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Parent Category: Products

Category: Headphone Measurements

Created: 15 May 2014

I measured the performance of the Audeze LCD-X headphones using a G.R.A.S. 43AG ear/cheek simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-Can headphone amplifier. Measurements were calibrated for ear reference point (ERP), which is roughly the point in space where your palm intersects with the axis of your ear canal when you press your hand against your ear, and the place where the front of a driver grille sits when you wear the headphones. This is a “flat” measurement; no diffuse-field or free-field compensation curve was used. I experimented with the positions of the earpads by moving them around slightly on the ear/cheek simulator, and settled on the positions that gave the best bass response and the most characteristic result overall.

The LCD-X’s frequency response is about what I’m used to seeing from planar-magnetic headphones: dead flat from about 50Hz to 1.2kHz, with a peak at around 2.5kHz, which is typical. The only anomaly is that the treble response is a little less than I’m used to seeing from planar magnetics. Note the difference in bass response between the right and left channels: Each represents the best measurement I was able to get in more than a half-dozen tries; however, because slight differences in the seal of the earpads against the ear/cheek simulator can have huge effects on the measured response, I have no way of knowing if this represents an actual imbalance or a measurement artifact. Regardless, I didn’t notice any difference in the sounds of the left and right channels in my listening to the Audezes.

Because planar-magnetic drivers have an almost purely resistive (i.e., flat) impedance curve, their tonal balance rarely changes with different source devices. I simulated a change in source device by adding 70 ohms output impedance to the V-Can’s 5-ohm output impedance, for a total of 75 ohms, which is typical of the low-quality headphone amps built into laptops and cheap MP3 players. As you can see, there’s no significant difference in the Audezes’ response.

This chart compares the LCD-X with Audeze’s top model, the LCD-3, and with Oppo Digital’s new PM-1 planar-magnetic headphones. You can see that the LCD-X and LCD-3 headphones are practically identical up to 7kHz, but that the LCD-3s have 4 to 6dB more output between 7 and 9kHz. This should, at least in theory, give the LCD-3s a slightly brighter sound, and probably an enhanced sense of “air” and spaciousness. The Oppo PM-1s have a flatter response, but less energy in the lower treble.

The spectral-decay (waterfall) plot shows a couple of mild resonances in the vicinities of 800Hz and 1.4kHz, but their duration and bandwidth are so low that you probably wouldn’t notice them.

This plot of the LCD-Xs’ total harmonic distortion vs. frequency is one of the cleanest I’ve seen. The orange trace is taken at 100dBA, a higher level than most people could stand to listen to for more than a few seconds; even so, distortion is practically nonexistent.

This spectrum plot of the distortion harmonics, again taken at very loud levels, provides still more evidence that these are super-clean-sounding headphones.

Open-back planar-magnetic headphones provide little or no isolation from outside sounds, and the LCD-Xs almost none at all -- along with your music, you’ll hear everything going on around you.

The LCD-Xs’ impedance magnitude is essentially flat at 22 ohms (which matches the specification), and the impedance phase shift is near zero.

The LCD-Xs’ average sensitivity from 300Hz to 3kHz, at the rated 22 ohms, measured 101.5dB, which is very high for planar-magnetic headphones.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 April 2014

I measured the NAD Viso HP20s using a G.R.A.S. RA0045 ear simulator, 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 headphone amplifier. Measurements were calibrated for drum reference point (DRP), the equivalent of the headphones’ response at the surface of the eardrum. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed. Except as noted, I used the HP20s’ medium standard eartips. I experimented with the fit of the eartips and earpieces by inserting and reinserting them in the RA0045, and settled on the positions that gave the best bass response and the most characteristic result overall.

Earphones don’t always sound like they measure, but the HP20s sure seemed to. (It probably helps that designer Paul Barton and I use similar measurement gear.) There’s a mild bass boost centered at 40Hz -- exactly as I heard -- and a lot of energy between 4 and 6.5kHz, which is surely why I occasionally perceived the sound as bright.

Adding 70 ohms to the V-CAN’s output impedance of 5 ohms, to simulate the effects of using a typical low-quality headphone amp, had no effect on the HP20s’ response above 25Hz. So as you plug them into, variously, your smartphone, your laptop, and your high-end headphone amp, the HP20s’ tonal character shouldn’t change.

