Reviewed on: SoundStage! Solo, November 2019
I measured the K371 headphones using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The headphones were amplified using a Musical Fidelity V-CAN. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the K371s’ frequency response, which definitely shows the influence of the Harman curve -- specifically in that it has a broad rise between 2 and 8kHz instead of two distinct bumps, and in that it has a squarish rise in the bass response below 100Hz.
This chart shows how the K371s’ tonal balance changes when they’re used with a high-impedance (75 ohms) source, such as a cheap laptop or some cheap professional headphone amps, or some exotic tube amps. There’s a difference, but it’s very subtle: about 0.5dB boost below 60Hz when the high-impedance source device is used.
This chart shows the K371s’ right-channel response compared with two pro models (the Status Audio CB-1s, which are the headphones I use for mixing and monitoring home recordings, and the iconic Sony MDR-7506 headphones) and one consumer model (the widely praised NAD Viso HP50 headphones). The K371s lie right in the middle of the pack, with a generally flattish response that’s similar to the NAD Viso HP50s.
The K371s’ spectral decay (waterfall) chart is fairly clean; we can start to see a little bit of resonance developing around 200Hz, probably some “spillover” from that rise in the bass below 100Hz.
The total harmonic distortion of the K371s is negligible. Even at the extremely loud level of 100dBA, it’s not really measurable until you get below 100Hz, and even at that, it’s only 5% at 20Hz; distortion at such a low frequency typically isn’t audible below about 10%.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The isolation of the K371s is about the same as you get from similar professional and consumer headphones.
The impedance magnitude of the K371s is fairly flat for dynamic headphones, running between 35 and 41Hz, and the phase response is generally flat, too.
Sensitivity of the K371s, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms rated impedance, is 106.7dB. That’s several dB below AKG’s rating, but still plenty enough that the K371s will play very loud from any source.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, November 2019
I measured the Frees using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. A MEE Audio Connect Bluetooth transmitter was used to send signals from the Clio 10 FW to the earphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that because of the latency introduced by Bluetooth, I wasn’t able to do a spectral-decay measurement, and of course my usual impedance and sensitivity measurements are irrelevant for wireless earphones. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the Frees’ frequency response measured with the RA0402 ear simulator (I wasn’t able to get an adequate seal using the KB5000 and KB5001 simulated pinnae). This is pretty much a “by the book” response for good-sounding earphones, and it’s the first time I’ve seen this in a set of true wireless earphones.
The impulse response shows that the latency with the MEE Connect is 283ms. This is typical for true wireless earphones, and it means you will almost certainly notice lip-sync errors when you watch videos using the Frees. Best to stick to music and podcasts with these.
This chart shows the Frees’ right-channel response compared with two other true wireless earphones (HiFiMan TWS600s and Sennheiser Momentum True Wirelesses), as well as with the AKG N5005s, the earphones said to best reflect the Harman curve. The Frees are at least in the ballpark of the Harman curve; they’re likely to sound a little softer than the AKG N5005s, and because their bass resonance is centered at a higher frequency of 80Hz, they’re likely to sound a tad soft, at least relative to the AKGs.
Because of the latency of the Bluetooth connection, I could not use Clio’s sine-sweep function to measure total harmonic distortion (THD) versus frequency, so I did discrete THD measurements of sine tones in one-octave steps. While distortion is very low at all frequencies and levels, note that I couldn’t get the Frees to play loud enough (at least when fed by the MEE Connect transmitter) to do a measurement at 100dBA.
This chart shows the Frees’ isolation versus a couple of other true wireless models (1More E1026BT-1 Stylish and Sennheiser Momentum True Wireless earphones) and a passive (wired) model with a foam tip (Campfire Comet earphones). The Frees’ isolation is excellent for a true wireless earphone without active noise canceling, and it actually comes pretty close to the isolation of some models with active noise canceling.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, October 2019
I measured the Simgot EK3 earphones using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the EK3s’ frequency response measured in Strong Bass mode (the generally preferred mode of our listening panelists) with the Balanced eartips. This is a fairly ordinary result except for a couple of things. First, there are separate response peaks at 1.8 and 3kHz; normally we’d expect to see a single peak centered at about 2.8kHz. But that’s probably no big deal. The peak centered at about 6.8kHz is pretty common, although a little higher than typical. The only real issue here is the channel imbalance, with the right channel measuring about 2dB louder than the left from 150Hz to 4kHz. This result held up when I switched to using the cylindrical coupler that comes with the RA0402 instead of the full ear/cheek simulator. There’s a certain amount of uncertainty in earphone channel-balance measurements because of the slightly different response you see every time you remove and reinsert the earphone, but this is a pretty big difference, and suggests the factory QC process might stand improvement.
