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Three Bluetooth Device Review - Pendulumic Stance S1 Wireless Headphone, Audioengine B1 Premium Bluetooth Music Receiver, Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter


Pendulumic Stance S1 Headphone: $199
Audioengine B1 Receiver: $189
Miccus Mini-jack TX4 Transmitter: $65

by Wayne Myers


Wireless technology has been edging its way into the world of high fidelity audio more and more in recent years. Bluetooth, with its recent aptX extensions, appears destined to take its place as a truly hi-fi wireless option. And when one has tripped over and stepped on as many wires and cables as I have over the years, a technology that can reduce cabling without sacrificing audio quality will at least get a thorough tryout.

This review covers three Bluetooth products which could find their way into an audio or home theater enthusiast's setup. We will cover the Pendulumic Stance S1 Wireless Headphone, the Audioengine B1 Premium Bluetooth Music Receiver, and the Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter. All three are Bluetooth 4.0 devices and include aptX capability, which promises to deliver CD-quality sound. One of the three, the TX4 transmitter, is also Low-Latency capable.

Website Links

Pendulumic Stance S1 Headphone
Audioengine B1 Receiver
Miccus Mini-jack TX4 Transmitter

High Fidelity Comes To Bluetooth

There are many profiles defined for Bluetooth, having to do with hardware form factors, data, and application types. The most common profile one will run across when discussing audio is A2DP, the basic stereo profile. Any Bluetooth product involving stereo sound makes use of this profile. The quality level is similar to a high-bitrate MP3, or the AC3 encoding that is part of the original Dolby standard. Lossy compression algorithms are employed to determine what parts of the audio signal can be thrown away to reduce the data rate while keeping the sound quality pretty much the same. "Pretty much" is the key idea here. The compression algorithms are designed around psychoacoustical principles to be transparent, but given the right equipment, program material, and a little guidance, almost any listener with healthy hearing can pick out the degradation that results.

Many listeners do not care, and for them the A2DP profile provides more than adequate sound quality, depending on application. But many do care, and for them there are higher data rates and newer codecs which make near-lossless, lossless, and even high-resolution Bluetooth audio possible. The aptX codec and its variants are the first of these bringing Bluetooth products to market for the serious listener, often with smartphone communication conveniences built in.

AptX technology is licensed by CSR, the British company which owns the patents. The levels of capability we are concerned with are as follows:
  • The aptX logo alone, which means CD quality - 16-bit, 44.1-kHz (16-44).
  • The aptX Low Latency designation, which means that latency, or delay times, in the neighborhood of 32 milliseconds are possible. Without that designation, latency times can be 100 mS, 200 mS, or even more. For streaming audio with no absolute time reference, that is not a problem. For watching a movie or television, video and audio end up way out of sync.
  • The aptX Lossless designation, which means that true byte-accurate audio transmission is possible. High-resolution 24-96 transmissions can even be accommodated. There are variables to choose from in the design of a given product, however, which can make it difficult to know what to expect if not clearly stated in product specs. One is the possibility of a near-lossless mode when data rates are compromised. Another trade-off is the possibility of extremely-low-latency audio, as low as 1 millisecond, with the trade-off of audio quality being limited to 48 kHz, or "DVD quality."
There are a couple of important rules to remember when looking at products and determining how well they will work together. The A2DP capability is implied where stereo sound is involved. Beyond that, assume nothing. In order for a transmitter and receiver to work together at any higher capability level, both must have that level of capability designed in, and should state it explicitly. For instance, a transmitter with aptX Low Latency capability and a receiver with aptX capability will be able to work together to provide CD quality sound, but not with low-latency delay times.

For this review, audio quality was verified using both listening tests and two measurement methods beyond the typical. The reason for this detailed level of testing was to verify not just product performance, but also the claimed "CD-quality" capability of the aptX and Bluetooth technology itself. The measurements are not straightforward because the encoding distortion we are talking about is created dynamically during changes in the music, so regular frequency response and distortion measurements do not trigger the generation of those artifacts. Short of expensive specialized gear, the best way I found to catch them was to identify a short musical passage that would cause the distortion, set up a loop using a Digital Audio Workstation (DAW - Reaper in this case) so it could be precisely repeated, and capture a spectrum analysis of the loop at the different quality levels in question. Zooming in on the high-frequency spectrum measurements, I found with A2DP that the strong frequencies which make up the main sound of small chimes, for example, were significantly attenuated, while weaker "side tones" which add richness to the sound were left the same or even amplified, yielding a harsh or splattery sound. In numerous instances where the listening test indicated this dynamic distortion, it could be seen by zooming in and comparing captured high-frequency spectrum analysis plots. Where the higher quality aptX transmission was measured for the same passages, the captured spectrum analysis plots showed no such distortion. See the diagrams below for an example.

