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PC Speakers (T Line Box)

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  • #16
    Using eyeballs, not cad, the drawing is fine and material thickness is easily determined. The two inner piece lengths are not called out, but are easily interpreted. At least to me.

    your speakers look very nice. I have a pair of Tyger 23's Mariposas with that woofer and little Dayton tweeter, in solid aspen. Sound nice.

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    • #17
      Yeah i realised that the dimensions were pretty close after i wrote that first post.

      Very nice looking set of 2.1 i like the contrast between the light timber and the darker drivers. If i had more confidence with the cross over i would have liked to put a tweeter in there, but i guess that can be the second attempt at them if i feel adventurous later. Are they powered?

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      • #18
        Originally posted by Chris Roemer View Post
        Line length looks to be about 24"-25", with the driver at 1/3 wave?
        sorry mate, not sure what that means. Unless it is the length it travels inside the box until it exits the port?

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        • #19
          There are two driver locations along a T-line that work out best, one at 20% from the beginning of the line and the other at 33% from the beginning of the line. Your drawing and build indicate the driver is at the 33% location (i.e., 1/3). But, the driver doesn't necessarily have to be located at exactly 1/5 or 1/3, just essentially so. Later today, I plan to model what you've built based on the drawing and the published specs of the driver used, then share it here.
          Paul

          Originally posted by 3rutu5 View Post

          sorry mate, not sure what that means. Unless it is the length it travels inside the box until it exits the port?

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          • #20
            Originally posted by djg View Post
            Using eyeballs, not cad, the drawing is fine and material thickness is easily determined. The two inner piece lengths are not called out, but are easily interpreted. At least to me.

            your speakers look very nice. I have a pair of Tyger 23's Mariposas with that woofer and little Dayton tweeter, in solid aspen. Sound nice.
            Nice job on the Mariposas. I considered doing a larger ported version. It's on the list somewhere. ;)

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            • #21
              Originally posted by 3rutu5 View Post
              Yeah i realised that the dimensions were pretty close after i wrote that first post.

              Very nice looking set of 2.1 i like the contrast between the light timber and the darker drivers. If i had more confidence with the cross over i would have liked to put a tweeter in there, but i guess that can be the second attempt at them if i feel adventurous later. Are they powered?
              Bedside internet radio system with a 2.1 chip amp.

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              • #22
                I modeled the line as built by "3rutu5", but before you view the modeling results I need to make a few comments. When designing a TL the first thing to choose, after choosing a driver, is to estimate what system tuning frequency is likely to be appropriate for that driver such that the overall response shape is reasonably smooth. In the "olden" days that was the driver's fs, but that's only true if the driver's Qts is equal or close to 0.4. When Qts is lower than 0.4, the system tuning frequency will need to be higher than fs, and if Qts is higher than 0.4, the system tuning frequency will need to be lower than fs. This driver's Qts is 1.07, and the system tuning frequency will need to significantly lower that the driver's fs of 92 Hz. So, I've attached some modeling results which I hope are adequately clear. For the record, I prefer drivers for TLs to have a Qts of 0.35 to 0.50.
                Paul
                3rutu5 TL.doc

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                • #23
                  Originally posted by Paul K. View Post
                  I modeled the line as built by "3rutu5", but before you view the modeling results I need to make a few comments. When designing a TL the first thing to choose, after choosing a driver, is to estimate what system tuning frequency is likely to be appropriate for that driver such that the overall response shape is reasonably smooth. In the "olden" days that was the driver's fs, but that's only true if the driver's Qts is equal or close to 0.4. When Qts is lower than 0.4, the system tuning frequency will need to be higher than fs, and if Qts is higher than 0.4, the system tuning frequency will need to be lower than fs. This driver's Qts is 1.07, and the system tuning frequency will need to significantly lower that the driver's fs of 92 Hz. So, I've attached some modeling results which I hope are adequately clear. For the record, I prefer drivers for TLs to have a Qts of 0.35 to 0.50.
                  Paul
                  [ATTACH]n1389354[/ATTACH]
                  Thanks Paul, very incite-full, honestly i didnt look too much into the specs of the driver when purchasing, (will probably get shot for saying this) but more looking and copying somebody else's design, parts etc based on what they wrote about. What i'm reading in this with my limited (no) experience with this to date, is the length "run" within the box is really too short in order to accommodate the drivers Hz, with almost twice the length required optimally. Am i correct with reading that if i stuff 2/3rds it will improve the tuning and smooth out the curve, but still be inefficient due to the higher than normal Qts?

                  Originally I was going to get the DA ND91's which have the qts at 0.47 which could have worked better in a TL? Maybe should have stuck to my guns and asked about the box.

                  I will look at stuffing these boxes further as i originally removed it thinking that it reduced the bass (only to my ears) on one side, but this was done as a test prior to assembly to make sure i dont put it together and there was a dodgy component or solder.

