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Design Aspects Standard Features
- Alps RK097 Volume Control and On/Off Switch
-
Bass Boost Toggle Switch
- DC Auxiliary Power Jack
- Automatically powers On/Off when headphones
are connected/disconnected
- Texas Instruments OPA2227 Opamp in a gold-plated DIP
Socket
-
Texas Instruments
TLE2426 Precision Virtual Ground
- Decoupling Capacitors on all IC Supply Pins
- Components tweaked for natural frequency
response (with bass boost off)
- Custom cMoyBB PCB: Version 2.02 utilizes
a compact layout with a ground plane for excellent signal transfer
Exclusive Bass Boost Switch
The cMoyBB ships with an internal bass boost toggle
switch. 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.
Do-it-yourself builders have the option to substitute the bass
boost toggle switch for a boost boost control knob.
Printed
Circuit Board
Most cMoys are
built on protoboard and use thin wires to transfer the audio
signal, making them highly prone to interference.
The cMoyBB v2.02 uses a top-layer ground plane and tightly optimized signal
traces, easily outperforming hand-soldered protoboard connections.
Power
System
A Texas Instruments TLE2426 precision rail splitter and a
25V, low noise Nichicon 470 uF capacitor are used to eliminate the unbalanced
resistor divider power system found in standard cMoys. The cMoyBB handles 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.
The cMoyBB v2.02 also employs 0.1uF ceramic decoupling
capacitors on all IC power pins. Decoupling helps to prevent IC supply ringing,
which improves opamp stability and sound quality.
DC Auxiliary Power Input Jack
Any linear-regulated 9-24V DC power adapter
with a 2.5mm submini jack can be used to power the cMoyBB amplifier. Plugging in a DC power
supply automatically and safely disconnects the 9V battery (it is not a charging
circuit).
JDS Labs does not sell or include AC/DC adapters. However, a
DC adapter can be
purchased for as little as $10
(USD) in North America.
Enclosure
The cMoyBB v2.02 is cased inside of a brand new*
Altoids Peppermint tin, protecting
the circuit from some forms of external EMI / RF interference. 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! |
