TB2SA - Active Monitor

The TB2S-AII is the larger of the two radical activated monitors in the Professional range. It shares the astonishing transparency and neutral balance of its smaller brother the DB1S-AII, but features with its greatly extended ATL (Advanced Transmission Line) and larger 6.5” LF driver which allows for higher SPL’s, greater bass extension and dynamics.

The TB2S-AII is the ideal high resolution monitor for critical evaluation within either small to medium sized control rooms in either stereo or surround when partnered with a TLE1S powered sub.

The exceptional II upgrades

Firstly, the TB2S2-AII has undergone fine tuning with component upgrades to the precision crossover network which further enhances the transparency of the mid/vocal region. The power plant has also undergone drastic improvements with the inclusion of PMC’s all new DS-001, a cutting edge Class D power module. This unit increases the power from the previous module’s output of 100W to 200W, and radically reduces distortion producing a significantly cleaner, faster more neutral presentation across the full bandwidth. This innovative ultra low noise design is not load dependant and along with the highly accurate ATL™ (Advanced Transmission Line) bass loading system, produces a supremely flat response. A single feedback loop circuit senses the loudspeaker load and adjusts the frequency response accordingly, making output impedance of this amplifier design extremely low and bettering many larger, audiophile ‘Class A’ analogue designs.

Taking the lid off
The PMC Transmission line design
The transmission line (TL) is the theoretical ideal and most complex construction to load a moving coil loudspeaker design. Theory is all very well but it does present us with a rather large cabinet, as the perfect transmission line design would have an internal structure that was totally acoustically absorbent to the entire rear radiation from the drive units. This would make it infinitly long, which even Stephen Hawkin would have trouble visualising. The most practical implementation is to create a long tunnel within a cabinet by introducing internal partitioning that folds the line up and down the length of the cabinet. At the very end of the line there is a very specific size of hole that vents directly into the room. A major benefit to this construction is that the labyrinth braces the entire structure from beginning to end. This nearly eradicates cabinet colouration created by the effects of the outer walls of the cabinet flexing. Cabinet integrity and internal panel damping are essential to produce a successful design due to the TL's inherent ability to produce phenomenal LF extension, even from a modest box.

The main driver is placed at one end of the TL, which is heavily damped with absorbent acoustic material. The most predictable and accurate absorber is a highly specified foam material that took a vast amount of R&D to derive the correct formula of profile, pore size and density of the polymer. The foam, probably the least visually dramatic of the components is tremendously important. It has to absorb all the upper bass frequencies and allow the lower frequencies to exit the vent at the far end of the line in phase with the main driver. It must also be exactly specified to ensure a consistent and balanced backpressure on the driver by interfacing smoothly with the column of air within the line. With too higher damping, the driver cannot move freely enough, and conversely too little damping produces a lack of control and the result is a LF response similar to that of a regular ported design. 

When this equilibrium is achieved between length of line and the acoustic absorbency, the air density increases by up to 30% making the 'effective' line length far greater than it's physical length. This backpressure holds the main driver in a vice like grip and the control is effective over a huge frequency range, reducing unwanted cone movement which lowers audible distortion. This lack of harmonic distortion in the LF creates superb midrange clarity as it eradicates the effects of masking. The consistent air loading also facilitates full audible bandwidth at all monitoring levels allowing for extended periods of monitoring without the risk of fatigue.

PMC's innovative approach using their transmission line technology offers the following advantages over a conventional ported or sealed monitor:

• Exceptional low frequency extension
• Lower colouration
• Neutral yet dynamic performance
• Consistent balance at all levels
• Higher SPL's without distortion or compression
• Stable and consistent 3D image

TB2S-AII Specifications

• Type: Activated
• Useable freq response: 40Hz-25kHz PeakSPL@1M:111dB
• Effective line length: 1.5m 4.92ft
• Drive units: LF Doped 170mm cast alloy chassis, HF 27mm fabric soft dome.
• Crossover Frequency: 2kHz
• Finish: black
• Dimensions:
• H 400mm 15.7"
• W 200mm 7.8"
• D 350mm 13.7"
• Weight (each): 10.7kg
• Amplifier:
• Input connection: Balanced XLR
• Input Impedance:
• Input sensitivity:
• Max power output: 200W
• THD:
• Residual Noise:
• S/N Ratio:
• Vol Adjust: Min 16dB - Max 33dB
• Idle power consumption: < 6W
• Mains connection: IEC 3 pole
• Options: Magnetic Shielding (M Suffix), Matching TLE1S Active Sub, Custom Stands(Tube104™)