The other measurement method, more general in nature, involved making a recording of a track which had passed through the transmitter-receiver loop, carefully lining up the recording with the original, inverting one, and summing them together. If the two recordings are identical, the result will be complete cancellation and silence. With A2DP, the two tracks were so different that the naked eye could see the difference between the waveforms on the computer monitor. Even the time scaling managed to drift significantly on the signal that had been through the A2DP loop. Cancellation amounted to varying amounts of phaser-like comb filtering at best. With the signal that had been through the aptX loop, there was only a small amount of very gradual time scale drift, and the two signals looked identical, although they were usually not quite. The hoped-for cancellation was sometimes perfect for several seconds at a time - why it could be 100% perfect in places including dynamic high-frequency content and not so all the time is a mystery - but usually amounted to a 15 to 20 dB attenuation, sometimes more, the remaining sound recognizable but dull and strongly filtered. Overall this tells us that the aptX processes had changed the music very little.

What the measurements and listening tests indicate is that the A2DP quality signal is indeed lossy and roughly analogous to MP3 quality. The aptX signal quality level, on the other hand, proved to be highly accurate and the listening equivalent to CD quality sound, as advertised.


Measurement Graphs

Dropout and Noise Tests - Signal Integrity with Distance and Time

Long-term noise testing was performed by preparing a 1-hour sine wave track to be played on one of several Bluetooth transmitting devices and receiving each with the B1 receiver while monitoring with spectrum analysis for noise that would indicate data errors. The same approach was used to determine clear transmission distance without dropouts or noise. This method was first verified as effective with the following test waveforms:

Verification of Test Method

All signals are stereo.

A pure sine wave with no errors produced no noise outside the spectrum target (blue).

A 10-second sine wave with a single error byte produced this easily detectable noise profile.

A 10-second sine wave with one byte removed (shortened by one byte) produced this noise profile.

A 10-second sine wave with one byte added (lengthened by one byte) produced this noise profile.

A 10-second sine wave with one byte repeated (replacing the adjacent intended byte) produced this noise profile.

Test Results

Asus tablet to B1 receiver @ 6 ft, 15 ft, 20 ft, 25 ft:

Asus tablet to B1 receiver @ 35 ft:

LG G3 smartphone to B1 receiver @ 6 ft, 15 ft, 20 ft, 25 ft:

LG G3 smartphone to B1 receiver @ 35 ft:

TX4 transmitter to B1 receiver @ 6 ft, 15 ft, 20 ft, 25 ft:

TX4 transmitter to B1 receiver @ 35 ft:

Processing Distortion - A2DP vs. aptX

The captured spectrum analysis of short test track segments shows the difference between A2DP and aptX signal integrity with high-pitched, dynamic sounds. The sound focused on was the first instance, just a few seconds long, of tiny high-pitched chimes at the beginning of Compassion, by Todd Rundgren.

Captured spectrum of original track segment:

Captured spectrum of track segment from TX4 transmitter to B1 receiver (aptX); the primary chime tones are barely affected, and the sound remains clear like the original track:

Captured spectrum of track segment from Asus tablet to B1 receiver (A2DP); the primary chime tones are attenuated and the complex "side" tones are as strong or stronger than before, causing a "splattery" distorted sound:

General Performance Test Results

TX4 to B1 Frequency Response:

TX4 to B1 Distortion - Measurement Noise Floor:

TX4 to B1 Distortion at -20 dB FS stays well below 0.1%:

TX4 to B1 Distortion - -5 dB FS stays well below 0.1%:

IM Distortion (DIN) - TX4 to B1:
@ -20 dB FS = 0.21%
@ -5 dB FS = 0.22%

TX4 to B1 Impulse Response, 2 mS view:

TX4 to B1 Step Response, 200 mS view, shows a small amount of sub-sonic overshoot, recovered from in one cycle, of no practical concern:

TX4 to B1 Step Response, 2 mS view, shows a small amount of high-frequency ringing, recovered from quickly; transient response is very good in the Bluetooth realm:

Total latency delay time:
TX4 transmitter to B1 receiver = 210 mS
TX4 transmitter to S1 headphone = 115 mS

Signal gain, TX4 transmitter to B1 receiver:
13 dB

Maximum input level @ TX4 input before clipping, TX4 transmitter to B1 receiver:
0.44 Vrms

Maximum input level @ TX4 input before clipping, TX4 transmitter to S1 headphone:
0.44 Vrms

