Model 750

Operation

While the Model 750 Audio Mixer is quite simple to operate, there are nuances to its design that make a detailed discussion worthwhile. While you can certainly con- sider the Model 750 a “small” audio mixer, its roots are from the much larger audio consoles that are used in broadcast and recording settings. We’ll start with a dis- cussion of the individual sections that make up the Model 750. Then we’ll review how the sections work together to become your audio “master control.”

Mic/Line Inputs

Four identical input channels are provided, each being compatible with a microphone or line-level signal. A detailed description of one mic/line channel follows:

Input Sensitivity

The mic/line button is used to select the sensitivity of the input circuitry. In the mic (out) position, the expected nominal input level is –55 to –35dBu. In the line (in) position, a 40dB pad is inserted into the circuit, making the expected nominal input level –15 to +5dBu. The input circuitry is compatible with a wide range of signal levels and is protected from overload. In most cases, an input signal whose nomi- nal level is outside the expected range shouldn’t pose a problem.

Phantom Power

The button labeled +48V is used to acti- vate “phantom power” for use with con- denser-type microphones. The +48V power supply and related circuitry was carefully designed to allow virtually any microphone that requires phantom power to operate correctly. When the button is in

the off (out) position, power is not applied to the mic/line input connector. When the button is in the on (in) position, and the mic/line button is in the mic (out) position, +48Vdc is applied to the input connector.

When the mic/line button is set for mic, and a condenser microphone is con- nected, changing the phantom power on/off status may result in loud “pops” being generated. As such, it is best not to change the position of the +48V button while its associated input is “live” or “on-air.”

While it is a good idea to leave the +48V button in the off position except when phantom power is required, no damage should occur to dynamic or ribbon micro- phones when they’re connected to the input with phantom voltage present. (Wow, that’s why they call it “phantom power”—if a device doesn’t require power it doesn’t “see” it!)

Low-Cut Filter

The button associated with the “bent line” graphic symbol is used to select the low- cut filter function. (If you are a stickler for semantics, it’s actually a high-pass filter function!) In the off (out) position the filter is not placed in the audio path, leaving the signal essentially “flat.” In the on (in) position the signal is routed through the filter circuit, removing low-frequency energy.

The filter is useful for eliminating wind noise, traffic rumble, and AC mains hum. It was carefully designed to give a steep slope (18dB/octave), with the –3dB point at 85Hz. For most voice applications the filter can be left activated. For wide-band- width signals, such as music, the filter should be used only as necessary.

Model 750 User Guide

Issue 3, May 1997

Studio Technologies, Inc.

Page 23

Page 19 Page 21
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Fostex 750 manual Operation, Mic/Line Inputs
Page 19 Page 21

750 specifications

The Fostex 750 is a premium closed-back headphone that has garnered attention for its combination of advanced technology, comfort, and sound fidelity. Designed primarily for studio applications, the Fostex 750 delivers an exceptional listening experience that caters to both professionals and audiophiles alike.

One of the main features of the Fostex 750 is its dynamic driver technology. The headphones are equipped with large 50mm titanium-coated drivers that provide a powerful and clear sound reproduction. This driver configuration is engineered to deliver a wide frequency response, ranging from deep bass to sparkling highs, ensuring that every detail of the audio is captured. With an impedance of 25 Ohms, the headphones are highly efficient and can be easily driven by a variety of devices, including portable music players and digital audio converters.

Comfort is another highlight of the Fostex 750. The headphones feature plush ear pads made from soft polyurethane, which provide excellent cushioning for extended listening sessions. The adjustable headband offers a customizable fit, allowing users to achieve an optimal acoustic seal that enhances sound isolation. This is particularly beneficial in studio environments, where external noise can interfere with critical listening.

In terms of build quality, the Fostex 750 boasts a robust yet lightweight design. The combination of high-quality plastics and metal components contributes to its durability, while the foldable structure makes it portable and convenient for travel. This practicality is further enhanced by the detachable cable, which allows for easy replacement in case of wear.

Another notable technology integrated into the Fostex 750 is the use of new acoustic engineering principles. These headphones feature a closed-back design that minimizes sound leakage and provides an immersive listening experience. This design is complemented by the innovative bass reflex system, which enhances low-end response without compromising clarity in other frequency ranges.

Overall, the Fostex 750 is an impressive headphone that combines advanced sound technology, comfort, and durability. Its dynamic drivers, ergonomic design, and acoustic engineering make it an ideal choice for both professional monitoring and casual listening. Whether you are mixing in a studio or enjoying music on the go, the Fostex 750 delivers an unmatched audio experience that is sure to satisfy even the most discerning listeners.
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