What kind of system should I build for my driver?
Check out our system guide for details about system designs and tradeoffs.
Can I harm a driver with too little power?
No, not ever. In fact, aside from rather unimpressive SPL levels, all transducers actually perform their absolute best at very low power levels. This is where TSP’s are measured and you can expect near linear results and zero thermal compression, flux modulation and other dynamic distortion mechanisms to be absent from the system. The problem is, with very low signals and power levels comes very low SPL.
Can I harm a driver with a clipped signal?
No, not unless the signal is high enough to potentially cause mechanical or thermal failure. A clipped signal of relatively small magnitude is harmless. The issue is that normally amplifiers clip at high power levels near or beyond the driver’s mechanical and/or thermal limit which is why people often associate clipping with damage.
Do sealed subwoofers really sound better than ported?
In short no. One of the most critical aspects of a subwoofer system is linear response and it tends to be easier to get linear response in a sealed system because there is not a reflex system boosting the response, then unloading it below tuning. Depending on the TS parameters of the driver, some woofers are difficult to achieve linear response in either a sealed or bass reflex boxes. People tend to think it’s ports fault when really it’s a function of the driver with the box and with the equalization settings or better yet, lack thereof. Unfortunately in car audio, equalization is not often implemented, and it can be a very crucial component into making a subwoofer sound good or at least protecting it in the case of a higher ordered systems such as bass reflex boxes. Equalization is also especially important in a car or room where certain frequencies can be peaky and others can be absent due to room coupling or standing waves which also affects the subjective sound quality of the system
What is a passive radiator?
A passive radiator, such as the TC Sounds VMP is a resonator much like a port. A port consists of air in the port (mass) and internal air pressure in the box (spring). The area and length of the port affects how the pressure of that moving mass resonates. This resonator physically displaces air for a very narrow frequency range when it resonates from the active driver much like pushing on a child on a swing at the exact time they reach you again. Careful alignment can lead to linear frequency response with an active woofer and a port resonator. Together they make a 4th system that is more efficient than a sealed or infinite baffle system type. Ported systems are often able to extend to lower frequencies where the demand for displacement reach beyond the woofers ability and hence a resonator is required. Passive radiators do the exact same thing as port, but use weight for the mass and a spider suspension system for the spring. As far as frequency response and SPL, passive radiators and ports should perform about the same with about a 1 to 2 db SPL advantage to the port; However passive radiators have several advantages over ports such as the ability to adjust frequency at which they resonant simply by adding or removing mass. Passive radiators also commonly exhibit lower audible compression characteristics like port chuffing and don’t produce unwanted port resonance distortion which can plague long ports.
What is a subsonic filter?
A subsonic filter is truly a high pass filter that cuts off frequencies below a give frequency. Ideally subsonic filters should be used to protect woofers in (usually) 4th order bass reflex (vented, or PR) systems where driver excursion increases exponentially with no compliance protection below resonance. In a sealed box, the internal air pressure acts as a protection against over excursion. Secondly, in a sealed box, woofer excursion does not increase as fast below resonance as a bass reflex system so it’s not a significant concern. In a typical bass reflex system the filter should cut off the woofer below tuning and you will observe a peak in the driver’s excursion at a frequency above the tuning point. Below that, the driver starts to approach a point of almost no movement and at that frequency the port air velocity will be at the absolute maximum, the phase will be zero and the impedance will be at a minimum for the system. The woofer will be drawing the most power from the amplifier and it will be at its greatest risk of thermal failure. This is tuning! Below that the resonator (port or PR) quickly unloads and loses all efficiency since loading cannot occur below resonance. There is truly no more useful bass left and the driver’s excursion becomes widely out of control. It is necessary to cut off the active driver at that point to protect it from damage. The high pass filter does this, but it should do it in such a way that the woofer’s excursion below tuning should match, but not exceed, that of what it did above that frequency. There will be two peaks and ideally they should be symmetrical and of equal amplitude (excursion).
What is the difference between SVC, DVC and QVC?
There is really no advantage to any of these voice coil configurations. Ideally speaking, they are the same coil but broken up into smaller pieces in order to wire them at difference resistance and ultimately impedance loads. The idea is to match a driver to an amplifier’s maximum performance. There are differences in the TSP parameters, but simply speaking, these differences typically cancel out. Because wire gauge and gap dimensions don’t always completely match up, there are always small advantages from one coil option to the next, however these differences may only result in 0.25 to 0.5db sensitivity advantage from a higher BL2/Re factor, but such differences are not very audible. A simple way to understand the coils are like this:

  • SVC can only be wired one way.
  • DVC can only be wired at twice the coil load or half the coil load. e.g. D2 = 1 ohm or 4 ohms, or it can be driven with a 2 channel amp at 2 ohms per channel.
  • QVC can only be wired at the ohm load or one quarter or four times. e.g. Q2 = 0.5, 2 or 8 ohms. Or a two channel amp at either 4 or 1 ohm per channel.
  • More complex methods can be achieved using multiple woofers.

It’s important to understand that impedance is not a single number and in fact it is rarely ever the number listed. Impedance is a two dimensional relationship of the resistance and frequency. Normally we list a nominal impedance load that is at best, a guess as to what the amplifier will see at the lowest point along the curve. What you should consider is that the DCR (raw resistance of the voice coil) is the absolute minimum load that the amplifier will see, however it’s never quite that low due to non-linear electrical effects of the motor. Because most amplifiers are constant voltage, the amplifier will deliver the least power at the impedance peak and the most power at the dip. Therefore the level of power that is actually running across the driver’s coil is directly related to the frequency.

Can I just use one of the coils because it’s a better match for my amp?
Absolutely not! Drastic TSP differences and huge performance losses will occur including unpredictable distortion and irregular mechanical behaviors from the unused voice coil. You should expect no more than half the performance on virtually all fronts of the transducer and you’re better off using a less demanding driver that is a better match for the amplifier.
Where should I place my subwoofer in my vehicle?
Ideally the subwoofer should be placed so that it has high acoustic coupling with the internal dimensions of the vehicle used. If the car is a wagon or SUV, the rear, or front (if possible) corners serve best for this. If the vehicle is a truck, than it becomes difficult because the internal cabin is very close to a square and unwanted cancellations can occur resulting in loss of system efficiency. In that case, some experimentation may be required or EQ can used.

Where should I place my subwoofer in my room?The room can be just a challenging as the car. Ideally, the same rule applies and the subwoofer should be coupled to a corner to benefit from the most gain. In general, two subwoofers are better than one for producing even response around the room. The best results would actually be a subwoofer in each corner of the room which will produce nearly flat bass for the widest area. If you’re using a single subwoofer, then you will likely be challenged to product a flat response which means room correction (eq) may be necessary or an investment in an additional subwoofer to help balance out the response might be required.