Announcement

Collapse
No announcement yet.

Flex Your PCD Mettle:

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Re: Flex Your PCD Mettle:

    OK great - as to the baffle I would front flush mount the WG, and rear mount the woofer? 3/4" difference as w/ the Deluxe? Do I need to passively High pass the whole box say at 60 or 80Hz or just let the miniDSP do all that(which as of now I know nothing about). In it's eventual HT setting(hopefully will work as a decent center channel) control will be from the AVR's Audyssey MultiQ XT32.
    I am only building one(for now, maybe the would be decent surrounds as well? Was going full height LA for surrounds but who knows).
    Have lots of 9 ply 1/2" BB on hand so was thinking would laminate to 1", or could use 3/4 MDF. A 1 cf box is small so whatever is best.
    In building this, I also want to learn, so to that end I have acquired a Cross Spec Labs calibrated Dayton mic, and a Tascam 122MkII "sound card" to plug into a laptop. What would yall suggest I load up on the laptop to do measuring, modeling, polar maps, etc and any other essential hardware?
    Finally, would the miniDSP be a permanent xover, or do I make a passive one from the final DSP settings?

    Comment


    • Re: Flex Your PCD Mettle:

      Originally posted by gmannel View Post
      OK great - as to the baffle I would front flush mount the WG, and rear mount the woofer? 3/4" difference as w/ the Deluxe? Do I need to passively High pass the whole box say at 60 or 80Hz or just let the miniDSP do all that(which as of now I know nothing about). In it's eventual HT setting(hopefully will work as a decent center channel) control will be from the AVR's Audyssey MultiQ XT32.
      I am only building one(for now, maybe the would be decent surrounds as well? Was going full height LA for surrounds but who knows).
      Have lots of 9 ply 1/2" BB on hand so was thinking would laminate to 1", or could use 3/4 MDF. A 1 cf box is small so whatever is best.
      In building this, I also want to learn, so to that end I have acquired a Cross Spec Labs calibrated Dayton mic, and a Tascam 122MkII "sound card" to plug into a laptop. What would yall suggest I load up on the laptop to do measuring, modeling, polar maps, etc and any other essential hardware?
      Finally, would the miniDSP be a permanent xover, or do I make a passive one from the final DSP settings?
      Baffle question: yes, like the Deluxe.

      Your receiver will do the 80Hz HP function in the final setup, so you won't need one on your design.

      The BB is excellent material, but I'd think that a sandwich with it and MDF would be great. Use the BB underneath to act as the base for the mounting hardware, and use the finished MDF surface for your paint/veneer.

      Holm Impulse is a nice little freebie package that will allow you to get all your measurements.

      I'd opt for a passive XO once finished. But that's just me.
      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

      95% of Climate Models Agree: The Observations Must be Wrong
      "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

      Comment


      • Re: Flex Your PCD Mettle:

        Does anybody have any thoughts on this measurement (DE250 on the QSC waveguide)? Mine is red, Zilch's is green. As you can see, there is a significant difference in the crossover region (note the 2dB/line scale)...



        Brandon's measurement seems to split the difference, partly:


        By the way, somebody should really change the png and gif requirements to no size limit and 30-100kB. Uploading graphs as jpg files is worse quality and takes 5-10 times as much space, but it's the only option right now.
        Attached Files

        Comment


        • Re: Flex Your PCD Mettle:

          Thanks. Why the Deltalite 2512 and why such a small and sealed box? (remember I'm learning here) And stuff it w/ what?
          Do the WG and CD need to be enclosed or can they be mounted on an open baffle shared w/ a sealed woofer box below or can a 1 cf box hold both drivers?
          Recommended driver spacing? Same as Deluxe?

          Comment


          • Re: Flex Your PCD Mettle:

            I think I can answer most of this while I see if anyone has any answers for me .
            Originally posted by gmannel View Post
            Thanks. Why the Deltalite 2512 and why such a small and sealed box? (remember I'm learning here) And stuff it w/ what?
            Originally posted by gmannel View Post
            Do the WG and CD need to be enclosed or can they be mounted on an open baffle shared w/ a sealed woofer box below or can a 1 cf box hold both drivers?
            after whatever you put in the box.

            Originally posted by gmannel View Post
            Recommended driver spacing? Same as Deluxe?
            You are missing something rather important here. All of the work is already done for you: Delite 12 :D

            Comment


            • Re: Flex Your PCD Mettle:

              OK - the Delite is in that trap PA box which is bigger than the above recommended 1 cf enclosure but closer to the 2cf mentioned, so just build a box to roughly the same dimensions as that trap box or even a little taller to get closer to 2cf?
              Ordered the WG and CD just now. Woofer soon but awaiting any other input on that particular driver or other recs.
              Is it a straight forward process to build a passive xover after getting exactly what you want w/ the miniDSP - eg do the DSP settings readily translate into a passive design? Or, as the DSP is not expensive and enough amp channels to bi-amp are already here, is staying bi-amped and active OK?

