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Old School: A Classic Altec Lansing Build

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  • Old School: A Classic Altec Lansing Build

    Since I was a teenager I've been enthralled by the bold and purposeful looks of Altec horn systems, especially the classic A5/A7s as seen in so many rock concerts and behind the screens in old movie theaters. For years I knew that I wanted to build something that evoked those classic speakers, but in a format - however large - that would present well in a home environment.

    To this end, over the last five or six years I've been collecting the components necessary for such a project. Because I'm on a very limited budget, this project required lots of bartering, bargain hunting, and flipping, along with a substantial amount of salvaged wood. I finally started on the project early this year, and it took me five months to complete. But the resulting speakers have fulfilled all of my wild fantasies and sonic desires, making it the project that has given me the most fulfillment and fun of any of my many other builds.

    The components consist of those found is many of the Altec "A" series enclosures:
    -- Altec 416 - 8Z woofers.
    -- Altec 802D compression drivers
    -- Altec 511B horns
    -- Beyma CP21/F Super Horn tweeter (the only non-Altec major component)

    Because in most cases standard Altec crossover networks were little more than standard second order units with an L-pad, I elected to build my own crossovers designed for this specific application. I ended up with 12dB/octave LR units crossed at 800Hz, with built in horn attenuation, CD compensation, and adjustable midrange characteristics.

    I'm overjoyed by the resulting sound of these classic components. Tons of research into the work of others allowed me to build a horn-based system with no hint of "horniness," while retaining the intimate midrange response that draw so many people into the world of horns.

    I hope you enjoy the results of this journey in speaker-building-on-a-budget. I had so much fun that I'm a little depressed to be finished.

    GeeDeeEmm
    A budget build: the frame was made from some kitchen corner cabinets. Basic crossover: PIO capacitors. Horn equalization circuit added later. All cabinet walls were doubled and tripled in thickness, which ranges from a minimum 1" to 2"

  • #2
    My initial plans were to mount the beautiful green horns naked on top of the cabinet, but wife and neighbors convinced me to build a matching cab for the horn, as well. That's when I realized that the size was getting out of control. With the horn enclosures mounted, these now stand 48" tall, weigh well in excess of 200 lbs each. Internal volume is 6.5 cubic feet.

    GeeDeeEmm

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    • #3
      The finished product. I absolutely LOVE the sound of these, but the size in my 12X20 bedroom is ridiculous. But, it's my room, and the wife has agreed to simply not look inside!

      GeeDeeEmm

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      • #4
        Oh boy I wish I could hear these. Way to make your dreams come true!

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        • #5
          Beautiful veneer and finish work!
          Where are the super tweeter horns? Are they coax with the big mid horns?
          Andy.

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          • #6
            Originally posted by andykriech View Post
            Beautiful veneer and finish work!
            Where are the super tweeter horns? Are they coax with the big mid horns?
            Andy.
            Looks like they might be coax with the woofers
            It is estimated that one percent of the general population are psychopaths - New Criminologist: Understanding Psychopaths

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            • #7
              Thanks, guys. The Beyma super tweeters are hidden behind the grills.

              GeeDeeEmm

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              • #8
                Originally posted by gdmoore28 View Post
                Thanks, guys. The Beyma super tweeters are hidden behind the grills.

                GeeDeeEmm
                Did you need to do anything crossover-wise for those? The crossovers shown seem to have a High and Low output.

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                • #9
                  Few more pics. The Beyma super tweeters are so sweet. The Altec 802D horn drivers begin a rapid attenuation at 12Khz. The super tweets are incorporated with a simple first order crossover at 10Khz and add that "air" and crispness that I enjoy so much. I have no testing equipment other than my own ears, but the integration between the horn and the tweet sounds seamless. (I'm sure I'd be shocked and disappointed to see what the FR looks like on a graph! In my case, ignorance really is bliss.)

