligator clipped test leads when you order the XO parts.


                            That's what I would do.
                            djg!

                            Excellent suggestions and I do appreciate Chris's response as I understand that he had to spend a little time to help me.

                            Thanks, man!



                            Steve.


                            Comment


                            • #15
                              Originally posted by Kornbread View Post

                              Why am I thinking drummer who wants realistic, in a sense tactile reproduction of drums, might be interested in something like the Trump Tower build?
                              Are the Trump Speaker Towers YUGE or just Big and Beautiful?

                              :D


                              Love it - get some political humor along with building advice . . .

                              In my workshop I have a pair of BIC America https://www.parts-express.com/bic-fo...eaker--303-434
                              speakers mounted on their side at ear level on 5" thick open cell foam blocks about a foot from the wall that I added dampening material too
                              and also reduced their internal volume slightly with a 5" X 5" X 1.5" closed cell foam.

                              Steely Dan-Gold album is so alive on these things and this is the sound I am after - drums sound like I am sitting on the kit playing them.
                              They go deep too and I got rid of the sub-woofer in that setup because of them.

                              (That ^ is a really well sound engineered recording on CD).




                              The links in your sig line are good references and I will look them over in detail later.

                              Later, man.

                              Steve.



                              Comment

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