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  • Tips for choosing tweeter and crossover to match woofers

    Hey guys,

    I know this generally isn't the right order to do things, but I helped a friend out at one point and bought a pair of GRS 8PR-8 off of him.

    Now, I currently have a pair of Boston Acoustics CR5 as the only speakers in a TV/Movie/Games system. They're fine for music, but they fail to convey any LFE. I figured these 8PR8s might do OK as additional fronts to deliver the low-end that the Bostons can't handle. To help the GRSs reach lower, I would either go with a ported enclosure or use a passive radiator (8" or 10"). Size is not an issue.

    My other option is to make a some two-way speakers and run the Bostons as surrounds. In that case, I need advice on choosing tweeters and building a crossover. I have no idea where to start, and I'm sorry for being constrained to these woofers, but that's my situation.

    Any advice is much appreciated!

  • #2
    Re: Tips for choosing tweeter and crossover to match woofers

    How large of an enclosure are you considering? What is the max size?
    HAGD,
    Marc

    Even though I try to tell everyone upfront, understand that I am still a Newb. I wish the status of Seasoned Veteran/Senior Member, etc. was earned with time not posts...

    TMWW thread

    Maurbacs DCR Tower

    Comment


    • #3
      Re: Tips for choosing tweeter and crossover to match woofers

      You won't get what out of those. You would need a huge box for the high QTS of those babies. Check some of the designs posted and post what your desires are. You will receive plenty of advice.
      Kenny

      http://www.diy-ny.com/
      DIY NY/NJ 2014 https://www.youtube.com/watch?v=FGwA...ature=youtu.be
      Man does not live by measurements alone, a little music helps.

      Comment


      • #4
        Re: Tips for choosing tweeter and crossover to match woofers

        Originally posted by Stein View Post
        My other option is to make a some two-way speakers and run the Bostons as surrounds. In that case, I need advice on choosing tweeters and building a crossover. I have no idea where to start, and I'm sorry for being constrained to these woofers, but that's my situation.
        To design your own speakers, you need at least a tool to measure impedance and frequency response - for example a Dayton DATS, Mic Preamp, and Mic at the very least. Along with the cost of tweeters and crossovers, it would probably end up costing quite a good bit for a pair of 10 dollar woofers. Especially since 8" drivers are difficult to mate to tweeters in the upper midrange. Even if you manage to get useable measurements online, your best bet would probably be a 2" midtweeter rather than a true tweeter - I don't think you want to be shelling out 50-75 bucks for RS28s and SB29s - but then you have to make sure it's efficient enough to do passively.

        I'm not trying to be negative here. But your best bet is to find someone nearby to help you out with things like measurements and general advice. Where do you live?
        :blues: Flat frequency response, a smooth sound power response free of resonance, careful driver-integration, and high dynamic range both upward and downward :blues:

        Comment


        • #5
          Re: Tips for choosing tweeter and crossover to match woofers

          So you want to use the GRS drivers as subwoofers? Unfortunately, they will not work well for that purpose. The important number/spec here is Qts, and that driver has a Qts of 1.11, which is one of the highest I've ever seen and have never seen in any project/design. You want a Qts of between .30 and about .60 for the driver to be able to work properly in a sealed or ported box. Plus the excursion/Xmax is only 3mm...not enough for a subwoofer. You can see this using a program like WinISD:

          http://www.linearteam.dk/default.aspx?pageid=WinISD


          Entering the T/S parameters, which Qts is one of, you'll be able to see how large of a box it will suggest based on the T/S numbers. I would not consider using it in a ported box with a Qts like that driver has, even though the spec page gives a ported volume spec. I guess you could run the numbers through WinISD and see if it generates something you could work with. Definitely sealed. If I saw a driver with a QTS of 1.11, it wouldn't be a contender for any application. Paul has done a great write-up/FAQ's about this stuff:

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


          Read everything under "Resources" at the right. It will only take a few minutes and the info and knowledge you'll gain will be invaluable when you might need to choose another driver for another project/idea. And also why some of us are giving certain advice and suggestions. Don't hesitate to ask ?'s if something isn't clear...no question is too dumb or redundant. The Speaker Building "sticky" at the top has tons of great info, and a read through Paul's info will get you the basics and a good foundation to start from.


