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  • Help with Crossover Schematic

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    Can anyone help me figure this schematic out. I get the woofer circuit obviously.
    It is a vintage 3 way speaker, with a horn mid.
    It has a High, Normal Low switch for the mid and tweeter.

    I am having trouble figuring what direction things take depending on the switch positions for the mid and high attenuators.

  • #2
    That's definitely a funky one.
    Basically, it looks like the tweeter follows whatever the mid does, since it gets its signal from (what I assume is) the mid's "+" term.
    The mid has a (1st order) series cap HP filter, and is attenuated by a 47ohm resistor (w/the 3-way sw. set to "LO").
    In the middle position, that large value resistor gets bypassed w/a 0.5uF cap, letting it cross a bit lower.
    In the "HI" postion, it's bypassed by a larger 1.0uF cap, crossing it lower (and louder) still.

    The tweeter circuit is really odd. Following the mid's output, there's an additional 1uF series cap, with a 10ohm SHUNT resistor to gnd. AHEAD of the driver. Still, it'll cause a voltage drop and bring down the tweeter's output (a piezo, perhaps?).
    In the middle position, that 10ohm shunt switches to 5.6ohms, which'll drop the tweeter's output even more.
    In the "LO" pos., there's basically a shunt to ground ahead of the tweeter's input. So . . . I'd actually call THAT position "OFF".

    Not a topology I'd care to emulate, but it only uses ONE small COIL. Resistors are cheap and npe caps co$t next to nothing. I'm guessin' that that woofer runs nearly full bore up to around 3kHz anyhow. The mid horn probably doesn't do 20k anyway, so no need for an LP filter on it.

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    • #3
      Quick review see what I missed
      John H

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

      Comment


      • #4
        Originally posted by Chris Roemer View Post
        That's definitely a funky one.
        Basically, it looks like the tweeter follows whatever the mid does, since it gets its signal from (what I assume is) the mid's "+" term.
        The mid has a (1st order) series cap HP filter, and is attenuated by a 47ohm resistor (w/the 3-way sw. set to "LO").
        In the middle position, that large value resistor gets bypassed w/a 0.5uF cap, letting it cross a bit lower.
        In the "HI" postion, it's bypassed by a larger 1.0uF cap, crossing it lower (and louder) still.

        The tweeter circuit is really odd. Following the mid's output, there's an additional 1uF series cap, with a 10ohm SHUNT resistor to gnd. AHEAD of the driver. Still, it'll cause a voltage drop and bring down the tweeter's output (a piezo, perhaps?).
        In the middle position, that 10ohm shunt switches to 5.6ohms, which'll drop the tweeter's output even more.
        In the "LO" pos., there's basically a shunt to ground ahead of the tweeter's input. So . . . I'd actually call THAT position "OFF".

        Not a topology I'd care to emulate, but it only uses ONE small COIL. Resistors are cheap and npe caps co$t next to nothing. I'm guessin' that that woofer runs nearly full bore up to around 3kHz anyhow. The mid horn probably doesn't do 20k anyway, so no need for an LP filter on it.


        To throw a wrench in .......There are actually 2 separate switches. One for mids one for Tweeter.

        The tweeter is not a piezo, but a 4 inch cone. (vintage 60's stuff)
        The woofer runs up to about 800hz. It is a 12"

        With separate switches on each upper driver, would it still work the same basically?

        Comment


        • #5
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          The speakers in question.

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          • #6
            John, at first I thought you drew that from my explanation, but by the time stamp, it must have been concurrent.
            Anyway, that's exactly how I see it, except I saw 2 separate switches. Except for the tweeter being independent (except for the fact that the HP circuit gets its signal through the mid (also HP) filter, the two versions would still be functionally the same. Still, that LOW setting on the tweeter seems like it would completely shunt it off.

            It would be interesting to have some measurements on the drivers. Maybe kevin can just tell us the DCR of the 3 of them. If I just plug in 3 8ohm drivers (all rated 90dB) with flat-line impedances, it looks like the woofer runs up to the 2k-4k range, although if the horn's appreciably louder (like 100dB), it would cross lower, but it seems like it would be screamin'.

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            • #7
              If I get some time maybe I can dummy some responses into xsim.
              John H

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

              Comment


              • #8
                The CR filter won't change the xover frequency, but highly tilt the response on the mid. There is already a cap out front.
                I don't know what Chris means by the resistor being ahead of the tweeter, as it's just across it like normally utilized. There is still a cap out front of that shunt resistor here as well.
                The mid switch is hard to tell what contacts are in use when it changes positions to me. Is this supposed to be a slide-switch?

