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Listening to the NSMT Lepai amplifier with Bluetooth

NSMT Modified Lepai Amp with BluetoothBluetooth

"Bluetooth is implemented very nicely." Customer comment

 Buy NSMT-Lepai Amp

There is a lot of debate about the audiophile quality of music using a Bluetooth connection, but no dispute about Bluetooth's convenience.

Our solomonic solution is to add a Bluetooth option to our modified Lepai amplifier as a toggled on feature that is activated by a toggle switch on the back of the amplifier, so that with Bluetooth toggled off, the amplifier's performance is unaffected. Moreover, we will continue to offer the amplifier without the Bluetooth option.

All Bluetooth receivers are not created equal. Some are indeed quite harsh. The Bluetooth feature we have added to our Modified Lepai amplifier is one of the best available.

I have spent the last few weeks putting our Modified Lepai amplifier with optional Bluetooth through the paces and I can assure you that the listening experience is quite pleasant and very rewarding.

I listened to our Modified Lepai  amp with Bluetooth driving either a pair of Role Audio Sampan or Sampan FTL loudspeakers connected to our modified Lepai via an eight foot pair of our MasterSource speaker cables.

For source I mostly used a Moto X smart phone connected to the amp via Bluetooth and compared that to a FiiO X3 connected via the line out to the RCA jacks of the Modified  Lepai. The music I used was WAV files copied from CDs.

The Sampans were set up against one long wall with the Lepai sitting on a table slightly behind them. The Sampan FTLs were set up on the same table as our modified Lepai amplifier. Most of the time I was working at my desk about six feet from, and a little in front of, the leftmost Sampan, and listening to music played on the Moto X's stock Android music player connected to our modified Lepai via Bluetooth.

I found it convenient to set the volume knob on the Modified Lepai at about 1 O'clock. Then I was able to adjust the volume up or down via the Moto X. The ease and flexibility of the Android music player interface is simply amazing. If my phone rang I didn't have to run over and turn down my music in order to answer the phone. The Moto X muted the phone automatically. Also the phone notified me bad weather, calls, tweets, etc. which I could attend to or ignore. To approach this level of control playing background music through the typical stereo while I am working I would have had to use a remote for volume and one for source. My Moto X does all that and more.

For critical evaluation I sat on a couch about six feet in front of the speakers to mitigate some of the faults of the room.

So how does music played via the Moto X connect to the Modified Lepai via Bluetooth sound and how does it compare to music played on the FiiO X3 connected to our Modified Lepai via RCA jacks?

The sound of the Moto X connected to our Modified Lepai amp via Bluetooth is very pleasant. In my notes I used such adjectives as analog, smooth, laid back, slightly muted highs, like FM radio, and musical.

How does the Moto X source compare to the Fii0 X3? At low volume, say up to 85 dBs, I struggled to characterize the differences.

Note for comparable volume level I had to set the Lepai volume control to 9 O'clock when listening to the Fii0, compared to the roughly 1 O'clock setting for the Moto X. The Fii0's output volume is that much higher.

The Lepai benefits from a high input volume but on some albums that are recorded at a very high level such as Sade's “Solder of Love,” The Fii0's output overloaded the Lepai causing distortion. In such cases I had to switch to using the Fii0's headphone jack and volume control.*

As the volume went up though the differences between the two sources became more obvious. The Fii0 resolves more information, the delineation of the bass and the bass weight is better, definition across the board is better, the sound stage is a little deeper and the layering is more delineated.  I listened to Luther Vandross' Superstar, a song I have used as a reference for decades. At low to moderate levels I had to concentrate to discern differences between music sourced via the Moto X and Bluetooth vs music sourced from the Fii0 X3. All the spatial cues are present is both cases but the delineation and clarity are superior on the Fii0 X3.

One thing for sure, the benefits and ease of using the smartphone interface are obvious compared to the Fii0 X3's interface which is challenging and not very flexible.

In sum the audiophile differences between music sourced from my Moto X via Bluetooth and music sourced from the Fii0 X3 are clear. However for ease and convenience listening to background music the Moto X Bluetooth combination trumps listening to music sourced from the Fii0 X3. And while the Fii0 X3 has better resolution. At low to moderate listening levels those differences are not very obvious.

So what did I find out aver a few weeks of listening. Bluetooth provides an ease and flexibility for listening to music that is unmatched. Sure there are dropout that can occur at almost any distance but this is easily cured by repositioning the smartphone and maintaining a direct line of sight between Bluetooth transceiver and amplifier. But again, the facility it presents for listening to music is unparalleled.

My overall take on Bluetooth is that it is is not perfect but it allows me to listen to more music on the go and while working, simply because of its convenience and because I am willing to compromise on quality for the ease of listening.

My goal in adding the Bluetooth feature to our modified Lepai amp is to extent the uses for the amplifier and to make it easier for you to listen to music reproduced with the best possible fidelity.

Regardless of where you stand on the purist vs convenience divide you will find satisfaction with either our Modified Lepai amplifier of the amplifier with the Bluetooth option.

Happy listening.


* The X3  has  a line output designed to feed a hi-fi amplifier through a 3.5mm jack that delivers a fixed 1.7V maximum. The Fii0 delivers .3V  through the headphone socket which is 50% more output than most CD players, and many times the output of most portable music players. Hence, the Fii0 provides about 10dB more dynamic range than CDs.

Our Modified Lepai amp: Latest development

NSMT Modified Lepai amplifier

Over the course of our involvement with the Lepai amplifier we have been impressed with the improvement in the manufacturer's quality control. In one of the first units we received the outputs for the two channels were completely reversed. However recent units are mostly flawless.

There was also a lot of noise in the tone controls for which we developed a mod. Although we still install the mod, noise from the tone controls is pretty much gone now. 

Surprisingly, the amplifier has been very reliable. So while there has been a lot of banter about the quality of the amplifier on the web, it seems mostly to refer to the early units.

The little amplifier is pretty amazing to begin with; so we have concentrated on improving the sonic performance and the usability of the amplifier.

Our latest mod includes an improved Baltic white birch plywood cabinet, with all edges rounded, that is sealed against any possible formaldehyde off-gassing  and painted with several coats of a water-based nontoxic clear paint.

(Formaldehyde, a carcinogen, is still used in most manufactured boards, especially those used to make loudspeakers. And most paints and adhesives used in consumer electronics are toxic. Your exposure is not massive, but it is something to think about if you are using these products daily, up close. Ported speakers are a double whammy because you are exposed to off-gassing from outside as well as inside.)

Over the course of our involvement with the amp we have experimented with different power supplies and moved from the 2 AMP power supply to a 3.5 and, most recently, to a 5 AMP power supply. Moving to more powerful power supplies has increased the bass, especially bass definition, soundstage definition, and the loudness of the amplifier. The midrange remain pristine, especially considering the price.

We feel the sound and appearance of the amplifier cannot be beat for the price.

Modifying the amp is fun but it is not a profit center for us. While it may not be obvious to consumers, mainly because of the small size of the amp, modifying it is tedious and time consuming work.

However, we are quite pleased with the results of our modification and the word from our customers is that they also are quite pleased. Our modified amplifier has received two very strong reviews from Positive Feedback which we encourage prospective buyers to read.

Review 1

Review 2