Microshar uAMP107B

Microshar uAMP107BIt’s small, it’s black… it’s a simple headphone amp

It’s powerful enough to drive 8 Ohm speakers. The unit doesn’t actually turn on until you plug into both the input and output jacks. The volume knob on the front turns smooth with no static or noise. By the way, it’s made in the USA… just throwing that out there.


The unit is encased in plastic, so don’t sit on it.

Cool little thing that will maintain your portable system’s audiophile grade. At $135, it’s not going to break your bank. What it lacks in features is more than compensated for in battery life: up to 230 hours. That’s about four times as long as its nearest competitors.

Check the Amazon website here for more information on this product.


Bite-size Stereo Headphone Amp


Cool little thing that will maintain your portable system’s audiophile grade. At $135, it’s not going to break your bank.
Microshar makes one sick little headphone amp.  It’s simple, inconspicuous and unobtrusive, and its function is probably most appreciated in a portable setup.   The uAMP107B and your iPod can both easily fit into your pocket or fanny pack.

The battery on the uAMP107B lasts for about 230 hours when fully charged.  This is a week and a half straight!  You could listen to the entire Zappa catalogue on one charge.  The charger looks like a computer mouse and fully charges the unit in about four hours.  There is a small blue LED that indicates the battery’s level by how bright it is.

One great feature of the uAMP107B is automatic power-up.  Similar to a guitar pedal, the unit will not power up until both input and output jacks are plugged in.

The input and output jacks are standard eighth-inch.  The input is flexible and can handle virtually any audio signal from any source (iPods, CD players, etc.).

The Microshar uAMP107B is powerful enough to run 8 Ohm speakers.  This is great and all, but be careful when you have headphones on, especially if the unit is placed in your pocket.  The loudness knob can easily be turned to a high level and accidentally send you a dangerously loud signal (dangerous for your headphones and your ears).  For units that fit into bags or pockets, I’d like to see a way to lock the volume.  At the very least, it’d be great if this unit had a gain control to limit the signal.

So how does it sound?  Nice… I like!  It’s crystal clear.  I’m pumping a digital signal from an iMod (modified iPod) into the unit, and it’s driving Sennheiser HD650 headphones.  With the loudness knob set in the middle (at 12 o’clock), the Microshar uAMP107B delivers a detailed, intelligible signal.  It doesn’t distort the phones until about the 2 o’clock position (don’t do that, by the way).

For the past few hours, I’ve been listening to the Exodus  album through the amp (particularly to the vocal treatments on Marley’s voice).  When you can hear specific production qualities of the music, you know you have quality gear.

Where to Purchase:

Check Out the the Amazon Website Here.

Technical Info:

Input Impedance: 10,000 Ohm/channel
Input Level: 0V to 75mV (1200mV max.)
Frequency Response: 5Hz – 115kHz (+/-1dB)
Output Power: up to 350mW/channel RMS
Output Impedance: < 8 Ohm each output
Gain: 0 to 900% (+19dB) each channel
Signal to Noise Ratio: > 110dB
THD+N: < 0.006% (10Hz – 20kHz)
Battery Life: up to 230 hours
Charge Time: 4 hours
Price: $135

See the Amazon website for Microshar uAMP107B

Bass Boost CMoy Headphone Amp

Philips SHS3200/37 EarbudsPortable headphone amp with a bass boost feature


It’s in an Altoids box. That’s kind of cool. It uses a high-grade Texas Instruments chip. The gain gives a good even boost, and the bass boost feature really fills up the bottom end, delivering awesome presence.


There is a great deal of noise when the gain is not engaged. Same goes for the bass boost – when it’s not engaged, there is a little bit of noise. There is no volume control, either. That’s dependent solely on your audio device or an inline volume control.


For almost $40, not a bad deal at all! The bass boost feature is absolutely awesome. I’m a little disappointed there is no volume control, but I guess there’s only so much room in an Altoids box.


Curiously Strong Bass

For almost $40, not a bad deal at all! The bass boost feature is absolutely awesome. I’m a little disappointed there is no volume control, but I guess there’s only so much room in an Altoids box.