                Here's what I'm NOT seeing. The tweeter appears to be further attenuated in the 'high' position than in the low, as the 5.6 ohm and 10 ohm will be in parallel.

                Later,
                Wolf
                "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
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                "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

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                http://techtalk.parts-express.com/blog.php?u=4102

                Comment


                • #9
                  Originally posted by Chris Roemer View Post
                  John, at first I thought you drew that from my explanation, but by the time stamp, it must have been concurrent.
                  Anyway, that's exactly how I see it, except I saw 2 separate switches. Except for the tweeter being independent (except for the fact that the HP circuit gets its signal through the mid (also HP) filter, the two versions would still be functionally the same. Still, that LOW setting on the tweeter seems like it would completely shunt it off.

                  It would be interesting to have some measurements on the drivers. Maybe kevin can just tell us the DCR of the 3 of them. If I just plug in 3 8ohm drivers (all rated 90dB) with flat-line impedances, it looks like the woofer runs up to the 2k-4k range, although if the horn's appreciably louder (like 100dB), it would cross lower, but it seems like it would be screamin'.


                  The bad: I do not have these at home currently. In storage in another state (Long story), but have used them in the past, and know their sound fairly well, although have never measured them or anything.

                  I can say from my listening, the woofer really does seem to roll off under 1000hz, (the speakers says 800hz I believe) The mid and tweeter seem fairly level with the woofer on the mid setting, on the high setting, the mids were a bit too strong, and the tweeter sounded better.

                  The low setting seemed a bit too rolled off, and I hate to say this, as chris mentioned the tweeter being shunted off completely, I think he may be right, as I remember the low setting on the tweeter circuit seemed not that listenable. I think the Mid driver though, went up fairly high as there seems to be no passband filter on it, but just a high pass.

                  Comment


                  • #10
                    Originally posted by Wolf View Post
                    The CR filter won't change the xover frequency, but highly tilt the response on the mid. There is already a cap out front.
                    I don't know what Chris means by the resistor being ahead of the tweeter, as it's just across it like normally utilized. There is still a cap out front of that shunt resistor here as well.
                    The mid switch is hard to tell what contacts are in use when it changes positions to me. Is this supposed to be a slide-switch?

                    Here's what I'm NOT seeing. The tweeter appears to be further attenuated in the 'high' position than in the low, as the 5.6 ohm and 10 ohm will be in parallel.

                    Later,
                    Wolf
                    I forgot about this thread a while back, but the tweeter is "louder" on the high position for sure.
                    On the low setting, I remember the tweeter having "no" output at all, but was not sure if slide switches were defective or not.


                    As to the mid switch on LOW---it goes thru 4uf and 47ohm
                    Normal---it bypasses 47 ohm with a .5uf cap
                    High---it bypasses 47 ohm with a 1uf cap

                    FYI, the horn is the mid, the round smaller driver a weird tweeter like 4-5"

                    Comment


                    • #11
                      Originally posted by Chris Roemer View Post
                      John, at first I thought you drew that from my explanation, but by the time stamp, it must have been concurrent.
                      Anyway, that's exactly how I see it, except I saw 2 separate switches. Except for the tweeter being independent (except for the fact that the HP circuit gets its signal through the mid (also HP) filter, the two versions would still be functionally the same. Still, that LOW setting on the tweeter seems like it would completely shunt it off.

                      It would be interesting to have some measurements on the drivers. Maybe kevin can just tell us the DCR of the 3 of them. If I just plug in 3 8ohm drivers (all rated 90dB) with flat-line impedances, it looks like the woofer runs up to the 2k-4k range, although if the horn's appreciably louder (like 100dB), it would cross lower, but it seems like it would be screamin'.
                      I no longer have these, ended up getting rid of them a few months back, sad, but were in storage and had no use I guess.

                      The woofers though, seemed to roll off around 800-1kHz about. The specs say 800 Hz so makes sense.
                      I had one quick listen when I sold them, but was not able to measure anything at all.

                      They kinda reminded me of Klipsch Heresy sound, but with actual deep bass and less of the glaring forward sound. The mids were VERY nice and smooth sounding with the horn, but the highs were the uh..."low" point, to the sound, just not like a modern day tweeter at all. maybe the tweeters were old and just not working right.

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