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C-Note - Iron Driver Build

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  • C-Note - Iron Driver Build

    My C-Notes came in 5th in the recent Iron Driver contest in NYC. After experimenting with some budget woofers I decided that the cost restraints were going to limit me to a two way if I wanted a quality crossover. That led to a fairly straight forward MTM using the Iron Driver and a Vifa XT25SC90-04 tweeter. The 1.2 cu. ft. box was constructed with 1/2" Baltic birch and braced with 1/2" dowels through the side panels. They were designed to place the tweeter at ear level while placed on the required 24" stand. I'll try to post the box dimensions after I get them back. (too many box plans in the pile)

    Imageshack has dropped my account. You can find all the images here.

    Stacking the side panels to drill through drill holes for dowel bracing.

    Gluing strips to the edges of the side panels to allow for round overs later.

    Gluing up the boxes.

    Driver hole cutouts.

    Filling the holes left by the 1/2" dowels. I left the dowels short so they wouldn't telegraph through the veneer.

    The boxes with the 1" roundovers done on the router table.

    Black Formica applied to the back and top.

    Furring strips were installed around the inside of the cabinet bottom to fasten the removable bottom panels.

    Titebond II glue applied to the box.

    Titebond II glue applied to the NBL quartered walnut veneer.

    Ironing on the veneer.

    Ready to trim.


    Finished with dark walnut Watco Danish Oil with a top coat of satin poly.

    Tweeter rebate template in place.

    Tweeter rebate cut with top bearing router bit.

    Ready for drivers?

    Boxes lined with acoustic foam.

    Really ready for drivers.

    Boxes with the drivers and port installed.

    The crossover.

    1/2 pound of Acoustistuff kept in place with tape wrapped around the dowels in the top section of the box.

    Ready to wire.

    The crossover. 12db/Oct electrical low pass for 24db/Oct acoustic low pass. 24db/Oct high pass with series notch filter network across the tweeter.

    Uploaded with

    C-Note Iron Speaker Parts List

    Quantity & Part Discription
    2 - Peerless XT25SC90-04 Tweeter
    4 - Peerless 830656 5 1/4" Woofer
    2 - 3.9 Ohm 5 Watt Resistor R1
    2 - 4 Ohm 10 Watt Resistor R13
    2 - 47 uF Non-Polar Cap C2
    4 - 12 uF Polypropylene Cap C8 & C11
    2 - 18 uF Polypropylene Cap C5
    2 - .70 mH 20 AGW Inductor L3
    2 - .10 mH 18 AGW Inductor L6
    2 - 1.5 mH 18 AGW I-Core Inductor L9 (Modified by removing 18 turns to make 1.2 mH)

    PE Numbers

    Total parts cost for drivers and crossover parts for 2 speakers - $188.96.

    The PE port used.

    R-Carpenter's wonderful measurements can be found here.

    From the measurements it was pointed out that the port was tuned a little low. It was tuned lower than the Sim I did while designing and I plan to fix that when I get them back. The design called for a slightly small box tuned lower than normal to push the excursion limit below 40Hz and keep F10 up. That seems to work but will work better when I move the port tuning up a little.

    I couldn't be happier with how these turned out and thank everyone for their input and comments.

    Next stop - DIY Iowa 2012 in Grinnell.

    Last edited by Ron_E; 01-08-2023, 10:04 PM.
    C-Note Iron Driver Build
    The Cherry π's

  • #2
    Re: C-Note - Iron Driver Build

    These are absolutely gorgeous. Wow.:applause:
    Builds - C-Killa - Speedsters - LithMTM - Talking Sticks - Pocket Rockets - Khanspires - Dayton RS Center - RS225/28A - Kairos - Adelphos - SEOS TD12X - Dayton 8 - Needles - 871S - eD6c - Overnight Sensations - Tritrix (ported) - Lineup F4 - Stentorians - The Cheapies - Tub Thumpers - Barbells - Tuba HT - Numerous subwoofers - probably missing a few...... :p


    • #3
      Re: C-Note - Iron Driver Build

      I really like the removable bottom design.
      John H

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


      • #4
        Re: C-Note - Iron Driver Build

        Beautiful job on a fantastic speaker.