                  Another characteristic of the Altec drivers (and most other horn drivers of the era, due to their intended use in sound reenforcement) is a severe rise in mid frequency response - up to 10dB rise at 6Khz. I think this characteristic is what a lot of folks have in mind when they speak of horns and their in-your-face "horniness." When Altec began making serious efforts at tailoring their speakers for home use, they addressed the issue by offering the 30923 "Attenuation/Equalizer Network." It's a simple RC network that attenuates the mid frequencies by 6-8dB, and it works like a charm. JBL and several other manufacturers incorporated similar networks, and even today many amplifiers, pre-amps, crossovers, and speaker management devices include a "CD Compensation" feature that smooths the frequency response curve.

                  I think I have my background info on this right, as I'm still learning. I'm not an EE, or even a knowledgeable neophyte on these matters, but I know that the incorporation of the CD equalization transforms a horn capable of parting your hair with ear-pulverizing mids into a smooth and pleasing "reproducer." Of course, this is the old way of doing this, as today's RTAs and DSPs will perform the same function faster, cheaper, and more accurately.

                  GeeDeeEmm

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                  • #10
                    OK, so you added them to the woofer box after you took the 4th picture in post #3?
                    Would you add a picture that shows where the tweeters are?
                    Thanks, they really do look professional and incredible.
                    Andy.

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                    • #11
                      Wow!
                      No matter where you go, there you are.
                      Website

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                      • #12
                        Those big horns are absolutely cool. Congrats on a super build.
                        John H

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

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                        • #13
                          Very nice! How did you finish the veneer? They look fantastic. Can that Beyma be crossed over as low as the JBL 077? I've been thinking about doing a Jubal clone.

                          Dan

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                          • #14
                            Originally posted by andykriech View Post
                            OK, so you added them to the woofer box after you took the 4th picture in post #3?
                            Would you add a picture that shows where the tweeters are?
                            Thanks, they really do look professional and incredible.
                            Andy.
                            Thanks, Andy!

                            I thought I'd taken pics of every stage of this build, but I can't find any of the Beymas mounted where they currently live. They are just above the direct center of the woofer in each cab, behind the center panel of the grills.

                            GeeDeeEmm

                            Note: I took chances in this build that no self-respecting modern designer would entertain, the biggest one being the wild time misalignment of the drivers. But rank amateurs like me are sometimes ridiculously lucky - or simply do not hear things that would drive seasoned builders/designers insane. At this point, though, I've noticed no ill effects from the misalignment.

                            Nor have I noticed any issues with the super tweet being located between the two vertical bars of the front grills. It seems that moving laterally across the listening area would reveal areas where the bars would interfere with the super tweet's dispersion. Yet, even listening carefully to FM hiss, I've been able to detect none.

                            Later, I'll be experimenting with my Behringer RTA and some online programs for speaker analysis, and at that point I'm sure I'll be able to see the anomalies that my dull, untrained ears cannot hear. Then I can get a new education in speaker building!

                            Maybe I'd be happier and much better off if I remain in blissful ignorance.

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                            • #15
                              Originally posted by saabracer23 View Post
                              Very nice! How did you finish the veneer? They look fantastic. Can that Beyma be crossed over as low as the JBL 077? I've been thinking about doing a Jubal clone.

                              Dan
                              Thanks, Dan.

                              The veneer was finished with three coats of Watco Teak Oil which was then followed (after 72 hrs. drying time) by three coats of MinWax Clear Matt Finish Polyuerethane. The first two coats of poly were heavily sanded and leveled with 180 grit paper on a palm sander.

                              Beyma recommends a minimum crossover (12dB/octave) of 5kHz, but their graph shows it holding up very well down to 3.5kHz. Like most manufacturers, I think their minimum crossover point is recommended as a matter of protecting the driver under the anticipated rugged pro sound abuse. Though I can't be sure of that in this case because Beyma does not publish the Fs for the CP21/F.

                              GeeDeeEmm

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