Associated Review Equipment

Measurement Methods

  • Asus Nexus 7 Tablet (2013) with Android 4.4.4
  • LG G3 Smartphone with Android 4.4.2
  • Asus G74SX Laptop, Intel I7-2670QM @ 2.2 GHz, 16 GB DDR3 Memory, Room EQ Wizard, foobar2000
  • Digital Audio Workstation, Phenom II x6 1100t @ 3.5 GHz, 16 GB DDR2 Memory, Room EQ Wizard, Reaper Digital Audio Workstation, foobar2000
  • Media Server, Phenom II x6 1055t @ 2.8 GHz, 8 GB DDR2 Memory, Room EQ Wizard, Reaper Digital Audio Workstation, foobar2000
  • Roland Quad-Capture Audio Interface
  • M-Audio Fast Track C600 Audio Interface
  • M-Audio Firewire 410 Audio Interface
  • 3Dio Freespace Binaural Microphone, modified, custom HRTF correction curve
  • Mackie 402-VLZ3 Preamp/Mixer
  • Beyerdynamic MM1 Measurement Microphone
  • American Recorder SPL-8810 Sound Level Meter
  • AKG K 601 Headphones
  • AKG K 701 Headphones
  • Beyerdynamic DT 880 Premium 250-Ohm Headphones
  • OPPO PM-1 Planar-Magnetic Headphones, Courtesy OPPO, Home Theater Shack Sponsor
  • Sony MDR-V6 Headphones
  • OPPO HA-1 DAC/Headphone Amplifier, Courtesy OPPO, Home Theater Shack Sponsor
  • Emotiva Pro Airmotiv 4 Powered Studio Monitors
  • Fluke 77 Digital Multimeter

Pendulumic Stance S1 Wireless Headphone

I was invited by Mike Johnson of Pendulumic to audition the Stance S1 Bluetooth headphones at Rocky Mountain Audio Fest (RMAF) in October. I honestly expected an OK-sounding set of 'phones with Bluetooth added on. I was immediately impressed by the sound quality and asked to do a detailed review. The more I have worked with the S1, the more impressed I have been by all aspects of the design.

The Stance S1 is a sealed, on-the-ear design that works in three high-fidelity listening modes: Bluetooth, direct-cabled, or amplified-cabled, selected by a 3-way slide switch on the back of the right earpiece. A fourth Phone Control mode is available when wired or working via Bluetooth with a smartphone. A rechargeable internal battery can be backed up by a pair of AAA batteries. An on-off-on selector switch on the front of the left earpiece determines which battery type is in use for either of the two powered modes, or turns power off (direct-cabled mode). A volume control on the back of the right earpiece (Bluetooth mode only) doubles as a push-button multi-function control. When cabled to a smartphone, the cable also includes a simple multi-function Bluetooth control for music and phone calls. A microphone built into the right earpiece supports telephone talk in Bluetooth and cabled modes.

The Stance S1 comes with a USB charging cable, a 3-conductor to 4-conductor braided audio cable with inline media and phone control, a 1/8" to 1/4" adapter, a dual plug adapter for laptop audio interface, a travel case, and a manual and quick start guide.

Using my LG G3 smartphone with Android 4.4.2 and Asus Nexus 7 (2013) with Android 4.4.4 as music sources - neither has aptX capability - it quickly was evident that the sound quality was lossy. The track that showed this the most clearly was Todd Rundgren's Compassion, which makes use of a set of high-pitched chimes, stroked numerous times through the song. The recording quality on these chimes and on the cymbals is excellent, and the chime and cymbal tones are normally crisp and clear. Through the S1 headphones from my phone or tablet, I could hear the cymbals turn to hash and the chime tones splatter on impact. Dense male vocal harmonies also became muddy.

Switching from Bluetooth to cabled mode, or from using the A2DP-encoded source to no coding/decoding at all, cleaned up all those compression artifacts. (The user who wishes to try this for himself should be aware that the transition to Bluetooth includes a connect delay and various clicks, thumps, and beeps - all part of listening "under the hood" to a Bluetooth startup. And a quirk of the S1 design cuts Bluetooth mode volume by about half while the cable is plugged into the earpiece, something one would not do in normal use.) The S1 being driven straight from a headphone amp played all the aforementioned test segments with pristine clarity.

Back to Bluetooth mode, but receiving from the TX4 transmitter, with the aptX codec built in, the audio quality stayed pure and pristine. There is very little audible difference between the Bluetooth mode with aptX and the straight cabled mode, until you go to very high volumes, where the Bluetooth encoder/decoder circuitry will hard clip when overloaded. The TX4 transmitter and S1 headphone combination, benefiting from the aptX codec, was able to deliver 105 dB peak SPLs before clipping, so this is not likely to be considered a practical limitation for most users.

