David Debertin’s Do-It-Yourself Speaker Building and Vintage Audio
Page
Home of
Truly Inexpensive DIY Loudspeaker
designs
DLDebertin@aol.com
Introduction
Are you looking for
low-budget, two- and three-way DIY loudspeaker designs? You’ve found the place!
This speaker building page is for those interested in building do-It yourself
speaker projects employing drivers of moderate to very moderate cost. The
typical driver cost for one of my speaker designs runs between $10 and $50 per
speaker. The crossover uses around $15 in parts, sometimes less. The box is made
from MDF and can be built with simple power tools, portable circular saw, saber
saw, sander and drill. Boxes cost about $10-15 per speaker in MDF (Medium
Density Fiberboard, readily available at places like Lowes and Home Depot), decking screws and glue, and are not
beyond the capability of a very casual woodworker.
Computer modeling using a
program called WinISD was used to develop basic box
sizes for the drivers employed, using the so-called T/S parameters. Crossover
design was not done on the computer, other than to use a spreadsheet program to
select crossover components based on the frequencies I wanted to try crossing
drivers. Beyond that, crossover designs were modified by running repeated
experiments using different crossover component values and configurations, and
comparing the sound with a speaker using the best previous configuration. They
should not be regarded as the perfect crossover for the drivers, but they are
the best sounding configuration I have been able to find so far for each speaker
design. So again, if you want a highly sophisticated crossover based on a lot of
computer modeling, you should check out any number of other
sites.
There are several
interesting projects outlined here that I currently enjoy. Furthermore, they are
simple enough so that nearly anyone can build them. All of these are works in
progress. I never regard a design as final. I rework these designs over and over. I
often end up exchanging drivers and rebuilding crossovers on a whim. I will keep
the most recent design posted here, the design I believe is the best of those I
have tried. Considering the cost,
each design offers excellent sound for the money. There could be a number of
ways to improve on these designs, and if you want to simply treat them as
starting points for a design of your own, that’s fine with me. These are not
sophisticated, high-end designs with a lot of polish.
Background
I spent some time in the
fall of 2003 at the Dayton Ohio DIY gathering, where I brought the recently
completed “Goldwood Project” along. I spent the day listening to everything from
super low-budget projects to high end semi-commercial designs. I came away from
that event with some very mixed feelings about the general state of DIY speaker
building. Part of the problem is
that I didn’t see any project at that event that I had any real desire to build.
Here are some of the problems with the designs I auditioned
there.
Overwhelming Highs. Of course, there was a lot of emphasis on projects
that when tested using computer listening software produced as close as possible
to a flat response curve. This leads to a lot of designs whereby the overall
frequency balance to my ears is tilted upwards. These speakers may be what the
computer finds as flat response, but to my ears they often sounded overly bright
and irritatingly harsh. These are the kinds of speaker that sound realistic for
ten minutes of listening. After that they are simply grating and irritating. My
ears were physically hurting for two days after doing these auditions. The
question I kept asking myself is how could I possibly
enjoy listening to such speakers over the long term in my home. Along with this
seemed to be a desire on the part of builders to not provide any high frequency
level control to compensate for what are obvious differences in various rooms’
ability to absorb sound. I find this curious at best
I
suggest that a variable L-pad be on every DIY speaker and that the plate on it
be labeled like this.
Where is the Listener? To me, most of the DIY builders who brought their
designs to
Room
Boundaries. Most designs were
made to be placed on tall stands well outward from walls and corners. Thus, room
boundary effects had minimal effect on bass performance, and contributed to the
overall upward tilt in the frequency balance. There were very few designs there
that actually tried to take advantage of walls and ceiling to reinforce the bass
performance, and then combined with the mid-and high frequency emphasis in the
usual small-woofer two-way design this tends to result in irritatingly screechy
and grating designs.
Baffle Step Compensation. In an effort to regain some low-end performance from
small-woofer designs positioned well outward from walls, many builders
incorporate some baffle step compensation in an effort to try to raise the
apparent volume of the deep bass relative to the upper bass and lower mid range.
This is accomplished typically by incorporating shunt or parallel components
which also tend to reduce the overall efficiency. For many two-way designs, the
overall SPL would be in the 80-82 db 1 watt one meter away from the
speaker. These designs quickly become very power hungry to operate at normal
volumes, and we were routinely clipping a decent 200 watts per channel amplifier
during listening tests at
I left the
My speaker designs are not
at all considered “finished” and they have been continually evolving over time
as I experiment with ways to solve problems. They will probably all evolve some
more as I keep running more experiments. If you want a plan that is more or less
“final” perhaps you should look elsewhere than here. If what you want is a DIY
design that sounds a lot like the majority of those I heard at
If you believe that the
route to good quality sound is by buying high-end, expensive parts, these are
likely not the designs for you either.