This chart shows the frequency response with in the EK3s’ different listening modes. I’ve doubled the dB resolution on this chart (to 5dB per major division rather than 10dB) so you can see the differences more easily. Note how close the Strong Bass mode is to the Bright Vocal mode, and how close the Exquisite Tone mode is to the Balanced Tuning mode. This shows that switch 2 has a large effect on the sound, but switch 1’s effect is small and perhaps could be considered superfluous.
The EK3s’ frequency response (shown in Strong Bass mode) changes a lot when you switch to a higher-impedance (in this case, 75 ohms) source device, such as a typical laptop or some professional headphone amps. Almost all balanced-armature earphones show some difference in response when switching from low- to high-impedance sources, but this is one of the biggest differences I can remember measuring. I’d strongly recommend using these earphones with a source device (preferably a portable music player or DAC-headphone amp) with output impedance of 5 ohms or lower.
This chart shows the EK3s’ right-channel response in Strong Bass mode compared with the Simgot EN700 Pros, Campfire Solarises, and AKG N5005s (the earphones said to best reflect the Harman curve) with their Reference filters installed. The similarity between the EK3s and the Solarises in this chart is interesting; the EN700 Pros are more like the AKG N5005s.
The EK3s’ spectral-decay (waterfall) plot shows a major, but well-damped, resonance centered at 6.5kHz. This resonance is high enough in magnitude and broad enough in bandwidth that I have to imagine it has some effect on the sound. There are also poorly damped but extremely high-Q (i.e., narrow) resonances at 6 and 12kHz, but these are so narrow and high in frequency that they’d be very unlikely to be audible. (If you’re curious, those are the fifth and sixth harmonics of the F# note at the second fret of the high E string on a guitar.)
Here you can see the EK3s’ total harmonic distortion (THD) versus frequency in Strong Bass mode; it’s fairly low for a balanced-armature model.
This chart pits the EK3s’ isolation versus several similar models, all fitted with silicone tips. Like most pinna-filling designs with over-ear cable routing, the EK3s’ isolation is pretty good, especially as the frequency rises past a couple hundred Hz, and assuming you get a good fit with whatever tips you’re using.
The impedance of the EK3s in Strong Bass mode shows large swings in magnitude and phase, which is why the earphones’ frequency response varies so much with high- and low-impedance sources.
This chart shows how the impedance magnitude of the EK3s changes with the different listening modes. The general shape of the impedance curve remains mostly the same, but switch 2 has a fairly large effect on the magnitude below 1.8kHz.
Sensitivity of the EK3s, measured between 300Hz and 3kHz, using a 1mW signal calculated for 16 ohms impedance (the rating is 14-18 ohms), is 116.2dB, one of the highest I have measured. That means the EK3s will play extremely loud from any source device, if you want them to.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, September 2019
I measured the MX4 Pros using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The headphones were amplified using a Musical Fidelity V-CAN. Except as noted, all measurements were made using the supplied medium-sized, single-flange silicone eartips, as these fit the ear/cheek simulator best. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the MX4 Pros’ frequency response, which is a fairly “textbook” response except for a boost of about 4dB centered at 4kHz. This looks like a very deliberate voicing decision, and it’s the reason for the lower-treble emphasis noted in the review.
This chart shows how the MX4 Pros’ tonal balance changes when they’re used with a high-impedance (75 ohms) source, such as a cheap laptop or some cheap professional headphone amps, or some exotic tube amps. There’s about 1dB more bass at 20Hz and 1dB more treble above 3kHz; my guess is that using a high-impedance source will make these sound just a tad brighter overall. Note that this is much less variance than I normally see with earphones using balanced armatures.
This chart shows the MX4 Pros’ right-channel response compared with the Campfire Comet (single balanced armature), 1More Quad Driver (one dynamic driver with three balanced armatures), and the AKG N5005 (one dynamic driver with four balanced armatures; when used with their reference filter, these earphones are said to best conform to the so-called “Harman curve,” the response that research shows delivers what most listeners consider the most natural sound) earphones. Clearly, the MX4 Pros’ deviation from the norm is that big 4kHz peak.
