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A truly linear, ultra low distortion driver

Introduction • Design • Specifications • Patents • Compare • Thiele-Small's • Enclosures  • Wiring
  Frame color: (Metallic red)
Single voice coil

15" LMS-4000 $598
Ships in 7-10 business days

12" LMS-4000 $465
Ships in 7-10 business days

10" LMS-4000 $379
Ships in 7-10 business days

For overseas shipping please order by email


The LMS-4000 (version 2) is the all new successor to the already unchallenged SQL driver that has previous been the pinnacle of subsonic translucence and distortion free bass –a true audiophile select. The improvements include an all new TC3LM motor that is 50% larger than the TC9 used before. The new motor allows for higher mechanical excursion, more Bl product, lower inductance and higher sensitivity. Secondly, a new detachable method is utilized that allows for even faster and tool-free replacements, and finally a new patented and proprietary TC Sounds frame that comes in a high gloss blinding metallic red finish you simply won't find on any other subwoofer in the world.

The key difference between TC Sounds LMS drivers and non linear subwoofers lies within the implementation of the voice coil. Our LMS drivers utilize a coil technology that maintains complete linear force as the subwoofer's diaphragm moves from its absolute minimum position to its maximum. No other method we know can match the low distortion results of our Linear Motor System, and we can confidently say, no other subwoofer sounds as clean.


Many high end audio manufactures claim to achieve "linear motor force", but all nonlinear drivers, including our own, inherently have a nonlinear force over displacement relationship where the force of the motor falls off at non linear rate as the coil approaches xmax. Linear Motor System technology essentially works increase the magnetic flux density generated by the voice coil towards the end of the coil winding. In turn (no pun intended) the force generated by the voice coil is virtually linearized over the effective displacement space.

In a nonlinear subwoofer, as the coil moves away from its center position in the gap, there is progressively more and more wire moving away from the fixed magnetic field which lowers the force. By making the coil denser near the extremities, we then can achieve linear force. Hence forth, no matter where the driver is relative to the gap plate, the force that is generated remains constant at all intervals at all times. We have measured our drivers using a multitude of different devices in including the highly respected Klippel analyzer system. The results were conclusive and unanimous -the driver has virtually perfect linear force. An accomplishment others told us was "impossible."

So what does all that mean? Simply put, the LMS-4000 can generally outgun two equally sized speakers at a given SPL within a limited THD constraint. In other words, If wanted to have the same quality, you would have to reduce the output of a normal speaker by at least 6dB, or one quarter of the power just to match this speaker.

Not to be overshadowed by its linear aspects, the LMS-4000 retains all that is awesome in a TC driver: An extra wide 10” poly-cotton spider with woven in leads is used to allow full excursion without mechanical obstruction. We employ a gorgeous patented high gloss powder coated aluminum cast baskets with screen guards. The frame includes our patented detachable threaded adaptor with a rubber lock washer in the event of failure or damage. The top assembly can literally be unscrewed from the motor in just ten seconds time with no additional tools. The entire replacement procedure can be accomplished in less than 20 seconds. The diaphragm consists of a dust cap free lightweight aluminum cone with a very linear half roll NBR surround. The total magnet structure weights an impressive 300 ounces, uses four 7.5” wide magnets and tolerates extra room in the gap for an extra long copper shorting ring to reduce flux modulation, inductance and dynamic alignment problems typically found in high excursion subwoofers with little regard to sound quality. Finally, the motor is finished with a beautifully machined low carbon steel T-yoke and gap plate.

Still unsure about how good the LMS-4000 is? Just post your concerns on our forums and read what our customers are saying.