Now that I have described
the characteristics of builders who are not going to be happy with my designs, I
can better explain where I am coming from.
First, I collect low-powered
vintage and semi-vintage receivers and my projects are designed to work well and
play to reasonably high volumes with 30-40 watts of power, and maybe as little
as 20 watts. These are not projects to be played at very high volumes with
high-wattage amplification, though some may be better in that regard than
others.
Second, the designs are for
real rooms with real walls and ceilings. The ceilings in my house are 8 feet
high. The projects can either be positioned back against a wall or even placed
in a corner. The Tower project has a rear-firing port and needs a foot or so of
space to the back wall. The Goldwood project is particularly suited to
situations where the speaker must be placed in a location partially hidden by
room furnishings, and can be placed against a wall. The three-way project is
designed to be placed on the floor.
The highs in all my designs
are well dispersed, but don’t expect them to burn your ears. Three of the
designs have high-frequency variable level controls to compensate for room
differences and I am contemplating adding high and mid-range level controls to
the three-way design as well.
Third, I enjoy listening to
Pipe organ music, so the emphasis is on designs that does well at
this.
Whenever I need inspiration for my
projects I turn to the budget speaker pages in my 1970 Allied Radio catalog.
Overview of the
Projects
The Tower
Project.
The tower project was my
first DIY project. I had some 6 ½ inch woofers I had purchased from Radio Shack
that I used in some EPI speakers whose woofers had tragically lost their
surrounds. They worked well in that application, but later I refoamed the original woofers and I reinstalled them. So I
was stuck with this pair of woofers in boxes. I decided to build a large ported tower
about the size of the EPI speakers in internal volume (1.4 cubic ft). I went down to home depot and had them
cut me 8 inch wide strips of MDF four foot long from a single 4 x 8 sheet. I
glued and screwed those together, added tops and bottoms, made them air tight
except for the port, and those became the boxes.
Interestingly, and not quite by accident,
these towers also had the same internal volume as the project that appeared in
the old Radio Shack/ David Weems “Building Speaker
Enclosures” book that used an earlier version of the Radio Shack 6 ½ inch woofer
along with a small Mylar dome tweeter. I tried to locate that tweeter, and
discovered that Radio Shack no longer sold it, but it was an Audax Mylar dome tweeter, in the Audax numbering system known as the TW010F1. I found that at
Madisound for about $5. At that point I needed a
crossover. The crossover used in the Weems book
(project 13) was a stock Radio Shack two-way but it was a very simple
first-order design with
a 4.7 uF capacitor in series on the
tweeter along with a small inductor in series on the woofer. Since this was a
simple first-order design, the inductor must be small as well, and I settled on
0.33 mH. Weems specified a
variable L-Pad on the tweeter and I did likewise. In essence this was the Weems project 13 built as a tower, using the most recent
version of the Radio Shack 6 ½ inch woofer. I lined the boxes with ½ poly quilt
batting on three sides, and put an extra heavy pad from an old pillow glued
directly behind the woofer.
This was the original tower
configuration and towers were satisfactory, but without much deep bass.
Gradually I convinced myself that the enclosure volume was too large for this
woofer. One of the problems of working with the late-generation Radio Shack
woofers is that somehow Radio Shack never made the T/S parameters available.
These have been accurately measured for previous versions, although even Weems claimed that the printed Radio Shack measurements were
inconsistent with what he measured. I didn’t have the equipment (or skill) to
measure the ones I have, and couldn’t find them anywhere on the Web.
At that point I purchased a
Jensen JS 1000A powered subwoofer on ebay, and the
towers in combination sounded quite nice as the sub effectively added the deep
bass.
I then built a kit pair of
Dayton/Parts Express BR-1s. I thought it might be useful to compare them with my
own projects. Assembly was easy, but the speakers were power hungry, and I was
not blown away by how they sounded. Somehow assembling the BR-1s was not a
challenge for me nor very interesting to do, and I lost
interest in listening to them as well. At that point I started on the so-called
Goldwood project (see below).
I decided to try to find a
pair of inexpensive woofers for the towers that I knew would be correct for the
1.4 cubic foot enclosure volume. I identified the $24 Vifa TC woofer, which was also available in buyout form as
the $14.38 Vifa TC/Infinity woofer. The price was
right and so I ordered a pair. They made a big improvement in the sound of the
towers, even with the simple first order crossover.