              Comment


              • Re: Flex Your PCD Mettle:

                If you already have the DSP, a source that has preamp level controlled outputs and the amps, I'd stay with that. Only downside is the neverending temptation to mess with it.
                Free & Free-form simulator/designer for Passive Crossovers
                SynergyCalc 5: design spreadsheet for Wooden horns and DIY Synergy Waveguides
                Super easy and cheap to make high performance sound diffusers

                Comment


                • Re: Flex Your PCD Mettle:

                  Originally posted by dtruck View Post
                  Does anybody have any thoughts on this measurement (DE250 on the QSC waveguide)? Mine is red, Zilch's is green. As you can see, there is a significant difference in the crossover region (note the 2dB/line scale)...



                  Brandon's measurement seems to split the difference, partly:


                  By the way, somebody should really change the png and gif requirements to no size limit and 30-100kB. Uploading graphs as jpg files is worse quality and takes 5-10 times as much space, but it's the only option right now.
                  Zilch did not have the WG on a flush baffle, but on the trapezoid knock down. There are large protruding edges on the trap enclosure, which have a detrimental effect on diffraction.
                  R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                  Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                  95% of Climate Models Agree: The Observations Must be Wrong
                  "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                  Comment


                  • Re: Flex Your PCD Mettle:

                    Here's mine. DE250 on QSC waveguide measured at ~42" at bottom of waveguide/top of woofer. I tried to match your gating value. I believe this was collected with the speaker in my entertainment center which has a baffle edge ~1-1.5 inches tall.

                    Why is your impulse response squiggly?
                    Attached Files

                    Comment


                    • Re: Flex Your PCD Mettle:

                      Check your alignment of the driver to the throat of the waveguide, might be off-center.

                      I don't know why yours doesn't show the dip at 1200Hz, though. Does it change if you move the time window out?
                      Free & Free-form simulator/designer for Passive Crossovers
                      SynergyCalc 5: design spreadsheet for Wooden horns and DIY Synergy Waveguides
                      Super easy and cheap to make high performance sound diffusers

                      Comment


                      • Re: Flex Your PCD Mettle:

                        Would this be a bad combo for lobing or other issues?
                        A line array of 4 of these:http://www.parts-express.com/pe/show...number=290-507,
                        or 6 of these:http://www.parts-express.com/pe/show...number=290-542,
                        w/ the QSC/250 combo on top, as a center ch behind an AT screen?
                        xover miniDSP, bass covered by LR line arrays and TubaHT sub.

                        Comment


                        • Re: Flex Your PCD Mettle:

                          Or 8 of these:http://www.parts-express.com/pe/show...number=295-342?

                          My LR MCLAs are the 4" version of this same driver so the match would be natural.

                          So any downside to a EconoWave LAY

                          Comment


                          • Re: Flex Your PCD Mettle:

                            Originally posted by bwaslo View Post
                            Check your alignment of the driver to the throat of the waveguide, might be off-center. I don't know why yours doesn't show the dip at 1200Hz, though. Does it change if you move the time window out?
                            No, I do start to get a ripple as I move the gate out, but it does not line up with the ~1200Hz dip. I have messed with the throat a little, and it seems to only effect much higher frequencies, but I'll be investigating more today.

                            Originally posted by donprice View Post
                            Here's mine. DE250 on QSC waveguide measured at ~42" at bottom of waveguide/top of woofer. I tried to match your gating value. I believe this was collected with the speaker in my entertainment center which has a baffle edge ~1-1.5 inches tall.

                            Why is your impulse response squiggly?
                            Thanks for posting it! Any chance you saved it as an frd/txt file? Your impulse is also squiggly (and inverted, by the way), as is Zilch's. Why mine is a little more uniformly squiggly, I do not know . Could be the lack of a protection cap on mine? I don't have anything big enough to use for that, although I guess I could try to create one from some electrolytics wired up in series-parallel with a film bypass... maybe I'll try that now.
                            Last edited by dtruck; 01-29-2012, 03:27 PM. Reason: added some more

                            Comment


                            • Re: Flex Your PCD Mettle:

                              FR txt file attached.

                              Yea, I noticed it was inverted...
                              Attached Files

                              Comment


                              • Re: Flex Your PCD Mettle:

                                Originally posted by gmannel View Post
                                Would this be a bad combo for lobing or other issues?
                                A line array of 4 of these:http://www.parts-express.com/pe/show...number=290-507,
                                or 6 of these:http://www.parts-express.com/pe/show...number=290-542,
                                w/ the QSC/250 combo on top, as a center ch behind an AT screen?
                                xover miniDSP, bass covered by LR line arrays and TubaHT sub.
                                Why not stick with something simple like a single Deltalite 2510 or 2512?

                                An MTM with a pair the Delta 8 and a 18Sound XD125 looks appealing...at least to my untrained eye.

                                Comment

                                Working...
                                X