Announcement

Collapse
No announcement yet.

Flex Your PCD Mettle:

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

  • Pete Schumacher
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by stgdz View Post
    I have a question though on the SR crossover

    Is the polarity reversed in this crossover for the tweeter?
    It certainly looks that way from the posted schematic.

    Leave a comment:


  • stgdz
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by giverago View Post
    Where can I get the waveguide to build the SR'S?
    You can't, unless you have a serial # for the HPR152i all points are cut off. There is no way to get them, QSC has shut it down and PE can't get the design rights to them.

    Do like I do and just build it with the regular econowave waveguide.


    I have a question though on the SR crossover

    Is the polarity reversed in this crossover for the tweeter?

    Leave a comment:


  • giverago
    replied
    Re: Flex Your PCD Mettle:

    Where can I get the waveguide to build the SR'S?

    Leave a comment:


  • stgdz
    replied
    Re: Flex Your PCD Mettle:

    so now that I am starting to learn the stuff with PCD, and starting to learn other things about crossovers and drivers.

    How can I tell if drivers are in phase with each other? Do the drivers and the total phase have to line up with each other?



    I should preface that I have a econo wave seven SR build that I was going to do, I didn't take measurements correctly and am down to an SR LCR build. Well the men in my head looked at all the left over drivers and said, hey why not build a dual woofer setup. I have been looking at the Zilch notes on JBL FAT and it appears he tricked PCD by doing a three way and then using the woofers and a woofer and midrange setup.



    yeah I am going off the deep end with this.


    OK so here is what I have, I modeled up a three way with the PA 310-8 as the midrange. The woofer region I tried to leave some of the existing crossover components in there so this is is what is in there but I took out the series section after the crossover and the midrange I just had PCD auto calculate the values for a third order parallel and then looked at the PE parts inventory and used the values closet to what was in PCD. For the 220ti I ended up removing the after series section of the crossover as it ended up gaining a couple of dB, the 220ti still rolls off at 6k though(slightly) though.


    I have attached all my hacks but what did I do wrong with this?
    Attached Files
    Last edited by stgdz; 03-11-2011, 02:13 AM.

    Leave a comment:


  • donprice
    replied
    Re: Flex Your PCD Mettle:

    Regarding the null, that was probably due to the tweeter polarity. The schematic shown reverse polarity, your model looks like it was set to normal. Toggle it and see if your null comes back.

    Yes, moving the drivers front/back (z-axis) has an impact on the phase relationship at the XO frequency. Going back and forth betweent the model and the measured response (max null) is how you determine the acoustic offset distance (similar to physical offset distance).

    Leave a comment:


  • stgdz
    replied
    Re: Flex Your PCD Mettle:

    Ok I got everything all correct now, I put in all the stuff for the crossovers. I still had a huge null in the middle of the crossover so i change both z-values(woof and tweet) to zero.

    That removed the null. So any little front to back change can have a huge effect on the over all performance of the system then huh?

    Leave a comment:


  • Pete Schumacher
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by stgdz View Post
    ok for the sake of exercise I am trying to learn this program and by doing that I am entering the data into PCD using to see if I understand it correctly.

    Anways, I using this crossover


    but when I go to input stuff, I can input all of the data for the woofer but I get confused on how to input the tweeter. I looked at the filter layouts in the tab but I couldn't figure out where R2 is entered. I have attached all my data entry's. When I run this data though I get a huge drop at around 1600hz.
    Nope, not quite.

    First, remove L3 and add it to the section where you have 6 Ohm and 125uF. That will take care of the parallel trap.



    To model R2, you have to "fake out" PCD just a bit. Add the last two components to the tweeter XO section, C10 and L10, but set C10 to a HUGE value, like 9999999999999, and set L10 to zero and it's series resistance to the value of R2.

    Leave a comment:


  • stgdz
    replied
    Re: Flex Your PCD Mettle:

    ok for the sake of exercise I am trying to learn this program and by doing that I am entering the data into PCD using to see if I understand it correctly.

    Anways, I using this crossover


    but when I go to input stuff, I can input all of the data for the woofer but I get confused on how to input the tweeter. I looked at the filter layouts in the tab but I couldn't figure out where R2 is entered. I have attached all my data entry's. When I run this data though I get a huge drop at around 1600hz.
    Attached Files

    Leave a comment:


  • Zvuchniak
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by stgdz View Post
    where can I get the FRD or ZMA files for the dayton 12" pro audio woofer and the selenium 220? I would really like to play around with the SR setup that zilch built at least the crossover that is.
    Here it is.

    http://techtalk.parts-express.com/sh...&postcount=444

    But that is d220ti OMF with QSC 152i waveguide. If you want the combination of D220Ti/JBL-PT look one or two pages back.

    Leave a comment:


  • stgdz
    replied
    Re: Flex Your PCD Mettle:

    where can I get the FRD or ZMA files for the dayton 12" pro audio woofer and the selenium 220? I would really like to play around with the SR setup that zilch built at least the crossover that is.

