This is the new revolutionary XIN SuperMicro Amp.  It has exactly the same core of the very popular XIN Super Mini Amp but uses only one AAA battery.  It weighs only one ounce (with battery) and is just slightly larger than a AA battery; so it can be used just like an inline remote or a pen that you can clip into your pocket (see how proud that little rabbit is!).  It has all the features of the Super Mini - multiple loops, CCS (cascode current source) class-A biasing, digital volume control, bypass able XinFeed, super blue power light, etc.  As the amp voltage is boosted up to 5.5V, it is even more powerful and could sound even better than the super mini amp; it has far more choices for op-amps and buffers.

 PC Magazine awarded 4-Stars to this SuperMicro amp:

"This minuscule pocket amp (2.5 by 1 by 0.6 inches, and just 1 ounce) has full, warm, and accurate sound quality. We were disappointed by battery life—the one triple-A lasted only 7 to 9 hours—and the music quality degraded before the power light indicated that the battery was going. For a mobile listener, though, this is the best choice."

Many thanks to PC Magarzine and Mr. Matthew D. Sarrel, PC Magazine Labs' technical director.

Note that the SuperMicro reviewed was an earlier version and the latest versions have been improved with better battery life.

Configuration:

bullet2.45in x 1.0in x 0.6in, 1.0 ounce (yes, w/ battery) - absolutely world's smallest amp
bulletSteady 5.5V operating voltage within the entire battery level from 0.7-1.65V
bulletThe latest audio op-amp AD8620 for tube-alike but better sound
bulletSeparately buffered output of 100mA clipping at 5.35V - drive any demanding headphones
bulletAmplification gain of 11 - make the weakest portable players rock
bulletCascode current source (CCS) class-A biasing for the lowest distortion
bullet1% precision resistors and audiophile film caps
bulletBattery life (continuously): 18Hrs w/ Sony AAA LR03 AM4 Alkaline; 12 Hrs w/ Energizer NH12-AAA 700mAh NiMH
bullet2-button 65-steps digital volume control
bulletXinFeed - fully bypass able cross-feed
bulletSuper red power light (optional blue)
bulletPower switch
bulletGold-plated jacks

Note that you need an mini-to-mini interconnect cable to use this amp (connected to the volume control side).  You may add the OFC cable into your shopping cart when you buy this amp.  You can buy such cable from others such as Radio Shack, but our cable is very flexible - the best for portable use.  You don't need anything else and this amp is truly plug-and-play.

The following picture shows how to connect it with a Sharp MD player and a pair of ER4S headphones. From the top to the bottom: input jack, power switch, power LED, XinFeed switch, volume control buttons and output jack. For how to use the switches, see the FAQ below.

FAQs

bulletHow to use the volume buttons?

Press or hold the up button to increase volume; press or hold the down button to decrease volume.  The first time you use the amp, hold the up button until you hear.  The last volume position is usually remembered even after you changed battery.  The best way to set volume is to leave the source volume between 1/3 and 2/3 or so and use the amp buttons for volume adjustment.  If you turn the source level to too low, the S/N (signal-to-noise ratio) becomes worse.

bulletHow to use the XinFeed bypass switch?

As showing in above picture, move the slide switch to right to enable XinFeed; move to left to bypass it.

bulletHow to use the ER4P-to-S bypass switch?

In order to set the switch, you must open the case cover.  The switch is located on the output jack.  Looking at above picture, push the slider down to bypass it (for HD580 etc.) or push it up (toward the input jack) to enable it (for ER4P etc.). When you use low-impedance headphones such as ER4P and Grado 60, you should enable this switch for the amp to work properly. This switch is no longer available.

bulletCan this amp drive HD580?

Absolutely yes, even the most power-hungry AKG 1000 is no problem.

bulletWhat headphone do you recommend?

The Koss KSC-50 available from BestBuy for only $17 is THE headphone everybody should get a pair.  Very portable, comfortable and affordable.  They sound so good with portables that you may not even want an amp for them.  If they sound too bassy to you, then drill a hole in the center of the foam pads.  If you want to know what's the best sound you can hear, then get the HD580 for $130 online.

bulletWhy sometime no sound from the amp?

Under some conditions, you may try unplug the headphones and re-plug them. For amps with a ER4P-to-S switch, enable the switch, especially while using low-impedance headphones such as ER4P and Grado 60.

bulletMay I add a shirt clip to this amp?

Yes.  You can buy an automatic pencil from Wal-Mart, cut off its tip and glue it to this amp as showing in this picture.  You should glue it to the case cover; so you can replace the cover (buy a battery case, 270-414, from Radio Shack) in case you don't want the clip later.

bulletNow, once this new SuperMicro amp is available, do you still want the Super Mini?

Yes, if the followings are your concern:

bulletA switching power circuit bothers you.
bulletYou use the amp with a portable radio AND listen to very weak stations.
bulletYou prefer analog volume control.
bulletYou need to use external/AC power.
bulletSize matters to you.  The super mini is already too small, you don't want anything smaller.

The SuperMicro amp's battery life seems short at first, especially if you have been spoiled by the super long battery life of super mini.  But remember, now you only need a single AAA battery.  With just one more AAA in your pocket as a backup (you needed three before), your music never stop!

The following pictures show tested noise level for Micro (top) and Mini (bottom).  Both amps are set to the highest volume (both have gain 11), open input (not shorted) and 100 ohm load at output.  As you see, the switching circuit used in Micro to boost voltage adds no extra noise.

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Copyright © 2005  Xin Feng Company
Last modified: June 22, 2005