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  • #46
    Originally posted by Mountainman Bob View Post
    Well tried a couple different value air chokes in line with the woofer to see if it would smooth out the transition, tried one which low passed at 4500hz; way above the tweets high pass of 2500hz......was trying to initiate the natural rolloff aspect a little earlier and maybe smoother.

    Also tried one that put the low and high pass right about at the the same 2500hz the way its supposed to be (Isuppose!)

    I figured out that anything you add to the signal, even with the higher end components apples for apples..... makes things sound like arse!

    I really don't understand why more manufacturers don't try to improve on this simple but effective design......strikes me a bit funny that only one woofer is made today for this application! ....well two if you count the Human. I wonder if there are more choices in the 8" woofer range?

    These PA255-8 10" pro woofers wired straight really arent bad at all as long as you stay off axis a bit......still gonna start putting money back to make a set of those seas A26 (H1411/T35C) for the #1 system.

    Frustrating stuff I tell ya what !

    Dont forget that the impedance rise with frequency makes a simple inductor in series with a woofer far less effective than a textbook filter chart would lead you to believe.
    Projects:

    Breezy Monitors: http://techtalk.parts-express.com/fo...reezy-monitors
    transcenD: http://techtalk.parts-express.com/fo...5035-transcend
    Summits: http://techtalk.parts-express.com/sh...75-The-Summits
    References: http://techtalk.parts-express.com/sh...-My-References
    Vintage Style 2-way: http://techtalk.parts-express.com/sh...-vintage-2-way

    Comment


    • #47
      Originally posted by dynamo View Post


      Dont forget that the impedance rise with frequency makes a simple inductor in series with a woofer far less effective than a textbook filter chart would lead you to believe.
      so what would the least invasive (passive) way to roll off the woofer at a certain freq? I'm thinking matching the woofer to the application seems the simplest all be it the most $$ as to trial and error.......what about active x overs with biamping? i've heard its less invasive but i'm sure it also affects sq ?

      what do you think of that dayton RS270P ? theres not a whole lot of real world feedback on it ?

      Comment


      • #48
        Please don't fetishize the number of components between your amplifier's output and your driver's input terminals.

        I doubt you have counted the number of components in your amplifier, preamplifier, and source(and with the integrated circuits in a digital source the numbers are fantastic).

        The only electrical difference in induction between, say, a whole millihenry in the voicecoil and half in the voicecoil and half outside the driver assembly is less variation with frequency(for the separated version).

        Neither is 'cleaner', neither is 'dirtier'.

        Comment


        • #50
          Originally posted by Mountainman Bob View Post

          so what would the least invasive (passive) way to roll off the woofer at a certain freq? I'm thinking matching the woofer to the application seems the simplest all be it the most $$ as to trial and error.......what about active x overs with biamping? i've heard its less invasive but i'm sure it also affects sq ?

          what do you think of that dayton RS270P ? theres not a whole lot of real world feedback on it ?

          Im far from a crossover expert but in my experience you will have a more effective crossover if you went second order, or added a zobel to the woofer with your inductor (which isn’t all that dissimilar to a damped second order). You may have to play with tweeter polarity as you change the crossover.

          My next step with the pa255 your speaker, which I understand only has a cap on the tweeter for a crossover, would be to add a zobel and a small gauge, highish resistance (1+ ohm dcr) inductor. I would also be looking into a tank filter, which is simply a small capacitor in parallel with the inductor to notch out that 5k resonance. I’m sorry but I don’t have the time at the moment to crunch the values for you.

          The rs270p is a nice driver but will still require a crossover of some sort due to a bit of a rise with a little cone breakup in addition to a natural roll off lower than some drivers but still higher than you want. May need to dial in the tweeter with an lpad if it is too hot with a lower efficiency driver too.

          if I was in your shoes I would reach out to Chris Roemer on the forum as he is a wizard with crossovers, especially for situations like yours. He could perhaps crunch out some part values that will get you close to ideal as you will get without measuring.
          Projects:

          Breezy Monitors: http://techtalk.parts-express.com/fo...reezy-monitors
          transcenD: http://techtalk.parts-express.com/fo...5035-transcend
          Summits: http://techtalk.parts-express.com/sh...75-The-Summits
          References: http://techtalk.parts-express.com/sh...-My-References
          Vintage Style 2-way: http://techtalk.parts-express.com/sh...-vintage-2-way

          Comment


          • #51
            Originally posted by davidB View Post
            Please don't fetishize the number of components between your amplifier's output and your driver's input terminals.

            I doubt you have counted the number of components in your amplifier, preamplifier, and source(and with the integrated circuits in a digital source the numbers are fantastic).