Next, I reworked the
tweeters. I had always felt that the Audax Mylars were beamy, and from my experience with the BR-1’s I
knew that the Dayton Silk domes (275-070) were far better, so when they came on
a DOTD sale at $9 each, I ordered a
pair. At that point I had the tweeters and RS woofers as spare parts. We will
pick up on that in the mini-monitor project. I ran the towers with these drivers
and the original simple first order crossover
Meanwhile, I was
experimenting with a 2nd order crossover on the Goldwood project, and
the first design I had come up with sounded quite nice. In that project, Out of
necessity (the tweeter supposedly could not be crossed over lower than 4000 Hz,
and the woofer wasn’t good beyond 3000 Hz) I had ended up choosing values that
underlapped the LR crossover frequencies by 1500
Hz—4500 Hz on the tweeter and 3000 Hz on the woofer. This actually sounded way
better than I thought it might.
So, I decided that if this
general design had worked well for the Goldwoods, why not a similar design for
the towers. But the
Then I built out one of the
towers with this crossover and compared it to the first-order crossover in the
other. The new design was the clear winner, and that remains the design I am
currently running. I have tried further variations, but have not yet come up
with something I am confident is better. This woofer in a large vented tower is
probably not the best choice if you want deep bass at very high volumes, but at
more moderate volumes, it is excellent.
The Goldwood Project
I have a lengthy discussion
of the Goldwood project at The
Goldwood Web site with more construction details. On this page I will only
highlight this as an effort to design a two-way module that can be used in a
variety of configurations much like EPI did in their 101 and 201 models in the
70s. It is also similar in configuration Winslow Burhoe (who founded EPI) uses in his Direct Acoustics
“Silent speakers” though that box is vented and I’m sure produces deeper bass
than mine do (see the Direct Acoustics Web site at http://www.directacoustics.com/ I also wanted to try
building a speaker that mounted the drivers in a floor-standing box with an
angled top panel.
I had the 1.2 cubic foot box
designed before I located the drivers. The project became an ultra-low budget
design when I discovered that an inexpensive Goldwood 6 ½ inch woofer (Parts
Express 290-305 @ $11.70 but on sale for around $9) was the best match I could
find given the cabinet volume. At that point, I decided to pair it with an
equally inexpensive Goldwood Mylar dome tweeter (PE 270-170 @ $1.95). However, I was nearing the frequency
limits of both drivers. That’s when I decided to underlap the second-order crossover frequencies as much as I
did. Amazingly, it all worked.
Here is the $1.95 Tweeter and the $11.70 woofer used in the Goldwood project.
I greatly enjoy listening to
these speakers. They have a bit more of an edge and an “in your face” quality to
them than the towers do, although they are not at all harsh and tiring. Those
who heard them at
It would be easy to
reconfigure the towers into this type of enclosure. The enclosure would need to
be about 2/10th of a cubic foot larger. I would add that volume by
widening the enclosure, which would then make adequate room for the Dayton silk
dome, which might need to be covered with a protective grille in that
configuration. I would add a 2 inch x 4 inch long port, probably to the front
base of the enclosure, so they could still be shoved back against a wall. The
resulting sound would likely be a bit more refined with a bit deeper bass.
Whether it would be better overall I cannot guess.
The Mini Monitors
I hate having drivers in
boxes. On completing the above projects I had the Radio Shack woofers and Audax Mylar tweeters that were originally in the towers back
in boxes. I was convinced that I was right about the RS woofers being unhappy in
the tower enclosure because it was too large, but these were still mystery
woofers with respect to optimal box size.
Perhaps Radio Shack
ultimately decided that their buyers were not enthusiastic about building 1.4
cubic foot ported boxes for a 6 ½ inch woofer (which was what was needed in the
Weems project), and redesigned the woofer so it would
fit more properly in a smaller box. What would be reasonable? Or, were I a Radio Shack customer, what
size of box would I likely build for a 6 ½ inch woofer if I knew nothing about
the driver? How about a half cubic
foot? Then decided to build a box I that could easily reconfigure and change the
baffle board if I changed my mind. So I built two half cubic foot boxes. I also
had to build a crossover. Since the second-order Linkwitz-Riley design with a 500 Hz underlap was working well in the towers, I decided that it
might work well in this design too. So the parts for this crossover and the
configuration ended up being identical to that used in the
tower.
