Hello, I have some problems understanding H-frame 😱
I have 21" Pro audio woofer. I want to make h-frame with it, but I don't quite get how deep should frame be. I need it to cross at 110-120hz. I believe my only concern is to make it shallow enough, so it doesn't have unwanted pipe resonance too close to desired crossover, right?
But I don't quite get how distance is measured to determine resulting path lenght.
Which is correct way?
Is it Red
or Green
Or Green + Blue?
Or all of them wrong. Please help I am realy stuck with this 😕

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I have 21" Pro audio woofer. I want to make h-frame with it, but I don't quite get how deep should frame be. I need it to cross at 110-120hz. I believe my only concern is to make it shallow enough, so it doesn't have unwanted pipe resonance too close to desired crossover, right?
But I don't quite get how distance is measured to determine resulting path lenght.
Which is correct way?
Is it Red
or Green
Or Green + Blue?
Or all of them wrong. Please help I am realy stuck with this 😕

ebay image hosting free
Hi, this tells you how to calculate it, you have to take into account the "effective radius" of the pipe, this is shown as r effective in the equations http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
FWIW I've been using Martins 18" Goldwood design for years now. Internal dims are 20"x20"x16". I moved my baffle a bit more to the front and cross at 70hz ish @ 24db. Great sound etc. Is your woofers QTS high enough or are you going to equalize etc?
Here's the project:
http://www.quarter-wave.com/Project08/Jordan.pdf
Here's the project:
http://www.quarter-wave.com/Project08/Jordan.pdf
FWIW I've been using Martins 18" Goldwood design for years now. Internal dims are 20"x20"x16". I moved my baffle a bit more to the front and cross at 70hz ish @ 24db. Great sound etc. Is your woofers QTS high enough or are you going to equalize etc?
Qts is about 0.75. Yes, I will equalize. I plan to buy mini DSP for that.
H frame dimensions
Hi there v: The width dimension you shown is 14" for your 21" driver, driver will not fit. The depth dimension of 9" per side of the H seems reasonable (18" total for a H frame). I tried shorter dimensions for the depth, however, ended up with 10" working, after extending experiments with cardboard. Have you considered a U frame (1/2 the total depth of a H frame? ...regards, Michael
Hello, I have some problems understanding H-frame 😱
I have 21" Pro audio woofer. I want to make h-frame with it, but I don't quite get how deep should frame be. I need it to cross at 110-120hz. I believe my only concern is to make it shallow enough, so it doesn't have unwanted pipe resonance too close to desired crossover, right?
But I don't quite get how distance is measured to determine resulting path lenght.
Which is correct way?
Is it Red
or Green
Or Green + Blue?
Or all of them wrong. Please help I am realy stuck with this 😕
ebay image hosting free
Hi there v: The width dimension you shown is 14" for your 21" driver, driver will not fit. The depth dimension of 9" per side of the H seems reasonable (18" total for a H frame). I tried shorter dimensions for the depth, however, ended up with 10" working, after extending experiments with cardboard. Have you considered a U frame (1/2 the total depth of a H frame? ...regards, Michael
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Hi there v: The width dimension you shown is 14" for your 21" driver, driver will not fit.
It's just random drawing from google. I already built my frames. They are performing as expected 🙂 Measurements show no peaks in pass band. Thanks for sugestions.
(may need to click on image to see non distorted image)


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Last edited:
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