HiFiCompass

Satori MW19TX-4

What is on the test bench?

The fourth review continues our introduction to the Satori TeXtreme line of speakers and today we're examining the newest 7.5" midwoofer from Sinar Baja Electric - Satori MW19TX-4.

TeXtreme is a new word that came into the "high-end world" in the spring of 2019 and has been exciting audiophiles minds ever since. It all started with the presentation by the Swedish company Oxeon of the newest type of membrane for speakers - TPCD (Thin Ply Carbon Diaphragm) based on TeXtreme, as evidenced by the publication in the AudioXpress magazine. This was followed by the presentation at the Munich HighEnd-2019 by the Satori brand of new speakers using TeXtreme membranes - the Satori TW29TXN tweeter and Satori MW16TX midwoofer, and a demonstration of based on them loudspeakers developed by Danesian Audio.

Oxeon was founded in 2003 and introduced the TeXtreme to the world in 2004. So the material is by no means that new. Since then, it has been widely used as a heavy-duty and lightweight composite material in aviation, sports and industry. It is used to manufacture body parts for racing cars, aircraft seats, protective helmets for athletes, bicycle frames, golf clubs, skis and many more. However, it came in audio only in 2019 with the invention of TPCD membranes.

TeXtreme is a trademark of the company that means three concepts at the same time:

the technology of converting a conventional multifilament (carbon, aramid, etc.), which is a thread of thousands of microfibers with a diameter of several microns, into a flat tape, where these fibers are strictly oriented parallel to each other (spread tow)
the technology of weaving fabrics from wide flat tapes (thin ply)
the fabric itself from these flat tapes

So, the term TeXtreme can mean both the technology of fabrication itself and the fabric itself. In the context of interest to all of us we will mean just the fabric and just from the spreaded carbon fiber.

The main advantages of TeXtreme over conventional carbon fabric are the strictly parallel arrangement of the fibers and the absence of their mutual twisting when they are distributed into flat tapes. This reduces the amount of voids in the yarn. Further, the wide flat tape weaving technology provides a much denser filling of a fabric surface with fibers, significantly reducing the amount of voids that must then be sealed with epoxy. Everything contributes to a higher specific content of carbon fibers in the fabric, greater strength and less weight.

Carbon fibers have been used in the manufacture of speaker membranes for many years and have already managed to take their place in the top models of speaker drivers and loudspeakers leading world companies - Rockport Technologies (USA), Magico (USA), Kharma (Netherlands), Morel (Israel). SB Acoustics also has in its portfolio several carbon fibers membrane models - SB17CRC35-4(8) and SB15CRC30-4(8). A distinctive feature of all the speakers of the aforementioned companies is their membranes are made using the "Rohacell foam/Carbon" sandwich technology, when between layers of thin carbon fabric there is a thick layer of light and strong Rohacell polyacrylate foam. Howether the mass of such membranes limits their use only to bass and midrange speakers.

The new TPCD membranes are a two-layer TeXtreme laminate structure, which already allows them to be used as membranes for tweeters. As a result, the new technology makes it possible to build a multi-way loudspeakers on speaker drivers with the same type of membrane. This should have a beneficial effect on the homogeneity of the overall sound.

For those who want to learn more about the TeXtreme technology features, I recommend reading the Oxeon presentation.

Here you can learn about the history of the SB Acoustics and Satori brands, as well as one of the world's largest speaker drivers manufacturer - Sinar Baja Electric (www.sinarbajaelectric.com).

Why do we test this?

Sinar Baja Electric has kindly provided seven of its latest models for independent testing:

Tweeter SB Acoustics SB21SDCN-C000-4
Tweeter SB Acoustics SB21RDCN-C000-4
Tweeter Satori TW29TXN-B
Tweeter Satori TW29BNWG-4
Midrange Satori MD60N-6
Midwoofer Satori MW16TX-4
Midwoofer Satori MW19TX-4

Since all the models are just beginning to enter the market, it is impossible to find any additional information, except for meager numbers from the datasheets. Today's review opens a series of tests, the purpose of which will try to make up for the lack of information and to acquaint everyone with detailed technical characteristics and application features of the new speaker models

I would like to express my deep gratitude to Sinar Baja Electric company for the provided new products, as well as personally Mark Thomsen (International Sales & Marketing Manager SB Audience | SB Acoustics) and Melly Wulandari (SB Acoustics Project Manager) for their assistance in implementing the series of reviews.

What did the manufacturer state?

The datasheet is quite detailed and contains all the parameters a loudspeaker designer needs. It is marked as "prototype", therefore, it is likely the production model may differs slightly.

