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Jims 3 way speaker build

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  • That's pretty normal I think. I bet it sounds pretty good. You can tell a lot playing just one speaker. For final voicing, you want to use both.

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    • Try this later, after you listen.

      Measure the woofer and mid from about 12" directly in between them. Then flip the polarity, and remeasure. Should get a dip one polarity or the other.

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      • didnt see your post, I increased the coil on the woofer, looks better I know below 300 hz it is difficult to measure bass. I will play some music and let you know but just from the sweep it appears to be better balanced.Click image for larger version  Name:	3 driver with XO +++ 8,4mh.jpg Views:	0 Size:	68.4 KB ID:	1492628

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        • johnny5jz
          johnny5jz commented
          Editing a comment
          That is looking much better!

      • sounds pretty good!! except that the coil is probably too large I went from 4.9 to 8.4 lol. I'll try to come up with something around 6 ish. too much bass taken away

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        • Originally posted by jimbones View Post
          sounds pretty good!!
          When you play two speakers, the tonal balance tends to have more warmth.

          That little jump in response at 500hz, may make it sound a little thin, or cold, or maybe forward. On the other hand, it may be what's needed for the room. If you wanted, you could add a little resistance to bring the mid and tweeter down slightly. Just keep in mind that it may change when you get both speakers playing in your room. Like I said earlier... Sneak up on it!

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          • jimbones
            jimbones commented
            Editing a comment
            well now I will build the other set to make a pair and sneak up on it. But your insight appear correct. They are a little forward and bass is not broken in as I have literally 0 hours on them lol

        • I liked the graph in post 165 much better with the original 4.9 mH inductor. That flat dip from 200 to 500 in post 168 will make the music sound cold and sterile. I'd be tempted to drop it down to around 4 mH to get a gradual downward slope.

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          • Originally posted by jimbones View Post
            sounds pretty good!! except that the coil is probably too large I went from 4.9 to 8.4 lol. I'll try to come up with something around 6 ish. too much bass taken away
            Keep in mind that you are measuring the room along with the speaker bass. Don't assume the speaker has too much bass based on your measurement. Trust your ears.

            What I suggested in post # 167 should help you see what's going on. Also, a close mic on the woofer from about 2" will show the woofer roll off without the room adding confusion. Play the woofer by itself for this. Maybe I can show one of mine as an example.

            Here's my 6.5" sealed box woofer. There is a high pass filter, so more bass than showing here. You can see what the woofer is doing. Pretty accurate up to about 1k.

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            • I attempted to balance the levels of your drivers to what should occur. The tweeter and midrange should end up around 89db output but the woofer, without room gain, is going to loose -6db from baffle step putting it around a target of 85db. Realistically you'll loose another db or so in series resistance from crossover coil so your final system sensitivity is aiming for around 84-85db.

              I suspect the chart in 168 to be far too bright and thin sounding long term. Sometimes we can get suckered into what sounds like brilliant clarity and detail on some tracks whilst testing only to find that extra detail we can hear is only because the tweeter is playing several db higher than everything else - change of music and suddenly that's very apparent.

              The midrange will require the most padding because not only is it as sensitive as the tweeter it effectively gets a bit of a boost over its entire range from the fact that the woofer and tweeter overlap it.

              In the end even this might require a few more db off the tweeter and mid to balance it out - but I think this will get a lot closer to balancing the whole system.

              Because you still measured the tweeter and midrange on the same axis (half way between) the simulation below has had to be based on an assumption that both align to the 0,0 listening point - I can't accurately simulate their actual offset to each other.

              Impedance remains above 6ohm most of the time with only a small dip to 5.5.


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              ​​
              Constructions: Dayton+SB 2-Way v1 | Dayton+SB 2-Way v2 | Fabios (SB Monitors)
              Refurbs: KLH 2 | Rega Ela Mk1

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              • DeZZar very strange. I inputted your values into my XSIM and get different results. Note that you have the Mid inverted I had to make it normal polarity. Also the impedance is quite different. I should know why the difference so I can correct myself. I shouold start by identifying the exact files I used.Ill be back later
                Attached Files

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                • OK so here are the files I used , for all drivers I used frd files dated 11_10.
                  For zma for SB34: used file 11_9, for AC130 I used AC130 Imp zma and for 27TAC I used 27TAC_Rzma.

                  I really need to have better naming convention apologies.

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                  • Jim, you should also be trying to optimize the phase relationship between drivers around the xo frequencies.

                    Assuming you have the correct relative acoustic center info (which I think you do), turn off the system phase in XSim and choose to show the phase for each individual driver instead. Now as you work the xo, try to also get the phase to line up as well as possible around the xo frequencies as you work to shape the summed frequency response as well.

                    Something else that can be helpful is to import your xo target curves into XSim and then to use them as guides as you shape the drivers responses. There are a couple of ways of doing this. I use Response Modeler to create the target curves, save them to a file and then import those into XSim. You'll need to create dummy drivers in XSim to import and display those curves too.

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                    • Lots of input on things today! I agree about optimizing the phase between mid, and tweeter. Woofer, and mid too, but not as critical.

                      The way I do this, is to look at the reverse null. If it's less than 10dB, I might change a cap or coil value and sweep again, looking for a deeper null. Then I switch the polarity back. When you're done, there's no doubt. With a sim, I think there's easily some doubt. Small errors add up.

                      So, Jim......................
                      ..... Dont change the mid lowpass, if you don't have too. Make a small change to the tweeter roll-off, and see if you can get a deeper null. You don't necessarily need a sim to figure this out. Trial and error can work. Might take longer. This might be a good time to pad the mid slightly. Adding a resistor after the xo might alter the shape of the mid response slightly. Lets hope not, it's nice like you have it.

                      Here's one of my recent xo nulls for an example. This was a trial and error xo. No sim at all.

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                      • How close to walls will the speakers be?

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                        • Yes lots of info to digest. The speaker is 3 feet from side wall and 4 feet from front wall

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                          • I do have a unrelated question. The port end is about 2 inches from rear panel. Could that present an issue

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                            • rpb
                              rpb commented
                              Editing a comment
                              That's probably too close.

                            • jimbones
                              jimbones commented
                              Editing a comment
                              OK so I will have to cut the port In WinISD I have a box vol of 70L and it gives me a port of 11 inches for 32 hz tuning. . I have a total port length of 11 inches (that includes an inch inside the flare where it is straight). I raised the tuning to 35 hz and I still get a nice curve and the port is only 8 1/4 inch so I have some room to cut off. so maybe I will cut 2 inches off and I can go in increments until i am where I need to be.

                            • rpb
                              rpb commented
                              Editing a comment
                              How about an elbow? I think 3.5" might be enough, I don't really know.
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