Announcement

Collapse
No announcement yet.

Hafnium

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

  • Hafnium

    Background: This project really got started when my younger son said "I miss those orange wood speakers". They were a pair of Ellis 1801's that I used to use as a reference, but have since passed on to someone else as I have plenty of speakers around these days. What he really meant was that he preferred that look to the painted speakers (most of them black). I had a pair of Parts Express Cherry 0.375 cabinets left from another project that I had parted out to sell the woofers. My first thought was that I could do a variation of my Matrix MT (blue pill) using some Fountek FW-146's as the woofers. In the long run, I just couldn't get excited about that - but fortunately a more interesting idea emerged.

    Drivers:

    Tang Band W5-1138SMF
    Vifa TC9FD-18-08
    Vifa OT19NC00-04

    Cost:

    The combination of budget drivers and a relatively simple crossover keeps cost low. Total cost for drivers and crossover is less than $225 for a pair of these.

    Cabinet:

    In keeping with the "Orange Wood" theme, we thought that a solid wood baffle roughly matching the cherry PE cabinets would be the way to go. There was some complexity to getting this done. The OT19 is really very easy to work with. I decided to go with a 1/2" roundover after cutting the requisite 1 1/8" through hole. The rear is then brought to the level where the roundover starts using a rabbeting bit.

    The TC9 has an oddly shaped frame, so I thought it would be a good idea to rear mount those as well. I decided to go for a 1/4" depth for that. I also needed an enclosure for the mid. The woofer requires a 3" diameter through hole to rear mount. On the back of the baffle, I rabbeted that out to 4" diameter, which happens to be the OD of 3" pvc couplings. I bought a couple of those, along with end caps that would insert into the couplings and that also had screw-in plugs - so we were all set on that front.

    The trick with the little Tang Band sub is that in order to get the bass out of it that it is capable of, you either need a high excursion passive radiator or a high l-to-d ratio port. There isn't a lot of room for a big port in the PE box, so my temporary solution is an L-shaped port with only a 1 3/8" ID and 10" total length. This gives a tuning frequency of 35 Hz, which models to an F3 of 31 Hz. In early listening, I haven't heard any unpleasant sounds from the ports - but we'll see what happens when these play the Grinnell Auditorium. I have left the ports removable in case a better option emerges.

    The cabinets are lined with R-9 Ultratouch Denim Insulation.

    I think I had generally good ideas with respect to the hardwood baffle, but not necessarily the woodworking skills to back them up, so I enliisted the help of TJ (takitaj) from Maine and his CNC, who was able to turn out very nice baffles for these in a matter of days.

    Crossover:

    The TC9 is a very wide range driver, which I thought I would take advantage of by using shallow crossover slopes. My target crossover points were 2nd order Linkwitz-Riley at 300 Hz and 3000 Hz. Another constraint is that the box is small enough that fitting in a 20+ component crossover would be difficult. Fortunately, as I started simulating, it became apparent that I wouldn't need that many components to get a reasonable crossover. The final count is 11, which is surprisingly low for a 3 way... It could have been even less, but the OT-19 seemed to need a notch filter to control its resonant frequency peak.

    Measurements:

    The on axis response is flat to +/- 2 dB from the lower limit of my gated measurement accuracy (200-300 Hz) out to at least 20 kHz. The reverse nulls indicate crossover points of approximately 340 Hz and 2.6 kHz with reasonable phase tracking. The main deviations from linearity are a dip around the mid-tweeter crossover followed by a slight peak centered at around 4.3 kHz. The off-axis plot shows these features smoothing out off-axis and no significant beaming or flaring anywhere else - which one might hope for with small drivers in very close proximity. The impedance dips to around 3.5 ohms at 100 Hz, but is only below 5 ohms from 80 Hz to 200 Hz. This plot indicates a port tuning frequency of 32.5 Hz.

    Impressions:

    As with Lithium, I'll leave most of the impressions to those who hear them at DIY Iowa 2012. They has been fun to listen to these during crossover development and even now that they are finalized. They do things that a speaker that size (or cost) shouldn't be able to do. There are some tradeoffs that come with a project like this. There will be some SPL limitations that come along with a 5" woofer tuned in the 30's by a 1 3/8" port - but these are sufficiently inefficient that it will take a substantial amp to expose those limitations. If you can live with their limitations, there is an awful lot to offer here for the size and cost.
    Attached Files
    Last edited by scottsehlin; 10-17-2012, 09:41 PM. Reason: typo
    Keep an open mind, but don't let your brain fall out.

    Argon | Helium | Lithium | LithMTM | Hafnium
    Mercury | Matrix | Shrubbery

  • #2
    Re: Hafnium

    Here is the impedance plot...
    Attached Files
    Keep an open mind, but don't let your brain fall out.

