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"Angel Fire 1"
Floorstanding
"MTW" LoudSpeakers
Project, Text and
Images courtesy of Scott Anderson
"Did you ever wish
that your favorite rock band would back a truck up to your house and set
up in your living room? I didn't either but I wanted it to sound that way.
That's what this speaker is all about, recreating the sound and levels of
live music in your living room..."
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Overview
- A high power 3 way design using a
15" Dayton
woofer, Morel
dome tweeter and Morel midrange.
- Response: 30hz - 20,000hz
- Sensitivity: 90db 1w/1m
- Power handling: 300w RMS/425w Max
These specs are estimated based
on driver specs since I have no test equipment.
Design Goals
- Achieve high spl. in a home
environment
- Very low distortion
- Well defined bass
- Clear midrange and highs
- Optimized for rock music
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Drivers
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Dayton Series II
15" Woofer
Price and performance = Value
Full
Specifications
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Power
handling: 300 watts RMS/425 watts max
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Voice
coil diameter: 2-1/2", Voice coil inductance: 4.4 mH
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Nominal
impedance: 8 ohms, DC
resistance: 6.3 ohms
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Frequency
response: 19-1,000 Hz
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Fs:
19.0 Hz, SPL: 89.5 dB 1W/1m, Vas:
9.64 cu. ft., Qms: 10.46, Qes:
.35, Qts: .34
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Magnet
weight: 90 oz., Xmax:
8.0mm
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Morel MDM 55 Midrange
Why this Dome? It
rocks!
Full
Specifications
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Power handling: 200
watts RMS/285 watts max
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Voice coil diameter:
2-1/8", Voice coil inductance: .19 mH
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Impedance: 8 ohms, DC
resistance: 6.3 ohms
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Frequency response:
500-6,500 Hz
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Fs: 380 Hz, SPL: 90.5
dB 1W/1m
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Morel MDT 37 Tweeter
It blends so well with the MDM-55,
they become as one and sound oh so sweet.
Full
Specifications
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Power handling: 200
watts RMS/280 watts max
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Voice coil diameter:
1-1/8"
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Impedance: 8 ohms, DC
resistance: 5.2 ohms
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Frequency response:
1,800-22,000 Hz
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Fs: 700 Hz, SPL: 93 dB
1W/1m
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Crossover
- 1st Order
- Low 750hz
- Band pass 750hz low 5150hz high
- High 5150hz
14 Gauge Perfect Layer Wound Air Core
Inductors
Mills 12w Non-inductive Resistors
Solen 400v Metalized Polypropylene
Capacitors
The crossovers are built on
8"x 12" pieces of 1/4" hard board. All components are hot glued
to the board and soldered lead to lead as much as possible. Some caps are
paralleled and some resistors are in series to get correct values (see
parts list). I only used wire in two places: a jumper from the + side
connecting the low pass to the band pass and one from the zobel back to
ground.
The crossovers are mounted in the bottom of the cabinets. Be sure to put the
two inductors in opposite corners of the board. The leads to the speakers and
the binding posts are made from 11GA. Monster
cable.
Cabinet Details
Driver : Dayton Series II 15"
Box type : Vented
Box size : 3.500 ft^3
Tuning frequency : 25.00 Hz
Vent : 2 vent(s)
0.1524 m length for each
0.0508 m round
Freq Gain SPL
| [Hz] |
[dB] |
[dB] |
| 20.00 |
-10.66 |
78.84 |
| 25.00 |
-5.63 |
83.87 |
| 30.00 |
-2.35 |
87.15 |
| 35.00 |
-0.51 |
88.99 |
| 40.00 |
0.35 |
89.85 |
| 45.00 |
0.69 |
90.19 |
| 50.00 |
0.78 |
90.28 |
| 55.00 |
0.77 |
90.27 |
| 60.00 |
0.72 |
90.22 |
| 65.00 |
0.66 |
90.16 |
| 70.00 |
0.60 |
90.10 |
| 75.00 |
0.54 |
90.04 |
| 80.00 |
0.49 |
89.99 |
| 85.00 |
0.44 |
89.94 |
| 90.00 |
0.40 |
89.90 |
| 95.00 |
0.36 |
89.86 |
| 100.00 |
0.33 |
89.83 |
Data from Win
ISD
I used pre-sanded pine
project panels from Lowes.
