---

MODEL SPX-1 MICROPHONE SPLITTER/MIXER

PRODUCTS

THE SPX-1 IS NOT IN PRODUCTION AT THIS TIME. SOUND CHOICE WILL CONSIDER A PRODUCTION RUN WITH A MINIMUM ORDER OF 10 UNITS. PLEASE CONTACT US FOR DETAILS. IF YOU NEED A GENERAL PURPOSE AUDIO MIXER (WHICH THIS MODEL IS NOT) WE SUGGEST UNITS MANUFACTURED BY MACKIE, ROLLS, BEHRINGER, ALESIS, YAMAHA, TASCAM OR OTHER GENERAL PURPOSE PRO-AUDIO MANUFACTURERS.

 

 

PRODUCT DESCRIPTION:

 

Designed for court and government applications, the Sound Choice model SPX-1 Microphone Splitter/Mixer couples the Sound Choice SC-186K Assistive Listening Transmitter, or other assistive transmitters, to existing four-track transcription recording systems without compromising the recording system or requiring unusual setup modes on often found on these recorders. The recorder continues to be operated in its usual manner.

The Splitter/Mixer passes audio signals and phantom power from each of four discrete microphone lines directly out to the transcription recorder. At the same time, audio from each of the mic lines is buffered and transparently split off from each of the discrete lines. The mic line splits are actively mixed to mono line level outputs which are routed to the External Line Input jack on the SC-186K Infrared Audio Transmitter. A second line output may be used to simultaneously feed a sound reinforcement system, broadcast line feed, or a single track recorder. Multiple Splitter/Mixer boxes may be cascaded together to provide for more than four mic lines while still generating a single final line output. Microphone inputs and outputs are balanced XLR connectors. 1/4" TRS balanced phone jacks are used for line level outputs and the cascade line input. The unmixed direct mic lines will continue to pass signal even if the SPX-1's power is turned off.

The line level outputs only may be silenced during sidebar or other private discussions using a front panel mute switch which has a flashing reminder indicator. The SPX-1 may also be ordered with a front panel remote mute mini-DIN connector in place of the mute switch. In this configuration the SPX-1 can be muted remotely using the Sound Choice SC-RMS Remote Mute Switch, available as an extra-cost option. Operating power is supplied by a UL/CSA approved low voltage transformer.

 

---

SPECIFICATIONS: 

• Inputs:
  • 4 - XLR gold female balanced mic level (will pass phantom power)
  • 1 - 1/4" TRS line level input >10k ohms
• Outputs:
  • 4 - XLR gold male balanced mic level (passive unmixed, will pass phantom power)
  • 2 - 1/4" TRS line level outputs 600 ohms (with level contol)
• Operating Controls:
  • Power On-Off (with indicator)
  • Mute On-Off (with Indicator)
  • Line Level Output Gain Knob
  • Internal individual mic level set-up trimmers

• Preamp/mixer gain: greater than 60 dB
• Crosstalk (unmixed mic inputs/outputs): greater than 80 dB
• Signal to Noise Ratio: greater than 70 dB
• Frequency Response: ±2 dB 20 - 18,000 Hz
• Power requirements:14-20 volts AC, 250 mA
• Enclosure:high impact RF protective 20 guage steel measuring
• 8" w x 2.5" h x 3.5" deep

SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE

---

INTERNAL BLOCK DIAGRAM:

---

TYPICAL CONFIGURATIONS:

 

---

SIMPLIFIED OPERATING INSTRUCTIONS:

---

SOUND CHOICE ASSISTIVE LISTENING, INC.
MODEL SPX-1 MICROPHONE SPLITTER/MIXER

ENGINEERING AND PURCHASING SPECIFICATIONS:

 

The audio device shall perform the combined operations of a 4 channel microphone line splitter with 4 direct feed-through outputs, and a 4 input microphone mixer and preamplifier. Each of 4 microphone lines shall have a female XLR balanced input and a male XLR balanced direct output. There shall be no audible crosstalk between the lines having isolation greater than 80 dB between lines. Each individual microphone direct line shall be capable of passing phantom microphone power in either direction without transferring phantom power to any other unpowered microphone line. Each individual microphone direct line shall be capable of passing microphone audio and phantom power even when the mixer section is unpowered.

The split branch of each microphone line shall be of a buffered nature and of such an impedance that the source microphone signal shall remain unattenuated. The split branches of each microphone line shall be internally level adjustable, combined (electrically summed) and gain amplified at least 60 dB with a signal to noise ratio of 70 dB or better. A line level +4 dBm balanced input via a TRS 1/4" jack shall be combined with the mic lines so that multiple splitter/mixer devices may be cascaded together to provide for additional microphone inputs. The combined output shall be at a standard +4 dBm 600‡ line level available at 2 balanced TRS 1/4" jacks. A master output volume control shall be provided.

A switch and a visual indicator means shall be provided for muting the combined mixer line outputs when necessary to a level of at least -70 dB below the unmuted signal level. The muting circuit shall not affect the signal of the unmixed microphone lines routed to the direct outputs. The muting circuit shall not create undue clicking or other electrical noise when changing operational states.

The enclosure shall incorporate full RF shielding. Low voltage power shall be provided by UL/CSA approved transformer. 

The Sound Choice Assistive Listening, Inc. model SPX-1 Splitter/Mixer is specified.