In building out these
speakers, I became convinced that the half cubic foot box, sealed was doing
about as well with these woofers as could be done. They don’t sound boomy. There is not a lot of bass, but what is there is very
smooth. And the crossover to the tweeter works well. The Audax dome Mylar worked better in this design than it did in
the towers. However, subsequently I decided that it would be fun to try an
inexpensive Neodymium textile dome. I wanted a tweeter that would fit the
existing hole and baffle board space I considered three different tweeters: 1.
Tang Band 25-302S PE 264-804 ($13.96); 2. Peerless 811-435 PE 277-402 ($16.50), and 3. Audax TM025F1 PE
276-102
($15.20). On due consultation with those who had worked with
these tweeters on the PE board, I finally settled on the Audax, although I think any of the options would have
worked.
These speakers sound quite
good. They are reasonably efficient and produce clean, well-dispersed highs. The
difficulty is that the Radio Shack poly woofer 40-1033 is no longer being made,
though there may still be a few around in store back rooms. I have not yet
identified a suitable substitute woofer for this project that would work in the
sealed half cubic foot box, though I don’t doubt there are some out
there.
The
Like some of my other
projects, the three-way project has gone through several revisions. Originally,
a message board friend had sent me some ten-inch woofers from 1970s from Zenith
Allegros, and the original idea was to come up with a two-way design with
inexpensive Piezo tweeters, letting the Allegros run
free over a wide range. I constructed boxes similar to those I made for the mini
monitors except approximately double the internal volume, or 1 cubic foot. This
design worked, although the Allegro woofers were quite efficient, and kept
overpowering the tweeters unless I added line resistance on the woofers.
Further, in the box configuration I had built, male voices sounded tubby. I
suspected that this was because the box was undersized.
I finally decided that part
of the problem was that the Piezos had an inadequate
mid range, and I started thinking about a three-way design. I found an
inexpensive Vifa buyout Mid-range driver PE 299-488
(now $3.97) and, since I had good luck with the Mylar tweeters in the Goldwoods,
I ordered a pair of those ($1.95 each)
Having a real mid-range
driver improved the sound, but male voices still sounded tubby. So I finally
decided the Allegros were going to have to go into a bigger, perhaps ported box.
Interestingly, the
Then there was the
crossover. Going into a three-way design, I expected that the most difficult
part would be to get the tweeter to mesh seamlessly with the mid-range driver.
As it turned out, that was not difficult. Getting the mid-range to woofer
interface right was much more difficult, and I have tried many different
configurations. Curt C and Dick M have both had substantial input into the mid
and low frequency crossover design, with Curt providing many of the ideas for
the mid pass and Dick the low pass. Technically, the low-pass in a second order
design with a Zobel. I’m not at all certain the Zobel adds anything. The mid pass is a first-order design,
as is the high pass. Resistors are to better match the output of the drivers.
Recently I exchanged the Goldwood tweeters in favor of Audax tweeters similar to those I used on the mini-monitors
that I found on sale at Parts Express for $8.04 each. They are PE 276-102. These are a 6-ohm design, and I added a
couple of ohms series resistance to better balance the
output.
The current version of the
three-way project is clearly the best of the designs I’ve built so far, but they
remain something of a work in progress. They have excellent bass—far better than
a small-woofer design, and can be built for similar $ to a small-woofer
two-way.
Box Construction
Notes
Tower Project
The boxes for both speakers
are crafted from a single sheet of ¾ inch MDF, I had Home Depot cut eight strips
8 inches wide and 4 ft long from a 4 x 8 sheet which runs about $16. There will
be plenty of scrap for tops and bottoms. The towers when assembled are thus
slightly deeper than they are wide. The port is located on the rear, near the
base. This means that the speakers must be located a foot or so from the wall.
You could do a front-firing port.
The cabinets are assembled with liquid nails and recessed 2 ½ inch long
deck screws. The cabinets have small braces inside positioned so they don’t
block the path to the port. I use closed cell foam instead of caulk for sealing
drivers. Ace Hardware has proven a better source of items needed than the local
Radio Shack. Here are some parts from ACE that come in
handy
Ace Self Adhesive Closed
cell sponge rubber weatherstrip Super Firm 1/8 inch
thick x 3/8 inch wide. ACE 57625. This is
great for woofer gaskets. There is also a 1/4 inch wide version (Ace 50560) that
works well for making gaskets for small dome tweeters.
Ace 16 gauge primary wire.
The wire comes in red, black and blue. Great for wiring
drivers and crossovers together. You can use this also to seal MDF box
joints so that one side, top or bottom is removable, for making
changes.