These are made up of edge glued 1"x2" pine strips. We used to make
PA speakers this way back in high school except we had to glue the panels
ourselves. The advantage of this type of construction is that the laminated
wood damps well and they are not too heavy to move. I can easily pick one up
and move it by myself. Now you can buy ready made panels, this is a real time
saver. The side panels measure 36"x 12"x 3/4". The Top and
bottom are cut from the same size panel to make two pieces 17 1/2"x
12"x 3/4". The front and back are 36"x 16"x 3/4".
This method of construction only requires 4 saw cuts on the outside panels
which saves time and limits mistakes. 1"x2" select grade pine lumber
is used for bracing and glue blocks. I ran these full length along all joints.
I also ran cross braces at about the 1/3 point from each end of each panel and
above and below each of the drivers. All of these are glued flat against the
panels. The cabinet is assembled using butt joints and secured with titebond
wood glue and drywall screws. Pre-drill all of your holes to keep the wood
from splitting. Be sure to seal the inside of the cabinet with something. I
used a 50/50 mixture of glue and water on the inside of the panels and
silicone caulk on the joints. For extra damping I used Acoustic
damping sheets on all panels between the braces. The enclosure is lined on
all sides except the front baffle with 3 1/2" fiberglass insulation. I
used the new type that is encapsulated ( doesn't itch). Screw holes are filled
with wood filler and sanded smooth. I cut the driver holes using a jigsaw.The
speakers are painted with black lacquer spray paint. The only power tools used
where a circular saw, orbital sander, jigsaw and a cordless drill. Other
options for building this cabinet could include plywood or MDF. If you've got
the tools and want to try another material and/or finish then go for it.
Driver Layout
All drivers are mounted on the center line
of the baffle in an MTW layout. Layout on 16"x 36" baffle is: From
top down 3" - 7" - 18 1/2". The ports are 4 1/2" up from
the bottom and 3" over from each edge. Drivers and ports are sealed in
using 1/4" weather stripping. I decided to cover the area of the front
baffle inside the grill frame with automotive carpet to help kill
diffractions. It seems to have worked. I used a piece of black carpet
16"x 28". I tried several different driver layouts while developing
this speaker and this one is the best. I don't recommend offsetting the
drivers but if you decide to try it be sure to keep the Domes in a straight
line. The sound suffers badly otherwise.
| Grills
Grill frames are made from
3/4" square poplar with metal angle brackets on the corners. These
are available at most hardware stores. The frames measure 17 1/2"x
30". They are covered with black
grill cloth from PE that is secured with 1/4" staples. The
grills are attached using Grill
Guides also from PE. |
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Development Process
Much progress has been made on speaker
design in recent years but the laws of physics dictate that if you want bass
you must use large drivers. Yes I know that you can get good bass out of an
8" driver but most have no soul and give a kind of mono tone response. So
I selected an appropriate 15" woofer. At first I had my doubts about this
moderately priced driver but not any more this is a fine woofer for the money.
The sound is rich and deep. But the real advantage to using a large woofer is
dynamics, and this Dayton delivers all you could ask for. Music is reproduced
with all the power and punch of the original. Electric guitars and drums sound
like they are in the room with you. One of the first compromises I had to make
was in cabinet size. This driver would be more at home in slightly larger box
but I (read wife) had set a size limit prior to starting this project so I
went with the realistic minimum cabinet volume for this driver.
