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DIY Tweeter Box. Home Made Speakers.

Discussion in 'Amps and Cabs [BG]' started by ValveLover78, Nov 20, 2018.


  1. ValveLover78

    ValveLover78

    Aug 13, 2011
    Hi all, I have a lovely Barefaced Supertwin (3rd Gen), which interestingly enough was the first one off the "production line". I've changed bands recently and now I want something with a horn. But I can't afford to upgrade to a big twin or the equivelent 2x12 with horn. Nor do I want to sell the SuperTwin. So my idea was to build a seperate "Tweeter Box" to sit between the cab and the head. The Micromark combos have a similar little satellite speeker, which is where I got the idea.

    Originally I was thinking of making it active with its own class D power amp (50-100w) and feeding it from the unbalanced line out of my Ashdown ABM 500 III RC. An easier build technically. the amp and power where all going to go in the box with a high pass filter. But its a lot of compontents to buy and suddenly its quite expensive.

    So really I want it to be passive. Ideally Id like it to sit after the amp in the signal chain taking what signal/power it needs from a crossover with the remainder of the signal being sent to the Super twin.

    I.E. putting all the electronics and horn from something like the big twin into a seperate box.

    While I'm sure this is possible and quite simple to do it is a little beyond my current know how. For instance, how is this achieved while maintaining a 4oh impedance over the whole system. If its an 100w horn how does it not get destroyed buy the 575w amp etc.

    In all other regard Soldering, building, I'm very capable, and I love a project but if someone with some DIY speaker building know how could steer me through the components I might need and rough circuit diagram that would be really kind.

    Very best.

    Raph
     
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    I think this can be distilled down into a much simpler project than you have started out with.

    1. You will end up with as good (or better) results by not trying to design and build an active tweeter box.

    2. Your "100 watt" horn is really about 20 watts, but that's not an issue because the crossover (that's needed, no make that essential) limits both the low frequencies and the power that the horn sees.

    3. The crossover also insures that the horn's contribution to any change of the cabinet's impedance is insignificant.

    4. All you need is the horn, a crossover (4000 Hz, 12dB/octave is a good starting point) and a box.

    Good luck.
     
  3. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Stand alone cabinet top horns have been around since the 1930’s. They are used in hi-fi and pro-audio. It’s a good approach and doesn’t have to be elaborate like the one below.


    7C480A34-9E4B-4495-A178-0429428EAF8E.

    Note, often horns and compression drivers are sold separately. Check out places such as parts-express and antique electronics.
     
    basscapes likes this.
  4. Jim C

    Jim C Is that what you meant to play or is this jazz? Supporting Member

    Nov 29, 2008
    Bethesda, MD
    And to think the nightmares of moving a VOTT from the 80's had started to fade...
     
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    They filled the room of all those theaters that had them hiding behind the curtains. :)
     
    basscapes and AstroSonic like this.
  6. Jim C

    Jim C Is that what you meant to play or is this jazz? Supporting Member

    Nov 29, 2008
    Bethesda, MD
    And wasn't a bad PA for the day especially if you were on a budget.
    There were tons of these on the used market back then.
    I think we paid $350 for the pair and sold them for $400.
     
    beans-on-toast likes this.
  7. ValveLover78

    ValveLover78

    Aug 13, 2011
    Thanks for your responces, those Altec PA cabs are the business, looks wise at least. Anyway this seems easy enough going to get a decent horn and compression driver and cross over and put them in a birch ply box the same width as the super twin. Two more questions for anyone who's got the time.

    1: Crossovers have a wattage rating, my ashdown is rated at 575w into 4ohms (from memory) and that's RMS in their case. should I be looking for a Crossover of a similar rating 600w? Or More or Less? And I guess I'm getting a 4ohm one?

    2: Box dimensions are much less important at these frequencies I can pretty much stick this Driver and horn in any shaped box and it will sound ok Correct?

    Thanks in advance and I'll keep you posted how this build goes.

    P.S. For clarity I'm not aiming for a lot of boost in the treble for slap or hifi bass sound anything. Most cabs with horns I've played through I like to wined the horn back to 1/3-1/2. But even for finger styles I just find that little bit of boost in to the 2k-5k - range really makes a big difference and i miss it on cabs without horns.
     
