Alpha 15a h-frame

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EProvenzano

Alpha 15a h-frame
« on: 7 Sep 2017, 02:02 am »
Hello all,

I have a pair of these drivers that i want to deploy for bass duties paired with tb w8-1808.

My plan is to create seperate h-frame enclosures for the woofers as per MJKs recomended dimensions.
I do have a couple questions for clarification.

The plans suggest an h-frame with 7" wings.  Does that mean 7" forward and 7" behind the driver?
Or 3.5" forward and 3.5" behind?

Also does the h-frame require a top and bottom panel, or only the two sides?
If a top and bottom are required, can the floor function as the bottom panel?

Thank you!

jparkhur

Re: Alpha 15a h-frame
« Reply #1 on: 7 Sep 2017, 11:07 am »
The one I built has a total of 7 in front and in back if driver.  Yes you need to create a box frame so all sides are covered on woofer orbit won't work.  It is a great project. Have fun.  Search out a good xo

mcgsxr

Re: Alpha 15a h-frame
« Reply #2 on: 7 Sep 2017, 04:20 pm »
Ed if you look at any of the build threads from folks who built Danny's GR Research OB subs up, you can review pics of how an H frame is constructed.

I have not built what you are describing, but I can say that I did a quick and dirty ~8 inch (16 total) H baffle for a car sub on OB years ago.  I built the H, mounted the driver, and then placed it on the floor.  I used the floor as the bottom of the "enclosure" and placed an IKEA LACK table over the H frame as the "top".

It absolutely worked well enough to inform me of what I wanted to learn from the experiment.  I later built OB subs on a much flatter baffle and used them for 10 years.

Here is a pic of the sub mule...




MJK

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Re: Alpha 15a h-frame
« Reply #3 on: 7 Sep 2017, 10:16 pm »
Does that mean 7" forward and 7" behind the driver?


Yes, the total depth of the finished H frame will be ~15 inches including the baffle holding the driver. You get flat bass into the 30 Hz range from an enclosure about 17" x 17" x 15", with 3/4" thick plywood, which is fairly compact and light. Adding a dead weight to the top will help firm up the low frequencies.

Quote

Also does the h-frame require a top and bottom panel, or only the two sides?
If a top and bottom are required, can the floor function as the bottom panel?


Yes, you want an air tight "box" so I recommend a top and bottom panel glued to the two side panels.

EProvenzano

Re: Alpha 15a h-frame
« Reply #4 on: 8 Sep 2017, 12:41 am »
Thanks everyone for the detailed responses.

MJK - special thanks for your design work!