                  I find the wood working and physical/aesthetics design of the boxes very interesting but may cut corners with using the software as i dont currently understand this end of things. Next time i will consult the masses prior to construction as i would have redesigned the box or ordered different drivers.
                  ​​​​​​

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                  • #24
                    Always happy to help. Drivers with a Qts much above 0.5 are much less prone to perform well in a TL based on my experience. A driver with a Qts of 0.47 would almost assuredly perform much better than the driver you used, but the line would have to be designed to suit its fs and Qts. Without any stuffing, or very little, you definitely heard more apparent bass. Looking at the 3 graphs I posted you'll notice that the driver has a peak in its response around 120 Hz, which was reduced in magnitude by, first, lengthening the line and lowering the tuning frequency, then, second, stuffing the whole line instead of just the first 2/3. So, if you do the opposite by removing the stuffing or decreasing its density, that peak at 120 Hz will become larger and larger. For a tapered line, which is essentially what you built, and using appropriate drivers, I've found that stuffing the first 2/3 of the line at a density of 0.75 lb/ft3 works well almost all of the time, but each design needs to be viewed as what's best for it and your design goals. For your build keep in mind that the first graph in my attachment shows what should result if you stuff the first 2/3 of the line at 1 lb/ft3. For the record if it's necessary to use a stuffing density greater than 1 lb/ft3 and/or to stuff the whole length of a line to achieve a good response, there's something lacking in the design and should be re-thought [assuming the designer wants an overall response shape that's appreciably smooth as well as getting support in the bass from the line's terminus (exit)].
                    Paul

                    Originally posted by 3rutu5 View Post

                    Thanks Paul, very incite-full, honestly i didnt look too much into the specs of the driver when purchasing, (will probably get shot for saying this) but more looking and copying somebody else's design, parts etc based on what they wrote about. What i'm reading in this with my limited (no) experience with this to date, is the length "run" within the box is really too short in order to accommodate the drivers Hz, with almost twice the length required optimally. Am i correct with reading that if i stuff 2/3rds it will improve the tuning and smooth out the curve, but still be inefficient due to the higher than normal Qts?

                    Originally I was going to get the DA ND91's which have the qts at 0.47 which could have worked better in a TL? Maybe should have stuck to my guns and asked about the box.

                    I will look at stuffing these boxes further as i originally removed it thinking that it reduced the bass (only to my ears) on one side, but this was done as a test prior to assembly to make sure i dont put it together and there was a dodgy component or solder.

                    I find the wood working and physical/aesthetics design of the boxes very interesting but may cut corners with using the software as i dont currently understand this end of things. Next time i will consult the masses prior to construction as i would have redesigned the box or ordered different drivers.
                    ​​​​​​

                    Comment


                    • #25
                      Originally posted by djg View Post
                      Using eyeballs, not cad, the drawing is fine and material thickness is easily determined. The two inner piece lengths are not called out, but are easily interpreted. At least to me.

                      your speakers look very nice. I have a pair of Tyger 23's Mariposas with that woofer and little Dayton tweeter, in solid aspen. Sound nice.
                      after having these set up and running, i'm quite happy with how they sound for the application, but after seeing what Paul K posted and seeing your Mariposas, im wondering what they can sound like. I like the novelty of the T Line, but watching folks doing horns etc. For these Drivers to work better, it looks like the length needs to be doubled. honestly more interested in doing the woodworking side of these and would love to build something solid and laminate some timber. if i was to design a horn or another t line, what would be the smallest box size required to make these drivers sounds awesome. I could be tempted to get some little DA tweeters, but would need my hand held with a cross over design and how you actually assemble these things.

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                      • #26
                        One note. There is a diyaudio.com thread on these speakers where someone measured the T/S specs and came out with a much lower QTS and FS (and higher VAS) than the published specs. So they may be better suited for a TL than the published specs would indicate.
                        Using published specs, a sealed box with maybe a passive assist seem better.

                        Comment


                        • #27
                          Originally posted by djg View Post
                          Using eyeballs, not cad, the drawing is fine and material thickness is easily determined. The two inner piece lengths are not called out, but are easily interpreted. At least to me.

                          your speakers look very nice. I have a pair of Tyger 23's Mariposas with that woofer and little Dayton tweeter, in solid aspen. Sound nice.
                          Those speakers of yours, are they in a sealed enclosure? How would they sound without the sub? I'm looking into some options for a Bluetooth rig and noticed the recommendation size for a sealed box being .1ft3 which I'm under the assumption that this would be a good example for a passive radiator.

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                          • #28
                            Nope. Even though many have the idea that a PR design is similar to closed ('cause there's no open "hole" - I guess), it's actually VERY close to a ported design. The mass on a PR is used to tune the box, the same way the mass of air in a port tube tunes a box.

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                            • #29
                              Originally posted by Chris Roemer View Post
                              Nope. Even though many have the idea that a PR design is similar to closed ('cause there's no open "hole" - I guess), it's actually VERY close to a ported design. The mass on a PR is used to tune the box, the same way the mass of air in a port tube tunes a box.
                              Oh right, I'm not sure a lot of folks actually look at the volume requirements when doing these smaller kits. I've only been looking at YouTube as I don't really understand the nitty gritty designs involved in speaker, but have noticed a tiny enclosure with the use of the PR, can't really tell the quality of the output either as it is through a mpeg.

                              I guess an alternative is using the 2.5 driver with a 4inch passive, but using the volume requirements of a vented box.

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                              • #30
                                Yeah ... part of the FUN of all this speaker design/building hobby is running simulations. WinISD ( from linearteam.org ) uses T/S (Thiele/Small) parameters (mainly Qts, Fs, and Vas) to determine the proper box style (closed or ported), internal volume, and tuning (if vented). The "designers" on here don't just take a guess at what might work (although that kinda WAS S.O.P. back 40 yrs ago), it uses up too much time, material, and money. A box sim tells you how low your selected woofer will be able to play, and a crossover simulator helps in the design of a crossover (mostly for 2-ways and 3-ways). It's often POSSIBLE to run such an accurate sim that if you build it, then measure it, it ends up running within a dB or 2 of your design sim.

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