The S1 in cabled mode and in Bluetooth mode with an aptX transmission source performerd very well, as the measurements below testify, with frequency response, distortion, and dynamic performance sounding very much the same in normal use. The TX4 transmitter added some gain, about 13 dB, so the signal path needed to be managed to realize that equivalence.

The cabled-amplified mode has quite a different sound, with bass and treble both boosted relative to the midrange, although not severely so, a distinctly tailored sound. While I preferred the flat response of the other two modes, I can see some users enjoying this tailored response with rock and pop tracks. It was a little much for the sound of natural instruments - strings and horns especially tended to lose enough of their midrange tones to be distracting. The flat response of the Bluetooth and straight cabled modes, however was indeed very flat-sounding, and aside from a small amount of bass boost peaking at 100 Hz rivals the flatness of more expensive industry standard headphones by the likes of Sennheiser and AKG. The upper-mid and high-frequency ranges came across very smooth, flat, even, and natural, not an easy accomplishment at all. Distortion was low at medium and lower listening levels, and dynamic characteristics were very fast and clean for a product in its price range.

Listening Scores

In terms of scoring the S1 performance - using Home Theater Shack's Headphone Roundup scoring method - scores apply to the Bluetooth/aptX and direct cabled mode - soundstage and imaging were both very good. The soundstage was wide and spacious, very natural and enjoyable (9.0 / 10). Imaging was a little soft in the midrange but very stable and quite sharp overall (8.0 / 10). Dynamic response (9.0 / 10) with my speed tracks was very good as well, and clarity (8.5 / 10) only suffered as volume levels rose, and even then not terribly. I found no fault with the frequency response (9.6 / 10) except the bass being slightly emphasized, and it could have gone deeper but would only benefit from it on rare tracks, and the overall listening experience score was easy to give a perfect score (10 / 10) - the Stance S1 was simply a great-sounding set of 'phones to work with.

Listening Test Notes

Broken Bells, Perfect World:
BLUETOOTH: The kick drum starts in with good, tight focus, punchy, good depth, and fairly FLAT. High end - does not sound like a headphone high end, does not sound peaky, is pretty clean. Vocals sound very natural. The soundstage is BIG, spacious, natural. Are they reference flat? They sound close.
AMPLIFIED: tailored tonality, mids are pulled back, upper mids & highs are smoothed, pushed forward.
CABLE: Mids & top end very natural, very smooth.

Nickel Creek, House of Tom Bombadil:
BLUETOOTH: Beginning of this track is custom mixed to mono - Imaging is pretty good, 7 of 10. Second time, levels controlled more carefully, imaging is tighter, 8/10. String plucks are lively, lovely. Can JUST hear a little midrange dip, very slight. The standup bass sounds a little recessed.
AMPLIFIED: Strings still sound OK, a little recessed with mids pulled back.
CABLE: The bass is a little clearer, string sounds are a little more natural with mids slightly more present.

Mindy Smith, I Know The Reason:
BLUETOOTH: Imaging is definitely a little soft on the vocals. The vocal sheen is pristine, clear. Vocal handling is very nice. Bass goes quite deep. The midrange dip is JUST enough to keep the ear from being overwhelmed, not enough to the point where you feel you are missing anything, feels like it is all there and well balanced. Nice detail on plucked strings.
AMPLIFIED: Tailored sound, deeper scoop, works well for rock, pop, vocal. Upper-mids & highs really smoothed out.
CABLE:Mids definitely more natural, highs OK but a little recessed, tonality works very well. Bass seems tighter, better defined.

Todd Rundgren, Compassion:
BLUETOOTH: Can hear the LF resonance point. Want head straight or leaned forward slightly for positioning to get best upper-mids & HF. Volume control good resolution, multi-turn, nice design. Bells splattery - MP3-320K quality - with A2DP. Much better with aptX, CD quality. Dense vocal harmonies - mushy & less clear with A2DP, very clean with aptX source. Cymbals have good clear image placement. When I lean my head back and the 'phones shift slightly, I lose the high end - tightness vs. comfort always a tradeoff.
AMPLIFIED: Hear more bass resonance. Cymbals well defined, very clear, as are the bells.
CABLE: Cymbal & bell frequencies a little more natural w/o the amp.

Civil Wars, Poison and Wine:
BLUETOOTH: Top end really seems smooth, no peaky sharpness common with headphones. Deep bass is just the right amount, plenty strong and DEEP. When song volume rises, can hear compression (A2DP) - Bluetooth, not the 'phones. Better with aptX, hear no compression. Sibilants sound crisp, not harsh.
AMPLIFIED: Upper bass a little strong, hear some distortion on voices.
CABLE: Upper bass clear again, mids just right for me.

