Stereo Line Inputs, Main Outputs

Model 750

microphone or line-level signals. To mini- mize noise and other problems, it is rec- ommended that the mic/line signals aren’t wired by way of points on the patch bay.

Stereo Line Inputs

The Model 750 contains two stereo line- level input channels. They are intended for connection to sources located within the vehicle, specifically the audio output channels from videotape machines. The direct-coupled, electronically-balanced circuitry has extremely low noise, high common-mode rejection, but no special protection from overvoltage or static. (Don’t get us wrong—the stereo line input circuitry is better than what’s found on most audio mixers available today— they’re just not as “tough” as the mic/line inputs!) The stereo line input circuitry is intended for connection to balanced, line- level signals with a nominal operating level of +4dBu.

Each stereo line input channel uses two 3-pin female XLR-type connectors. Pre- pare the mating connectors (males) so that pin 2 is signal high (+ or hot), pin 3 is low (– or cold), and pin 1 is shield. With an unbalanced source connect pin 2 to high (+ or hot), and pins 1 and 3 to shield. If connecting to an unbalanced source in this manner results in hum or noise, con- nect pin 2 to high (+ or hot) and pin 3 to shield; leave pin 1 unterminated. For flexibility of use it is recommended that the stereo line input connections be routed through points on the patch bay.

Main Outputs

The Model 750 contains three sets of stereo outputs associated with the main audio bus. Main Outputs 1 and 2 are

electronically balanced, have a nominal level of +4dBu, and are capable of driving balanced or unbalanced loads of 600 ohms or greater. Main Output 3 is trans- former balanced, with its output level selectable, using a front-panel button, for microphone or line level. It is capable of driving full level into balanced or unbal- anced loads of 2k ohms or greater.

Main Output 1 and 2

Main Output 1 and 2 are intended for connection to devices located within the vehicle. It is recommended that either Main Output 1 or 2 be used as the “on-air” source. Each output utilizes two ¼-inch

3-conductor phone jacks for interconnec- tion. Prepare the mating connectors (plugs) so that tip is signal high (+ or hot), ring is low (– or cold), and sleeve is shield. Whether these outputs are wired via the patch bay will depend on the specific installation.

Note that while the electronically-balanced output circuitry is capable of driving loads of 600 ohms or greater, the output level will drop slightly as the load impedance approaches 600 ohms. A 0.5dB difference in output level can be expected as the load impedance changes from 10k ohms to 600 ohms.

While balanced operation is preferred, unbalanced operation is not a problem for the electronically-balanced output circuitry. To connect to an unbalanced load connect the tip to high (+ or hot), and both the ring and sleeve to shield. For optimal unbalanced operation, it is impor- tant to connect both the ring and sleeve together on the plug that mates with the Model 750.

Issue 3, May 1997	Model 750 User Guide
Page 12	Studio Technologies, Inc.

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.