Of all the parameters I would highlight the high sensitivity - 93 dB/2.83 Volt*1m. In general, the entire set of parameters and design features allows to classify the MW19TX-4 as a top midwoofer.

Visual inspection

The MW19TX-4 comes in a sturdy glossy corrugated cardboard packaging. Inside the box the speaker "sits" in the hole of the U-shaped cardboard frame and is pressed from the front side with a double cardboard spacer. To prevent the speaker from rotation around its own axis there is an additional cardboard frame with a hexagonal cutout, in which the basket spokes are fixed. Everything is simple and reliable. Good packaging.

The midwoofer is built on the same chassis as the previous model with a paper membrane Satori MW19P-4, and differs only in the membrane and surround.

The production quality is exemplary, there is nothing to complain about. Perfectly fitted parts, complete absence of any cosmetic defects, no burrs, distortions, chips and traces of glue. The label is perfectly aligned.

The acoustically very transparent basket is made of aluminum alloy and coated with black micro-textured powder coating. The flange thickness is 7.5 mm, the spokes are very strong. They did not spared much on material. The baskets of some speakers, when tapped on them with a finger, ring like a tuning fork. One of the most demonstrative examples of this is the Accuton S280-6-282. The MW19TX-4 is not familiar with such problem. The magnetic system is equipped with a rubber ring with shaped elements that visually continue the spokes of the basket. It has no serious functionality, but it nicely complements the design of the basket. A foam gasket is glued to the back of the flange.

All the motor parts are made not by simple casting or stamping, but by precise machining, as evidenced by the traces of the cutter on their outer surfaces. This is one of the conditions for narrowing manufacturing tolerances and improving the consistancy of parameters, as well as an attribute of the highest class speakers. Inside the pole piece there is a vent ending in a 45 degree bevel at both ends. The ring neodymium magnet is not visible as it is covered with the decorative rubber ring.

The surround is made of low loss NBR rubber with a classic half-roll profile. In shape and appearance (due to its micro-roughness) it is more similar to the surrounds of 6" midwoofers of the SB Acoustics SB17xxx35 line compared to the smooth rubber surround of its "paper" sibling Satori MW19P-4.

The four wave spider is made of modern BIMAX material.

The voice coil former has six vent holes through which the copper sleeve on the pole piece is visible.

The flexible silver lead wires are quite stiff and attached to the voice coil former symmetrically at 180 degrees. This contributes to better balancing of the moving system.

The gold-plated terminals are pressed into the aluminum holder and sit very firmly in it. Thanks to the large amount of free space around them, connecting to them is very convenient and simple.

The TeXtreme membrane is about 0.2 mm thick and consists of two layers rotated 45 degrees relative to each other. Unlike classic carbon membranes, it is perfectly smooth with a pleasant matte silky sheen and, thanks to the microfiber structure, shimmers very beautifully at different angles of incidence of light. The sound response of the membrane when tapped or stroked with a finger is very similar to the response of a ping-pong ball, there is no better association.

An unusual element is visible between the voice coil former and the membrane - a cone adapter made of TeXtreme. It serves to transfer and distribute force from the voice coil to the membrane in the most optimal point to reduce the excitation of parasitic vibrations of the membrane.

During visual inspection of the speaker I didn't find any traces of felt, so I wondered what does the “With felt damping” label on the speaker box mean? I asked the designer Ulrik Schmidt about this label and he replied:

Ulrik Schmidt: It refers to a piece of felt that sits between the pole core and the copper sleeve. The pole piece is under-cut. Without the felt, there would be an air cavity/space between the two parts and some vibration of the long copper sleeve. The solution was to support the copper sleeve in its entire length below the tip of the pole piece with a piece of felt that would be slightly compressed when mounting the copper sleeve. It relates of all the Satori MW13/MR13, MW16/MR16, MW19 speakers.

Visual inspection revealed excellent modern construction, beautiful design and excellent workmanship.

Impedance frequency response

The first two plots show the impedance frequency responses for one sample of the MW19TX-4 before and after broken-in. The broken-in was carried out for 60 minutes with a sinusoidal voltage of 33 Hz at the level corresponding to the membrane excursion of 9 mm. As you can see, the shape of the curves has changed only in the region of the resonant frequency due to its decrease from 35 Hz to 31.63 Hz. The effect is mainly related to softening the spider. This was also accompanied by a slight decrease in the total Q factor from 0.317 to 0.286.

The second two plots show at different scales the impedance responses of the two MW19TX-4 samples before broken-in. As you can see, the impedance curves match each other perfectly.