    AstroSonic likes this.
  8. Wasnex

    Wasnex

    Dec 25, 2011

    You might find this interesting.
    fEARful Headcase
     
  9. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Would it be sensible to have an lpad or the like in the mix so the horn can be dialed back a bit if it's more sensitive than the main unit?
     
    basscapes likes this.
  10. BogeyBass

    BogeyBass

    Sep 14, 2010
    Could use a Eminence ASD:1001
    Somewhat affordable 1" horn driver.

    I'll assume your shooting for 3 to 5k crossover point.

    Then whatever size horn flare you decide to build a box around. Since your your not limited to baffle area. Could use a nice sized flare and be in the bandwidth you need. Say 3 to 10k ish

    Say for instance a Eminence APT 150s

    1001 driver impedance would cross over well at 3.5k
    So Eminence PXB 3K5 crossover.

    I'll assume your around 99 ish dB with the 10" drivers so you'll add a padding resistor to pad down or lower the tweeter level since it will be higher around 110/112 ish dB

    You could have a switch once you find values for 2 different resistors. One setting would pad down to say 98 to 100dB for 2x10 and another which pads down to say 100 to 103 for a 4x10.
     
  11. Wasnex

    Wasnex

    Dec 25, 2011

    The APT80 might be a good choice as well. My GK 700RB/112 has one that runs 5K up.. It sounds fine and is capable of way more output than is required. I think they run $35.
     

    Attached Files:

  12. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    You will need a proper L-pad after the crossover so that the crossover frequency doesn't change with position of the control AND the L-Pad doesn't see the full output of the amp.
     
  13. Especially "liked" on point number 4!

    Unless the end user plans on truly "flat" response, he's better off just doing what you've said.

    I've still got my Dual Horn Tweeter Box, which I built using those great sounding Radio Shack 40-1377 (Really Foster H016N36s!) somewhere in storage. Back in the day when I wanted extended response that didn't rip one's head off, I just set that bad boy up on top of whatever cab, and let the twang and clickity-click begin (ala Greg Lake! LOL)...
     
  14. john m

    john m Supporting Member

    Jan 15, 2006
    I’ve got a horn (practically new) that I removed from my GK neo 212- I could sell you it really cheap. Pm me if interested.

    If you by the x-over from GK (or equivalent)- your good to go.

    For what it’s worth— I prefer 6.5” mid drivers. That’s what I put in my GK with a proper cross over. It was easier to leave the old cross over in place because I still needed the jacks and plate.
     
  15. Not exactly what the OP wants, but I can vouch for just how efficient those bad boys are.

    Good friend in home town has a pair being driven by a pair of mono 10 Watt Eico tube amps- he can get near concert volume with them in his listening room!

    But that's what they were designed for- back in "the day" (1930-50s) movie houses didn't have much more than 10- 15 Watts of power at their disposal (and sound was usually mono (save for one or two "special projects" like Disney's Fantasia, for eg.), so speaker efficiency ruled the roost.
     
    beans-on-toast likes this.
  16. john m

    john m Supporting Member

    Jan 15, 2006
    I’ve got a horn (practically new) that I removed from my GK neo 212- I could sell you it really cheap. Pm me if interested.

    If you by the x-over from GK (or equivalent)- your good to go.

    For what it’s worth— I prefer 6.5” mid drivers. That’s what I put in my GK with a proper cross over. It was easier to leave the old cross over in place because I still needed the jacks and plate.
     
  17. If they worked for Hendrix (they had a pair of VOTTs, a Shure 4 channel mixer, and about 100 Watts of tube power for the TOTAL PA during the Experience era, IIRC)...
     
    beans-on-toast likes this.
  18. Yes, that should go without saying.
     
    saabfender likes this.
  19. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Is there an approximate rule of thumb for what sort of power handling it would be sensible to allow for an HF unit? I do understand it would be completely dependant on crossover frequency.
     
  20. Rockbobmel

    Rockbobmel Supporting Member

  21. rtav

    rtav Millionaire Stuntman, Half-Jackalope

    Dec 12, 2008
    Chicago, IL
    Then there’s the Trace Elliot 4052h Bright Box, with one model incorporating a horn.

    Here’s mine (4x5 drivers)
    85779A44-47CC-44CA-A30B-853915B6A336.
     

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