3" diameter aluminum wire linear voice coil using LMS Technology (Pat. Pend.)
Quadruple stacked 3/4" tall, 7.5" wide ferrite magnets
300oz motor structure
xmax of 30mm (one way completely linear Bl )
Single (10"/8.5") poly-cotton spider with intergraded woven leads (15/12,10)
Extra clearance under the suspension for dynamic high excursions
Detachable cast aluminum basket with high gloss power coating
Single 3Ω aluminum voice coil with four layers
800 watts sustained (2500 dynamic)
High quality thermal flexible epoxies to ensure longevity
Rigid lightweight brushed aluminum cone
Vented flared pole piece
3" Long copper shorting ring for low inductance
Rubber half roll surround allows for linear travel
Dressed in a rubber magnet boot and gasket
Hand built in our San Diego, CA factory


No. US D455,733 S (Speaker Driver Frame)
No. US D451,7499 S (Speaker Driver Frame)
No. US 7,031,490 B2 (Speaker Driver with Detachable Motor and Basket)
Pending (Frame Threaded Adaptor)
Pending (Linear Voice Coil)

Driver Cutout Diameter Basket Diameter Gasket Height Mounting Depth  Displacement   Weight 
10LMS-4000 9.25" 10.65" 0.65" 9.0" 0.10ft3 36.5lb
12LMS-4000 11.25" 12.65" 0.65" 9.75" 0.12ft3 37.6lb
15LMS-4000 14.10" 15.65" 0.65" 10.75" 0.14ft3 39.0lb

*mounting depth includes 0.8" spacing for rear poll venting


The comparison chart is simple and fast way to compare our drivers to one another. This method in no way pertains to drivers other than TC Sounds own product line. The chart is empirically graded on a scale of 1 to 10 to show relative performance among our drivers. All subwoofers can be graded based on four simply categories. In practice, no driver can achieve a perfect perforce score in all four categories, at least one must be compromised to better another. In a nut shell:

Linearity: This can also be thought of the as the sound quality of the driver. The linearity of the driver is literally the driver's ability to do what it is supposed to do without non-linear anomalies which create distortion. Linearity pertains to electrical properties of the motor, and the mechanical properties of the soft parts including the BL product, inductance compliance and power compression. Simply put: high linearity attenuates distortion.

Sensitivity: This can be thought of in terms of how loud the subwoofer can get. Because all of our drivers are high excursion, xmax can be neglected and we can look purely at the sensitivity of the subwoofer to understand how loud it will play based on a given input of power. The higher the sensitivity, the louder the speaker will be if the power handling is the same. Sensitivity also becomes incredibly important when limited power is a concern.

Power handling: This term is often though of how loud a subwoofer can get, but in truth this is really the power compression limit. Once the power compression limit is reached, a speaker will not be able to take more power and generate more output. Power compression is literately the maximum limit at which a driver can convert electrical energy into acoustical energy. Larger voice coils have higher power compression limits.

Excursion: Contrary to popular belief, this actually has much less to do with how loud a subwoofer will be but rather how low it will go. The higher the excursion, the greater the ability it has as reproducing deeper bass. In order to maintain the same SPL at one octave lower, four times the excursion is required. Very high excursion is necessary for subsonic reproduction.

Driver LMS-4000
Power Handling

Thiele Small Parameters

10" LMS-4000 SVC

Qts 0.414
Qes 0.435
Qms 8.85
Fs 17.8Hz
Res 2.77Ω
Ls 1.05mH
Lp 3.56mH
Rp 2.39Ω
Dia 202mm
Vas 80l
mms 171g
cms 461um/N
bl 11.1T*m
Spl 81.1dB

12" LMS-4000 SVC


15" LMS-4000 SVC

Recommended enclosures

The LMS-4000 subwoofers are engineered for larger sealed or ported box enclosures and designed for high input power capabilities. The driver is geared strictly for audiophiles who demand the lowest distortion bass possible. We recommend only low tuning frequency alignments to take maximum advantage of the driver’s capabilities. An amplifier between 600 and 2500 watts RMS per driver in to the load configuration to which your subwoofer(s) is/are wired is recommended. In you are interest in alternative enclosure designs, look for further system designs in our tutorial section or ask on our forums.

There is no single perfect box. Much of what we offer is a merely a general guideline to get you started. All of our system recommendations are geared for flat response and it is important to note that in our recommendations, we use a 4th order Linkwitz-Riley low pass filter in combination with a PEQ or a high pass filter to achieve linear response, but room gain and/or car cabin gain may change the frequency response of your system. If you are serious about system design you can download WinISD for free to get started.