    Argon | Helium | Lithium | LithMTM | Hafnium
    Mercury | Matrix | Shrubbery

    Comment


    • #3
      Re: Hafnium

      Very nice! Technically a 6dB electrical on the mid and tweeter, plus conjugates as needed.
      (I also commend you on the CrossCap choice for the midrange.)

      Shame I cannot hear them...
      Wolf
      "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
      "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
      "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
      "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

      *InDIYana event website*

      Photobucket pages:
      http://photobucket.com/Wolf-Speakers_and_more

      My blog/writeups/thoughts here at PE:
      http://techtalk.parts-express.com/blog.php?u=4102

      Comment


      • #4
        Re: Hafnium

        Wow, good job, Wolf didn't have a single nit-pick :D

        रेतुर्न तो थे स्रोत
        return to the source
        leviathan system thread
        deadhorse thread
        shockwave build thread

        instagram :: greywarden_13

        in war, victory . . . in peace, vigilance . . . in death, sacrifice.

        Comment


        • #5
          Re: Hafnium

          Well Done across the bored. Speakers with distinct purpose always seem to come out more creative and well thought out. I bet they sound great, even if they do not play over 105dB. Realistically in a room, even at moderate volumes they should absoultely sing.
          .

          Comment


          • #6
            Re: Hafnium

            Hey, they came out sweet! It looks like they matched up pretty well too. Thank you for the mention. It's nice to see some of my work in a finished state. What folks don't know is those 1" thick maple baffles are as hard as a ROCK. Darn near broke a bit cutting these! I wish I could get a listen as well.

            TJ
            Hybrid floor stander build - The Tikki Lau - D8's

            CNC baffle cutting services

            Comment


            • #7
              Re: Hafnium

              How did you rear mount those tweeters? Some details would be appreciated.

              Comment


              • #8
                Re: Hafnium

                Originally posted by keith_correa View Post
                How did you rear mount those tweeters? Some details would be appreciated.
                The link below gives a good general idea about how I rear mounted the OT19. The only differences were that the baffle was 1" thick instead of 3/4", so I used a deeper countersink on the back of the baffle and, as a result, didn't need the side blocks that Zaph used to run the screws through. The wood block I used across the back of the tweeter was just a 3/4" by 3/4" by 5" mdf scrap I had laying around (I had to cut it to length). I ran the wood block horizontally across the back of the tweeter and had the terminals oriented top and bottom - it helps not to block those

                http://www.zaphaudio.com/tidbits/D26...lfinchhorn.pdf
                Keep an open mind, but don't let your brain fall out.

                Argon | Helium | Lithium | LithMTM | Hafnium
                Mercury | Matrix | Shrubbery

                Comment


                • #9
                  Re: Hafnium

                  Scott, these were very well done and my favorite of the three you demo'd today.
                  Don't listen to me - I have not sold any $150,000 speakers.

                  Comment


                  • #10
                    Re: Hafnium

                    I agree with Johnny. That Vifa mid sounded so good. That band pass filter is so simple! Great job.
                    Expensive caps need time to break in. More expensive caps take a long time. Cheap caps sound great right out of the box.

                    Why I don't spray in first gear: http://s1138.photobucket.com/albums/...t=100_2585.mp4

                    Comment


                    • #11
                      Re: Hafnium

                      Scott- These were a real treat. I thought for sure that port was going to be a problem. Definitely thought we'd hear it whistle, but in the end, it didn't seem to make any noise whatsoever.

                      The sound from the Hafnium was very balanced and powerful from such a small package – and a 3-way to boot. I’m pretty sure I’ve not seen a smaller 3-way. Whatever you did with the crossover works for sure. In fact, each of your three designs were very good. You gots some mad XO skillz.
                      Bryan K.

                      Midwest Audio Club

                      Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

                      Comment


                      • #12
                        Re: Hafnium

                        Yes- Scott has mad skillz!
                        Wolf
                        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                        *InDIYana event website*

                        Photobucket pages:
                        http://photobucket.com/Wolf-Speakers_and_more

                        My blog/writeups/thoughts here at PE:
                        http://techtalk.parts-express.com/blog.php?u=4102

                        Comment


                        • #13
                          Re: Hafnium

                          Why a 2.6kHz tweeter crossover instead of the 3.5 to 4kHz that many would chose considering distortion and FR meausements for the Vifa midrange?

                          Comment


                          • #14
                            Re: Hafnium

                            The tweeter can easily handle the 2.6 kHz crossover point and I was confident that I could retain smooth off-axis response crossing there. IMO crossing at 3.5 to 4 kHz almost always represents a less than optimal situation off axis.
                            Keep an open mind, but don't let your brain fall out.

                            Argon | Helium | Lithium | LithMTM | Hafnium
                            Mercury | Matrix | Shrubbery

                            Comment


                            • #15
                              Re: Hafnium

                              I commend you. This seems a very well thought out design. A rare desk stop 3 way and i budget build at that. Is the inner enclosure for the mid range just pvc?

                              Comment

                              Working...
                              X