Lansche Audio 5.1 loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Lansche 5.1's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield and spatially averaged room responses. The Lansche is specified as having a voltage sensitivity of 91dB/2.83V/m; my estimate on the tweeter axis was 90.5dB(B), which is both within experimental error of the specification and usefully higher than average.

Fig.1 shows the Lansche 5.1's electrical impedance phase angle, following the modification to the crossover. The impedance is considerably higher in the region covered by the ionic tweeter. This will not be a problem with a typical solid-state amplifier, with its low source impedance, but it will bring up the level of the treble with tube amplifiers. At lower frequencies, however, the speaker is very difficult to drive. Not only does the impedance drop below 5 ohms below 200Hz, reaching a minimum magnitude of 2.65 ohms at 80Hz, there is also a combination of 3.4 ohms and –48° phase angle at 62Hz, a frequency where music can have significant levels of energy. An amplifier capable of driving 2 ohm loads with aplomb is a must with this speaker.

Fig.1 Lansche Audio 5.1, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

One peculiarity I noted while measuring the 5.1's impedance was that there was noticeable RF noise in the oscilloscope trace. (I always use an oscilloscope to monitor what I am measuring with the Audio Precision, as a visual check on what is happening.) I suspect that this RF noise is due to the fact that the Lansche tweeter is transformer coupled; some of the arc generator's noise is reflecting back through the transformer to the partnering amplifier. This will not be an issue with tube amplifiers, which tend to have a low level of overall negative feedback and a curtailed ultrasonic response. But with high-feedback, solid-state amplifiers, the speaker terminals are also an input port via the feedback circuit, and not all amplifiers will deal gracefully with RF noise input in this manner. It's possible that this might have been, at least in part, why I felt the tubed Audio Research amplifier proved a more synergistic match with the Lansche than the wide-bandwidth, solid-state MBL amplifiers.

The traces in fig.1 are free from the small discontinuities that would imply the existence of cabinet resonances. Checking the panels' vibrational behavior with a plastic-tape accelerometer, I found a couple of low-level modes between 200 and 300Hz on all surfaces (fig.2). Overall, the Lansche's enclosure is well damped. There was a higher-level mode present at 350Hz on the top panel, but this was eliminated by the VPI bricks I used for my listening.

Fig.2 Lansche Audio 5.1, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel adjacent to point midway between woofers (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The saddle centered on 25Hz in the impedance-magnitude trace suggests that this is the tuning frequency of the large port near the bottom of the speaker's rear panel. The nearfield output of the woofers (fig.3, blue trace; the woofers behaved identically) does indeed have the expected minimum-motion notch at that frequency, which is when the back pressure from the port resonance holds the woofer cones still. The port's output (fig.3, red trace) peaks between 15 and 60Hz, with a sharp rolloff above that region. Three resonant peaks are visible in the port's midrange output, however, though these are well down in level and their audibility will be reduced by the fact that the port faces away from the listener. The woofers roll off above 80Hz, but the midrange drive-unit (fig.3, green trace) comes in a little too high in frequency for optimal integration with the woofers.

Fig.3 Lansche Audio 5.1, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with nearfield responses of midrange unit (green), woofers (blue), port (red), and their complex sum (black), plotted below 500, 1000, 750, 300Hz, respectively.

These nearfield responses are all boosted by a few dB, due to the implicit assumption in the measurement methodology that the radiators are mounted in a true infinite baffle; ie, one that extends to infinity in all directions. But they do suggest that the Lansche 5.1's low-frequency alignment is somewhat overdamped. These measurements were taken with the rear-panel low-frequency jumper set to "0"; setting this to "–3" reduced by 3.6dB the output level at 75Hz, but the woofer response below 50 and above 200Hz wasn't changed.

Higher in frequency in fig.3, the overall balance is flat, though with a slight excess of energy apparent between 1.5 and 3kHz. This is actually due to the tweeter having too high an output at the bottom of its passband—a horn artifact?—though the midrange unit rolls off smoothly in this region (not shown). Before the modification to the crossover, this excess of energy extended more than an octave higher in frequency. The high-frequency jumpers on the terminal are marked "+1," "0," "–1," and "–2." Before the modification, these numbers roughly corresponded to the change in the tweeter level; after the modification, the difference in this level at 10kHz between "+1" and "–2" was just 1dB.

While the Lansche's horizontal dispersion in the bass and midrange is wide and superbly even, the tweeter's horn loading makes the speaker increasingly directional as the frequency rises (fig.4). This might well make the 5.1 sound too mellow in large rooms. In the vertical plane (fig.5), a large suckout develops at the crossover frequency more than 5° above the tweeter axis, but the speaker maintains its balance below that axis. This is appropriate, given the height of the tweeter, which is 37" from the floor.

Fig.4 Lansche Audio 5.1, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

Fig.5 Lansche Audio 5.1, vertical response family at 50", normalized to response on listening axis, from back to front: differences in response 15–5° above axis, reference response, differences in response 5–10° below axis.