The MX4 Pros’ spectral decay (waterfall) chart looks mostly clean, except for some well-damped resonances at about 3.2 and 11kHz.
The total harmonic distortion of the MX4 Pros is fairly mild, not even breaking 2% at the extremely loud listening level of 100dBA. What’s unusual, though, is that the distortion tends to be higher in the midrange than in the bass; this is probably because the balanced armatures can’t match the power handling of the dynamic driver.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. I chose silicone tips for this measurement to ensure a level playing field; some of these models (especially the Campfire Comet earphones) will achieve much better isolation with foam tips. Isolation of the MX4 Pros with the silicone tips is outstanding, probably because of the ear-filling design and the over-ear cable routing.
The impedance magnitude of the MX4 Pros is admirably flat for a hybrid model. It’s about 9 ohms when you’re in the range of the dynamic driver, and once the armatures kick in (apparently around 1kHz), the impedance rises to 19 ohms at 20kHz, measuring about 33 ohms up to 1.5kHz, with a couple of slight impedance peaks that correspond with the frequency response peaks in the treble. Impedance phase is fairly flat, as well.
Sensitivity of the MX4 Pro earphones, measured between 300Hz and 3kHz, using a 1mW signal calculated for 12 ohms rated impedance, is 100.7dB. That’s a little low for earphones, but still plenty enough to ensure loud volumes from almost any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, September 2019
I measured the TWS600 earphones using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. A MEE Audio Connect Bluetooth transmitter was used to send signals from the Clio 10 FW to the earphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that because of the latency introduced by Bluetooth, I wasn’t able to do a spectral decay measurement, and of course my usual impedance and sensitivity measurements are irrelevant for wireless earphones. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the TWS600s’ frequency response measured with the KB5000 and KB5001 anthropomorphic simulated pinnae. You’ll note right away that the mids and lower treble are super-strong, and there’s not much bass. I worried that this might be an artifact due to Bluetooth latency, so I ran the same measurement using pink noise and a real-time analyzer, and compared that measurement with similar ones I’ve taken of other earphones with a subjectively flatter response, and it appears that the curve you see here is representative. Moving up from the bass, if the peaks you see in the 1.8kHz and 4kHz ranges were shifted up by about half an octave, to about 2.8 and 5.3kHz, and there were more bass, these earphones would have a “normal” response. As it is, the relatively low frequency of the 1.8kHz peak is what gives these earphones their strong midrange emphasis. Note also that output between about 5 and 12kHz is low relative to the 1.8kHz peak.
The impulse response shows that the latency with the MEE Audio Connect is 260ms. This isn’t bad for true wireless earphones; the Cambridge Audio Melomania 1 earphones measured 320ms. In my opinion, though, it’s not a low-enough figure to justify the claim of low latency that HiFiMan makes on the TWS600 web page, and it will create lip-sync problems with video content and will create lag problems when playing some video games.
This chart shows the TWS600s’ right-channel response compared with the 1More E1026BT-I and Sennheiser Momentum True Wireless earphones. Obviously, the response curve of the TWS600s is anomalous; the others are much flatter.
Because of the latency of the Bluetooth connection, I could not use Clio’s sine sweep function to measure total harmonic distortion (THD) versus frequency, so I did discrete THD measurements of sine tones in one-octave steps. This is a little more demanding than a swept tone because the tones have to play longer and the voice coil in the driver gets a lot hotter. Note that distortion is very low at all frequencies, and that the TWS600s can easily play at 100dBA -- something not true of some true wireless models. Note also that for some reason, I wasn’t able to get a valid measurement at 32Hz/90dBA.