Cincinnati Pops, Gayne Ballet, Adagio (from '2001')
BLUETOOTH: Strings warm and natural. Hear a creaking - no that is my neck. Volume UP - at max, get a couple of "volume warning" beeps, a little loud, could be softer. So far all instruments sound very natural.
AMPLIFIED: Not so natural.
CABLE: Strings definitely have a more natural sound.

Scott Davie (Rachmaninoff), Lilacs:
BLUETOOTH: Missing a little of the Overs piano tinkle in the upper-mid scoop. Hear a little processing distortion (A2DP). On the weakest part of the track, top tinkle fell into the scoop.
AMPLIFIED: No tinkle at all. Where did it go?
CABLE: Same as Bluetooth.

Midlake, Roscoe:
BLUETOOTH: At 1/2 hour of listening, beginning to notice slight discomfort from ear pressure. Good detail on guitar sounds. Really good soundstage.
AMPLIFIED: Good sound for rock with vocals.
CABLE: Better bass balance.

Tower of Power, Fanfare, You Know It:
BLUETOOTH: Top volume good, not excessive, pretty good safety point, maybe up around 90 with hotter mixes. Can just hear the scoop on the horns & sax, but still sound natural, any more and they would suffer, but just OK.
AMPLIFIED: Horns not good.
CABLE: Much better horn sound than amplified, sax way more natural.

Muse, Supermassive Black Hole:
BLUETOOTH: Nice stereo width. Nice rock high end, stays clean at high volume. Wide sounds are really wide in the soundstage.
AMPLIFIED: GREAT for rock tracks like this, a little accent at bottom & top, not so obvious here.

Atoms For Peace, Before Your Very Eyes:
BLUETOOTH: Kick drum rise time maybe softened a bit, not muddy, but not sharp, either. Hear one bass peak, certain tones are accented a little. On this track the Bluetooth process distortion (A2DP) barely is noticeable in certain spots, sufficiently clean for most listeners. Bluetooth/A2DP not at critical listening quality, though, need aptX for that. Like the spaciousness of big reverb sounds. Does the closed design hold in the reverb, keep it from getting away, make it sound even bigger? Distortion on lowest notes at end of track.

Todd Rundgren, Pulse, ending:
BLUETOOTH: xylophone notes very focused, good tone.
CABLE: YES, more natural, better focus, more punch.

Non-Listening Scores

Design: It is as though all aspects of the design "go to 11." From the initial un-boxing through multiple listening and measuring sessions and just wearing them around the house listening for fun, they continued to draw smiles of admiration. They are solid and durable, fold flat, and come with a tough, compact carrying case, complete with a zippered inner pocket for accessories. All controls are easy to find and operate. The volume/push-button knob is designed after the classic windup knob found on wrist-watches. It is easy to find and operate, simply a tactile marvel, "practically perfect in every way," with a nice little mechanical feedback "click" as it is turned in either direction. The S1 is very comfortable, with leather earpads and adjustable-tension headband (9 / 10, only because you do notice them, but only after quite awhile, and there are 'phones out there that you could wear for days), they stay on well (although shifting slightly with head movement), they look sharp, they feel good in your hands, they include rechargeable and backup battery modes, they can be used cordless or corded. Score for design: 10 / 10, even though there were a couple of flaws. To use them cabled with a regular 3-conductor-connector source, the user will need a 3-conductor to 3-conductor cable, not supplied, and not explained; and the supplied 1/8" or 1/4" adapter will not work properly with the supplied cable, also not explained. STILL, they get 10 points for design, everything else works that well. The design team must have stayed up late many nights bringing the S1 to fruition. Or maybe there were elves or fairies involved.

Operating range (not scored), line-of-sight indoors, was only about 25 feet, with any of my Bluetooth sources, but there are higher-powered devices that would certainly increase that range. At 25 feet, an occasional drop-out ensued, annoying enough one would venture no farther. Latency is not low, but that is a separate design target perhaps to be addressed in another model, so no points lost. Latency was 115 mS with the TX4, a number that will vary with the transmitter in use. That is long enough to be annoying where sync to video is involved. A fast rock drummer will easily appear a beat ahead of the sound on a YouTube video, for instance.