In a mini box where about 75 small, white, edible disks once sat, there is now headphone amp circuitry.  It’s cool, it’s creative… it’s a headphone amp encased in an Altoids box.  It has a few things missing, but makes up for it with two great features and quality components, relative to other Cmoys.

There is no volume control on the unit.  That’s determined by your sound source’s output (iPod, portable turntable, etc).  The maker’s explanation for a fixed gain is pretty practical: no potentiometer means less circuitry the signal has to pass through.  That’s combined with an ergonomic reason: when you access your sound source, your hands are already there and it should have a volume control… and how many do you really need?  So instead of a volume control on the amp, there is a gain control.  This gives a good, even boost to your headphones.  That’s more important when dealing with high-impedance headphones in the range of 150+ Ohms, but I’ve had it engaged all day, just for fun.

When the gain is not engaged, there is a small grounding problem.  I have the unit hooked up to the audio output of my PowerBook, and there is a hum in the AKG K701 headphones I’m using.  As soon as the unit is placed on my computer’s titanium shell and cuddled with my hand, the hum goes away.  It also goes away when the gain switch is flipped on.

The BassBoost feature alone is well worth buying the unit.  It gives such an incredibly clear and powerful lift on the lower end (14.1dB, almost three times bass loudness), adding more low frequency presence than any other headphone amp I’ve ever heard.  Big bass is a signature of my generation, and a design to emphasize this is perhaps best delegated to someone of my generation.

The designer of the BassBoost Cmoy is an engineering undergrad at the University of Missouri.  He set out to improve the general Cmoy design as well as to innovate the functions and features.  The result is a tweaked version of a regular Cmoy, employing the same TI opamp (OPA2227P) but with higher quality components and even custom-printed circuit boards for a professional look.

One non-audio improvement is a DC power jack.  Although it’s not included, recommendations are made to get your own for under $10.  The entire unit will run on a 9V battery, but when DC power is plugged in, the battery is politely bypassed.

Normally, I am not a huge fan of the AKG K701 headphones.  However, when they are met with a great amp and given a little pat on the behind (a.k.a. bass boost) they come alive.  Such is the case with the BassBoost Cmoy.  It delivers such incredible bass response that it’s actually hard for me to listen to anything else right after using the feature.  However, with lesser headphones like the AblePlanet Clear Harmony phones, the bass boost can muddy up the mix, especially at louder volumes.

Some people may not like the frequency spectrum being altered because it doesn’t accurately reflect the master recording.  However, that’s very subjective and depends on your personal preferences.  Some people hook up massive car audio systems with bass that can be heard two blocks away (including me) because that’s how they like to hear their music.  I’m happy this Cmoy has an option to adjust the bass.

So there it is.  Leave it to a young entrepreneur to take a great product and make it greater.

Technical Info

Price: $40

JDS Labs cMoy Bass Boost v2.00

Philips SHS3200/37 EarbudsSecond version of cMoyBB, debugged and with new features


All the great things about the first version are still here: high-grade circuit components, a great bass boost feature, and an Altoids enclosure that’ll make rubber gloves snap at airports. The drawbacks to the first version are pretty much completely resolved. There is no more noise issue, which was my biggest problem with it. That’s because the gain switch has been eliminated and a volume pot is in its place.


So far, so good.


I’m a sucker for second generations of most products. It usually means the kinks have been worked out of the first. Although the debut cMoy Bass Boost from JDS Labs was a killer product, its second-coming is a truly superior product. The Bass Boost feature, alone, is worth the price.


Logitech FreePulse Wireless: Conveniently Cordless and Bluetooth

Although the Logitech FreePulse Wireless shines when it comes to wireless convenience, the lack of comfort, limited usage time and less than fantastic sound may be enough to deter some users. But if you can withstand these imperfections than the Logitech FreePulse Wireless can become a reasonable buy.

