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Thread: New Mid Bass (mod rod pt. 2)

  1. #11
    Senior Hostboard Member Steve Mac's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    Quote Originally Posted by GM View Post
    Well, we're basically dealing with a 1 WL of 300 Hz/4 = 75 Hz = ~58" dia. wave, so ~29" from the horn centerline down will drape over the mids and part of the subs, so ideally need to square them up and use closed cell foam insulation or similar to seal the joints, then a 36" w x 36" rounded up and seal the horn/baffle joint.

    This might be sufficient, but it's now going to reinforce some part of the sub's, mid's output, so it ideally needs to be well braced, recommending 'boxing' the horn in [open back] to the depth of the mids cab and placing concrete bricks or similar on the bottom plate to mass load it. Better still, Velcro one or two to the horn.

    Reinforce the back perimeter, toss in enough damping to mute any hollow sound and the sum total will for sure load to < 75 Hz, which would need to be measured, but a basic pipe end correction would be ~29" x 0.613 = ~17.8"+ ~181 = ~198.8" = ~13543/198.8 = ~68 Hz, so pretty confident it will load at least this low as the sides of the mid/tweet cab will contribute some also even though at 90 deg.
    I have read this through a few times and understand what you are saying...thank you...great info!
    Stepping back a minute there’s a fellow who makes what ha calls 300hz horns...markus horns.
    This one I liked...
    9
    10

  2. #12
    Senior Hostboard Member Steve Mac's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    this has fewer cells:
    11

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    Senior Hostboard Member GM's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    You're welcome!

    No dims, but just eyeball scaling using the driver sure makes them look like 500 Hz to me and of course the baffle will work with it too, just need more work to seal it up. Beautiful workmanship for sure!
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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    Senior Hostboard Member Steve Mac's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    Quote Originally Posted by GM View Post
    You're welcome!

    No dims, but just eyeball scaling using the driver sure makes them look like 500 Hz to me and of course the baffle will work with it too, just need more work to seal it up. Beautiful workmanship for sure!
    I wanna say the 1st pics are 805B’s ?

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    Senior Hostboard Member bowtie427ss's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    Quote Originally Posted by Steve Mac View Post
    I wanna say the 1st pics are 805B’s ?
    Facsimiles, not Altec built.
    Not all vegetables make good leaders.

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    Senior Hostboard Member Steve Mac's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    Quote Originally Posted by GM View Post
    You're welcome!

    No dims, but just eyeball scaling using the driver sure makes them look like 500 Hz to me and of course the baffle will work with it too, just need more work to seal it up. Beautiful workmanship for sure!
    I see what theyve done....the Fc is 300 Hz

  7. #17
    Senior Hostboard Member Steve Mac's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    Quote Originally Posted by bowtie427ss View Post
    Facsimiles, not Altec built.
    I thought about something @GM said about the machining at the throat...
    In the examples shown I could see no pics at the throats of those wood horns and that’s what is most concerning about the design. Maybe it’s great, but I have no idea...

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    Senior Hostboard Member bowtie427ss's Avatar
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    Re: New Mid Bass (mod rod pt. 2)

    I thought about something @GM said about the machining at the throat...
    In particular, his words i remember most are in reference to, and the importance of the entry of each cell and the partition between cells being free of acoustically reflective surfaces, also a classic Emerson, Lake, & Palmer tune...

    Knife Edge.

    Last edited by bowtie427ss; April 27th, 2021 at 06:07 AM.
    Not all vegetables make good leaders.

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    Re: New Mid Bass (mod rod pt. 2)

    Right, as critical as it is to seamlessly line up a 511/811 throat to the driver for max [smooth] HF extension, just think about a bunch of round/square/whatever throats dumping into a collector [low pass filter] that in turn adapts to the driver!

    Once I learned from experience just how critical it is, I had a much greater appreciation that these huge horns/drivers could top 12 kHz at high SPL at a time when 8-9 kHz was the max available signal.

    Wish I still had the pics of the super rare Jensen [32] cell/500 Hz horn; talk about attention to detail! Must have been made by pocket watch and/or 'sailing ship in bottle' craftsmen.

    - - - Updated - - -

    Quote Originally Posted by Steve Mac View Post
    I could see no pics at the throats
    One thing I've noticed is that all these [installed] wood horns have super tweeters [not to mention they are typically offered by said wood horn manufacturers as a set], so assume the throats, etc., quality are more typical of large PA horns [~ 8 kHz upper limit].
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  10. #20
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    New Mid Bass (mod rod pt. 2)


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    Re: New Mid Bass (mod rod pt. 2)

    Is this it?
    12
    Your neighbors called. They like your music.

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