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Rs100-4 in a sharp does it need a bsc?

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  • Rs100-4 in a sharp does it need a bsc?

    Sorry in advance, i had issues adding to my previous post...im going to put in an order for the RS100-4 drivers as they model slightly better than i throught and on paper appear to have a higher frequency response than the other ones in the series (100 vs 100P). Its going into the Sharp Boombox i have, but not sure if in a vented setup whether or not i would need a BSC?

    I was also curious what ther cut off for the frequency response is for when a driver is called a mid range and not a full range? i think i could actually fit the RS125 series, but think that 12000 hz is potentially in the woofer terriorty and not FR?
    Attached Files

  • #2
    I'm confused. Why would it not need BSC?

    There's no clear line between a midrange driver and full range. I'll note the dispersion of the RS100-4 narrows a lot past 6kHz, so hardly optimum treble, unless you sit right on-axis.
    Francis

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    • #3
      Originally posted by fpitas View Post
      I'm confused. Why would it not need BSC?

      There's no clear line between a midrange driver and full range. I'll note the dispersion of the RS100-4 narrows a lot past 6kHz, so hardly optimum treble, unless you sit right on-axis.
      i'm not sure, to be honest, the last few projects i've done were pretty low fi and low powered so didnt use anything and the phantom clone didnt have one either.

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      • fpitas
        fpitas commented
        Editing a comment
        Well it sounds like you've made your choice.

      • 3rutu5
        3rutu5 commented
        Editing a comment
        Thanks.for the comment

    • #4
      With the DSP enabled amp boards now available, I'd personally use those and measure then EQ the system electronically. Without DSP, I'd still always measure and do a passive contour network.

      Bass output or at least perception of bass output is what separates a meh bluetooth box from a good one. My opinion anyway... granted, I like bass.
      Electronics engineer, woofer enthusiast, and musician.
      Wogg Music
      Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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      • #5
        Modeling in WinISD (RS100-4, the orig. Al cone: Qts=0.53, Vas=0.05cf, Fs=82) in 0.14cf (my best guess as to your volume from your posts), I see an F3 near 50Hz w/a tuning in the high 50s (1-1/4"id port by 6" long).

        You CAN add a passive contour network (co$ts money AND sensitivity), but some (very successful) designers opt for a higher tuning which can help simulate BSC (at the expense of a slightly higher F3). Using this method you actually gain sensitivity - compared to using a filter.

        If you shorten that vent down to 3"-4" (raising the tuning into the low 70s), your F3 does go up about 10Hz, but you end up w/a 3-4dB boost near the bottom end.

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        • #6
          I'd take the RS100 paper version over the aluminum version every time for mid range duty. If I was concern about bass response the RS125 can reach higher SPL at a lower f3.
          John H

          Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

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          • #7
            Originally posted by Chris Roemer View Post
            If you shorten that vent down to 3"-4" (raising the tuning into the low 70s), your F3 does go up about 10Hz, but you end up w/a 3-4dB boost near the bottom end.
            Chris' suggestion and Wogg's comment align with most BT speakers I have heard. They tend to favor a plump 80 to 120hz range to give the impression of full bass.

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            • #8
              Originally posted by wogg View Post
              With the DSP enabled amp boards now available, I'd personally use those and measure then EQ the system electronically. Without DSP, I'd still always measure and do a passive contour network.

              Bass output or at least perception of bass output is what separates a meh bluetooth box from a good one. My opinion anyway... granted, I like bass.
              well i do have one of those sure 2*50w boards (exactly the same as DA KAB one) in my stash that has the DSP pots on it, i completely forgot about it. i'll have to check which model it was as there were 3 at the time and im sure there have been more since. I agree regarding the full bass, my home made one with the TEBM65's hit some low bass and i quite like it, albeit i dont really get to crank it these days as it annoys the kids.

              I did think about a few different options like putting some big PR's on the back, potentially a 5/6inch sub, but as i'm building in a 40 year old unit i'm trying to limit the amount of butchering, so manipulating electronically could be a really good option.

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              • #9
                Originally posted by jhollander View Post
                I'd take the RS100 paper version over the aluminum version every time for mid range duty. If I was concern about bass response the RS125 can reach higher SPL at a lower f3.
                ok, i guess i suggested the RS125 as the opening was around 95/97mm, but wasnt sure due to it only reaching 12000hz, that was the only think driving the mentioning of that. But in saying that the RS100P is only considered a mid range on the loudspeakerdatabase due to an upper end of 12500hz, for the green person this is slightly confusing for my simple brain.

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                • #10
                  Originally posted by Chris Roemer View Post
                  Modeling in WinISD (RS100-4, the orig. Al cone: Qts=0.53, Vas=0.05cf, Fs=82) in 0.14cf (my best guess as to your volume from your posts), I see an F3 near 50Hz w/a tuning in the high 50s (1-1/4"id port by 6" long).

                  You CAN add a passive contour network (co$ts money AND sensitivity), but some (very successful) designers opt for a higher tuning which can help simulate BSC (at the expense of a slightly higher F3). Using this method you actually gain sensitivity - compared to using a filter.