We specify three different system designs for each driver. Each of which provides linear output to 20Hz which is ideal for home audio or large rooms, For each linear extension mode, there are three types of enclosures. As a general rule of thumb, sealed systems are the smallest design, but require the most power and provide the least output. Ported systems require less power and provide more output, but require a larger box. Finally, passive systems have the output of the ported, but don’t require a long port; hence, in enclosure designs where a long port is unfeasible, a passive system could be used without compromising tuning frequency. The passive system also eliminates port resonance and turbulence issues. There are many other differences among the system designs, but we leave that up to you do decide and debate. There is plenty of great information about system design on the net and of course, you can just ask in our forums and we’ll gladly assist you in your design. Remember, there is no single perfect box!


Volume: Net internal volume of the enclouser minus the total port volume (if any) and minus the displament of the subwoofer which can almost unanimously be estamante as 0.1 cubic foot. We also recommend stuffing about half of the net volume with poly fill or fiberglass for all enclosures for dampening purposes.

Diameter: This is either the diameter of the port(s) or the diameter of the passive radiators to be used. We specify port diameter in terms multiples of 4" ports because they are standard but others can be used as long as the net area matches, and we recommend using only TC Sounds' passive radiators because of the necessary excursion. Others just won’t cut it.

Length / Mass: As stated, this is either the length or the mass to be used. The length applies exclusively to ported systems and the mass applies exclusively to passive systems. All passive radiators are weighted. If you are using TC Sounds passives, simply adjust the washers on the back of the driver to the number of grams specified.

Low Pass Fq This is the crossover control frequency. We assume a standard Linkwitz-Riley fourth order 24dB peroctave filter. Others will work, but you will need to model the T/S yourself to get a flat response in the higher frequencies . Without this filter or one like it, it is unlikely you will achieve a flat response in your system.

PEQ/HPF Fq: This is either the parametric equalization frequency or the second order high pass filter frequency. If you have a PEQ, then this is the frequency to set it to. Like the high pass filter, we suggest a PEQ to help flatten out the response in the lower frequencies with seal enclosures. For ported or passive enclosure we recommend only a second order high pass filter merely as a means of protecting the driver for over excursion below tuning frequency where output is negligible. The PEQ filter should not be omitted for sealed systems otherwise the response curve will not be linear.

PEQ/HPF Q: Parametric or high pass filter equalization Q or dampening. This one of three parameters necessary for the PEQ and one of two parameters necessary for the high pass filter.

PEQ Q: Parametric equalization amplitude. This one of three parameters necessary for the PEQ.

20Hz Extention Systems (Audiophile -3dB at ~16Hz)

Type Volume Diameter Len. / Mass Low Pass Fq PEQ/HPF Fq PEQ/HPF Q PEQ A
Sealed 1.5ft3 NA NA 80Hz 15Hz 1.2 +9dB
Ported 1.8ft 1x 3" 21" 80Hz 17Hz 0.707 NA
Passive 1.7ft3 2x 10" PR's 600g each 80Hz 16Hz 0.9 NA

Type Volume Diameter Len. / Mass Low Pass Fq PEQ/HPF Fq PEQ/HPF Q PEQ A
Sealed 3.0ft3 NA NA 80Hz 14Hz 1.4 +8dB
Ported 4.5ft3 1x 4" 22.5" 80Hz 14Hz 0.8 NA
Passive 4.5ft3 2x 12" PR's 800g each 80Hz 15Hz 0.9 NA

Type Volume Diameter Len. / Mass Low Pass Fq PEQ/HPF Fq PEQ/HPF Q PEQ A
Sealed 6.0ft3 NA NA 80Hz 15Hz 1.2 +8dB
Ported 8.0ft3 3x 4" 31.4 80Hz 17Hz 1.0 NA
Passive 8.0ft3 2x 15" PR's 900g each 80Hz 17Hz 1.0 NA


More configurations may be available depending on the number of amplifiers and/or drivers. The impedance given is the DC resistance which is the measurable resistance of the circuit while the driver(s) are rest. The nominal impedance, or the load the amplifier will see while in operation, will be higher than the DCR by factor depending on the frequency. You can safely add 30% to the DRC for the estimated nominal impedance.