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Thread: My DIY Altec 828

  1. #1
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    Cool My DIY Altec 828

    Hello everyone!
    Then the time came for me to sign up! Just wrote a good presentation of my DIY speakers, and then the whole went white on this webpage... So you will only get the shorter one now (autosave does NOT work). I have come across this site many times when searching for old speaker constructions, and I must say, you guys love old speaker stuff! And Im totally with you!! This spring I finished my Altec 828 project. I have bin around full range speakers for some years, and I have had a great experience with my latest Fostex FX200 project. I wanted to bring the system closer to the stage in musical expression, and have heard good and bad things about Altec horns. I wanted to give it a shoot to see what I could bring to the surface. Ive always loved the look of the horns, and the discipline of designing good ones. This is mys first horn project, and it brings a lot of joy. I started out with buying some old 416-16z, then the idea of horn appeared, and why not try out a high sensitivity system. So this spring I finished the 828 cabs.

    Enjoy:

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    Speakerunits in the system at the moment: JBL 2226H, Radian PB850-16 in 2380a horn, crossed at 800 Hz, 1. order

    This is a system that will stay! It is a step in the right direction! even thou Im only about 10% done

    Looking forward to hear from you!

    Best
    Martin

  2. #2
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    Looks nice!
    having no Altec drivers is a bit disappointing (coming from this Altec fan), but a fine looking horn, nonetheless.
    I am curious as to how you arrived at your choices in drivers, particularly the Radian (versus say the d4400ti or EV DH1A), and even how you decided on 2" vs a small format drivers. Also, are you using passive XOs, or running active?

  3. #3
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    Hello alien shore

    so sorry for not having Altec drivers in the system for the moment I use to have the 416 playing the bass part, along with a JBL 2445j for the hf. It sounded very good! Except of codes the limitations in tweeter area. Then a good offer came up on a set of old JBL parts. A pair of 2226 that needed a reconing. So I bought the parts, and did it. That brought a very different tone to the system! The Altecs liked the lower midrange better than JBLs, but JBL had much more energy in the low end. It is all about taste, but after listening to the 2226 I found the 416's a little to clinic in the lows. The bass was there with the same extension in the low frequency response but without the "soul" and attack I desire. In the end I decided to sell the Altecs. It is okay to throw tomatoes at me . So... Have I found the final bass driver? NO! But it is totally okay for now! .
    The thing I enjoy when listening to my old 2445 is its ability to do the 500-2000 Hz area. It has much more "body" and power than my Radian down there. The reason why I am using the Radian is its overall nice harmonic sound. I have no supertweeter for now, and just a basic crossover. For The moment I am making some bigger hf horns, and working on soon been able to cross it around 400 Hz, 4 order. To save the 2226 from doing lower mid area.

    Any good ideas?

    best
    Martin

  4. #4
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    Just found some more pictures.

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    The annoying thing was that I had to put them together inside the house because it was winter (I could not wait for the spring to come ) They took up a big amount of space cause I had to flip them many times and only had a little room to do it in. The final work and sanding was made when spring came.

    I assume other people from this forum also have A5, A7 at there homes based on the pictures in here??
    Has any of you tried to fill the inside of the wave guides with sand? I received a hint with that idea. It should have some positive effects in the midrange ive heard...?

    Best
    Martin

  5. #5
    Senior Member Lee in Montreal's Avatar
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    Thanks for sharing. I love what you did for the port(s). I am sure that with the proper woofer you get great bass reflex sound, plus that midrange. Congratulations. BTW To which frequency is the BR tuned?

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    Thanks for replying!

    You are right, the right woofer is needed. The port tuning with 2226 is about 28-30 Hz. Thats also close to the Altec 416 I had. That tuning is to deep! both woofers are only low woofers, not sub woofers. I just havent done any thing to the ports yet, they length is standard 8-9". I have not ended the search for the right woofer yet and it is difficult to cut the reflex port longer

    Im looking for a woofer with high sensitivity and good extension in the 300 Liter Altec 828 cab. A woofer that dont loose sensitivity below 100Hz when tuned to around 30Hz. The TAD 1601b does the job on paper... but... the price...

    Best
    Martin

  7. #7
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    And here are some measurements:

    First the two 2226 units in the cab. Microphone is 15" from the woofer

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    Then the two 2226 in cab. Microphone in listening position pointing in the direction of the cabs. (no EQ added)

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    The two 2226 with the Radian drivers in 2380a horns crossed at 500 Hz 4. orden (a little EQ added in the the bass, no EQ from 150 Hz and up) Note: The output between 20 and 30hz are included noise from the soundcard. These are older measurements, I do them with a interface now, and the measurements are "cleaner" now.