            The only electrical difference in induction between, say, a whole millihenry in the voicecoil and half in the voicecoil and half outside the driver assembly is less variation with frequency(for the separated version).

            Neither is 'cleaner', neither is 'dirtier'.
            Hey David, I had to look up fetishize to make sure, but I don’t feel that going after the purist sound possible is getting carried away......and yes I do try to keep as much out of the path as possible. The difference in turning on the pure direct mode of my amp on a hq recording is night and day......no offense but i’ll keep my fetish thank you!

            Comment


            • #52
              Originally posted by dynamo View Post


              Im far from a crossover expert but in my experience you will have a more effective crossover if you went second order, or added a zobel to the woofer with your inductor (which isn’t all that dissimilar to a damped second order). You may have to play with tweeter polarity as you change the crossover.

              My next step with the pa255 your speaker, which I understand only has a cap on the tweeter for a crossover, would be to add a zobel and a small gauge, highish resistance (1+ ohm dcr) inductor. I would also be looking into a tank filter, which is simply a small capacitor in parallel with the inductor to notch out that 5k resonance. I’m sorry but I don’t have the time at the moment to crunch the values for you.

              The rs270p is a nice driver but will still require a crossover of some sort due to a bit of a rise with a little cone breakup in addition to a natural roll off lower than some drivers but still higher than you want. May need to dial in the tweeter with an lpad if it is too hot with a lower efficiency driver too.

              if I was in your shoes I would reach out to Chris Roemer on the forum as he is a wizard with crossovers, especially for situations like yours. He could perhaps crunch out some part values that will get you close to ideal as you will get without measuring.
              Thanks for all your help so far, I’ll be the 1st one to admit my understanding of crossovers is elementary at best but I do pride myself on some pretty decent ears and know the sound i’m after happens to be ‘clean’ (sorry David!) and I’ve come to the conclusion after many yrs as a half arse audiophile that sound (everything else equal) for me is.found in the EPI like setups .....but I also realize that comes with some compromises who ever said it was easy! i’ll try to get up with Chris to see if he can shed some light.
              Hey Civit could you maybe measure the woofer in the same manner? I know yours is an 8” but it might give me an idea of what curve i’m actually looking for....thanks man.
              Does anyone have any response curves of a original EPI / burhoe 10” woofer kicking around?
              Edit: can’t find a Chris roemer on the members list......what’s his handle?
              Thanks everyone,
              Bob

              Comment


              • #53
                I think you missed my point. What makes the connector on the back of your amp special?
                If you don't look inside are there no components in the signal path?

                Now, I have in my family six pairs of EPIs. But a different box(out of the fourty or so shapes they sold) works best in each different room, because there was no compensating for the different shapes except altering placement or(gasp!) equalisation.
                Yes, horrible, I know, but they sound good when it all comes together
                . But we don't listen the way we measure- no anechoic room or infinite baffle. And I am not going to sit one meter from a pair of 180s(I have two pair).

                Boxes and rooms differ, we try to measure in a denatured sort of way when presenting a bare driver, then measure in the box we want to use to deal with those issues.
                Then we put the boxes in a room and salt to taste.

                Those graphs are not how those drivers will act in your room, in a(your) box.
                They are a sort of platonic ideal of how they would act in half-space(that's why we who lack the anechoic chamber have to get close and/or gate to get any sort of standardised measurements in our differing environments).

                Comment


                • #54
                  Originally posted by Mountainman Bob View Post

                  Thanks for all your help so far, I’ll be the 1st one to admit my understanding of crossovers is elementary at best but I do pride myself on some pretty decent ears and know the sound i’m after happens to be ‘clean’ (sorry David!) and I’ve come to the conclusion after many yrs as a half arse audiophile that sound (everything else equal) for me is.found in the EPI like setups .....but I also realize that comes with some compromises who ever said it was easy! i’ll try to get up with Chris to see if he can shed some light.
                  Hey Civit could you maybe measure the woofer in the same manner? I know yours is an 8” but it might give me an idea of what curve i’m actually looking for....thanks man.
                  Does anyone have any response curves of a original EPI / burhoe 10” woofer kicking around?
                  Edit: can’t find a Chris roemer on the members list......what’s his handle?
                  Thanks everyone,
                  Bob
                  It’s: Chris Roemer, just as you typed. Maybe try to send him a PM
                  Projects:

                  Breezy Monitors: http://techtalk.parts-express.com/fo...reezy-monitors
                  transcenD: http://techtalk.parts-express.com/fo...5035-transcend
                  Summits: http://techtalk.parts-express.com/sh...75-The-Summits
                  References: http://techtalk.parts-express.com/sh...-My-References
                  Vintage Style 2-way: http://techtalk.parts-express.com/sh...-vintage-2-way

                  Comment


                  • #55
                    Originally posted by davidB View Post
                    I think you missed my point. What makes the connector on the back of your amp special?
                    If you don't look inside are there no components in the signal path?