This comparison of the HP20s with Bowers & Wilkins’ C5 and RBH’s EP-1 suggests that, at least alongside those esteemed competitors, the HP20s’ response is relatively flat, with a more even balance of bass and treble than the two other models. Note the RBHs’ extra bass, and the B&Ws’ relative lack of energy in the treble.

The spectral-decay (waterfall) plot shows a fairly strong resonance at 5kHz and a weaker one at 6kHz, both of which correlate with the response peak in the treble.

The HP20s’ total harmonic distortion (THD) at 90 and 100dBA is very, very low

The spectrum of a 500Hz sinewave suggests that if you push the HP20s really, really loud, you’ll get a roughly equal mix of second- and third-harmonic distortion. But if you play the HP20s at levels high enough to make it audibly distort, you won’t have much hearing left for long.

For reasons I can’t explain, the HP20s delivered superb isolation at the lower frequencies of the audioband, where it really matters (and where jet engines roar): from -10 to -28dB, up to 4kHz. At higher frequencies, however, their isolation was less than the norm.

The HP20s’ impedance magnitude was effectively flat at 16.5 ohms; the impedance phase was also effectively flat.

The HP20s’ average sensitivity, from 300Hz to 3kHz at the rated 16 ohms, measured 106.9dB.

All things considered, nothing in these measurements suggests even the slightest reason for concern.

. . . Brent Butterworth
brentb@soundstagenetwork.com 

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Parent Category: Products

Category: Headphone Measurements

Created: 15 March 2014

I measured the performance of the Audeze LCD-3 headphones using a G.R.A.S. 43AG ear/cheek simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN headphone amplifier. Measurements were calibrated for ear reference point (ERP), which is roughly the point in space where your palm intersects with the axis of your ear canal when you press your hand against your ear, and the place where the front of the headphones’ driver grilles will sit when you wear them. This is a “flat” measurement: no diffuse-field or free-field compensation curve was used. I experimented with the position of the earpads by moving them around slightly on the ear/cheek simulator, and settled on the positions that gave the best bass response and the most characteristic result overall.

The LCD-3’s frequency response is textbook for planar-magnetic headphones, with essentially flat response below 1kHz, a strong response peak at 2.8kHz, and minor response peaks at 6 and 8.5kHz. This generally conforms to the typical diffuse-field equalization used in many headphones.

Thanks to the resistive impedance of the planar-magnetic driver, adding 70 ohms output impedance to the V-CAN’s 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp had zero audible effect. I could measure a difference only below 20Hz.

This chart compares the LCD-3 with another highly regarded planar-magnetic headphone, the HiFiMan HE-6, and a respected, new dynamic open-back headphone, the AKG K712. The responses of all three are similar below 1kHz, but between 3.3 and 6.5kHz the HE-6 has a lot more output than the LCD-3, which should make it sound brighter than the Audeze. The K712 should sound substantially different from its planar-magnetic competitors, with less output in the octave between 2.5 and 5kHz.

The spectral-decay (waterfall) plot shows a series of strong but narrow resonances between 2 and 4kHz.

For logistical reasons, I was unable to run a 90dB SPL distortion measurement on the LCD-3, but considering that the 100dB measurement shows near-zero distortion, the 90dB result could only be better.

The LCD-3 being an open-back planar-magnetic headphone, it provides almost no isolation from outside sounds. There is no significant attenuation below 2kHz, and only -5dB of isolation at 5kHz.

The impedance magnitude is essentially flat at 47 ohms, and the impedance phase is at 0 degrees through almost the entire audioband, rising to +5 degrees at 20kHz.

At its claimed impedance of 45 ohms, the LCD-3’s average sensitivity from 300Hz to 3kHz measured 94.5dB.

. . . Brent Butterworth
brentb@soundstagenetwork.com 

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Parent Category: Products

Category: Headphone Measurements

Created: 01 March 2014

I measured the Sony XBA-H1s using a G.R.A.S. RA0045 ear simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN headphone amplifier. Measurements were calibrated for drum reference point (DRP): the equivalent of a headphone’s response at the surface of your eardrum. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed. Except as noted, I used the XBA-H1s’ medium standard tips. I experimented with the fit of the tips/earpieces by inserting and reinserting them in the RA0045, settling on the positions that gave the best bass response and the most characteristic result overall.