This driver has plenty of power handling so
the next step was the hard part, finding a mid. The type of speaker I had in
mind called for using either a horn or a dome so my options got narrowed down
fast. Horns are fine in large rooms where the sound has room to spread out but
not so good in my listening room. This left me with choosing a dome and lucky
for me Morel had just what I needed, a high power, excellent sounding dome. I
also happened on the tweeter at the same time and it looked like a likely
candidate for testing so I sent in my order. The tweeter is a semi-horn design
but does not suffer the pitfalls of typical horn tweeters and it has a very
smooth sound.
Crossover design was a real challenge
working from a text book starting point and swapping parts. I spent nearly two
weeks tweaking and listening with help from my teenage kids we finally found
the magic formula. After final assembly I did extensive listening tests with
friends and family. We all agree the sound is right on.
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Results
The final product is an excellent
sounding mid sized floor standing speaker. Sound levels are more than
enough for a medium sized room with lots of headroom. My listening room
is 13'Wx 18'Lx 10'H and the speakers will shake the floor with live
volume levels and with no precivable distortion at less than 2/3 power
with an 80w amp. Just the way we like it. My wife and I enjoy watching
live concert DVD's and have started a collection. That pastime was a
driving force in this project and was fully rewarded with a sound that
feels live. The speakers are used as part of a home theater system
placed well away from the TV (no shielding) and work great for that as
well.
While these speakers where designed
for rock music they also do very well with New Age, Jazz, and classical
which we listen to from time to time. The sound stage is large and deep
with fairly good imaging considering the wide baffle design. Trying
different positions for the speakers we discovered that the sound stage
is improved if the speakers are raised about a foot off the floor. YMMV
I recommend at least an 80w amp for mid sized rooms, for larger rooms a
100 - 200w amp may be in order. I haven't tried higher power amps yet
but I'd guess with 250+ watts these would make good DJ speakers or could
even be used in a small club.
I have no way of testing the speakers
other than listening so all I can tell you is they sound fantastic. I
would like to get them tested someday. If someone in the DFW area has
the gear and doesn't mind doing it send me an e-mail.
One final note, the drivers will
require quite a bit of break-in time to realize their potential,
especially the woofer. |
| Parts List
All of the speaker parts for this
project where purchased from Parts
Express.
2 - Dayton 15" Series II Woofers #295-130
2 - Morel MDM-55 Compact Dome Midrange #287-020
2 - Morel MDT-37 Soft Dome Horn Tweeter #277-045
4 - 2" port tubes #260-387
2 - Gold Heavy Duty Binding Post pr. #091-1245
8 - Cabinet Feet #260-771
1 - Grill Guides 12pk. #260-367
1 - Black Grill Cloth yd. #260-335
2 - 1.8mh 14GA. Perfect Layer Inductor #266-365
2 - .30mh 14GA. Perfect Layer Inductor #266-315
4 - Solen 20.0uf Polypropylene Cap #027-582
2 - Solen 51.0uf Polypropylene Cap #027-602
2 - Solen 3.0uf Polypropylene Cap #027-542
2 - Solen 4.7uf Polypropylene Cap #027-552
2 - Solen 8.2uf Polypropylene Cap #027-564
2 - Mills 2 OHM 12w Non-Inductive Resistor #005-2
2 - Mills 20 OHM 12w Non-Inductive Resistor #005-20
2 - Mills 4 OHM 12w Non-Inductive Resistor #005-4
4 - Mills 8 OHM 12w Non-Inductive Resistor #005-8
20' - 11 GA. Monster High Definition Speaker Cable #100-660
24 - Acoustic Damping Sheet 10"x 10" #
268-010 |
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About the Designer
"I am 36 and live in the Dallas/Ft. Worth area. I work
in the commercial construction
business as a supervisor. I've been married 15 years and have 3 kids
2 of which are teenagers. I have been an avid music lover since childhood.
And of course I love live rock music.
If you're wondering where the name for the speaker
comes from... our house has
the nickname "The Angel Fire Inn" because that's the name of our
street and because of it's many teenage and other visitors that never seem
to go home."
Special thanks to Scott Anderson for
submitting this great project!
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