Measurements and Specifications

Measurement Graphs
Pendulumic Stance S1

  • Type = Closed-back dynamic
  • Driver = 40-mm (1.6in) neodymium driver
  • Sound pressure level (SPL) = 110dB (1 kHz / 1 Vrms)
  • Impedance = 32 Ohms
  • Weight = 220 g (8oz) without cables or accessories
  • Bluetooth® version = 4.0 with aptX®
  • Frequency response = 15Hz – 22kHz (10Hz – 24kHz with aptX® enhancement)
  • External battery = 2 x AAA batteries
  • Wireless playback duration = up to 30 hours (with external AAA batteries)
  • Wireless operating range = up to 50 feet (15m)
  • Ear Cup Diameter = 70mm (2.7in)
  • Materials
    • Robust steel headband
    • Aluminum-steel alloy
    • High-quality bonded leather
    • Braided cable
Frequency Response of the three music listening modes; Bluetooth and Cabled modes are almost identical, very flat-sounding with slight bass boost; the Amplified response (bottom) has enhanced treble and bass:

Cabled Distortion at 75 dB SPL - well below 1% above 100 Hz, peaking near 1% at 70 Hz, all in all very good dynamic headphone performance:

Cabled Distortion at 85 dB SPL - 0.3% in midrange, about 3% at 70 Hz, still good:

Cabled Distortion at 95 dB SPL - above 1% at some frequencies, and low-frequency distortion will be audible, but still well under control for this high volume level:

Harmonic Distortion - Cabled:
L @ 75 dB SPL = 0.42% @ 100 Hz, 0.25% @ 2 kHz
R @ 75 dB SPL = 0.35% @ 100 Hz, 0.50% @ 2 kHz
L @ 85 dB SPL = 0.82% @ 100 Hz, 0.17% @ 2 kHz
R @ 85 dB SPL = 0.40% @ 100 Hz, 0.23% @ 2 kHz
L @ 95 dB SPL = 2.2% @ 100 Hz, 0.46% @ 2 kHz
R @ 95 dB SPL = 1.2% @ 100 Hz, 0.29% @ 2 kHz

IM Distortion (DIN) - Cabled:
L @ 75 dB SPL = 0.34%
R @ 75 dB SPL = 0.40%
L @ 85 dB SPL = 0.62%
R @ 85 dB SPL = 0.87%
L @ 95 dB SPL = 2.1%
R @ 95 dB SPL = 3.0%

Harmonic Distortion - Bluetooth - dB Below Clipping:
L @ -30 dB (75 dB SPL) = 0.42% @ 100 Hz, 0.25% @ 2 kHz
R @ -30 dB (75 dB SPL) = 0.35% @ 100 Hz, 0.50% @ 2 kHz
L @ -20 dB (85 dB SPL) = 0.82% @ 100 Hz, 0.17% @ 2 kHz
R @ -20 dB (85 dB SPL) = 0.40% @ 100 Hz, 0.23% @ 2 kHz
L @ -10 dB (95 dB SPL) = 2.2% @ 100 Hz, 0.46% @ 2 kHz
R @ -10 dB (95 dB SPL) = 1.2% @ 100 Hz, 0.29% @ 2 kHz

IM Distortion (DIN) - Bluetooth - dB Below Clipping:
L @ -30 dB (75 dB SPL) = 0.18%
R @ -30 dB (75 dB SPL) = 0.38%
L @ -20 dB (85 dB SPL) = 0.36%
R @ -20 dB (85 dB SPL) = 0.52%
L @ -10 dB (95 dB SPL) = 0.77%
R @ -10 dB (95 dB SPL) = 1.4%

Harmonic Distortion - Amplified:
L @ 85 dB SPL = 1.4% @ 100 Hz, 0.13% @ 2 kHz
R @ 85 dB SPL = 0.50% @ 100 Hz, 0.16% @ 2 kHz

Impulse and Step Response: Very clean and fast for dynamic headphones. Cabled mode is slightly susperior to Bluetooth, Amplified mode is the worst of the three, but still quite good.

Group delay:

Impedance: Driver impedance matching is good, easy to drive from a low source impedance.

Maximum input level @ TX4 input before clipping, TX4 transmitter to S1 headphone:
0.418 Vrms

Other Factors - not part of the Overall Performance Score

  • Reference headphone: Yes.
  • Drivable with portable media devices: No, but ALMOST. My standard is to reach 90 dB SPL with a loud track from a typical smartphone or tablet, and the S1 fell just short of that. If you listen at moderate levels, they will satisfy you, but if you are hoping to use them to split atoms - or blast at very high volumes - from your i-/Android device, the S1 might not do the job.
  • Isolation: 4 dB, not as much as my other sealed 'phones. On an airline trip, the person next to you is going to hear your tunes pretty clearly at higher playback levels.
Pendulumic Stance S1 Evaluation Scores

  • Imaging: 8.0
  • Soundstage: 9.0
  • Clarity: 8.5
  • Speed: 9.0
  • Frequency Response: 9.6 (Flat Profile)
  • Overall Listening Experience: 10
  • Comfort: 9
  • Design: 10
  • MSRP/Street: $199/$199
  • Overall Performance Score: 9.4 out of 10
In Summary

Ah, the convenience of not having a cable to deal with, that can spoil you really fast. Being a long-time headphone user, there is a natural time to deal with the cable response tbat one is conditioned to expect with putting a set of 'phones on, moving around much, taking them off, and I experienced numerous little moments of joy with Bluetooth freedom. I found myself looking for opportunities to use the Stance S1 headphones just because it was fun, and sounded that good.