    Leave a comment:


  • bruson
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by jonpike View Post

    ......Anyway, hope the story gets folks to think a little wider. To the poster who seemed to hear a difference with the hanging parts, do you have a metal bench top? Might be a similar effect. Or iron or steel parts, screws, driver magnets, etc... unusually close to your inductors? Sometimes there's something right in front of you that you didn't think about.

    Happy hunting!
    No metal top.
    All inductors were sitting on the black painted MDF box for the B&C 10PS26.

    Now one air core is 3" from the back of the B&C DE250-8. Before it was suspended, it was about 3", too. Could the magnetic field from that driver affect that inductor as well as the others 5" and 6" away? If so why would lifting up make any difference? They were 5"-6" away before.

    The 2 teflon caps I use are enclosed in metal and the end caps are steel that a magnet can attach too. I tried. Their cylinder is non magnetic metal.

    When I screw the iron core inductor in place, I'll be using brass screws. Just in case the steel screws mess up the magnetic field. Good output transformers use brass screws for this reason. Or so a handmade tranny maker once told me.

    I don't have an answer, I just hear the little difference. It's something I'll be doing in the final iteration of this speaker.
    ........................................

    I'm also be selling the 1/4" wood dowels, 1/2" plastic pipe, coated 18GA copper and pink sewing thread I use to construct this audiophile structure.
    One inductor rising audio improving quality structure is $350. A stereo pair is $695, a whole $5 savings!

    Inductor structure using audiophile quality parts: Ebony wood dowels, teflon pipe and 99.9999% pure OCCC copper wire with foamed teflon coating and organic cotton uncolored thread.
    Sound is fabulous!
    Cost is astronomical! $1,150 each monostructure

    Go to www.audiofoolandmoneysoonparted.con for more info

    ;)

    Leave a comment:


  • jonpike
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by Starkiller4299 View Post
    It's possible that the mdf has a slight amount of magnetic/conductive material suspended in it. That may be altering the characteristics of components over it.
    As an empiricist myself... I agree with what Pete is saying.

    That said, you want to keep your mind open to surprises and secondary effects... The first time I measured crossover parts, I got a surprise. At my work we had a nice, $3000 LCR meter. I was going to get a good assessment of how accurate those parts were! The caps were very close, even closer than their 5% rating. But the inductors were off. Way off, like 30% high! I couldn't imagine that they could be so far off, with a 5% or better rating.

    Then I lifted one up, and it changed dramatically... down to less than 5% of its listed value. I realized what happened. Due to the LCR meter sitting on a shelf, I had set the parts I was measuring on top of the meter's case... which was a steel box! :eek: Of COURSE the inductor was changing, it had a nice bit of "iron core" added to it by being near the case!

    Anyway, hope the story gets folks to think a little wider. To the poster who seemed to hear a difference with the hanging parts, do you have a metal bench top? Might be a similar effect. Or iron or steel parts, screws, driver magnets, etc... unusually close to your inductors? Sometimes there's something right in front of you that you didn't think about.

    Happy hunting!

    Leave a comment:


  • Pete Schumacher
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by Zvuchniak View Post
    Have you tried it both way and then came to the conclusion that there is no sonic/audible difference ? I just, always presumed that there is

    I would very much like to know your personal experiences with this issue (if it is an issue at all).

    Regards...
    The electrons, which are responsible for the entire thing, don't see a difference. Like I said, the source is a dead short, meaning that the series input section, and the load shunt section, are actually in parallel, with current flowing in each section, adding up to the total voltage at the load. Makes no difference where in the circuit you put an item, it's parasitic impedances will still play a part in the total voltage presented to the load.

    Leave a comment:


  • Zvuchniak
    replied
    Re: Flex Your PCD Mettle:

    It really makes no difference, whether those components are shunt or series. They are there to modify the electrical transfer function, so all of the components are contributing. It makes no difference whether they are the parts directly between the amp and the driver, or those across the driver terminals.

    And while different caps or inductors may or may not have audible differences at the minuscule power levels they're used at, it won't matter whether you put that iron core inductor in the shunt part of the circuit, or the series part. It's in the signal path, and that's all that matters.

    ...................................

    Have you tried it both way and then came to the conclusion that there is no sonic/audible difference ? I just, always presumed that there is

    I would very much like to know your personal experiences with this issue (if it is an issue at all).

    Regards...

    Leave a comment:


  • Pete Schumacher
    replied
    Re: Flex Your PCD Mettle:

    Originally posted by Zvuchniak View Post
    When notch filters are shunt, it should be more immune on that influences (resistance of inductors and certain parameters of capacitors that are used).

    Regards, Z...
    It really makes no difference, whether those components are shunt or series. They are there to modify the electrical transfer function, so all of the components are contributing. It makes no difference whether they are the parts directly between the amp and the driver, or those across the driver terminals.

    And while different caps or inductors may or may not have audible differences at the minuscule power levels they're used at, it won't matter whether you put that iron core inductor in the shunt part of the circuit, or the series part. It's in the signal path, and that's all that matters.

    For AC circuit purposes, the source is a dead short. So if you look at the woofer circuit below with the input shorted to ground, you'll see that the 3mH "series" portion is now a shunt, just like the 4.7uF cap.

    Leave a comment:

Working...
X