Announcement

Collapse

Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
See more
See less

Update and some questions

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

  • Update and some questions

    So this is by far my most ambitious and hopefully last (at least for myself--love bldg for friends and family) build. I've waited a long time to purchase these drivers and just waiting for some warmer weather to begin. It is a multinational effort: Quenze drivers from Denmark, Acoustic Elegance from good ole USA, and Aurum Cantus AMT tweeters from China. M

    My plan is to do outdoor testing (bought a little 80W 12V marine amplifier and an outboard external sound card with phantom mic that can run off the same batteries (Li+ ions from my e-cig habit) using a pair of the pictured tripods jacked up to max height along with a laser to accurately aim the mic. ARTA software and once I have the msmts, likely do both digital and passive xovers. My question is twofold--first is whether I will run into problems with vibration: The other part of the question is for a simple way to mount the mic to the msmt pod. I'm thinking of using PVC as the sleeve connected to a small platform that can accommodate a mic holder and the laser. Is there a fly in this ointment? Any feedback appreciated. For msmts using a couple of the 0.5 cu' PE boxes--and will sleeve fit those to fit the stands.

  • #2
    Wow! Nice drivers! Sticking those high in the air on a pole might even make
    me nervous... And I don't think it is necessary, getting them up like 5 feet
    should be fine down to 300hz or so, ground plane will work for the rest.

    Pete S works with all of these drivers and loves them! Getting his insight
    on this reference system seems like a very good idea.
    Guess xmax's age.

    My guess: 15. His grammar is passable. His trolling is good.

    Comment


    • #3
      I will definitely solicit his advice. I'd like to hand off to the woofer somewhere around 250 so you are definitely right bout 5'. I think at this point there is something about the challenge of it all. Just being able to do it outdoors has motivated another cool project I'll get around to posting next week--basically what I talked about in the first [post combined with Overnight Night Sensations and that fits into an old fashioned looking toolbox. All blue tooth,of course, and with the tripods perfect for camping, giving lectures, or just sharing good music from my youth with my students.

      Comment


      • #4
        Is this going to be an open baffle design, or a more traditional 3-way?

        A x-over for a 3-way can be done, or arrived at, in multiple ways. All of which can be a challenge.

        I like HOLM for measurements. I've done 3-ways indoors, but it's not quite an exact science, the way I go about it.

        Working outdoors wouldn't work for me, because I'd be at it too long. One set of measurements would not be enough. (For the way I do it.)

        One issue I ran into was that the sunlight totally washed out the monitor screen.

        Comment


        • #5
          Sweet project!

          Nice choice of drivers there! Mine back-burner project will be similar in it's diverse nationality.

          Comment


          • #6
            I think once you find you can get all but the lowest frequencies to match your outdoor measurement
            you will be able to continue indoors! (coming from someone that does lots of outdoor measurements)
            Guess xmax's age.

            My guess: 15. His grammar is passable. His trolling is good.

            Comment


            • #7
              When measuring outdoors you need to look for reflections from items behind the mic as well as in front. The laser and mic platform might be an issue. I had issues getting a long enough mic cable and the mic cable wanting to pull over the stand. As I recall I slotted some 1"(?) PVC pipe to make a mic holder for the stand.
              John H

              Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

              Comment


              • #8
                Thanks for all the tips. Re open baffle--no more of a conventional 3 way with the exception that the woofers will remain in their own dedicated box. Currently the AE15H is vented, but I'm looking to get some big Class D amps and use brute force to get them to low 30's. I also happen to have one of the Dayton reference 18" drivers that I have 2KW amp to drive them with. That's gonna have to wait for much bigger room. I plan to do the measurements in a nearby park at the crack of dawn. I know there are also different schools of thought on this issue--taking a spatial average through +/- 10 degrees to use for the template to base the digital filters on.

                As far as reflections, my be overkill but considering something like this: I don't know if that would make matters better or worse. Finally, I may add one of the AC cheap ribbons pointing backwards but in my prsesnt room, that for sure wouldn't help as I have glass behind both speakers.

                Comment


                • #9
                  One other thing, once I have msmts--I'm gonna need some help with the passive xovers. With almost 2 octaves of overlap between the three drivers, it should be pretty simple. I've been wanting for a long time to compare identical speakers with dig xovers vs passives.

