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Helium - a true micromonitor

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  • #31
    Re: Helium - a true micromonitor

    Here is a shopping cart. Can Scott or someone you please confirm?
    Click image for larger version

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    Click image for larger version

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    • #32
      Re: Helium - a true micromonitor

      That will work. I see that Dayton doesn't have a 14 ohm resistor, but 15 ohms is close enough. For caps, I used the dynavox 4uF met. poly and a surplus met poly 2uF capacitor from Madisound. The NPE's you chose should be okay. You could pick up the Dayton 027-414 for something similar for the 2uF... The NPE's will make it easier to fit the crossover in the box and you probably won't hear any difference.
      Keep an open mind, but don't let your brain fall out.

      Sehlin Sound Solutions

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      • #33
        Re: Helium - a true micromonitor

        Originally posted by scottsehlin View Post
        The port is 3/4" pvc. There are two straight sections and an elbow (which barely fits in the box). I'll check the length of the straight sections tonight, but the tuning frequency should be between 65 and 70 Hz. Total length is about 6.5"-7".
        Ahah, thank you! That's almost twice as long as I tried. And it makes sense considering what I was hearing. I was trying to keep a straight 1"ID to reduce port noise, but I see now that might be a pipe dream. The ND91-4 can move a lot of air, but I guess you didn't have any trouble with port noise?

        Do you mean 3/4"ID PVC?

        I found that with such a small box, it's a real trick to keep the inside port opening from being jammed against the walls.

        Parts on order to try out your x-over and tweet solution in my project.

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        • #34
          Re: Helium - a true micromonitor

          Yes, 3/4" ID on the PVC. I have not heard any port noise and it wasn't for lack of trying :D The bass is rolling off pretty steeply below 60 Hz, which I think is helping.
          Keep an open mind, but don't let your brain fall out.

          Sehlin Sound Solutions

          Comment


          • #35
            Re: Helium - a true micromonitor

            Originally posted by scottsehlin View Post
            Yes, 3/4" ID on the PVC. I have not heard any port noise and it wasn't for lack of trying :D The bass is rolling off pretty steeply below 60 Hz, which I think is helping.
            I'll second that since I was sort of involved in pushing these tiny puppies in Grinnell. Great little speaker.
            Bryan K.

            Midwest Audio Club

            Speedster | Sub Attach | The Wildeman | Sean's NLA Towers | COGAR, COUGAR II and COGAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

            Comment


            • #36
              Re: Helium - a true micromonitor

              Just wondering if the new 11.00 Dayton ribbon tweeter would have any advantages in this application. http://www.parts-express.com/dayton-...6-ohm--275-083

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              • #37
                Re: Helium - a true micromonitor

                Originally posted by scottsehlin View Post
                Yes, 3/4" ID on the PVC. I have not heard any port noise and it wasn't for lack of trying :D The bass is rolling off pretty steeply below 60 Hz, which I think is helping.
                Thanks for clarifying. Good to hear that port noise won't be an issue ;. If you pushed it, then my wee little SMSL SA-S1 shouldn't pose a threat. Cheers!

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                • #38
                  Re: Helium - a true micromonitor

                  Originally posted by Zephyr View Post
                  Just wondering if the new 11.00 Dayton ribbon tweeter would have any advantages in this application. http://www.parts-express.com/dayton-...6-ohm--275-083
                  I was wondering the same thing. The main issue I see is that the cabinet would have to be taller than the standard flat pack I chose. Personally, if I were to start down that path, I would shoot for a somewhat larger cabinet volume and use the ND-90 instead of the ND-91 to get a little more bass extension. It would handle less power, though, so one wouldn't want to get too carried away.
                  Keep an open mind, but don't let your brain fall out.

                  Sehlin Sound Solutions

                  Comment


                  • #39
                    Re: Helium - a true micromonitor

                    I don't know, this appears to be the very elusive and long sought design, near perfect for my application...installation in a custom motorhome. I'd like em to be even smaller if possible but everything I've heard so far has been overwhelmingly positive. Planning to build several in solid walnut, along with a sub, possibly doing an active system to boot. The only known alternative is the Bose system, around 2500.00, and gimmicky sound.

                    Thank you so much for this design. Looks like a killer ap for coaches. I may give the ribbons a try just for the heck of it.

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                    • #40
                      Re: Helium - a true micromonitor

                      Originally posted by andykriech View Post
                      Hi Scott,

                      I am interested in the dimensions and port size as well.
                      Planning on building a set for my desk at work, now that I sold my set of Wolf's PCs to a co-worker.

                      Thanks, Andy.
                      Baffle dimensions and layout are now included in the first post. The build is based on the PE 0.04 cu. ft. flat pack. 6.5" tall by 4.5" wide by 5" deep. 1/2" mdf all around.
                      Keep an open mind, but don't let your brain fall out.

                      Sehlin Sound Solutions

                      Comment


                      • #41
                        Re: Helium - a true micromonitor

                        Just ordered the parts myself. Going to put them in some old minimus 7 inclosures my sister picked up for my. Can't wait!

                        Comment


                        • #42
                          Re: Helium - a true micromonitor

                          Originally posted by jacobwayne154 View Post
                          Just ordered the parts myself. Going to put them in some old minimus 7 inclosures my sister picked up for my. Can't wait!
                          Can anyone confirm the interior volume of the aluminum M7s? I believe it's right around 0.07cu ft or 1.85L which would actually make it too big for this project without compensating for the extra interior volume. Great idea though as you can score old M7s on fleabay for next to nothing.
                          Bryan K.

                          Midwest Audio Club

                          Speedster | Sub Attach | The Wildeman | Sean's NLA Towers | COGAR, COUGAR II and COGAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

                          Comment


                          • #43
                            Re: Helium - a true micromonitor

                            Not sure on the volume but easy enough to adjust. Larger port or a block of something. Got the aluminium minimus 7s for $8.00. They are in great shape. They have no bass and become fatiguing very quick. Lots of positive opinions on this design. Looking forward to hearing it for myself.

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                            • #44
                              Re: Helium - a true micromonitor

                              Originally posted by bkeane1259 View Post
                              Can anyone confirm the interior volume of the aluminum M7s? I believe it's right around 0.07cu ft or 1.85L which would actually make it too big for this project without compensating for the extra interior volume. Great idea though as you can score old M7s on fleabay for next to nothing.
                              For an interior volume of 1.85L, you would make the port 5 1/2" long (assuming 3/4" schedule 40 PVC)
                              Keep an open mind, but don't let your brain fall out.

                              Sehlin Sound Solutions

                              Comment


                              • #45
                                Re: Helium - a true micromonitor

                                My m7s measure 4 1/8" by 4 1/2" by 7 1/8" seems like a real close match. I'll post some pictures when the parts come.

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