The Stance S1 might become my travel headphone of choice (keeping the volume down for fellow passengers' sake), they are that versatile and perform that well in every category. And, having tried numerous sets of headphones proported to be "reference" quality sealed headphones, they are the closest I have found without spending at least twice the money.

Audioengine B1 Premium Bluetooth Music Receiver

The Audioengine B1 is a high-fidelity receiver that easily allows you to stream music from a Bluetooth-enabled smartphone, tablet, or computer into your music system. The tough little unit has an aluminum case with attached swiveling antenna and 3-stage redundant power regulation to keep noise to a minimum. The B1 supports A2DP (of course), and aptX for true CD-quality sound. Included are an RCA hookup cable, power supply, a microfiber bag for taking the B1 on walkabout - it is certainly small and light enough to consider portable - and a setup guide. The B1 has stereo-RCA outputs and a TOSLINK digital optical output.

A single push button and a single indicator LED on the front panel provide all the operator input and output for the unit. This is fairly common in Bluetooth devices, and can be perplexing until you get the hang of an individual unit's operating sequences. Luckily, there are Bluetooth profiles that simplify the way transmitters and receivers interact, and much of the time they figure out what to do and work in spite of the operator's confusion.

The B1 uses the AKM AK4396 D/A converter, an upsampling converter with 24-bit 48-kHz capability. All signals regardless of bit depth are upsampled to 24 bits. Input data rate is determined by the source material, the source device, and the Bluetooth protocol. The digital output always operates at 24-bits / 48-kHz. Noise and distortion specs are exemplary, better than my ability to measure, and were verified by my listening tests.

Much of what has been said previously applies directly to the B1. Technology-wise, it must be paired with an aptX-capable source for it to sound its best. There are no settings involved in making this happen. As two devices "pair," they determine common capabilities and enter the right modes automatically. With an aptX source, the B1 cranked out CD-quality sound as advertised.

Most of the testing in the High Fidelity Comes To Bluetooth section above directly involved the B1. My tests verified that the B1, when paired with an appropriate source, did indeed deliver audio quality virtually indistinguishable from the CD source file. In my listening tests I found I had a slight preference for the digital output into my audio interface vs. the analog output, but that might well have been because the latter involved an extra set of D/A and A/D conversions. The difference was a minor subtlety at best.

Latency is stated to be 30 mS, but the B1 specs do not state that it is aptX Low Latency capable. When paired with my aptX Low Latency-enabled transmitter, I measured 210 mS of latency, so audio-video sync issues must be considered in applications where they matter.

I found the B1 extremely simple to operate - just pair it with another unit and it runs. It was completely dependable, never locked up or misbehaved, never produced any mysterious pops or clicks. It is a well-behaved little unit, always doing what you expect of it, or better.

An operating range of up to 100 feet is claimed. As mentioned before, none of my transmitting devices could come anywhere close to delivering on that promise, but there are higher-powered transmitters available which would give better distance performance.

The Audioengine B1 Premium Bluetooth Music Receiver gave a solid CD-quality performance in all of my testing, is easy to use, looks sharp, and should last a good long time, even getting carried around and beat up a bit. There are less-expensive receivers out there, but when you consider build quality, durability, and all that Audioengine has done to ensure pristine high-fidelity audio into your sound system, the B1 ends up looking like a solid buy. It is a worthy addition to the serious audiophile's system.


Audioengine B1 Premium Bluetooth Music Receiver

  • Bluetooth receiver type = Bluetooth 4.0 audio with aptX codec
  • Supported Bluetooth profiles = aptX, A2DP, and AVRCP
  • Inputs = Bluetooth
  • Outputs = Stereo analog RCA, Digital optical (SPDIF)
  • Required power = 5V, 200mA
  • Operation range = up to 100ft (30m) typical
  • Full-scale output 2.0V RMS
  • Output impedance = 57 Ohms
  • D/A converter = AKM AK4396
  • Power filtering = 3-stage redundant regulation
  • SNR (DC to 20 kHz) = >100dB
  • THD+N (1 kHz FS 96 kS/s) = <0.02%
  • Frequency response = 10Hz - 20kHz (+/-0.5dB)
  • Crosstalk = >-86dB
  • Input bit depth = 24-bit (upsampled)
  • Input data rate = Determined by Bluetooth
  • Latency = 30 milliseconds (ms)
  • Product dimensions = 3.5 x 4.0 x 1”
  • Includes built-in AKM4396 DAC for superior 24-bit upsampled playback
  • Aluminum case with audiophile-grade connectors
  • Analog and optical outputs
  • 2.0Vrms maximum output level

Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter

The Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter features the aptX Low Latency codec and supports two connections simultaneously. Its form factor is not what you might go looking for to add to your high-end audio system of home theater, but there is not much available yet that is small, Bluetooth 4.0, and aptX capable, including the Low Latency designation. Throw in dual transmission streams, and the TX4 fills a niche with little competition to date. It comes with an extension audio cable and a USB charging cable.

