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Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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PLLXO v2 done and working

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  • PLLXO v2 done and working

    Not really a finished speaker project, so I figured I'd post here.

    I've been asking lots of questions about PLLXO design here, diyaudio.com, elsewhere. Finally I read some chapters on RC concepts and figured it out.

    This is my v2. One thing different over v1 is that I added an L-pad section so I can match the insertions losses between the HP and LP. I still then need to adjust the gains on my amps to accommodate differences in efficiency between my satellites and subs, but that is the way I like it.

    I wanted this so I could replace my active Rolls 2-way crossover. I was just getting too much noise w/ the Rolls.

    So far I like the sound a lot. It doesn't sound a lot different than the Rolls. Less noise for sure.

    I only finished it this afternoon, so I don't know if any veils will be lifted, or not.

    If I do a V3, it will be to clean-up the wiring, plus anything else I learn from V2 after listening for a while.

    The towels are audiophile sound-absorption towels, to reduce reflections.

  • #2
    Nice job Phil. I've always wanted to mess with these, but I've never done it. What order did you do on HP and LP? Just simple RC circuits or is there more to it than that?

    Dan
    _____________________________
    Tall Boys
    NRNP Computer Sub
    The Boxers
    The Hurricanes
    The Baronettes
    Conneccentric
    UX3

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    • #3
      I did 2nd order 300-Hz. They’re just typical RC circuits and even though I found a spreadsheet for calculating values, there were some concepts I struggled with, especially when comparing differing sites with information on passive line level crossovers.

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      • #4
        With PLLXOs, calculation of component values targeting a specific XO point requires knowledge of the amp's input impedance.

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        • #5
          Originally posted by Millstonemike View Post
          With PLLXOs, calculation of component values targeting a specific XO point requires knowledge of the amp's input impedance.
          Yep, and preferably a higher input impedance. In my case, 69k for both SMSL 98E amplifiers.

          Also you want the output impedance of the source (in my case a Hifiberry DAC Pro+) to be on the lower side.

          And there are other trade-offs. For example, there is quite a bit of insertion loss with a 2nd order unit. In my case, my HifiBerry can do 2.1Vrms, so still enough output to play plenty loud (louder than I should be listening). Add to that the fact that I've been listening at lower volumes lately, trying to preserve my hearing.

          The benefits are eliminating an inexpensively produced active crossover. I haven't opened that Rolls xover but I imagine I'd find some fairly inexpensive components.

          The noise and hum I was getting are gone, everything is extremely quiet. The Rolls was a bit maddening, I had to adjust power cords every few days to keep the very slight hum in check.

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          • #6
            I tried to swap the Rolls back in just so I could do some comparisons.

            It seems to be that the top end of the passive is far more details than the Rolls, and I wanted to give the Rolls another chance.

            BUT, so much noise immediately. I think I'm going to call the company tomorrow and see if there is maybe just something wrong with the thing.

            I can't be too upset, I knew what I was getting into when I purchased a $100 unit. But I think I'd be better-off, if I want active and small, would be to hunt-down an old Nakamichi car unit or something.

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            • #7
              So I've had a chance to really listen to this thing for a while.

              I changed from 2nd to 1st order on the LP sections. This made the integration between the sub and the full-range better. It also reduced insertion loss to the point where I have turned down the amps in hopes I or my wife don't accidentally blow up a driver.

              Cymbals are amazing, I cannot believe the difference between the active and the passive filters. It is akin to the difference between a medium-resolution MP3, and uncompressed. And I'm certain good active is amazing, but I'm coming to the conclusion that I wasted an awful lot of time on that Rolls unit.

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              • #8
                Originally posted by philthien View Post
                So I've had a chance to really listen to this thing for a while.

                I changed from 2nd to 1st order on the LP sections. This made the integration between the sub and the full-range better. It also reduced insertion loss to the point where I have turned down the amps in hopes I or my wife don't accidentally blow up a driver.

                Cymbals are amazing, I cannot believe the difference between the active and the passive filters. It is akin to the difference between a medium-resolution MP3, and uncompressed. And I'm certain good active is amazing, but I'm coming to the conclusion that I wasted an awful lot of time on that Rolls unit.
                SO what components did you use and brands if applicable (resistors and caps)? That is, the types of resistors and capacitors (e.g., metal film resistor).

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                • #9
                  Out of curiousity, what tweeters are you using?
                  Ann

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                  • #10
                    Originally posted by annjones13 View Post
                    Out of curiousity, what tweeters are you using?
                    Ann
                    No tweeters, Faital 3FE22-4 full-range drivers. My first post in this thread shows the satellites with the Faital drivers, if you're interested.

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                    • #11
                      Originally posted by Millstonemike View Post

                      SO what components did you use and brands if applicable (resistors and caps)? That is, the types of resistors and capacitors (e.g., metal film resistor).
                      I'm using metallized poly film caps, specifically these from Panasonic (I source them from Digi-Key or Mouser):

                      https://industrial.panasonic.com/ww/...wfl/ECWF6113HL

                      For resistors I'm using thin metal film from an assortment I have.

                      Yesterday and this morning I've been listening to all sorts of material and I realize that, recordings that should sound bright/forward never really did with that Rolls.

                      For example, the difference between the original The Wall (black print) and the remastered (red print) discs is night and day, with the original being pretty typical of early-CD bright. With the Rolls, however, it didn't sound bright at all.

                      With the passive xover, the original sounds bright compared to the remastered version.

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                      • #12
                        On the "never sounded bright" theme, the Steely Dan remasters (1998 to 2000 I guess) are overly bright and forward, but never sounded as such with the Rolls.

                        They sure do with the passive EQ.

                        Those Steely Dan remasters were an enormous disappointment. Steely Dan doesn't overwhelm with bass and you'd have to say the mixes all the way back to vinyl were about as bright as you could make them without them becoming thin and unlistenable.

                        So the remasters come out and they do the unthinkable.

                        Ugh.

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