The red trace in fig.6 shows how its quasi-anechoic response measurements translate to the Lansche speaker's in-room behavior. This spatially averaged graph is produced by using SMUG Software's Fuzzmeasure program to take 10 response measurements for each speaker, in a vertical grid centered on the positions of my ears. (The speakers were driven by the Lamm amplifiers for this measurement, with the tweeter jumpers set to "+1.") Other than a slight excess of energy at the bottom of the tweeter's passband, the treble is smooth, with a slight downward trend due to the increasing absorptivity of the room's furnishings in the top octaves. However, the lower midrange is shelved down, and while the low frequencies are aided by the lowest-frequency resonances in my room, they are still a little light compared with the level in the treble. The blue trace in fig.6 was taken for the speakers before the crossover modification. Even though the tweeter jumpers were set to "–1," there is just too much low-treble energy present in the room, which is why I found the original speakers to sound so forward. This excess also threw into contrast the shelving-down of the 5.1's lower midrange, emphasizing the leanness. The production change to the crossover brought the speakers' in-room response into better balance (red trace).

Fig.6 Lansche Audio 5.1, spatially averaged, 1/6-octave response in JA's listening room of: first version (blue), revised version (red).

In the time domain, the Lansche 5.1's step response on the tweeter axis (fig.7) reveals that its tweeter and woofers are connected in positive acoustic polarity, the midrange unit in inverted polarity. The setback of the horn tweeter means that the start of the midrange unit's negative-going step can be just seen before the positive-going spike of the tweeter's step at the 4ms mark. The cumulative spectral-decay plot on the tweeter axis is superbly clean in the upper midrange and treble (fig.8).

Fig.7 Lansche Audio 5.1, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.8 Lansche Audio 5.1, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

The Lansche 5.1's measured performance indicates that it will never be a warmly balanced speaker, but the revision to its crossover brings that extraordinary tweeter into better balance with the speaker's lower ranges.—John Atkinson

Company Info
Lansche Audio
US distributor: Aaudio Imports
4871 Raintree Drive
Parker, CO 80134
(720) 851-2525
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Comments
EVOnix's picture
Really?

Shame on you Stereophile for even promoting a product such as this.

John Atkinson's picture
Re:Really

Quote:
Shame on you Stereophile for even promoting a product such as this.

I think you need to examine where you learned of the problems you mention that lead you to this conclusion, EVOnix.

John Atkinson

Editor, Stereophile

PS: the original comment to which I was responding seems to have disappeared? I must have hit "Edit" rather than "Reply." Apologies EVOnix. I have reinstated the text that was preserved. - JA

audiocaptain's picture
I had this speaker in my listening room for 6 months

Just a quick comment on these as I had a pair of 4.1 in my listening room for over 6 months. 

They were very interesting speaker. I have not read the article so not to be influenced by the writers comments on a very similiar product. I can say the 4.1 is a discontinued product and the newer models impress me more which is a good thing as products should improve and not just change with time. We used some very interesting equipment many may not recognize including the Delta Sigma integrated amp from Italy. We also used Sino Speaker cable and the complete Reimyo CD system and all their associated wiring. The room has cork walls covered in drywall and 8 dedicated circuits of which two are 30 amp. The ceiling is a special material designed for studios and costs about $10,000.00 for a 25' x 19' room and features 95 percent absorption, the walls are 9.5 feet in height. No windows and a concrete floor covered in carpet 

Really Great Sound and something to spend time with. The End

Stereorealist's picture
Audiophiles or equipmentphiles?

It's always great to have technological pioneers create uber expensive sota equipment whose tech will later filter down to more "affordable" models or to the used-gear markets. Stereophile's contribution to the world is of course, to bring awareness, and inspire people to dream of hearing and later owning gear that appeal to their ears, someday.

The prices of such uber expensive equipment have risen in tandem with the widespread materialism, speculation, greed and inflation that affect the world today. For every realist who spends money wisely on pragmatic and worthwhile assets, there will be well heeled "audiophiles" who buy audio gear that depreciates at spectacular rates. For every What Hi-fi reader who pursues the greatest bang for the buck, there will be teenagers happy to amble along with their ipods, headphones, or modest home setup. Who's right? Who's wrong? Who's extravagant? Who's an audio cheapskate? Is the love of music really the motivation behind equipment chasing and tweaking? Can we never get enough of audio excesses?

Here's an insightful 70s song that speaks of materialism:

http://www.youtube.com/watch?v=Tr-xrNAtKOo

Hopefully, unstoppable global market forces and the winds of economic upheaval will bring equilibrium in favor of sanity.

soulful.terrain's picture
..but then again..

 

Maybe people just simply enjoy the fruits of their labor. That would be purchasing uber expensive audio gear.

soulful.terrain's picture
Lansche loudspeakers

These sounded so sweet in Atlanta at Axpona. They were driven by B.M.C. amplification. Great combo!  Great write-up JA!

JItterjaber's picture
I have never heard these

I have never heard these speakers. I just hope that more blog space is used for speakers that the next generation of audiophiles might buy. Still, thanks for the in depth review.

That being said, I think the audiophile community can learn from the Pro Audio industry - and vice versa....The companies that truly bring products that impress me are companies like Benchmark, CEntrance, and Hegel - creating innovative products that truly employ unique original designs. 

prices have become obscene, and I for one support those companies that understand this issue.

Cheers, young Hi Fi lovers unite -

www.hifiqc.com

gadgety's picture
Cymbals on plasma/ion tweeters

I haven't heard this speaker but the Acapella ones. Indeed the ion tweeters make cymbals sound eerily real.

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