As with the other devices reviewed, the TX4 is a one-button, one-LED device. Operation is simple, though, and the Bluetooth pairing and connecting sequences are generally seamless enough that you will rarely need to refer to instructions. I did run into connections that I did not expect. "Now there is no sound from my tablet, why is that? - Oh, the TX4 is connected to it, too." I got in the habit of disconnecting a device and then turning Bluetooth off when using my tablet just to help eliminate the unexpected. Most users will not need to go to this trouble, but beware of the possibility.

As with previous discussions, the TX4 sent out CD-quality music when appropriately paired. It also operated cleanly and predictably. As indicated in the High Fidelity Comes To Bluetooth section above, it reliably transmitted CD-quality audio when appropriately paired.

Distances of up to 45 feet are specified, but this is most likely an echoing of Bluetooth technology capability, not tested performance level. My 25-foot limit involved a line-of-sight connection between the TX4 and both the B1 receiver and the S1 headphones, so that is the maximum one should expect from this tiny unit with its internal antenna. At that point dropouts began to occur, a fraction of a second long but annoying enough that you would not stretch that distance limit.

Battery life of 10 hours per charge is specified, though I never came close to running out of battery power. I tried running with USB power connected but hum was introduced. This was probably due to a ground loop resulting in my system and might or might not be typical.

The TX4 is small, weighs almost nothing, and of the units tested was the only one that I worried about damaging. I always used the extension audio cable so I did not have to force the rotating plug on the TX4 itself into a tight jack on my phone or tablet. A 1/8" stereo jack to dual 1/4" plug converter cable came in handy to run the TX4 with my audio interface. But even though the unit seems vulnerable, it endured my testing, although it never received any rough treatment. And it is intended for portable use, so who can complain about it being small and light?

The form factor might not be what you are looking for, as it was not initially for me, but its portability is a real plus. I grabbed it to round out the review and have on hand for... whatever. It will probably be replaced at some point by a higher-powered transmitter with similar capability and become a knock-around unit.


Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter

  • Bluetooth v4.0 with APT-X Low Latency
  • Operating Range = 45 ft. (14m)
  • Frequency = 2.4 GHz
  • Bluetooth stereo profile = A2DP
  • Sleep mode for power conservation
  • Power supply = Charges via Micro USB cable
  • Operation Time = Up to 10 hours per charge or continuous when connected to USB power
  • Weight = 0.8 ounces
  • Dimensions = 2.8 x 0.8 x 0.6 inches
  • Batteries = 1 Lithium ion battery required (included)


While Bluetooth is not about to replace cables or TOSLINK as a way to move critical audio around your room or facility, it is ready and able to deliver 16-44 and 16-48 quality sound from mobile devices and into headgear. And as aptX Low Latency and aptX Lossless devices become more available, they will be worthy of performing more and more hi-fidelity chores in your movie/listening room without cables.

The Pendulumic Stance S1 Wireless Headphone is a must-audition piece of audio gear for the serious listener who wants solid - no, make that downright excellent - listening performance in Bluetooth-enabled headphones. The S1 is an all-around great pair of 'phones for the money, with the added benefit of true CD-quality cordless freedom.

The Audioengine B1 Premium Bluetooth Music Receiver is the perfect device for the discerning listener who has multiple media-capable Bluetooth-enabled devices in his life - who does that NOT include? - and wants the convenience of pair them and play rather than digging for and tripping over cables. When a guest drops by with hot new tunes to play for you, you say, "Pair it up with my B1 and let's hear them." Simple as that!

The Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter is a big performer in a tiny, portable package.

Go to the Three Bluetooth Device Review Discussion Thread - Pendulumic Stance S1 Wireless Headphone, Audioengine B1 Premium Bluetooth Music Receiver, Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter.http://www.hometheatershack.com/for...4-bluetooth-music-transmitter.html#post989521

Go to the Headphone Roundup Overview for scoring and comparison details.

Pendulumic Stance S1 Wireless Headphone

Audioengine B1 Premium Bluetooth Music Receiver

Miccus Mini-jack TX4 Wireless Bluetooth 4.0 Music Transmitter

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