                  If you shorten that vent down to 3"-4" (raising the tuning into the low 70s), your F3 does go up about 10Hz, but you end up w/a 3-4dB boost near the bottom end

                  I see an F3 around 60Hz w/the RS100P-4 (1-1/4"id equivalent port, 5" long) in 0.14 cf. That Coax won't go that low.
                  The TCP woofers LOOK to do 50Hz (in WinISD) but MY little desktop speakers also looked like they'd do 50, but in reality (on the desktop) they do a STRONG 40Hz.
                  They'd need an equivalent port that's an inch or 2 longer (than the RS100) to get there .


                  actually did some rough measurements and took out a little volume by the time i print a divider and remove space for the amp/batteries and it looks like i have closer to 0.18cuft each side. I woke up this morning thinking to do "repurpose" my desktop speakers you helped me do last time, but i cant bring myself to pulling those ones apart even though im not using them that and really i've only ever used the tectonic BMR's.
                  So if i'm understanding correctly if i increase my box tuning to 70hz over the 60hz i put in this would reduce the F3 but would give me a bump in DB's.

                  Also i missed the point of your previous message in the other post, but now see, you were recommended the paper variants over the aluminum ones even though they didnt reach 20000hz as they will sounds better. I think what i cut in pasted from the other post is very doable, if not the ability to get more volume out of the current space, the 0.14 looks too small, unless its that space minus a port and some other items, so could be very conservative.

                  Im still a little bummed as i still want to use those TCP's, but worried that the opening the previous tweeters sat in would be restrictive, otherswise i would be asking for that x-over using the tiny tangbangs.I dont know if i could impose on your goodwill to sim up the x-over incase i change my mind over the weekend as i'll put in my order later today/tomorrow (weekend in Australia) and i can stop ummm'ing and arrr'ing and just put in an order.

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                  • #11
                    Hi 3rutu5,

                    I received four of the RS100-4's last week, burned them in and measured with a DATS v3. Measurements are at the bottom of this post, pretty close to mfg specs but they do model a little differently. Red line is yours, green line is an average of the 4 actual measurements.

                    Below is your model of 0.15 cf tuned to 60Hz. While the transfer function LOOKS like you will have an F3 of 52Hz take a look at cone excursion. At 15 watts you exceed xmax in the 90Hz range and run out of xmax below 52Hz anyways. In this box and tuning a 1.25" port is 5.2" long.

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                    Now look at a 0.12 cf box tuned to 74Hz. Transfer function looks like an F3 of 60 Hz but your realistically running out of excursion around 63Hz. BUT you have better cone control everywhere else (this is with the same 15 watts but you can get more SPL because you can run it to 20 watts without exceeding xmax.

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                    I would guess that the difference in F3 of 60 Hz or 52 Hz isn't going to make a perceptible difference. BUT, you now have the bump that Wogg, Chris, and Squib mention. The extra 2-3db bump at the low end with the 74Hz tuning is going to be perceived as more bass. And for convenience the port is now 4" long.

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                    • Billet
                      Billet commented
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                      Very descriptive post...

                    • Billet
                      Billet commented
                      Editing a comment
                      Is it also a good idea to add a high pass filter below the port tuning frequency to prevent over-excursion with deep bass? A 500 uF non-polarized electrolytic capacitor maybe?

                  • #12
                    Yeah (not really),
                    problem being w/the double Z-peaks (that vented boxes have).
                    A 500uF series cap CAN pull the output down about -3.5dB @ 70Hz (Fb), but near 50Hz (the lower Z-peak) you're back up to only -1dB before it THEN starts to drop...
                    about -6dB @ 40, -10 @ 30, and -14 @ 20.

                    You COULD Zobel the driver, but to flatten out the double peaks (significantly) you need even more capacitance, and the Z-nom of the 4ohm driver approaches 2ohms, AND then the F3 rolloff reaches even higher to the point of losing the "bump" you designed in (around 100-200Hz) AND bottom end output.
                    It's best just to avoid exceeding Xmax w/the volume control - IMO (or EQ your source for a rapid attenuation below tuning). <- ;-)

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                    • #13
                      FYI i got a pair of RS100-4's, they are small. I sort of wish that there were something in that 5 inch range that are full rangers, but hey ill make it work.

                      First step will be printing a mount for these to plug into the stock holes, then a divider and port holes to make it look like it was factory with vents. I will shorten the length as suggested as well to increase the f3 and give that perception of fuller bass as well. So unless i should run out and get some parts for a BSC maybe thats it from the speaker side, after that will be figuring out what AMP/BT combo i want and a suitable battery board.

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                      • #14
                        What is the baffle size of the boom box and the driver mounting locations? We could do a quick sim with the response blender and add a filter or two in Xsim.
                        John H

                        Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

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                        • #15
                          Originally posted by jhollander View Post
                          What is the baffle size of the boom box and the driver mounting locations? We could do a quick sim with the response blender and add a filter or two in Xsim.
                          The boombox itself is 500mm wide and the drivers will be rear mounted and approximately 100mm from the outside edge to the center of the cone
                          Attached Files

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