TRM10.1/12.1 FUNCTIONAL BLOCK DIAGRAMS

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INPUT CIRCUIT

The stereo input signals are connected to the amplifier through balanced XLR connectors, or unbalanced RCA con- nector TP2. Unbalanced operation can be selected with switch DS1, which grounds the RCA shell through R37. Input buffers U1 and U10 provide a stable input imped- ance, dominated by R10, R4, R42, and R32. The left and right balanced summing amplifiers U4A and U3A sum the inverting and non-inverting signals to form unbalanced right and left channel outputs RCH and LCH. The Common Mode Rejection Ratio (CMRR) of each channel is optimized with trimpots R8 and R58.

MONO SUM/GAIN CIRCUIT

Left and right input signals LCH and RCH are summed to mono through R49 and R51. The mono signal is then attenuated in two stages with dual potentiometer RV1 which is accessible from the rear panel heatsink and serves as the gain control. R56 and R83 determine the maximum achievable attenuation level. R59 and R66 help to reduce the tracking errors of RV1 due to absolute resistance toler- ances. Buffer U3B unloads the attenuators and provides 6dB of gain with R25 and R73.

PHASE CONTROL CIRCUIT

The output signal of U3B goes directly to U4B if DS2 is left open

(0 degrees phase shift). If only DS2 is closed, the signal goes through 2 cascaded phase shift stages built around U6A and U6B, and experiences a 270 degree phase shift. Additionally closing DS3 causes the phase shift to be 180 degrees. Adding another closed switch DS4 results in only 90 degrees of phase shift. DS2, DS3, and DS4 are labeled 2,3, and 4 respectively on the rear panel heatsink.

BUFFER/GAIN TRIM CIRCUIT

U4B works as a buffer, and as a factory gain trim using trimpot R136.

The voltage gain of the stage is (R74+R136)/R137.

FILTER CIRCUITS

U112A and U112B form two cascaded 2nd order variable low pass crossover filters, for an overall 4th order 24dB/octave Linkwitz-Riley response. The quad potentiometer R29 is accessible from the rear panel heatsink and indicates the 40Hz–140Hz range of the variable Low-Pass crossover. Following these circuits is a 2nd order subsonic High-Pass filter at U2A. The signal then connects to the Class-G amplifier.

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Hafler TRM10.1 Input Circuit, Mono SUM/GAIN Circuit, Phase Control Circuit, BUFFER/GAIN Trim Circuit, Filter Circuits
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TRM12.1, TRM10.1 specifications

The Hafler TRM12.1 and TRM10.1 are professional studio monitors engineered to deliver exceptional sound reproduction within various audio environments. As part of Hafler's prestigious legacy in audio equipment, these monitors cater to audio professionals seeking durability, accuracy, and an impressive performance for mixing, mastering, and high-fidelity playback.

One of the standout features of the TRM12.1 is its 12-inch woofer, which provides a deep and powerful bass response, ensuring that low frequencies are rendered with clarity and precision. This is especially important in genres that emphasize bass, such as electronic music and hip-hop. The TRM10.1, on the other hand, is equipped with a slightly smaller 10-inch woofer, making it an ideal choice for smaller spaces or for users who prefer a more compact solution without sacrificing sound quality.

Both models utilize advanced drive technologies and high-quality components. The tweeter in each speaker is designed for wide dispersion and low distortion, allowing for a balanced high-frequency response that is essential for detailed mixing tasks. This design ensures that the monitors provide a natural and transparent sonic experience, making it easier for audio professionals to make critical listening decisions.

The unique enclosure design of the TRM series minimizes resonance and acoustic interference, which helps to achieve a cleaner and more precise sound stage. The cabinets are constructed from high-density materials to reduce vibration, providing a stable platform for the drivers to perform optimally.

Connectivity is another strong point of the TRM12.1 and TRM10.1. Both monitors feature a variety of input options, including balanced XLR and TRS connectors, making them versatile for integration into different studio setups. This flexibility allows users to connect the monitors to various types of audio interfaces and mixers easily.

User control is facilitated by adjustable rear bass and treble EQ controls, empowering users to tailor the sound to better fit their room acoustics. This feature is particularly useful in situations where room reflections may affect sound quality.

In conclusion, the Hafler TRM12.1 and TRM10.1 studio monitors represent a blend of advanced technology, robust construction, and user-friendly features. Whether in a professional mixing environment or a home studio, these monitors provide the fidelity and reliability that audio professionals depend on to bring their creative visions to life. With their impressive performance and thoughtful design, the TRM series continues to uphold Hafler's tradition of excellence in audio engineering.
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