For an earphone, the XBA-H1s’ frequency response looks pretty flat overall, with perhaps a slight excess of energy between 3 and 5kHz. (Almost all headphones have a peak or two somewhere in this region.)

Adding 70 ohms output impedance to the V-CAN’s 5-ohm output impedance, to simulate the effects of using a typical low-quality headphone amp, tilts up the XBA-H1s’ response, dropping their bass output -1dB at 80Hz and kicking up the treble +5dB at 10kHz. Given my perception that the XBA-H1s sounded ever-so-slightly bright, even with the low-impedance output of my iPod Touch, I’d recommend using these headphones only with Apple or higher-end Android products, or with a separate headphone amplifier that has a low output impedance, preferably under 20 ohms.

Above 500Hz the XBA-H1s are fairly similar to the Audiofly AF78 hybrid and the RBH EP1 dynamic earphones, but the Sonys’ bass response looks much more neutral.

The spectral-decay (waterfall) plot looks very clean, with no notable resonances.

Total harmonic distortion (THD) at 100dBA is quite moderate overall, but with a little 10% peak centered near 3kHz; this drops to 3% at 90dBA. Considering that the first and second distortion harmonics of 3kHz are at 6 and 9kHz, respectively, your sensitivity to this distortion will vary inversely with your age, and more so if you’re male. (Translation: Your ability to hear higher frequencies decreases with age, especially in males.)

The spectrum of a 500Hz sinewave shows that the second and third distortion harmonics are nearly equal in level. It’d be nicer to see more second and less third, because odd-order harmonics are more objectionable, but the distortion is moderate anyway, so no big deal.

There’s not much isolation in the bass -- only about -8dB at 100Hz -- but it improves dramatically as the frequency rises: to -20dB at 1kHz, and about -30dB from 2.5 to 8kHz. That’s with the standard tips. The noise-isolating tip didn’t make a big difference, at least not when used in the cold-steel cone of the RA0045 ear simulator. It gave me an improvement of -8 to -15dB, but only at high frequencies: from 3 to 14kHz. I wonder how the results vary when the tips are inserted into a soft, warm ear canal.

The XBA-H1s’ impedance rises dramatically with frequency, running about 32 ohms below 1kHz, then rising to 186 ohms at 20kHz. The impedance phase rises similarly; it’s right near 0° at low frequencies, but jumps to +65° at 20kHz. Impedance swings at high frequencies are common in balanced-armature drivers, but I’d never before seen one so extreme. This causes the shift in tonal balance when the XBA-H1s are used with source devices that have a high output impedance.

The Sony XBA-H1s’ average sensitivity from 300Hz to 3kHz at the rated 40 ohms was very high, at 109.3dB.

. . . Brent Butterworth
brentb@soundstagenetwork.com 

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Parent Category: Products

Category: Headphone Measurements

Created: 15 November 2013

I measured the performance of the ADL H118 headphones using a G.R.A.S. 43AG ear/cheek simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-Can headphone amplifier. Measurements were calibrated for ear reference point (ERP) -- roughly, the point in space where your palm intersects with the axis of your ear canal when you press your hand against your ear, and the place where the front of the headphone’s driver grille will sit when you wear the headphone. This is a “flat” measurement; no diffuse-field or free-field compensation curve was used. I experimented with the position of the earpads by moving them around slightly on the ear/cheek simulator, and settled on the positions that gave the best bass response and the most characteristic result overall.

The H118s’ frequency response shows the strong peak centered at 2.8kHz that’s often found in headphone response measurements, as well as a broad, strong boost between 6 and 10kHz. This is similar to the typical diffuse-field equalization used in many headphones.

Adding 70 ohms output impedance to the V-Can’s 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp produced a slight increase (about +1dB) in bass response between 40 and 90Hz.

You can see in the chart above that the ADLs’ tonal balance and overall response are quite similar to those of the B&W P7s -- which most reviewers liked. Compared with PSB’s M4U 1 headphones, which some consider to be a reference for a $300 passive design, the ADLs have notably less bass, a little more energy in the 3kHz range (i.e., closer to the classic diffuse-field curve used for many headphones), and less energy in the 8-10kHz range (so probably a bit less “air” than the PSBs).