In this chart, the red line indicates an external noise level of 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The TWS600s’ isolation (with the medium-size, single-flange silicone tips, which gave me the best results) is well above average compared with its true wireless competitors.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, August 2019
I measured the Beyerdynamic Lagoon ANC headphones using a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with the KB5000 and KB5001 anthropomorphic simulated pinnae, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amp. For measurements in Bluetooth mode, I used a MEE Audio Connect Bluetooth transmitter to get the signal to the headphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The above chart shows the Lagoon ANCs’ frequency response measured in what I expect will be the headphones’ most-used mode: Bluetooth and noise canceling in ANC 2 mode. This curve is unusual in a few ways. First is the channel mismatch, which varied a lot with different positionings of the headphones on the ear/cheek simulator, and to some extent with the different usage modes, but remained pretty consistent throughout my measurement session (and wasn’t seen in the other headphones I measured in the same session). Second is the very broad peak centered at 2kHz in the right channel; it’s common to see a peak like this, but usually it’s only about an octave wide, rather than about 3.5 octaves wide as seen here. Third is that the high-frequency peak, in this case between 5 and 7kHz, is higher in magnitude than the 2kHz peak; usually it’s the reverse.
This chart shows how the noise canceling affects the response of the Lagoon ANCs. The response is the same in both ANC modes, and while the sound with ANC off is definitely different (and flatter in response), the character of the sound should remain quite similar. We often see much larger differences on this measurement.
This chart compares the response with the Lagoon ANCs in three modes with ANC off: wired passive (power off), wired active (power on), and Bluetooth. There are slight differences, but overall, the sound character remains largely the same in all modes.
This graph confirms what I noted above. The AKG, Bose, and NAD noise-canceling Bluetooth headphones shown here have a remarkably similar frequency response, and the Lagoon ANCs are a clear outlier. Of course, the Lagoon ANCs’ equalization app may bring them closer to the other headphones’ response.
The Lagoon ANCs’ spectral decay (waterfall) chart -- measured with a wired connection because of Bluetooth’s latency -- shows a distinct resonance at about 650Hz. But the Q of the resonance is extremely high (i.e., its bandwidth is narrow), and it’s down to -30dB within just a few milliseconds, so I doubt it’d be audible.
The Lagoon ANCs’ distortion is measured here with a wired connection; the internal amps of the headphones may add some distortion, but my analyzer can’t compensate for Bluetooth’s latency when doing distortion measurements. The distortion in the bass, below about 180Hz, is somewhat on the high side. At 90dBA it’s about 2%, which is unlikely to be audible, but it’s about 6% in the bass, which would probably be audible -- although 100dBA is louder than almost anyone really wants to (or should) listen for long.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. According to my measurements (and my ears), the Lagoon ANCs’ isolation is modest in the “airplane band” between about 100Hz and 1kHz, reducing noise by an average of about 5dB in ANC 1 and maybe 6dB in ANC 2. You’ll hear some noise canceling, but nothing like the near-silence that you hear from Bose models and the later Sonys.
The Lagoon ANCs’ impedance magnitude measurement in wired mode is unusual in that it’s only slightly higher when the headphones are in active mode: about 22 ohms with the headphones off (passive mode) and 47 ohms in active mode. This is unusual -- typically the impedance in active mode might be 300 to 1000 ohms -- but it’s no cause for concern. Impedance phase in both modes is essentially flat.
Bluetooth latency of the Lagoon ANCs used with the MEE Audio Connect transmitter (which, like the Lagoon ANCs, is equipped with the aptX Low Latency codec) was 36ms, which is typical for headphones using aptX LL. Thus, you will not experience lip sync problems using them for video or gaming. Sensitivity of the Lagoon ANCs with a wired connection with ANC off, measured between 300Hz and 3kHz using a 1mW signal calculated for the rated 32-ohms impedance, is 99.9dB in passive mode and 97.2dB in active mode. So if you have to use a wired connection, they should play fairly loud.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, August 2019
I measured the Periodic Audio Carbon earphones using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The headphones were amplified using a Musical Fidelity V-CAN. Except as noted, all measurements were made using medium-sized, single-flange silicone eartips, as these fit the ear/cheek simulator best. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the Carbons’ frequency response, which in terms of the shape of the curve is fairly textbook. There’s more bass than usual, though, and a little more energy around 5.5kHz than I’m used to seeing, but all of this is still fairly close to industry norms. Incidentally, substituting one of the supplied medium-sized foam tips had very little effect on the frequency response.
This chart shows how the Carbons’ tonal balance changes when they’re used with a high-impedance (75 ohms) source, such as a cheap laptop or some cheap professional headphone amps, or some exotic tube amps. As I usually see with earphones employing no balanced armatures, there’s very little difference in response with the high-impedance source, which means the Carbons should sound about the same no matter what you plug them into.