The T/S parameters after the broken-in Fs = 31.63 Hz and Qts = 0.286 almost don't differ from the datasheet's ones Fs = 32 Hz and Qts = 0.27. Good!

Thanks to the good motor with a solid copper sleeve on the pole piece, the impedance curve shows very low inductance and small rise with frequency. The response is very smooth, with a slight sign of the main membrane resonance at 5 kHz. As you can see, there are no obvious symptoms of a typical "surround/cone edge" resonance. Only a very large scale allows you to see the small irregularities at 500, 1100 and 2800 Hz.

The impedance response tells us about the well balanced low loss moving system (high mechanical quality factor Qm = 4.85) and the excellent motor.

On-axis frequency response

The measured sensitivity in the range from 150 Hz to 3 kHz averaged 91-93 dB, which is 1 - 1.5 dB lower the datasheet value. The frequency response has a flat character with no tilt and extends up to 12 kHz. In the region of 0.7-1.2 kHz the response does a step transition from 91 to 93 dB. The overall unevenness does not exceed 3 dB in the range 150 Hz - 4 kHz.Starting from 4 kHz the membrane begins to "break" and goes into the break-up mode, accompanied by a series of frequency response spikes. The main 8 dB peak is at 5 kHz. It is not as pronounced as in the case of the MW16TX-4, but is "smeared" over the 4-9 kHz range. This is followed by another small spike at 10.6 kHz. Otherwise, everything is just fine. In the 0.8-2 kHz region, which is very often problematic in terms of a "surround/cone edge" resonance, the response is smooth.

The frequency response does not imply any difficulties when designing a loudspeaker crossover. Thanks to its flat and very extended range going well beyond 2.5 kHz, it provides designers with great flexibility in the choice of crossover frequency and filter slope.

The responses of the two samples are almost identical to each other in shape. The discrepancy in the range up to 2.5 kHz does not exceed 0.2 dB. For non-matched at a factory midwoofers this is a very good result.

The measured frequency response corresponds fairly well with the datasheet.

Off-axis frequency responses (at 315 mm)

Above are the plots of the regular and normalized off-axis frequency responses. For the normalized plot the axial frequency response is taken as the reference and the off-axis ones reflect only the difference with it.

The 10.6 kHz resonance becomes more and more noticeable with an increase in the off-axis angle; its value weakly depends on the angle. This may require additional notch in a crossover at low filter orders.

The 30-degree frequency response from the datasheet agrees well with the measured one. But the 60-degree response is more like as if it was measured at 45-degree.

Harmonic distortion (at 315 mm)

Above are the harmonic distortions plots for the 2nd - 5th harmonics at average sound pressure levels of 88 and 103 dB (at voltages of 2 and 11.2 Volts respectively). To limit the speaker overload in terms of thermal power and membrane displacement when measuring harmonic distortion, a second-order Butterworth type high-pass filter with a cutoff frequency of 50 Hz was used. On these graphs we analyze the frequency range only from 200 Hz and above.

The second harmonic dominates the entire frequency range and at all sound pressure levels. The third harmonic goes several dB lower, and the fourth and fifth even lower with a large margin. The harmonic distortion pattern is stable at both frequency and SPL. There are no sudden abrupt jumps in distortion over the entire range due to the membrane break-up, especially at high SPL. With an increase in the input voltage, starting from 500 Hz and below, harmonics of all orders begin to grow monotonically.

At a frequency of 2.4 kHz only a burst of the 2nd harmonic is observed. Is it the trace of the up-shifted and well masked resonance of the edge of cone? In any case, this peak is so insignificant that it is not worthy of discussion.

I would rate the harmonic distortion above 200 Hz as "very low", one of the lowest I have ever seen in 7.5" midwoofers. Excellent!

Harmonic distortion (at 20 mm)

Above are the harmonic distortions plots for the 2nd - 5th harmonics measured in the near field at a distance of 20 mm from the membrane at voltages of 2 and 8 Volts. To limit the speaker overload in terms of the membrane displacement when measuring harmonic distortion, a second-order Butterworth type high-pass filter with a cutoff frequency of 20 Hz was used. This measurement method provides the more accurate estimate of the harmonic distortion below 200 Hz compared to the measurements at 315mm.

The 2nd harmonic is dominant in the range above 40 Hz. With decrease in frequency all harmonics increase monotonically, their behavior and hierarchy below 200 Hz are the same as above 200 Hz. The 2nd harmonic level below 100 Hz is higher than that of midwoofers of this size and class, while the higher orders remain quite low.