The spectral-decay (waterfall) plot shows a very clean decay above 500Hz, with no noticeable resonances.

The H118s’ total harmonic distortion (THD) at 100dBA is rather high in the bass, measuring 5 to 8%, and 2 to 3% at 90dBA. You’d probably notice this if you play music with lots of bass at high volumes.

The spectrum of a 500Hz sinewave shows that the distortion is primarily third harmonic (-55dBFS), with a strong presence of second harmonic (-66dBFS) -- it shouldn’t sound terribly objectionable.

Isolation is a tad less than average for over-ear headphones: -4dB at 1kHz, and typically -20dB at higher frequencies.

The impedance runs about 72 ohms, and the impedance phase is essentially flat.

The H118’s average sensitivity from 300Hz to 3kHz, at the rated 68 ohms, measured 103.9dB.

. . . Brent Butterworth
brentb@soundstagenetwork.com 

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Parent Category: Products

Category: Subwoofer Measurements

Created: 15 September 2018

Reviewed on: SoundStage! Access, September 2018

I measured the IW-S10EQ’s frequency response using an Audiomatica Clio FW 10 audio analyzer with the MIC-01 measurement microphone. For the frequency-response measurement I used the close-miked technique, with the microphone placed as close as possible (about 1/4”) to the woofer. For the power-compression measurement, I placed the mike on the ground 2m from the front of the sub.

I performed CEA-2010 measurements using an Earthworks M30 mike and M-Audio Mobile Pre USB interface with the CEA-2010 measurement software running on the Wavemetric Igor Pro scientific software package. Measurements recorded peak output at 2m. I measured the sub twice: once in a 48”-high box made with 6” studs 16” on-center (interior volume 2.08cf), and once in a box made with 4” studs but otherwise the same dimensions (interior volume 1.32cf). These enclosures reflect typical volumes encountered in in-wall mounting.

The two sets of measurements I’ve presented here -- CEA-2010 and the traditional method -- are essentially the same. CEA-2010 mandates that no matter how the sub is measured, the results must be scaled to the equivalent of a measurement at a distance of 1m using peak values. But the traditional measurement technique used by some audio websites and manufacturers reports results at 2m RMS equivalent, which is 9dB lower than CEA-2010. An L in the tables below indicates that the output was dictated by the subwoofer’s internal circuitry (i.e., Limiter), and not by exceeding the CEA-2010 distortion thresholds. Averages are calculated in pascals. (For more information about CEA-2010, see my “CEA-2010 Measurement Manual.”)

This chart shows the IW-S10EQ’s frequency response with the crossover frequency set to maximum and auto EQ off, and with the sub mounted in fake walls made with 4” and 6” studs. This isn’t the flat response we typically see from freestanding subs, because those subs are all factory-EQed for flat response -- something not possible with an in-wall sub because the enclosure volume is not known. However, it does show that the sub has usable response down to about 23Hz.

Above, you can see the effects of the app’s EQ modes. Their effects are pretty subtle: Cinema basically boosts the bass below 45Hz by about 1.5dB, while Music boosts the midbass by about 1.5dB in a peak centered at 72Hz.

This chart shows the effects of auto EQ with the IW-S10EQ placed in the corner of my listening room. The microphone was placed near my listening position, about 1’ from my head; I placed the smartphone in the same position when I ran the auto EQ. It definitely made the in-room response flatter, though it left most of the peak at 38Hz unaffected.

This chart shows how the IW-S10EQ’s frequency response (measured here in Normal mode from 2m) was affected by increases in volume. I measured starting at 88dB, calibrated at 63Hz, then raised the level 3dB for each successive measurement. You can see that the function of the sub’s internal limiter doesn’t change significantly with frequency.

If you haven’t seen subwoofer distortion numbers before and are used to looking at amplifier distortion specs, some of these may look high. But in loudspeakers, and especially subwoofers, much higher distortion levels are the norm, though typically such levels are inaudible. The generally accepted threshold for audibility of distortion in subwoofers is 10% THD; CEA-2010 thresholds permit maximum distortion of around 30% THD.

