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Design Aspects
Special Features
• Automatically powers on/off when you connect or
disconnect your headphones
•
Master Power switch also built into the volume control
• Exclusive Bass Boost switch for up to TWICE
the bass!
• Tweaked
for natural frequency response (with Bass Boost off)
• DC auxiliary power jack
•
OPA2227
opamp in a gold-plated DIP socket
•
Alps RK097 Volume Control
•
Built on the finest custom cMoy PCB: Version 2.01 utilizes a ground plane,
wide traces, and a compact layout for excellent signal transfer
First-Rate Distinctions
• 100% Satisfaction Guarantee
• Hand assembled and channel balanced
• Free lifetime support
High-Quality Components
The quality of an amplifier's capacitors, resistors, and
amplification chips plays a significant role in accurate sound reproduction.
Quite simply, cheap parts sound bad. Aided by theoretical calculations, I have
carefully selected and evaluated numerous components to optimize the sound
quality of the original cMoy design according to a simple goal: to create the
fullest, flattest sound possible. Each amp is built with fantastic sounding
polypropylene film capacitors. I hand match premium metal film resistors to
ensure their excellent sound is balanced between the left and right channels.
cMoys without hand matched resistors may produce slightly different volume
output in the left and right channels!
The amp utilizes a heavy duty 9V battery connector
with hand-twisted wires to avert electromagnetic interference. Other amps rely
on standard, flimsy battery connectors that tend to break easily, even when
rarely used. Equivalently robust 3.5mm stereo jacks provide high durability and
a cleanly transferred signal.
Optimized Sound Quality
Standard cMoys produce less-than-ideal
frequency response curves, meaning highs and lows are not what they should be.
The revised specifications employed solely by the cMoyBB v2.01 give it the
flattest, most natural response of any cMoy on eBay. No tonal range is
emphasized; that is reserved for Bass Boost. This cMoy sounds
the best.
Bass Boost Switch
The full and natural sound generated by my amps is sought
after by audiophiles. While other cMoys can plainly amplify the sound of your
music, my exclusive Bass Boost feature gives
you the option to take headphone amplification to the next level:
equalization. Switched off, the original, flat audio signal is amplified.
Switched on, bass is increased up to ~9.4 dB, just shy of a perceived 2x
increase in bass volume. My competitors may call this feature "artificial
distortion," but customer reviews tell otherwise.
 Printed
Circuit Board
Most cMoy amps
are built on cheap protoboard and use thin wires to transfer the audio
signal. High-end amplifiers, on the other hand, rely on PCBs to maximize
signal integrity and amplifier stability. Your amplifier is built on a
high-quality, well-engineered PCB I designed and special order from a
leading PCB manufacturer.
The circuit board uses wide 30mil traces, tight
component arrangement, and a ground plane to cleanly transfer over 4x the
electrical current demanded by a cMoy, easily outperforming hand-soldered
protoboard connections and cheap PCBs designed by unqualified amateurs.
Amplifiers built with protoboard cost less and can be easier to customize and
routinely assemble, so from my vantage point, why might I have opted to use
PCBs? The answer is simple: I intend to build the best sounding amplifiers, not
the easiest to assemble! Do not be fooled by claims of protoboard's superiority!
Amplifier Chip
The cMoyBB comes with a Texas Instruments
OPA2227 operational amplifier, one of my favorite professional audio
opamps. At least to my ears, the OPA2227 is a huge upgrade in
sound quality over the cheaper OPA2132/OPA2134 chips (they are less
detailed than the OPA2227 and have a less immersive sound).
The opamp is mounted in a gold-plated 8-pin
DIP socket, allowing you to purchase other chips to alter the amp's
"signature." Amplifier stability is an important concern when trying
alternative opamps, but you can be assured that my high-end PCB's
tight layout will deliver excellent results. For those interested in
trying alternative opamps, I highly recommend National
Semiconductor's LM4562NA. If you have are interested in purchasing
an LM4562NA opamp chip, feel free to contact me.
Please note that a DIP socket not only gives
you the option to try different opamps; it prevents the sensitive
opamp from experiencing damaging heat during amplifier construction.
In other words, opamps soldered directly to an amplifier by hand
can be slightly damaged from the intense heat! Direct
chip-to-board soldering should be left to carefully controlled
machines!
Volume Control
The cMoyBB v2.01 features the well-regarded Alps RK097
potentiometer paired with a brushed aluminum knob.
A headphone amplifier's volume control allows you to
attenuate the input signal before it is amplified. To best understand the
purpose of the volume control, pause your music and listen carefully to your
headphones. You may hear slight background hissing, known as the noise floor.
Amplifiers without volume controls amplify this noise floor, making the signal
sound worse. In contrast, headphone amplifiers with
volume controls compress the input signal and minimize the noise floor to
inaudible levels, effectively improving the signal.
 Power
System
A Texas Instruments TLE2426 rail splitter and high
voltage, low noise Nichicon 470 uF capacitor are used to eliminate the
unbalanced resistor divider power system found in lesser cMoys. Other builders
erroneously waste board space with higher capacity power supply capacitors,
claiming superior bass performance. I notice this
mistake again and again and admit I was sold on the cMoy with the largest
capacitors when shopped for my very first amplifier. In reality, 470 uF is over
twice the adequate value, and a well-built cMoy generally sounds no different
with this capacitor removed (ask me for a detailed explanation)!
The cMoyBB is designed to handle more than double the
voltage of most cMoys, meaning the dynamic range of high impedance headphones
can be extended even further when using a high voltage DC adapter.
I configure the blue LED to draw minimal power. Battery
life is thereby conserved and the LED will not be painfully bright.
DC Auxiliary Power Input Jack
You may use any linear-regulated 9-24V DC power adapter
with a 2.5mm submini jack to power your cMoyBB amplifier. Plugging in a DC power
supply automatically and safely disconnects the 9V battery (it is not a charging
circuit.). I do not sell or include AC/DC adapters. However, each amplifier
shipment includes documentation to purchase a DC adapter for as little as $10
(in North America), plus quick do-it-yourself instructions that may enable you
to turn an existing adapter into one usable by your amp.
Enclosure
The cMoyBB v2.01 is cased inside of a brand new*
Altoids Peppermint tin, protecting
the circuit from external EMI / RF interference (unlike plastic cases). Foam
support keeps the battery securely in place. I sometimes stock other mint
tins. Contact me if you have something specific in mind.
*Despite each tin being brand new, I have noticed Altoids tins
occasionally have some sort of scratch or dent (not always!). Additionally, you
should anticipate minor jack mounting imperfections due to the hand built nature
of the product. Please excuse these possible minor
cosmetic defects. Thank you! |