This chart shows the Carbons’ right-channel response compared with another single-dynamic-driver model, the Campfire Comets. I also included the recently reviewed Simgot EN700 Pro earphones, as well as the AKG N5005s, which, when used with their reference filter, are the earphones said to best conform to the so-called “Harman curve,” the response that research shows delivers what most listeners consider the most natural sound. Again, there’s more bass than usual, and a little more energy around 5.5kHz -- although also less around 7.5kHz, and less at higher frequencies. This might be the reason John Higgins and I described the Carbons as lacking a bit of “air” in the upper treble.
The Carbons’ spectral decay (waterfall) chart looks pretty clean, except for some resonance between 200 and 300Hz, and a very high-Q (i.e., narrow) resonance centered at about 5.2kHz. This seems to correspond with the second treble peak in the frequency response plot.
Periodic Audio’s claims about the Carbons’ ultra-low distortion seem to bear out. I can’t say with confidence that this is the lowest distortion I’ve measured, as once the distortion levels get this low, noise starts to intrude on the measurement. But I can say that the Carbons’ distortion ranks among the lowest I’ve ever measured. Without a doubt, 1% THD at 20Hz/100dBA is exceptional performance.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. Isolation of the Carbons with the silicone tips is so-so, but with the foam tips, it’s excellent.
The impedance magnitude of the Carbons is largely flat, measuring about 33 ohms up to 1.5kHz, with a couple of slight impedance peaks that correspond with the frequency response peaks in the treble. Impedance phase is very close to flat.
Sensitivity of the Carbons, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms-rated impedance, is 112.6dB, way higher than the rated 98dB, thus the Carbons will deliver ample volume from any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, July 2019
I measured the Campfire Audio IO earphones using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The headphones were amplified using a Musical Fidelity V-CAN. All measurements were made using medium-sized silicone eartips, as these fit the ear/cheek simulator much better than the supplied foam tips did. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.
The above chart shows the IOs’ frequency response. If you pushed those peaks at 1.7 and 3.9kHz up by about 1kHz each, this would look like a very typical measurement for high-quality earphones.
This chart shows how the IOs’ tonal balance changes when they’re used with a high-impedance (75 ohms) source, such as a cheap laptop or some cheap professional headphone amps. As usual with earphones using balanced-armature drivers, there’s a significant change in tonal balance when you switch to a source device with relatively high output impedance. In this case, a high-impedance source will give you several dB less bass and a couple dB less treble.
This chart shows the IOs’ right-channel response compared with two other Campfire Audio earphones: the affordable Comets and the super-high-end Solarises. I also included the AKG N5005 earphones, which when used with their reference filter are the earphones said to best conform to the so-called “Harman curve,” the response that research shows delivers what most listeners consider the most natural sound. It appears that the dip at 3kHz (the only very clear difference between the IOs and the other models) is what gives them a subjectively brighter tonal balance.
The IOs’ spectral decay (waterfall) chart shows that any resonances are well-damped and die out within a couple of milliseconds.
The IOs’ measured total harmonic distortion (THD) is surprising. Between 900Hz and 1.7kHz, it’s a little on the high side, at about 2%. However, the amount of distortion didn’t significantly change when I raised the level from 90dBA (which is very loud) to 100dBA (which is crazy loud). The Clio analyzer told me this is almost all second-order harmonic distortion -- which means it’s adding harmonics between 1.8 and 3.4kHz. I thought this might be spurious noise entering the measurement system, so I remeasured it a week later after a fresh setup and calibration, but I got the same result, and a check with a real-time spectrum analyzer told me there was no unusual noise in the room. I’m not sure if you’d notice this distortion, because 2% isn’t much for an audio transducer, but it is right in the most sensitive range of the human ear, so it might be an issue with some recordings.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. Isolation of the IOs is excellent, especially considering that I had to use the silicone tips; you’ll likely get even better results with the foam tips, assuming one of the supplied sizes fits you well.
The impedance magnitude of the IO earphones ranges from 13.5 ohms in the bass to 27 ohms in the midrange, with corresponding (but fairly mild) swings in phase. This is why the tonal balance changes when the output impedance of the source device changes.
Sensitivity of the IOs, measured between 300Hz and 3kHz, using a 1mW signal calculated for 26-ohms rated impedance, is 115.7dB, which is exceptionally high, so the IOs will deliver ample volume from any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
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