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  • Who wants to Sim a x-over?

    I picked up 2 of the new RS100p-8 4" Reference Paper Midwoofers on DOTD this week, and was wondering if anyone would want to toss together a crossover for me? I'm using the RS28F-4 1-1/8" Silk Dome Tweeter as a pair in a very small ~4L Box. The Baffle measure 5" x 9.5", will be 1/2" material. X-over point can be wherever it seems to work out best in your opinion, but I'm eyeballing ~3-4k.

    Have fun with it! Any questions let me know!

    Edit: I made the baffle a little thinner, now 5". Ignore the old thumbnails.



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    Attached Files

  • #2
    Re: Who wants to Sim a x-over?

    If you haven't already purchased the tweeters (or even if you have), I'd suggest using them with a larger woofer where their ability to cross lower would be put to better use. These 100Ps can go so high, that a smaller (cheaper) Neo tweeter would be just great. What're your thoughts?

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    • #3
      Re: Who wants to Sim a x-over?

      Already got the tweeters, I'll eventually use the with a rs180 but that won't be for quite some time. I figured this could be a kick *** small speaker till those get built.

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      • #4
        Re: Who wants to Sim a x-over?

        Where in the room will you be placing these? Near the wall, or out 3 or 4 feet from the walls in "audiophile" fashion?

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        • #5
          Re: Who wants to Sim a x-over?

          It will either be against a tv/monitor or on a bookshelf, near wall.

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          • #6
            Re: Who wants to Sim a x-over?

            Sealed design?

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            • #7
              Re: Who wants to Sim a x-over?

              Sealed, ~4L internal.

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              • #8
                Re: Who wants to Sim a x-over?

                Here's a link to distortion of FR measurements by JasonP, for reference, on the RS100P: http://techtalk.parts-express.com/sh...ghlight=rs100p

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                • #9
                  Re: Who wants to Sim a x-over?

                  If no one actually sims this for you, you could try this x-over. This is a WAG based on speculation, and on some x-overs I've done in the past. The tweeter filter was used on an RS28A. I'm ballparking on the woofer filter.
                  Attached Files

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                  • #10
                    Re: Who wants to Sim a x-over?

                    Looking at rpb's schemo (for reference):

                    LP: a #20 2.0mH series coil (1.2 ohms DCR), then a 12uF shunt cap (to gnd).

                    HP: Had to fiddle with 3 resistors to get what I liked (for me, "n" = ohms):
                    1n series resistor and 17uF series cap, then a #20 0.20mH shunt coil, then a 2n series resistor, and finally 2 shunts to gnd.; a 1.8n resistor and a 5.6uF cap. These are 10w resistor values (PE #016- . . . ).

                    Oh, about 80dB +/-1dB, with about +4dBSC from 1k down to 200Hz. Fc at 1.8k. Going higher and or trying for shallower slopes gets the impedance awful low (due to the broader overlapping of the 4 ohm nominal tweeter). Output only down to the 125-150Hz range probably. Worst case here is 3.5n between 3k and 4k.

                    Oops. Looks like negative polarity on the tweeter.
                    Last edited by Chris Roemer; 03-15-2014, 07:07 PM. Reason: oops

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                    • #11
                      Re: Who wants to Sim a x-over?

                      Originally posted by Chris Roemer View Post
                      Looking at rpb's schemo (for reference):

                      LP: a #20 2.0mH series coil (1.2 ohms DCR), then a 12uF shunt cap (to gnd).

                      HP: Had to fiddle with 3 resistors to get what I liked (for me, "n" = ohms):
                      1n series resistor and 17uF series cap, then a #20 0.20mH shunt coil, then a 2n series resistor, and finally 2 shunts to gnd.; a 1.8n resistor and a 5.6uF cap. These are 10w resistor values (PE #016- . . . ).

                      Oh, about 80dB +/-1dB, with about +4dBSC from 1k down to 200Hz. Fc at 1.8k. Going higher and or trying for shallower slopes gets the impedance awful low (due to the broader overlapping of the 4 ohm nominal tweeter). Output only down to the 125-150Hz range probably. Worst case here is 3.5n between 3k and 4k.
                      I love the way you do this! I just may be pm'ing you soon.

