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Old 09-14-2018, 08:23 PM   #1 (permalink)
 
Join Date: Aug 2010
Location: Bartlett, IL 60103
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I try to do a woodworking project each summer that allows me to use some of my garage tools. This project actually started in January when I started learning how to make audio speakers. The further down the rabbit hole you go the deeper it gets. I used two books, The Loudspeaker Cookbook and Speaker Building 201, created my own spreadsheet instead of using online calculators. i selected a Mark Audio CHR 70 full range driver and designed the box with a bass tuning of about 55Hz. I added a baffle step correction circuit and a Zobel filter to tame the highs.

The boxes are about .3 cubic feet internal volume, with a 1.5" diameter port. The boxes are made from 0.75" MDF and designed in Fusion 360. I thought I would use my Craftsman Compucarve (Carvewright) to make the baffles. Unfortunately, it worked well once and ruined two more baffles due to a z-axis error. Oh well, back to power and hand tools.

I couldn't get a could brush on paint finish so I got some textured stone like spray paint and it worked great.

They sound quite good with almost too much bass, I'm going to try to tweak it a little.

Thanks for looking.
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boxes.jpg   zobel.jpg   stuffed.jpg   final.jpg  
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Old 09-14-2018, 09:18 PM   #2 (permalink)
 
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Dude, that's AWESOME!!! Did you make box, speakers, and all?
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Old 09-14-2018, 09:53 PM   #3 (permalink)
 
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Hi Ernie
Thanks
I selected the speakers based on cost, frequency range and and how flat the response is across the range. Each speaker manufacturer provides technical specs that you use to calculate the internal box volume and the lowest frequency it will play. You can tweak the performance a little too.

I designed the boxes using a homegrown calculation spreadsheet. And made them from two sheets of 4'x4' MDF. I purchased the speakers and bass port from Madisound.com. The boxes are about 11x8x7.

Full range drivers work the best with vocals, jazz, and non bass heavy rock.


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Old 09-15-2018, 06:52 AM   #4 (permalink)
 
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Nice job! I had planned on making a couple bluetooth speakers for myself this year, back when I thought all you had to do was make a box and stick speakers in it. I put the project on the back burner when I began to understand how much I would have to learn to have a chance of making something that sounds good. Kudos to you for sticking with it and getting it done.

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Old 09-15-2018, 08:51 PM   #5 (permalink)
 
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I've been meaning to do a few custom speakers for a few years now, just haven't gotten around to it. Do you mind me asking approximate material cost for the pair of finished speakers?

Well done!
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Old 09-17-2018, 10:24 PM   #6 (permalink)
 
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Hi MiteyF
The speakers were 37$ each, the resistors, cap, and inductor for the filters were about $10. The stuffing comes in a big bag it was about 10$ but you can use it in quite a few speakers, depending on size.
I bought two 2 x 4 x0.75 MDF panels, I think they were $12 apiece. So for around $100 I got a great pair of speakers and the enjoyment of learning something new and of course making sawdust.

I have a little MDF left over just enough to make a portable boombox. Parts Express sells a kit with an amp and speakers for about $85.


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Old 09-18-2018, 06:21 PM   #7 (permalink)
 
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I've built a few car audio setups, but never ventured into home speakers. I've got a nice set of floor speakers from my parents college days which sound great to my likely ill-tuned ears, so it's one of those back burner projects I've always wanted to try, but could never justify.

Sooner or later I'll get to it :-) Thanks for the info!
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