JDS Labs cMoyBB Headphone Amp review

Patrick Nosker February 19, 2009 0


As someone who appreciates great sound, I've spent a larger portion of my money on what is best described as sound equipment.  One of the most overlooked components of mobile sound is the headphone amplifier.  While standard iPod headphones won't change much with a good amp, high impedance drivers in audiophile headphones such as those made by Sennheiser are almost lifeless without one.  One of the major complaints that I have against consumer level audio players such as the iPod and iPhone is that the amp within is good for 95% of the userbase but the other 5% who wants to be able to listen to lossless tracks with great reproduction will need a good amp along with good headphones.


Luckily, a great and cost-effective design is publicly available.  Electrical schematics are online and you could potentially build a decent amp for ~$30.  Many people don't have the time, tools, or skill needed to construct one however, so they must go for another option: pre-made.  John Seaber, an entrepreneur and Electrical Engineering student at the Missouri University of Science and Technology has modified the basic cMoy design, which is essentially a basic amplifier that creates a virtual ground so that a small opamp can operate, to be much more convenient and feature packed.

Some interesting added features of JDS Labs' cMoy:
-Only powers on when headphones are plugged in to save battery life
-Bass boost toggle switch
-Altoids case (added bonus of blocking EM interference)
-Alternate power source

Since using the cMoyBB, I have noticed several nuances in music that I missed before.  The differences are most noticeable at high volume levels, which I don't recommend for long-term listening.  With my iPhone turned to half volume, and the cMoy at half, my Triple.fi's are at a good volume level and I can make out many hidden parts of songs.  Battery life is good.  The initial dry cell battery it came with lasted about 2 weeks of moderate listening.   An alkaline lasted over a month.  Perhaps this is something that it should come with so dry cell batteries (though cheaper) can be saved for very-low-consumption gadgets instead.  The feel of the unit is surprisingly good for something that is composed mostly of an Altoids tin.  The build quality is great as well.  The board is held in firmly and the battery has a foam piece that keeps it sturdily attached.  My only complaint is that the blue LED that shows if it's on is very very bright.  I think perhaps a lower power 3mm LED would be more suitable and conserve power.

John Seaber sells the board itself on his site so you can build it yourself if you want to modify it.  The opamp is held in a socket so it can be easily swapped with other opamps if you want to try out different sounds.

Definitely get one of these if you have a low budget but want to hear more missing components of your favorite songs.


JSeaber cMoyBB – 9.5/10

[JDS Labs cMoyBB] – $65 / (Board and other components are available so self-construction can be less than $55)

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