                  Comment


                  • #10
                    Originally posted by JRS View Post
                    One other thing, once I have msmts--I'm gonna need some help with the passive xovers. With almost 2 octaves of overlap between the three drivers, it should be pretty simple. I've been wanting for a long time to compare identical speakers with dig xovers vs passives.
                    If you can measure, and verify everything, both can give good to excellent results. They might sound different, but they likely will measure different too. I've done a lot of passive x-overs with the same 4 drivers in different combinations. (Not same drivers as yours!) Most of the time, they sound pretty much the same with 80% of my music, and just slightly different with the other 20%. It's been hard for me to decide which x-over, or combination of drivers I like the most. I've decided I'm not going to loose sleep over it. If I can find all my notes, there should be two that I felt were the best on one of my favorite performances by Dave Mathews. They did "Time of the Season", and it's really something to crank up. One of the x-overs, or combinations just works better on that tune than most of the others. That's the one I want to settle on, and finish a pair of speakers.

                    You probably are aware of this, but just in case, the baffle of the woofer affect the mid and tweeter. So, when you put things up in the air, it needs to be all the drivers, and a baffle shape that is close to the final one. Even a ten pound box falling 6 feet can break bones, so be careful!
                    Last edited by rpb; 01-11-2019, 09:56 PM.

                    Comment


                    • #11
                      Originally posted by JRS View Post
                      One other thing, once I have msmts--I'm gonna need some help with the passive xovers. With almost 2 octaves of overlap between the three drivers, it should be pretty simple. I've been wanting for a long time to compare identical speakers with dig xovers vs passives.
                      If you want the most options for crossover order, then take the time to get the tweeter and midrange aligned acoustically. Then you can implement a 2nd order acoustic at both crossover points.
                      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


                      • #12
                        Which Aurum Cantus AMT's are those? AST 25120's?

                        Comment


                        • #13
                          Thanks for the input. Yes the 25120's. One thing I cannot tolerate is any glare (as I'm sure everyone would agree. One of the things about the AC 25120 that was really attractive given I m 62 and likely hearing is down about -20dB is the efficiency. I'm not a big believer in amps sound different school of thoughr, but with that kind of efficiency who knows I could play with SET amp. And thanks Pete for the reminder about getting the acoustic centers aligned. With the digital filters obviously one can fix such with delay, but if I want to do this right....

                          Haven't decided on the software yet for the x-overs and driver corrections, but leaning Bodio. The only turnoff is the need to have the laptop operating--one of the reasons I want the passives for backup.
                          .
                          As to experiments of this type I guilt a pair of Jeff B's Sartori based two wats for a friend. While I couldnt ABX, they sounded identical so far as I can tell. Snowing today--missed my opportunity yesterday to get the holes cut. Damn.

                          PS: The other thing about the AMT tweeter is I hav literally been waiting a lifetime of audio to honor Dr Heil. I'll never forget the day--I was a college freshman at Cal Irvine and was in this audio store in nearby Tustin when they turned on Albatross by Peter Green of old Fleetwood Mac. I was just dumbfounded.Those were fun times--The IRS sercostack reference, Dahlquist DQ-10's, stacked Advents, my AR-LST's,the ESS AMT's, classic JBL 100;s, Ohm F's.. Sony had just released a MOSFET amp, the Phase Linear 400 was an unheard of buck/watt,,,

                          Comment


                          • #14
                            Oh and one other question--I was looking at software and (I know many of the audio players can do this) is the ability to pre-convolve the transfer function so that you aren't reliant on a PC. But for the life of me cannot find the web page or even name of the outfit. They had basically a plug and play with bi-quad filters and again being able to pre-convolve your entire music collection. I know that the mini-DSP's are an option but want to do the entire transfer fx correction, not just x-overs.

                            Comment


                            • #15
                              Originally posted by JRS View Post
                              PS: The other thing about the AMT tweeter is I hav literally been waiting a lifetime of audio to honor Dr Heil. I'll never forget the day
                              I agree, I had not heard AMT's up until July of 2017. Awestruck as to what they could do. Been enamored with them ever since! My current 2-ch music speakers (bought, not built) feature them, and my back-burner project will be based around AMT's, have tested a few:




                              Can't wait to see you project unfold.

                              Comment

                              Working...
                              X