          John A.
          "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
          Emotiva UPA-2, USP-1, ERC-1 CD
          Yamaha KX-390 HX-Pro
          Pioneer TX-9500 II
          Yamaha YP-211 w/Grado GF3E+
          Statement Monitors
          Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
          Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
          Blogs: http://techtalk.parts-express.com/blog.php?u=2003

          Comment


          • #6
            Re: Tips for choosing tweeter and crossover to match woofers

            Originally posted by WernerM View Post
            How large of an enclosure are you considering? What is the max size?
            I'm constrained to a maximum height of 13", depth of 19" and width can be up to about two feet.

            Originally posted by GranteedEV View Post
            ...
            I'm not trying to be negative here. But your best bet is to find someone nearby to help you out with things like measurements and general advice. Where do you live?
            I'm located just east of Seattle, WA.
            So would you suggest just a 2" with the 8", or a 2" and another tweeter in addition? I was trying to avoid a 3-way crossover due to complexity, but if somebody else helps design it, I'm willing to solder it.

            Originally posted by johnastockman View Post
            So you want to use the GRS drivers as subwoofers? Unfortunately, they will not work well for that purpose. The important number/spec here is Qts, and that driver has a Qts of 1.11, which is one of the highest I've ever seen and have never seen in any project/design. You want a Qts of between .30 and about .60 for the driver to be able to work properly in a sealed or ported box. Plus the excursion/Xmax is only 3mm...not enough for a subwoofer. You can see this using a program like WinISD:

            ...

            John A.
            Thanks for the links! I was not really looking to use it as a subwoofer, because you're right, the range of motion on these is quite slim. I was thinking more of a deeper-reaching main to compliment my current speakers.

            What do you ride, if you don't mind my asking?

            Comment


            • #7
              Re: Tips for choosing tweeter and crossover to match woofers

              I'm near Chehalis, WA. I think I didn't read carefully enough about what you were wanting to use them for, sorry. Although the advice I mentioned about sub drivers in general was correct. If you run the numbers with WinISD, it can generate a "suggested" volume, so you could see if the volume will fit in your space. A 3-way XO is exponentially more difficult to design than a 2-way. A task I wouldn't recommend to someone starting out. I don't know of any posted or available designs that use that woofer. I'd have to look at a frequency response plot to see where it's break-up modes are, as you cannot go by the listed frequency response range, which for that driver is 40Hz - 5000Hz. I know from experience that an average 8" woofer will not like being crossed near 4-5000Hz. More like down around 2000Hz, if that. Don't be tempted to use an off-the-shelf pre-made XO either, or an online calculator. If it only asks for the driver's nominal/average impedance (4 or 8ohms) and an arbitrary cross-frequency, do not use it. Impedance varies with frequency and is never a fixed number. I'd see if someone wants to assist in a simple XO design. I'm in the process of learning a XO design program that uses freq. and impedance data. Maybe if there's some data files on those woofers, but I'm not proficient with it quite yet. I could take a stab at it, depending on how quickly you need to put this together. Only a 2-way as of now, but there's a lot of tweeters that might work in a 2-way. I could be talking out the bum. Just throwing out some options/ideas.

              I used to ride...a lot. I have a rare genetic collagen defect which has destroyed all the cartilage in every joint. Degenerative, it has worked it's magic on me over the years and I had to make the toughest decision of my life...stop riding. That was in 2010. I have a long story with my disability and the triumphs and tragedies of becoming a motorcyclist. My family when I grew up were all accomplished motorcyclists, men and women, grandpa and grandma, aunts and uncles, cousins, etc. My hips were fused together by the time I was 14 and I used crutches for about 12 years. I had a series of hip replacement surgeries between 1980 and 1993...3 surgeries/replacements between 1980 and 1983. I wanted to ride alongside my grandpa on my own motorcycle. I got my first street bike in '83 and didn't look back until 2010. Pretty good run for a handicapped motorcyclist, 310,000 miles on just the bikes I owned. With a lot more on various bikes I got to ride and evaluate including off-road bikes. I ended my riding career on a 2006 Ural Tourist 750 sidecar rig and a 2007 Suzuki Burgman 400. Before that I had a GL1500 Gold Wing for about 11 years and put 172,000 miles on that. I had a Yamaha SR500 that I raced in northwest amateur racing at the old SIR, PIR and Bremerton all through the mid 80's through the late 90's. If you want to talk bikes, send me a PM. The guys here will give you great advice about what you want to accomplish. They certainly steered me in the right direction, over 13 years ago.