        Take it easy
        "I like Brewski's threads, they always end up being hybrid beer/speaker threads based on the name of his newest creation." - Greywarden

        Breakfast Stout - HiVi RT2 II/Aurasound NS6
        Imperial Russian Stout - Vifa DX25/Fountek FW146/(2) Fountek FW168s - Built by Fastbike
        Ruination 2.5 way - Vifa DX25/Fountek FW168
        Levitation TM
        - Vifa BC25SG15/Fountek FW168


        • #5
          Re: C-Note - Iron Driver Build

          did I mention it's a super good looking and great sounding speaker?
          No? Well, there you go.


          • #6
            Re: C-Note - Iron Driver Build

            Great job. Very nice cabinet work. And you painfully remind me that Veneer can and should be easier than paint, yet I still end up painting.

            I guess its time for me to get a 1'' roundover bit too.


            • #7
              Re: C-Note - Iron Driver Build

              This is where it became tough, these were ALSO a fantastic speaker! It many ways, regardless of top to bottom ranking, it was a game of inches. I wish I got to hear these a little more but I got distracted somehow.


              • #8
                Re: C-Note - Iron Driver Build

                Excellent photos and writeup Ron. Great job! Can't wait to see and hear these in Grinnell.

                I drive way too fast to worry about cholesterol.


                • #9
                  Re: C-Note - Iron Driver Build

                  really nice ron. this make me a bit less afraid to try venneer.
                  " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

                  Quote Originally Posted by hongrn. Oct 2014
                  Do you realize that being an American is like winning the biggest jackpot ever??



                  • #10
                    Re: C-Note - Iron Driver Build

                    I liked them and in this contest the 9 entries were not far apart. The 200 price limit and the iron driver inclusion forced close competition.
                    Many times I found myself not being able to hear any differences from one speaker to the next.

                    It is also a real demo in how the internet can level many different playing fields in this case speaker design/building. The resources available to a diy guy/gal in this world are amazing.


                    • #11
                      Re: C-Note - Iron Driver Build

                      double post


                      • #12
                        Re: C-Note - Iron Driver Build


                        As a participating member of the judging panel I must agree with Mike it was a "it was a game of inches". Your craftsmanship and design was impecable and when I saw them I said "I want them!". Love the veneer choice.

                        I will be building a set of Iron drivers as a momento of my trip to NYC and as of now yours are top runner. I will be listening to Mike Z's entry again after he has "completed" them (added in a zobel putting the price over $200/pair).

                        Thanks for making DIY-NY such a success

                        Randy Duck

                        ps Removable bottom... Who does that (I will from now on)? GREAT IDEA!!!


                        • #13
                          Re: C-Note - Iron Driver Build

                          Originally posted by ROTECH View Post
                          Great job. Very nice cabinet work. And you painfully remind me that Veneer can and should be easier than paint, yet I still end up painting.

                          I guess its time for me to get a 1'' roundover bit too.
                          Originally posted by [email protected] View Post
                          really nice ron. this make me a bit less afraid to try venneer.
                          It's not all that hard to apply NBL veneer with the iron on method. Trimming it takes a little practice but with the right tools isn't too hard. It is not as cheap as paint and you still have to finish it. I've had problems with seams telegraphing on smooth grained veneers like cherry. With cherry I end up trying to get a piano like finish and that's been a lot of work sometimes. I find it's been much more forgiving to use veneer with grain like oak and the walnut I used on these. The texture of the grain tends to hide a lot of sins. It helps that over time I've learned to not have so many sins to hide. ;) I've started doing backs and in this case the backs and tops in Formica. It's very easy to apply, it's tough and there's nothing to finish. If you can put up with the seams it might be something to consider too.

                          C-Note Iron Driver Build
                          The Cherry π's


                          • #14
                            Re: C-Note - Iron Driver Build

                            PS Thanks for all the ataboys.

                            C-Note Iron Driver Build
                            The Cherry π's


                            • #15
                              Re: C-Note - Iron Driver Build

                              Ron, those looks great! I am just getting started with veneering, can you give some details of how you finished these speakers? I am starting by refinishing a pair of old Realistic speakers. See here. I have refinished these by simply sanding and rubbing Circa 1850 tung oil on them. I did 4 coats, rubbing 0000 Seel wool inbetween coats. They look great! Have a very nice sheen and good color. I want to protect the wood, so am thinking to do wipe-on polyurethane as well. I want to get it just right though, I'd hate to put anything on right now that makes the finish look worse.

                              By dark walnut danish oil, do you maen a pre-mixed oil and stain type of thing? I was thinking of using semi-gloss myself, but yours seem to have a bit of sheen with the satin finish.
                              I'm not deaf, I'm just not listening!