Wire Guard Twist-on connectors. Get a package of blue, a package of gray and a
package of orange. You can assemble crossovers and set them up so they can be
easily reconfigured without using any solder. You only need to think about
soldering your crossover together when you have come up with your final
permanent design.
Ace Terminal disconnects
22-18 AWG 3015393 These are the crimp-on disconnects in a good size for most
tweeters and small woofers.
I lined the towers on three
sides by hot gluing ½ thick quilt batting. I use pieces of polyfill glued on the back directly behind the woofer, while
keeping the air path between the woofer back and the port clear.
Box Construction Notes:
Goldwood Project
See the Information of the
Goldwood Page.
Box Construction Notes:
Mini Monitor Project
These are a basic unvented box of about 1/2 cubic foot internal volume made
from MDF shelving, screwed and glued. The external dimensions are 13 inches high
x 9 ½ inches wide x 9 ½ inches deep. I’m still experimenting with fill.
Currently, I have a 2-inch thick piece of poly on the back, sides top and
bottom. When I originally cut holes for the drivers, I wasn’t sure which tweeter
I would ultimately use. I am now using one that has a very small faceplate. Were
I to do this again, I would raise the woofer another inch so that it was closer
to the tweeter and further from the floor.
Box Construction Notes:
Three-Way Project:
This is a one cubic foot
version of the Mini Monitor box, with similar construction and poly fill.
External dimensions are 20 inches high x 13 inches wide x 10 inches deep. Fill
is similar to the mini-monitors with polyfill on the
back and sides. The tweeters are offset, and the speakers are mirror image
pairs.
Crossover
Notes
Crossover notes:
Towers
A schematic of the crossover
design for the towers, along with part numbers is at Crossovers . I have tried
the alternative values shown in the box. Those values increase the underlap between the woofer and the tweeter. The so-called
“Pepper Shaker” project posted on the PE message board used similar values. That
project was loosely based on these towers, but it also used a different Pioneer
Mid-tweet.
KenA
has been modeling the crossover design I used. He claims that the 0.8 mH inductor does little to alter the rolloff beyond it’s
natural acoustical rolloff, In this regard the 1.2 mH inductor is probably going to have a bit more effect.
I’ve tried both sets of values I can hear little if any difference between the
two. In theory, at least, the mids should sound
slightly more forward with the original values than with the alternate values. I
have experimented at length with both the original values and the alternate
values and I can detect very little if any difference. Feel free to experiment
and see which you like the best, but I don’t think the differences will jump out
a you.I set the L-pad on the tweeter about 2/3 up, but
again that is a matter of personal preference.
Crossover notes:
Goldwood Project
See the Goldwood Page at
at This location or The Crossover
page
Crossover Notes:
The Mini-Monitors
A schematic of the crossover
design for the towers, along with part numbers is at The crossover page .
I
The Mini Monitor Crossover
is a near textbook underlapped Linkwitz-Riley design which employs a variable L-Pad. I call
this my “almost generic” crossover, and is basically
identical to the one I used for the Towers. I had heard so many warnings from
other speaker builders regarding the lack of advisability of using a crossover
design that was not specific to the drivers, and I was anxious to test this
contention. The variable L-pad
compensates for differences in relative outputs. It turns out that this simple
second order crossover works very well in this design as well, and I would be
tempted to try it in many other small-woofer two-way designs. I wouldn’t call it
a “truly generic” crossover, but an almost generic design that might work in a
variety of small-woofer two-way designs.
Crossover Notes:
The
A schematic of the crossover design for the towers, along with part numbers is at The crossover page
The three-way crossover
design is second order on the woofer with a Zobel and
first order on the mid-range and tweeter.
Capacitors
101
An introduction to various
types of Capacitors used in Loudspeaker building
Capacitor and Inductor Spreadsheet
Calculator
Here is a capacitor and
Inductor calculator for first and second order textbook crossovers on a
spreadsheet.
LR, Butterworth 2nd order and
1st order spreadsheet calculator
Parts
Lists
I have put the parts lists
for all designs on a single spreadsheet, available here.
Photo
Album
Available here at DIY speaker
photos
Vintage Photo
Album
Available here at Vintage Gear Photos
New: Building a Home Theater System with a Combination of Vintage, DIY, New and Used Equipment
New: Building a Compact Subwoof using the Tang Band 5 1/4 inch Woofer
KLH
Loudspeakers
Information on various
models is available here at KLH
Speakers
Utah
Loudspeakers
Information on various
models is available here at Utah
Speakers
David Debertin does a
loudspeaker test disk The test
disk