              John A.
              "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
              Emotiva UPA-2, USP-1, ERC-1 CD
              Yamaha KX-390 HX-Pro
              Pioneer TX-9500 II
              Yamaha YP-211 w/Grado GF3E+
              Statement Monitors
              Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
              Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
              Blogs: http://techtalk.parts-express.com/blog.php?u=2003

              Comment


              • #8
                Re: Tips for choosing tweeter and crossover to match woofers

                Ok, I have built a TMWW ( thread is in my sig) using the 2 GRS 8PR-8's to cover the bottom end. Here is the thing, 2 will give some nice punch, BUT they require a huge tower (mine is 40"H x 10"W x 18"D ) to get there. My TMWW design is every bit as good as what you can find at any Best Buy, but after building someone else's design I realize there are some changes that would need to be made to get the full potential of sound quality, so I don't recommend building them. You are more than welcome however, to browse through it to get a perspective of the design process struggles, and learning that I went through. Bottom line is, I don't think the GRS's will fit the bill for what you are wanting. However, YMMV.
                HAGD,
                Marc

                Even though I try to tell everyone upfront, understand that I am still a Newb. I wish the status of Seasoned Veteran/Senior Member, etc. was earned with time not posts...

                TMWW thread

                Maurbacs DCR Tower

                Comment


                • #9
                  Re: Tips for choosing tweeter and crossover to match woofers

                  John, thanks for the response! I estimate about 5 ft^3 per box, but that seems high to me. I could do it, but I'll probably stick to 2-2.5 ft^3
                  Once I get more into WinISD I'll get a better volume number I hope.

                  Originally posted by WernerM View Post
                  Ok, I have built a TMWW ( thread is in my sig) using the 2 GRS 8PR-8's to cover the bottom end. Here is the thing, 2 will give some nice punch, BUT they require a huge tower (mine is 40"H x 10"W x 18"D ) to get there. My TMWW design is every bit as good as what you can find at any Best Buy, but after building someone else's design I realize there are some changes that would need to be made to get the full potential of sound quality, so I don't recommend building them. You are more than welcome however, to browse through it to get a perspective of the design process struggles, and learning that I went through. Bottom line is, I don't think the GRS's will fit the bill for what you are wanting. However, YMMV.
                  Thanks for the link. I actually stumbled upon that through Google a while back but it was more than I was looking to do. I'd like to not add more of these GRS drivers, and I'd like to keep it 2-way.
                  What volume did you end up using for your towers? And they were ported, correct?

                  Comment


                  • #10
                    Re: Tips for choosing tweeter and crossover to match woofers

                    For the money and sound quality and for a first build, I can suggest Paul Carmody's ClassixII's. I built a pair as my first. They sound good, have bass that is surprising for their size, and don't cost a fortune to build. I fancied mine up beyond his design a bit, and I think I've lost them to my roomie who was a Bose Acoustimat 5 owner before he heard the light. The evening I took them over to his old apartment, hooked them up to his Pioneer receiver and shoved The Eagles "Hotel California" into his CD carousel, I'm glad his neighbors liked it too. He kept cranking them up and up and up and they didn't sound bad, they just rattled the doors...

                    Comment


                    • #11
                      Re: Tips for choosing tweeter and crossover to match woofers

                      Originally posted by Stein View Post
                      So would you suggest just a 2" with the 8", or a 2" and another tweeter in addition? I was trying to avoid a 3-way crossover due to complexity, but if somebody else helps design it, I'm willing to solder it.
                      Avoid a 3-way not only because of complexity but it just doesnt seem worth the added cost for a ten dollar woofer. Of course, if you pick a good midtweeter, you can always repurpose it in a more ambitious build as a midrange!

                      A few midtweeters i would be looking at include the Fostex FF85wk, Faital Pro 3FE20, Tandband W3-1364Sa and the many peerless 2" units with over 85db/2.83v/m sensitivity (830983 being one)
                      :blues: Flat frequency response, a smooth sound power response free of resonance, careful driver-integration, and high dynamic range both upward and downward :blues:

                      Comment


                      • #12
                        Re: Tips for choosing tweeter and crossover to match woofers

                        Or, how about this:
                        http://www.parts-express.com/pe/show...umber=264-1046

                        A true high end aluminum full range with enough efficiency and clean response.
                        :blues: Flat frequency response, a smooth sound power response free of resonance, careful driver-integration, and high dynamic range both upward and downward :blues:

                        Comment


                        • #13
                          Re: Tips for choosing tweeter and crossover to match woofers

                          Originally posted by Stein View Post
                          Hey guys,

                          I know this generally isn't the right order to do things, but I helped a friend out at one point and bought a pair of GRS 8PR-8 off of him.

