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Tips and Links
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| Speakers home |
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Speaker Building Tips and Techniques
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| These techniques are for people who have at least some experience working with routers and power tools.
If you do not feel that you know enough to do it safely, then please don't employ these methods. |
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Perfect Box Edges
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| This process involves a simple butt-joint construction method which leaves a 1/8" overhang of excess MDF which
is then trimmed off using a straight cutting router bit with bearing. It assures almost perfect alignment and avoids
the problem of trying to align corners and ending up with the worst possible case where the side which is being
glued to an edge ends up short. |
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| Generally this method works if the box is assembled in the following sequence: top and bottom go between the sides;
front and back go on over that. |
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| Cut the top and bottom normal size. Cut the sides 1/8" oversize on the top and bottom (1/4" total). Cut
the front and back 1/8" oversize all around. |
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| Assemble the box so that the 1/8" extra sticks out beyond where the perfect edge would normally be. |
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| Trim the excess 1/8" off using a router with a straight cutting bit with bearing. The bearing rides on the
flat MDF surface as a guide thus creating a flush, square edge. |
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Determining Hole and Flush Mount Recess Sizes
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| When determining what hole size to cut, we need to take into acount the tools and methods we have available. Generally,
most speakers will have a flange in the 3/8" to 1/2" range. That means, that a 3/8" or 1/2"
rabbeting bit can be used to create the flush mount recess. |
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Work backwards to determine the cutout. Measure the overall outside diameter of the speaker then subtract two times
the flange width. As an example, the Dayton 295-305 6 1/2" woofer has an outside diameter of just a hair under
6 1/2" and a flange width of about 3/8". So, take 6 1/2" and subtract 3/4" (two times 3/8")
to get a cutout diameter of 5 3/4" and a rabbeting bit size of 3/8".
The Dayton 1 1/8" Silk Dome tweeter has an O.D. of 4 3/8" and a flange width of 1/2". Allow a 1/16"
clearance all around so assume a diameter of 4 1/2". Use a cutout of 3 1/2" and a 1/2" rabbeting
bit. |
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Driver Cutouts Using Templates
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| This method of making driver cutouts and flush mount recesses involves using templates. It has some advantages
and disadvantages compared to other methods, but has the capability to make perfect cutouts. A router mounted in
a router table, a straight cutting bit with bearing, and a template are needed. |
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| A template can be made from 1/4" hardboard (masonite), 1/4" plywood which has no voids, particle board,
or like the one I have for 6" - 6 1/2" woofers, 1/4" thick aluminum. |
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| The template should be exactly the same dimensions as the cutout you want. Draw the cutout on the template material
then use a jigsaw or scroll saw to cut out the hole. Sand the inside edge to make it a perfect as possible. Wood
templates should be sufficient to use on one or two pairs of speakers. The best option for more usage is to have
an aluminum (or steel) template made. |
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| Mount the template to the baffle being careful to align it exactly where the driver will go on the baffle. Use
some short drywall or sheetmetal screws to mount the template. Note, if the side you mount the template on is the
inside of the baffle, you don't have to worry about filling or patching the holes. |
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| Drill a hole for the router bit to start. Place the baffle on the router table with the template up and cutout
the hole. Make sure the bearing is riding on the template. Feed the material clockwise. Note: keep an eye on the
bearing to make sure no wood material is getting jammed under the bearing -- it can overheat and burn up very quickly! |
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Flush Mount Recess
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| Once the cutout is created, use a rabbeting bit with bearing to cut the flush mount recess. |
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| The bearing of the bit will ride on the edge of the cutout and create the recess. Set the depth to correspond
to the thickness of the speaker flange plus an allowance for a gasket or sealant (1/16"). The recesses are
best accomplished using a router table. |
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| Since the cutout is used as a guide for the rabbeting bit, it must be smooth and properly shaped. Any irregularities
in the cutout will be reflected in the flush mount recess. |
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| If you veneer the box, you can use the same rabbeting bit and same depth to trim the veneer. |
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Driver Cutout Using Jasper Jig
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| Another method used by many speaker builders employs a router jig such as the Jasper Jig sold by Parts Express.
A center pin is used as a pivot point for the router to cut circles. |
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| For speakers that are to be flush mounted, the jig is first used to cut the flush mount recess to the appropriate
diameter. Then, using the same center pin location, the jig is used to make the driver cutout. |
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| Here is a link to some instructions on using the Jasper Jig: http://www.partsexpress.com/Tech/365-250.html |
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| One limitation with this method is that, once the hole is cut, the center point is lost. This means that if you
want to trim veneer around the driver hole, it will have to be done using a knife or a very short laminate trimming
bit. To avoid this situation, some builders do the veneering before the driver flush mounts and cutouts are made. |
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Veneering Tips
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| Under Construction |
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Links to Other Speaker Project Sites and Speaker Building Resources
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| WinIsd. An excellent basic enclosure design program. Downloadable free. |
| http://www.linearteam.dk/ |
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| Math/Geometry Formulas for figuring volumns of speaker parts, and more: |
| http://mathforum.org/dr.math/faq/formulas/index.html |
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| How to Build Speakers. An excellent overview of the basics of driver selection and enclosure and crossover design. |
| http://www.partsexpress.com/resources/spkrbld.html |
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| Information on electrostatic loudspeakers. Hosted by Barry Waldron, long time electrostat builder and designer.
Barry also has parts available for building electrostatic panels and the associated electronics. |
| http://www.eslinformation4u.com/ |
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| Transmission Line Loudspeakers. Dave Dlugo's site which has numerous t-line resources and projects. |
| http://www.t-linespeakers.org/ |
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| High end amplifier site owned by an avid DIYer. Now has a DIY page for speakers, amps, etc. |
| http://www.passdiy.com/ |
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| Andy Gradds' link page. Lots of excellent links to DIY project pages and other things of interest. |
| http://users.tpg.com.au/users/gradds |
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| Wayne Jaeschke's Website. Wayne has expertly design several inexpensive and some not so expensive speakers. He
also has some very useful information on speaker designing. You may find this site is currently under revision,
but some projects are still available. |
| http://www.speakerbuilder.net/ |
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| PartsExpress Tech Talk. Forum for DIY speaker builders. |
| http://www.pesupport.com/cgi-bin/config.pl |
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| PartsExpress. Commercial source for parts and support for DIYers. |
| http://www.partsexpress.com/ |
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| Crossover Component Values. Tables to select first and second order crossover component values. |
| http://www.partsexpress.com/resources/xover.html |
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| Formulas relating to sound pressure level. What SPL is. |
| http://www-ccrma.stanford.edu/CCRMA/Courses/150/SPL.html#SECTION00037100000000000000 |
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| How to compute Baffle Step Compensation. |
| http://www.trueaudio.com/st_diff1.htm |
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| Interesting articles on various speaker design topics. |
| http://www.geocities.com/CapeCanaveral/Galaxy/9471/home.html |
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| Home page of True Audio with free Real Time Analyzer. |
| http://www.trueaudio.com/ |
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