The maximum output of the IW-S10EQ at higher frequencies isn’t impressive; from 40 to 63Hz, it’s roughly in line with what I’ve measured from some budget 10” standalone subs, and typically about 6dB lower than the best 10” standalone subs. But at lower frequencies it delivers output comparable to that of the best standalone 10” subs, and even delivers measurable output at 16Hz. This means you won’t get a lot of punch from a single IW-S10EQ, but neither will the sound thin out when you crank it up, as it can with subs that deliver a lot of output from 40 to 63Hz but much less from 20 to 31.5Hz. The IW-S10EQ’s output is a little lower from the smaller box made with 4” studs -- down an average of 3.7dB from 40 to 63Hz, and down 2.1dB from 20 to 31.5Hz.

This chart tracks the CEA-2010 results of the IW-S10EQ (blue trace) compared with two standalone 10” subs.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Subwoofer Measurements

Created: 15 February 2018

I measured the frequency response of the Monoprice Monolith THX Ultra 15” (product no. 24458) with an Audiomatica Clio FW 10 audio analyzer and MIC-01 measurement microphone, and in two different ways: the ground-plane technique, with the microphone on the ground 2m in front of the sub, and the result smoothed to 1/6 octave; and the close-miked technique, with the mike placed as close as possible (about 1/4”) to the woofer and ports, and the port responses scaled and summed with the woofer response. I show the close-miked results here because those graphs are clearer; the ground-plane results were within a couple of Hz of them. For the power-compression measurement, I placed the mike on the ground 2m from the front of the sub.

I performed CEA-2010 measurements using an Earthworks M30 mike and M-Audio Mobile Pre USB interface, with the CEA-2010 measurement software running on the Wavemetric Igor Pro scientific software package. Measurements recorded peak output at 2m. (For more information about CEA-2010, see this article.)

The two sets of measurements presented here -- CEA-2010 and the traditional method -- are essentially the same. CEA-2010 mandates that no matter how the sub is measured, the results must be scaled to the equivalent of a measurement at 1m distance using peak values. But the traditional measurement technique used by some audio websites and manufacturers reports results at 2m RMS equivalent, which is -9dB lower than CEA-2010. An “L” next to the result indicates that the output was dictated by the subwoofer’s internal circuitry (i.e., limiter), and not by exceeding the CEA-2010 distortion thresholds. Averages are calculated in pascals.

This chart shows the Monolith THX Ultra’s frequency response with the crossover frequency set to maximum and the sub set to Extended (rather than THX) mode. I’ll show the effects of the crossover and the THX mode in the next graph. You can see that the bass output gradually rises as more ports are opened, and that the response is pretty much flat up to 200Hz. With two and three ports open, the -3dB point (using the peak of the sub’s response curve as that +3dB reference point) is 14Hz. Even in sealed mode, it hits 16Hz.

This chart shows the response of the crossover and the effect of the THX mode, measured with all of the sub’s ports sealed. The crossover frequency was 80Hz, and, as the chart shows, the control is accurately calibrated (not usually the case), and the low-pass function is about -22dB/octave. The THX mode reduces bass output by about 4dB at 20Hz.

This chart shows how the Monolith THX Ultra’s frequency response is affected by increases in volume. I measured this with all three ports open in THX mode, starting at 106dB at 2m, calibrated at 63Hz, then raised the level 3dB for each successive measurement. You can see that the Monolith’s frequency response doesn’t change as it reaches its output limits; with many subs -- especially those with limiters that are set with higher thresholds, which allow greater distortion -- the bass response begins to weaken as the sub reaches the limits of its capabilities. Unfortunately, I had to return the sub in a hurry due to an upcoming trip, and didn’t have time to measure its output in the Extended (non-THX) mode, but based on the frequency-response measurements and what I heard, I expect the Extended-mode output measurements would average about 2dB higher than THX mode.

Please note that if you haven’t seen subwoofer distortion numbers before and are used to looking at amplifier distortion specs, some of these may look high. But in loudspeakers, and especially subwoofers, much higher distortion levels are the norm, and typically are inaudible. The generally accepted threshold for the audibility of total harmonic distortion in subwoofers is 10%, and CEA-2010 thresholds permit a maximum THD of around 30%.

The Monolith THX Ultra’s CEA-2010 output numbers are excellent -- among the best I’ve measured for a sub of this size and configuration.