                          Now, I currently have a pair of Boston Acoustics CR5 as the only speakers in a TV/Movie/Games system. They're fine for music, but they fail to convey any LFE. I figured these 8PR8s might do OK as additional fronts to deliver the low-end that the Bostons can't handle. To help the GRSs reach lower, I would either go with a ported enclosure or use a passive radiator (8" or 10"). Size is not an issue.

                          My other option is to make a some two-way speakers and run the Bostons as surrounds. In that case, I need advice on choosing tweeters and building a crossover. I have no idea where to start, and I'm sorry for being constrained to these woofers, but that's my situation.

                          Any advice is much appreciated!
                          In general an 8" woofer needs to be crossed at 1200Hz or lower for reasonable dispersion. This requires a very robust tweeter or a small mid/tweeter. The latter can have issues with dispersion itself at higher frequencies so you trade one issue for another. Since HT applications usually involve multiple listeners at a varying number of off axis seating areas it is always advisable to design the speaker for the best dispersion/off axis listening response.

                          So if you were to choose a tweeter with good dispersion that can cross low to your woofer you can expect to pay multiples for it compared to what your woofer cost. I think what others are trying to say is you would be better off choosing a good 5.25 or 6.5" midwoofer and tweeter. If you need high spl you can do MTMs or MMT configurations to improve ultimate spl.

                          Personally I think if you are set on this woofer then a 3 way is a better choice, yes it is a bit more complex to design and yes it involves more parts. But when you consider the cost of a high end tweeter that could mate to your woofer it might a better option financially to use a 3" midwoofer and 3/4" tweeter mated with your 8" woofer. Then cross that 3 way to a subwoofer at 80Hz as the 8" woofer you have chosen is going to be excursion limited plus you can get by with a smaller than optimum box since you won't be trying to get too much bass extension from them.
                          Dave

                          If you can read this, thank a teacher.
                          If you are reading it in English thank a Veteran
                          .

                          Comment


                          • #14
                            Re: Tips for choosing tweeter and crossover to match woofers

                            Originally posted by dthomas View Post
                            In general an 8" woofer needs to be crossed at 1200Hz or lower for reasonable dispersion. This requires a very robust tweeter or a small mid/tweeter. The latter can have issues with dispersion itself at higher frequencies so you trade one issue for another. Since HT applications usually involve multiple listeners at a varying number of off axis seating areas it is always advisable to design the speaker for the best dispersion/off axis listening response.
                            I don't disagree with anything you've said, but I do think that for HT applications, frequencies above 8-9khz aren't really all that vital, and below that a 2" tweeter can still have fine dispersion. Let's say you cross that vifa 65mm around 800hz or so... it has usable response at 30 deg off-axis at least up to 10khz (it doesn't look much worse than an XT25 actually), and the horizontal polars are probably going to be fine as well in the midrange.

                            I guess all I'm saying is that you can do pretty well if you're willing to sacrifice a bit of sparkle up top. And a supertweeter would probably be easier to implement 3rd or 4th order than dealing with a true 3-way.
                            :blues: Flat frequency response, a smooth sound power response free of resonance, careful driver-integration, and high dynamic range both upward and downward :blues:

                            Comment


                            • #15
                              Re: Tips for choosing tweeter and crossover to match woofers

                              Alright, so for making an actual, full-range speaker, I have three options:
                              Woofer + Tweeter
                              Woofer + Fullrange
                              Woofer + Mid + Tweeter

                              How much power does a fullrange need to be able to handle? Anything wrong with something along the lines of this?
                              What about going with a sealed mid for a three-way? This keeps the cabinet design simple.

                              Originally posted by GranteedEV View Post
                              I don't disagree with anything you've said, but I do think that for HT applications, frequencies above 8-9khz aren't really all that vital, and below that a 2" tweeter can still have fine dispersion. Let's say you cross that vifa 65mm around 800hz or so... it has usable response at 30 deg off-axis at least up to 10khz (it doesn't look much worse than an XT25 actually), and the horizontal polars are probably going to be fine as well in the midrange.

                              I guess all I'm saying is that you can do pretty well if you're willing to sacrifice a bit of sparkle up top. And a supertweeter would probably be easier to implement 3rd or 4th order than dealing with a true 3-way.
                              Could I have a link to that tweeter? And what do you mean by 3rd or 4th order? Does that refer to the crossover?

                              edit: Going a little more budget conscious with the full-range idea, how does this guy look?

                              Or one of these: http://www.parts-express.com/pe/show...number=297-427

                              Comment

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