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    More pics to come.

    Best
    Martin

  8. #8
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    Fantastic work, Martin.
    The construction pics give a much better appreciation for the hard work you've put in. I'm sure these sound great - the graphs look good. Are you using gated measurements?

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    Hello Mr. Alien

    Thanks for the nice words I enjoy woodwork in general, and have always some thing on my mind that I wana build! Probably some of you diy people can recognize this

    So.. gated measurements, do you think of the position of the mic according to standards? I have mostly measured in my listening position (about 3 meter to the speakers) mic. pointing towards the speaker measured, to include the room gain. But also a lot of close ones when I had to find the right crossover components. A good balance between your ears and measurements are needed to find the right harmonic cross area.
    Im using Holm Acoustics software, Behringer EMC 8000 Mic. and Tascam US-144mkII interface.

    Best
    Martin

  10. #10
    J.A.F.S.
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    Thumbs up FreeWare

    Quote Originally Posted by Ear4life View Post
    Hello Mr. Alien

    Thanks for the nice words I enjoy woodwork in general, and have always some thing on my mind that I wana build! Probably some of you diy people can recognize this

    So.. gated measurements, do you think of the position of the mic according to standards? I have mostly measured in my listening position (about 3 meter to the speakers) mic. pointing towards the speaker measured, to include the room gain. But also a lot of close ones when I had to find the right crossover components. A good balance between your ears and measurements are needed to find the right harmonic cross area.
    Im using Holm Acoustics software, Behringer EMC 8000 Mic. and Tascam US-144mkII interface.

    Best
    Martin
    Martin:

    A very nice job, indeed! I see you are doing some EQ and speaker testing. I use the same setup as you, but have tried another freeware program in addition to the Holm Acoustics software. The other package is called Room EQ Wizard (REW). It is available for download on the following site:

    http://www.hometheatershack.com/roomeq/

    It is a very nice package AND it is free just like the Holm package. It works very well with the Behringer EMC 8000 Mic. and Tascam US-144mkII interface -- that's what I use!


    Tim
    Amazed I'm still alive!
    Tim

  11. #11
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    Hey Tim

    Thanks for the comments, on my project! And the REW software you are referring to looks VERY good! I think I have to download, and try it out It seems to be a bigger package of opportunities. Nice!
    Thanks

    Martin

  12. #12
    Senior Member sbjacob's Avatar
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    Quote Originally Posted by Ear4life View Post
    Hey Tim

    Thanks for the comments, on my project! And the REW software you are referring to looks VERY good! I think I have to download, and try it out It seems to be a bigger package of opportunities. Nice!
    Thanks

    Martin
    Thank you very much for posting this info .

  13. #13
    Senior Member eso's Avatar
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    Quote Originally Posted by Ear4life View Post
    Has any of you tried to fill the inside of the wave guides with sand? I received a hint with that idea. It should have some positive effects in the midrange ive heard...?
    Extensive bracing added to the inside of the cabinet really helps to tighten up the bottom end, and properly damping the horn flares with improve the midbass clarity. I did both of those plus adjusting the vent size on my cabinets.

    Read this:
    https://dl.dropbox.com/u/4500648/Audio/smallVOT.pdf
    (The link should just give you a download prompt)



    Be aware that sand filling the flares adds a great deal of weight. I think i used about 150lbs of sand in each cabinet.

    eso
    30Hz Bass Horns/K151, Custom Midbass/D130, 280Hz Round Tractrix/2440, Fostex T925a: Full range horn loaded bliss.

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    Hey eso!

    Nice workshop, and A5s you have there Thanks for the link! Just what I needed, Its good to know the VOTT history!

    How have you done your extensive bracing? a picture maybe?? I have thought of improving my cabs in that direction when time comes.

    Im posting pics soon of my new HF horn project!

    Best
    Martin

  15. #15
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    ESO, what are the dimension of your vents? Im just starting to read up on changing the vent configuration. What driver are you using in those too? 416 or 515?

    Thanks
    Nick


    Quote Originally Posted by eso View Post
    Extensive bracing added to the inside of the cabinet really helps to tighten up the bottom end, and properly damping the horn flares with improve the midbass clarity. I did both of those plus adjusting the vent size on my cabinets.

    Read this:
    https://dl.dropbox.com/u/4500648/Audio/smallVOT.pdf
    (The link should just give you a download prompt)



    Be aware that sand filling the flares adds a great deal of weight. I think i used about 150lbs of sand in each cabinet.

    eso

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