The Logitech FreePulse Wireless Headphones gives the luxury of listening to your favorite music without being constricted by a pesky wire. Due to the Bluetooth 2.0 wireless technology, you can wear the Logitech FreePulse Wireless Headphones up to 33 feet away from your electronic device. It even comes equipped with a rechargeable battery that last for up to six hours. For unmatched comfort, it also provides a durable high carbon spring headband as well as custom-fit soft-touch comfort rings. The Logitech FreePulse Wireless Headphone is made to fit all 3.5mm adapters.

Technical Info

Bluetooth 2.0 with Enhanced Data Rate (EDR) wireless technology
Maximum Range: 33 Feet
Frequency: 2.4 GHz
Soft-Touch Comfort Rings
High-Carbon Spring-Steel Headband
Integrated Bass Boost
Transmission Format: Digital
Rechargeable Battery
Optional AC power adapter
Custom-fit for iPod, MP3, CD and DVD compatibility
Suggested Retail: $109.99

Micro CMoy Opamp2227

Philips SHS3200/37 EarbudsMini headphone amp encased in an Altoids box


It’s made from Texas Instruments amp circuitry. It’s actually in an Altoids box, so if it’s character you’re looking for, you got it. It’s kind of like a DIY kit, except it’s already done.

The knob is slightly larger than the thickness of the box, so it doesn’t sit perfectly flat on the table. That’s disastrous to me and anybody else with OCD. I’m also not a big fan of the toggle power switch; I’d rather see a button.


It’s inexpensive, made from consumer-quality components and very creative. All in all, for $35 it’s an amazing deal. You get what you pay for. In this case, it’s an Altoids box fitted with a headphone amp.


Curiously Strong Headphone Amp

It’s inexpensive, made from consumer-quality components and very creative.

Ok, let’s just get this out of the way: yes, it’s an Altoids box.  It’s cute, creative, and curiously strong.  Don’t get confused, though.  This is a quality headphone amp, designed with great components and craftsmanship, and it will drive your headphones like peppermint never did.

Let’s start with the not-so-hot stuff about the Micro Cmoy Opamp2227.  The loudness knob is slightly larger than the box, and protrudes beyond the bottom of the case.  This means it’ll never sit on a desk perfectly flat.  However, I’ve learned to deal with this over the hours.  I just rest my hand on top of the unit.  To make it louder, slide the unit to the right and it turns the knob “up” against the desk.  Slide the unit to the left and it turns it down.  Ridiculous?  You’re ridiculous.

Next, nothing is labeled.  There are two 1/8” jacks on the front, but they’re not labeled.  One is an input, one is an output, and your memory is your only friend.  This sucks for the elders, the Murphy’s Law-ers and the entire pot-smoking community.

My last “complaint” is about the unit’s interaction with petty thieves.  They intended to steal Altoids.  Everybody loses.

Now, on to the good stuff.  On the scale of innovation, the Cmoy gets ten stars.  It is the ultimate Rag Shop headphone amp.  I love the enclosure, and I love that every piece used to design the amp can be revealed.  The most significant parts are the opamp chip (a highly-regarded Texas-Instruments product) and the potentiometer (a highly-regarded Panasonic product).

If you itemize the parts used in the Cmoy, they come to about $20 (including cost of the Altoids).  I’m estimating that is about average for parts in headphone amps.  The difference is, markup on the Cmoys is significantly lower, so you get a fair deal.

How does it sound?  For an Altoids box, pretty darn good.  For a headphone amp, kind of average.  But (big but) it is the kind of average that’s contingent upon your wants and needs.  Remember, it uses some audiophile-grade components… and it’s $35.

I’m taking a signal straight from my PowerBook’s 1/8” output (volume halfway) and the Cmoy is driving AKG K701 headphones.  They sound crisp, clear, and “free,” as in loud but still preserving the dynamic range.  Plugged straight into the computer, the headphones sound and respond the same (audibly), only not as loud.

An interesting end note for the adventurous: the Cmoy is not exclusive to any one manufacturer.  It is a hobbyist’s creation, and there are several online tutorials that can guide you all the way from purchasing the parts to completion.

Technical Info

Price: $35