Voice coil current harmonic distortion

This type of measurement, despite its simplicity, is an excellent tool for assessing the linearity of a speaker motor. The above plots show the frequency dependences of the 2nd, 3rd, 4th and 5th harmonics of the voice coil current at 2 and 8 Volt. To limit the speaker overload in terms of the membrane displacement when measuring harmonic distortion, a second-order Butterworth type high-pass filter with a cutoff frequency of 50 Hz was used.

Voice coil current nonlinearity is the direct nonlinearity of the mechanical force driving the speaker cone, since this force is related to the current by a simple relationship F=B*L*I, where B is the magnetic field strength, L is the length of the voice coil wire inside the magnetic gap and I is the current. So, in principle, it is practically impossible to obtain sound pressure distortion lower than current distortion in the frequency range where the contribution of the motional nonlinearity becomes insignificant.

Above 150 Hz the second harmonic of the current also linearly depends on the voltage level, as well as the second harmonic of the sound pressure. The fourth about two times less depends on the voltage compared with the second. The third and fifth harmonics are almost independent of the input voltage. Below 150 Hz, due to an increase in the membrane displacement amplitude, a sharp increase in harmonics of all orders begins.

Intermodulation distortion

The intermodulation distortion measurement is one of way of analyzing device non-linearity. It is not an alternative, but an additional method and allows you to identify the spectral components of the inharmonious structure, which are much more harmful for high-quality sound reproduction and to which our hearing is more sensitive.

For testing I chose the frequencies of 30 Hz and 255 Hz. With this ratio (1: 8.5) the contribution of Doppler distortions is not yet dominant and the contribution of amplitude modulation can still be observed. In addition, this is a very realistic situation that occurs in both two-way and three-way loudspeakers. The measurements were performed for different 30 Hz cone excursions and their conditions are indicated in the lower left corner of each plot. By various colors are indicated:

test frequencies
2nd order harmonic distortion components for the test frequencies (2nd HD)
3rd order harmonic distortion components for the test frequencies (3rd HD)
2nd order intermodulation distortion amplitude (IMA2)
3rd order intermodulation distortion amplitude (IMA3)

As you can see, just a couple of frequencies at the speaker terminals give rise to a whole forest of parasitic components at its output. The level of intermodulation components of the second order was -29.5 dB and -25 dB for the cone excursion of 3 mm and 6 mm, respectively, which on average corresponds to the level of top-end 6-7" midwoofers from other manufacturers.

Step response

The transient response exhibits excellent slew rate and smooth aperiodic decay. In the interval up to 2 ms a decaying oscillatory process is observed, initiated by the 5 kHz peak of the frequency response. These oscillations are superimposed on the 10 kHz oscillations and mask them. After the 5 kHz fades out the 10 kHz oscillations begin to be visible in the 2-3 ms interval.

Waterfall

The waterfall shows the same effects as a step response, in addition exposing hidden resonances that are difficult to see in other types of measurements.

At 5.2 kHz we observe a ridge from the main resonance of the membrane, which completely disappears in just 2.5 ms.

The resonance at 10 kHz, which is not so pronounced on the axial frequency response, but very well manifested itself on the off-axis responses, is also well pronounced here by a sharp and long ridge. Up to 3 kHz everything is fine, the moving system calms down very quickly and in the 800 Hz - 2 kHz range everything is perfect.

Listening impressions. Satori MW19TX-4 versus Satori MW19P-4

It is extremely difficult to describe the sound of the speaker driver in words, since there is no single generally accepted terminology. In addition, everyone hears and describes their feelings in different ways. Much depends on the accumulated experience of listening and the number of "sound prints" of various speakers stored in the head. It is no less difficult to understand, feel and imagine a sound described by someone. This requires that describing and imagining people are in the same coordinate system and have a common reference point.

As such a reference point I decided to use the sound of the Satori MW19P-4 midwoofer. This pressed paper cone 7.5" midwoofer with reinforcing papyrus fibers has been the flagship of Sinar Baja Electric for nearly 10 years. During this time it managed to conquer thousands of audiophile hearts, including mine. In fact, since the MW19P hit the market, I consider it to be one of the best 7" midwoofers available no matter the price, which is confirmed by the choice of it for my 2-way Pharaoh loudspeakers. I think many are familiar with its sound, so it will be easier for them to understand me.

At first, let's make an objective comparison of the speakers according to their main characteristics. Both speakers are identical except for the moving systems. There is no point in comparing below 200 Hz, everything is almost the same there, and so are the T/S parameters. Therefore, we look only above 200 Hz.