                    Now, I have in my family six pairs of EPIs. But a different box(out of the fourty or so shapes they sold) works best in each different room, because there was no compensating for the different shapes except altering placement or(gasp!) equalisation.
                    Yes, horrible, I know, but they sound good when it all comes together
                    . But we don't listen the way we measure- no anechoic room or infinite baffle. And I am not going to sit one meter from a pair of 180s(I have two pair).

                    Boxes and rooms differ, we try to measure in a denatured sort of way when presenting a bare driver, then measure in the box we want to use to deal with those issues.
                    Then we put the boxes in a room and salt to taste.

                    Those graphs are not how those drivers will act in your room, in a(your) box.
                    They are a sort of platonic ideal of how they would act in half-space(that's why we who lack the anechoic chamber have to get close and/or gate to get any sort of standardised measurements in our differing environments).
                    Correct me if i’m wrong but wouldn’t knowing the response curve of the original driver help in the quest to find a comparable replacement?

                    Comment


                    • #56
                      Yes, if the electrical and T/S parameters, and the testing method are all close, you have a good start.
                      Then use a box similar to what you wish to emulate.
                      Then put it in your room and adjust to taste.
                      Even better if you can borrow a healthy original to compare the tone, makes it much quicker, you might even notice something you don't prefer in the original.
                      It happens.
                      180s are amazingly heavy for their size, but if you're near Vt, I could lend you a pair to play with.
                      If you are considering a different form or are far away, I suppose I could send a module for comparison, they are pretty tough re:shipping.

                      Comment


                      • #57
                        Originally posted by davidB View Post
                        Yes, if the electrical and T/S parameters, and the testing method are all close, you have a good start.
                        Then use a box similar to what you wish to emulate.
                        Then put it in your room and adjust to taste.
                        Even better if you can borrow a healthy original to compare the tone, makes it much quicker, you might even notice something you don't prefer in the original.
                        It happens.
                        180s are amazingly heavy for their size, but if you're near Vt, I could lend you a pair to play with.
                        If you are considering a different form or are far away, I suppose I could send a module for comparison, they are pretty tough re:shipping.
                        I've got a pair of burhoe blues that worked in their original state about a decade ago, the surrounds deteriorated and drivers were put in a 'safe' place for repair......long story short the place wasn't safe enough and were thrown out by the wife on a cleaning spree!
                        I know what they used to sound like, tried several woofer replacements over the last couple yrs including Human 'direct' replacements; and i'm also aware they were quite sensative to room location but thats just a matter of a couple days of shuffling.

                        I had found a pair of light blues in new york on ebay but the feller wouldn't ship whole or seperate the drivers even though I offered to pay the buy it now price for just the drivers.

                        the H1411 looks promising, but getting quite the collection of 'promising' drivers!

                        I appreciate your offer i'm in FL

                        i'm thinking the 10" from an EPI two way is the same woofer used in the burhoes......they were the same square magnet and one cap crossover so i'm just assuming so.

                        If anyone has a spare pair of 10" original EPI / Burhoe i'd give good coin for them!

                        does anyone know the t/s parameters for the originals?

                        Bob

                        Comment


                        • #58
                          My 120s need new surrounds, but one has only a small flaw, so I can measure them and compare to Huw's specs.
                          Maybe this weekend.
                          But two 8" EPI-types will work, and have an area a little larger than the ten, and about the same Vas. Together, a db or two louder in parallel, a little lower in series.

                          Comment


                          • #59
                            Originally posted by davidB View Post
                            My 120s need new surrounds, but one has only a small flaw, so I can measure them and compare to Huw's specs.
                            Maybe this weekend.
                            But two 8" EPI-types will work, and have an area a little larger than the ten, and about the same Vas. Together, a db or two louder in parallel, a little lower in series.
                            Thats great, thank you;

                            comparing to huw's is gonna be difficult unless you already have them, he doesn't offer any specs.......I suppose if i'm gonna get serious i'll need my own way to measure.

                            who makes a easy to use entry level measuring setup? my computing arsenal is limited to a HP chromebook and an IPad

                            Comment


                            • #60
                              The specs are on the woofers' pages.
                              PE's DATS will do most everything but FR response(TSPs,impedence,inductance,etc).

                              Comment

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