                      Comment


                      • #12
                        Re: Who wants to Sim a x-over?

                        Originally posted by Chris Roemer View Post
                        Looking at rpb's schemo (for reference):

                        LP: a #20 2.0mH series coil (1.2 ohms DCR), then a 12uF shunt cap (to gnd).

                        HP: Had to fiddle with 3 resistors to get what I liked (for me, "n" = ohms):
                        1n series resistor and 17uF series cap, then a #20 0.20mH shunt coil, then a 2n series resistor, and finally 2 shunts to gnd.; a 1.8n resistor and a 5.6uF cap. These are 10w resistor values (PE #016- . . . ).

                        Oh, about 80dB +/-1dB, with about +4dBSC from 1k down to 200Hz. Fc at 1.8k. Going higher and or trying for shallower slopes gets the impedance awful low (due to the broader overlapping of the 4 ohm nominal tweeter). Output only down to the 125-150Hz range probably. Worst case here is 3.5n between 3k and 4k.
                        Is this what you simmed? Polarity as shown?
                        Attached Files

                        Comment


                        • #13
                          Re: Who wants to Sim a x-over?

                          Ha! Funny, but just BEfore I read this, I re-read my post and realized that the tweeter needs to be flopped (and edited THAT post). Sorry.

                          So your schemo. looks good eXcept for the tweeter polarity.

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                          • #14
                            Re: Who wants to Sim a x-over?

                            ONE thing that's gotten to bother me (lately) is that about a year ago (or maybe 2?), PE (or DA) decided to break with their own long-standing tradition of spec'ing driver sensitivity at 2.83v/1m (which, in my mind, is the only proper way to spec. it) and went with the much more ambiguous dB/w/m. I have NO clue why they did this, but wish they hadn't. In a crossover sim, all we care about is that all drivers (in a passive design) see the same voltage. Also, (NOW) I have no clue when tracing an SPL curve whether or not it was generated at 2.83v, or 1w (which is the SAME, but only with an 8 ohm nominal driver). Not only THAT, but I'm pretty sure errors cropped up when the new spec. hit the new catalog (and maybe the online data as well, or NOT??). So . . .

                            Example. When you've got a 4 ohm (or maybe 6, or possibly even 16 or 2?) driver (let's use a tweeter, 'cause they're less ambiguous due to their narrower bandwidth and typically flatter response - esp. within the passband), and it's rated in the catalog (and online, let's say they match just for the sake) at 90dB/w (which we know is only 2v @ 4 ohms), and we look at a plot and it's CLEARLY running 93dB, I just HAVE to assume that the plot was done at 2.83v and NOT 1w. So I use the FR data "as is".

                            But, if I see a 90dB/w tweeter, and the plot also LOOKS like 90, then I feel as though I MUST add 3dB to the FR plot (since it MUST have been made at 2v, or 1w) to normalize my sim drivers to 2.83v. What do I do when a 4n driver is spec'd at 93dB/w and the FR plot is clearly 90dB? Do I assume the plot was at 1w (2v)? And that the 93dB rating is erroneous (and should really be 90dB/w, and/or 93dB/2.83v). With a driver I've never used (and I sim WAY more of those than drivers I've used myself), SOMEtimes there'll be a(nother) discrepancy between the catalog entry and online data. Then, 2 out of 3 wins? What do most of you guys do? (Maybe this uncertainty was planned to coax more people into purchasing their own DATS/and microphones?). Just thinkin'.

                            Chris

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                            • #15
                              Re: Who wants to Sim a x-over?

                              Originally posted by rpb View Post
                              Is this what you simmed? Polarity as shown?
                              I appreciate this! I was having a hard time visualizing that. haha.

                              I will go with this schematic if something else doesn't come up by monday morning, that's when I'm ordering all the parts.

                              I was playing with my minidsp using the settings from another one of my builds which has the tweeter x-over at ~1900 and the tweeter really does have a kick-*** sound. Very good through its whole bandwidth from what I was listening to! I'm very happy with the purchase, I was hesitant to put so much $$ into a tweeter, having only used $20 and under tweeters so far. Well worth it IMO.

                              I really appreciate all of your help both Chris and RPB!

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