This chart tracks the CEA-2010 results of the Monoprice Monolith THX Ultra (blue trace) compared with three other ported subs that are somewhat comparable: two 15” models (Hsu Research VTF-15H Mk.2 and Klipsch R-115SW), and one 13” model (SVS PC13-Ultra). The Monoprice doesn’t have quite as much output at higher bass frequencies as some models, but has more deep-bass output than the three other models, and a more consistent maximum output throughout the two octaves covered in the chart.

. . . Brent Butterworth
brentb@soundstagenetwork.com

Details

Parent Category: Products

Category: Subwoofer Measurements

Created: 15 February 2018

I measured the Adante SUB3070’s frequency response using an Audiomatica Clio FW 10 audio analyzer with the MIC-01 measurement microphone. For the frequency-response measurement I used the close-miked technique, with the mike placed as close as possible (about 1/4”) to one of the woofers. For the power-compression measurement I placed the mike on the floor, 2m in front of the sub.

I performed CEA-2010 measurements using an Earthworks M30 mike and M-Audio Mobile Pre USB interface, with the CEA-2010 measurement software running on the Wavemetric Igor Pro scientific software package. Measurements recorded peak output at 2m.

The two sets of measurements I’ve presented here -- CEA-2010 and the traditional method -- are essentially the same. CEA-2010 mandates that no matter how the sub is measured, the results must be scaled to the equivalent of a measurement taken at a distance of 1m using peak values. But the traditional measurement technique used by some audio websites and manufacturers reports results at an RMS equivalent of 2m, which is 9dB lower than CEA-2010. An L next to the result indicates that the output was dictated by the subwoofer’s internal circuitry (i.e., limiter), and not by exceeding the CEA-2010 distortion thresholds. Averages are calculated in pascals. (For more information about CEA-2010, see this article.)

This chart shows the SUB3070’s frequency response with the crossover frequency set to maximum and the sub set for its Flat, Cinema, Night, and Music modes. Flat mode is indeed almost perfectly flat from 30 to 130Hz. Night mode basically lowers the output by about 3dB. Cinema mode boosts output by a maximum of about 3dB, centered at 80Hz. Music mode does the same, but centers the boost at 40Hz. The -3dB point (using the peak of the sub’s response curve as the +3dB reference point) is 18Hz, and the low-pass function of the SUB3070’s crossover is -24dB/octave.

This chart shows the effects of the auto EQ processing with the SUB3070 placed in the corner of my listening room -- not the best spot for a single subwoofer if you want flat response, but it gives the auto EQ circuit a tougher challenge. The mike was placed near my listening position, about 1’ from my head; I placed the smartphone in the same position when I ran the auto EQ. In this case, the auto EQ processing seems to be making some pretty smart adjustments, flattening the response in general and ignoring the suckout at 73Hz, which is impossible for EQ to fill because it’s a cancellation -- the more energy you pump into it, the more will be canceled. Still, I was able to get a flatter curve using the parametric EQ function.

This chart shows how the SUB3070’s frequency response (measured here in Flat mode from 2m) is affected by increases in volume. I measured starting at 94dB, calibrated at 63Hz, then raised the level 3dB for each successive measurement. You can see that the sub’s internal limiter seems to be most restrictive between 30 and 60Hz.

If you’re used to looking at amplifier distortion specs, some of these may look high. But in loudspeakers, and especially subwoofers, much higher distortion levels are the norm, and typically are not audible. The generally accepted threshold for audibility of distortion in subwoofers is 10% THD; CEA-2010 thresholds permit maximum distortion of around 30% THD.

The output of the SUB3070 at 63Hz is, to the best of my recollection, the highest I’ve measured from a sub of this size. However, from there it falls rather quickly, albeit smoothly. Clearly, the SUB3070 is no home-theater bruiser; it focuses more on fidelity with typical music content, which seldom has much going on below 40Hz.

This chart tracks the CEA-2010 results of the SUB3070 (blue trace) and three other subwoofers that are to some extent comparable, though all are less expensive. While at 63Hz the SUB3070 beats even the mighty SVS PC13-Ultra, its bottom-octave output is more akin to that of a typical, less-expensive 12” model.

. . . Brent Butterworth
brentb@soundstagenetwork.com