The frequency response of the MW19TX is better everywhere except the peak at 10 kHz, which is clearly outside the potential operating frequency range of the midwoofer (up to 2 kHz) and will not create any problems. In the critical region of 0.8-4 kHz the MW19TX is better than the MW19P. The elevation of the frequency response in the membrane break-up region from 4 to 12 kHz are less for the MW19TX. The waterfall of the MW19TX is better too.

The MW19TX a lot better manages with the second harmonic distortion. The "surround/edge" resonance of the MW19P produces a huge burst of the 2nd harmonic.

By the 3rd harmonic there is a slight advantage the MW19P, for which I can't find a suitable technical explanation. It shouldn't be like that. Most likely, this is just an individual difference between specific samples of the speakers.

The cleanness by the 4th and 5th harmonics in the range 900-2200 Hz gives an undoubted advantage in favor of the MW19TX.

From an objective technical point of view the MW19TX-4 is one step higher than the MW19P-4.

Unfortunately, it was not possible to compare the midwoofers in real loudspeakers, so, I compared them only in the test baffle. The frequency range was limited by the second order Linkwitz-Riley filter with a cutoff frequency of 2 kHz.

The overall presentation and sound character of both speakers are similar, family traits and continuity can be clearly traced. You won't confuse it with the sound of ScanSpeak, SEAS, Purifi, Accuton or others. The results of the "by ear" assessment were completely in line with the results obtained when comparing 6" Satori TeXtreme MW16TX-4 and Satori paper MW16P-4, which you can read in detail about here. I will briefly repeat the main things.

MW19TX-4 advantages:

Instantly audible transparency. It feels like a very thin curtain has been removed between you and the speaker
Smoother and more balanced in timbre sound
At increased volume the MW19TX never lost control, the sound retained its light and transparent character, while the MW19P began to exhibit its "paper shouting" and loss of intelligibility in the upper middle
Treats the attack of percussion and stringed plucked instruments much better, sharper, more accented and outlined
It has noticeably higher micro-detail, better reveals the micro-texture of sound, which is especially evident on bowed string and wind instruments, when all the smallest air flows, vibrations and bow friction are heard

MW19P-4 advantages:

On some tracks it sounded a little, but with greater space and depth. There was a greater level of "blackness" in the sound, against which the TeXtreme version sounded slightly pale and restrained. "Readability", that is, the intelligibility of individual instruments in the total sound mass was slightly better. Musical instruments had a more pronounced body and the overall sound, although it was more "muddy", was more colorful and lively, emotional and contrasting. This was more noticeable in relatively simple music such as classical guitar solos, sonatas, blues, vocal solos accompanied by a single instrument.

"How to use" recomendations

The MW19TX-4 can be used equally well as a woofer in 3-way loudspeakers, a midwoofer in 2-way and 2.5-way loudspeakers (Menara is a great example), as well as a midrange in large 3-way loudspeakers up to 2 kHz.

My personal experience with the paper cone MW19P-4 midwoofer in the Pharaoh loudspeakers has shown its ability to deliver an impressive sound scale and dynamic performance that rivals many floorstanding loudspeakers. The only thing I had to put up with was the problematic surround/edge resonance in the 1.2 kHz region. The TeXtreme version is already completely free from this problem and I am eager to hear how clearing the 800-1500 Hz range can raise the sound level of the Pharaoh.

What is the price and where to purchase it?

The MW19TX-4 are already on the market. The retail price is €259-313 per piece excluding VAT. It can be purchased in the following online stores:

Summary

The MW19TX-4 is a worthy addition to the Satori line. It has surpassed its paper predecessor in terms of frequency response evenness, nonlinear distortion and sound resolution. I see no flaws in it, except for a slightly increased second order harmonic distortion below 250 Hz. The very extended frequency response gives loudspeaker designer a lot of flexibility, allowing almost any filtering order (slope) to be used. A more rigid TeXtreme membrane has added transparency and detail to the sound, but did it very delicately, without introducing into the sound of coldness, emptiness, ringing and sterility, as is often the case with metal or ceramic materials.

The MW19TX-4 is a unique speaker that combines low frequency potential, linear frequency response and low harmonic distortion across the entire range. Based on the measurements and listening results, I consider the MW19TX-4 one of the best available 7" midwoofers today regardless of price.

Summarizing the above, I can highlight the following:

Sensitivity above average - from 91 to 93 dB/2.83 V*1 m
Very extended and even frequency response
Very low harmonic distortion above 200 Hz
Increased 2nd order harmonic distortion below 250 Hz
The low frequency intermodulation distortion are quite low
It can be used up to 2 kHz
60-degrees off-axis frequency respons from the datasheet doesn't match to the measured one
Excellent consistency of parameters and characteristics
Excellent production quality