The document describes several speaker design projects by Ben Baker. Project 1 created 4-way tower speakers with no toe-in requirement and flat frequency response both on and off axis using a 2" dome mid-range driver. Project 2 made high-power 3-way tower speakers comparable to expensive B&W speakers. Project 3 designed an active subwoofer with high output capability. Project 4 adapted the tweeter design from Project 2 into bookshelf speakers competing with B&W 805s at lower cost. Project 5 created high-power 3-way PA speakers and Project 6 developed affordable amplifiers capable of over 200 watts per channel. Project 7 involved safety software for a power supply to only activate high voltage under

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Speaker Portfolio
Project #1 – Off Axis Heroes (4-way full range tower speakers)
Goals: Design a speaker that has no toe-in with full-range capabilities.
Challenges: Finding drivers that were flat both on and off-axis. Most mid-range woofers don’t have good
off-axis response at 5 kHz.
Outcomes: Design needed to be 4-way, and a 2” dome mid-range provided clean mid-range and perfect
off-axis.
Features:
 First and second-order crossovers for minimal group delay
 Designed to be within +/- 2 dB of axis up to 45 degrees
 - 3 dB point of 30 hz and 20 Khz
 full range system with no need for a subwoofer
 very low distortion drivers
 Can be offered in almost any finish
Basic enclosure schematic

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Crossover Schematic And Frequency response curve

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Impedance Curve
o Tower in living room with an unfinished texture(requested by customer)

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Project #2 – The Bio Hazards ( full range3-way tower speakers)
Goals: Make a speaker pair comparable to the B&W 800 Speakers for a fraction of the cost.
Challenges: Finding tweeters and mid-range that were sensitive enough but could handle the power
required for a premium sound comparable to one of the best (and most expensive) pro-sumer brands
available.
Outcomes: 8” mid-range for high-sensitivity and high-power handling. Aluminum dome for high-power
handling and excellent clarity, 2 10” subwoofers for power handling in bass region.
Features:
 Unique CAD-designed and CNC machined coaxial tweeter brackets are both highly
functional and aesthetically pleasing
 Continuous output of 117 dB per channel
 - 3dB point of 34 hz
 Coaxial tweeter design for best imaging
 Dual 4” flared ports for minimal port noise
 Add graphs

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o Crossover schematic and impedance curve
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The Biohazards Frequency response(above) vs The B&W 805 Frequency Response(below)

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The Biohazards in purple nicknamed “Barney”

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Project #3 – Black Beauty (active powered subwoofer)
Goals: Relatively low-cost, high-output subwoofer comparable to a velodyne 12” subwoofer.
Challenges: Finding a woofer with enough excursion capability to output high volume. Finding ideal
geometry that minimized port noise at high-volume.
Outcomes:
Relatively large enclosure with a port parallel to the vertical axis meeting the port noise objectives
without increasing the horizontal speaker footprint. Extremely high output capability with low distortion
sub-woofer for about $500.
Features
 Continuous output of 114 dB, -3dB point of 20hz
 Very clean low frequency, very large port for low port noise
Basic Enclosure schematic

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o

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Project #4 – Bio Hazard Book Shelves
Objectives: Create a design that competes with the B&W 805 speakers at 1/8 of the cost.
Challenges: Front-mounting the ports for near-field use while maintaining small vertical footprint and
optimal acoustic properties.
Outcomes: Using the same tweeter bracket from the Biohazard Towers created room for the port while
also giving better imaging and a unique, aesthetically pleasing look.
Features:
 +/- 2 dB on reference axis
 -3 dB point on low end of 45 hz
 Unique CAD-designed and CNC machined coaxial tweeter brackets are both highly
functional and aesthetically pleasing
 Coaxial tweeter design for best imaging
 Can be offered in almost any finish
Basic Crossover Schematic

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Impedance Curve(above)
Frequency response(below)

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Basic design specification
Comparison between B&W 805, and the Biohazard bookshelves , for size and looks.

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Project #5 – DJ Towers (3-way actively crossed PA system)
Goals: Make a high-performance Public Announcement speaker superior to all other commercially-
available speakers of its size.
Challenges: Finding high-power subwoofers with enough excursion to provide low-distortion bass and
lower frequencies than available from other speakers.
Outcomes: 4 lower-sensitivity 15” subwoofers that can handle 2x the power of comparable speakers for
the same cost.
Features:
 Continuous output of 138 dB at 1 meter within 10% distortion
 - 3 dB point at 32 hz
 Can power clubs or small outdoor venues with all music types
 Can be offered in almost any finish
Basic Enclosure schematic

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Project #6 – Amplifiers
Goals: Affordable amplifier capable of delivering more than 200 watts per channel.
Challenges: Heat dissipation while maintaining small package size and low-noise.
Outcomes: Class D designs so fans are not required. Class AB design with effective heat-sync to
aluminum case that allows a quiet fan to be used.
Class AB Class D designs
Class AB 350 watt x 2 into 4 ohms, .1% Total Harmonic Distortion
Class D 250 watts x 2 into 4 ohms, .1% Total Harmonic Distortion
110/220 VAC auto-switching input.
CNC Machined, aircraft aluminum cases with heat-sync, low-noise fans.
Project 7 – Safety software for power supply.
Requirements- This code must be on a platform that is well known and very widely used Such
that the interface wont be phased out in a very long time and can be purchased for a low price.
This power supply offers much higher efficiency over long distances due to the fact that it is
running at 240 volts AC; however, voltage like that can be extremely destructive to the human
body. Therefore this code must act as the standing wall between the safeties that can be
measured by the power supply.
Result- The code relies on 3 things to determine whether or not to turn on high voltage.
1. Is it grounded, and this can be measured using the ambient noise on the line
2. Is there a camera connected, which can be measured based on what type of noise is there
3. Is the camera on
All 3 conditions must be met in order to turn on the high voltage: however, There is low voltage
that must be applied in order to run the basic underlying functions of the camera. So once there
is a cable connected, there is an led that will pop up telling you a cable is connected and that
low voltage is applied, it will also tell you when the camera is on off, or connected. There is a
series of if else statements and while loops that only turn on voltage in certain arragements,
and breaks everything when there is no cable connected. Overall not too complex; However, it
can be hard to implement properly.