Audison bit SPM4 4-Channel Stereo Passive Mixer — 4 Inputs, 2 Outputs for Active OEM Multi-Way Systems

The Audison bit SPM4 is an unpowered 4-input, 2-output stereo passive mixer designed for active OEM multi-way systems, where each speaker is driven by its own amplified channel. It mixes the midrange/woofer and tweeter channels coming from the factory amplifier into one single mid-high channel, using four audio transformers developed for very low distortion and a highly linear response. It is especially recommended for adding input channels to Audison processors and DSP amplifiers that use de-equalization.

Key Features

• 4 input channels mixed down to 2 output channels (one stereo pair)
• Four audio transformers for very low distortion and linear response
• Unpowered (passive): no power connection needed
• Ch1 (L/R) inputs include an inverting input to apply a 180° phase shift, which often gives better mixing results
• Maximum input power: 25 W RMS / 50 W peak
• Designed to work with the de-equalizer in Audison processors and amplifiers with built-in DSP

Power and Technical Highlights

Output gain is -3 dB, frequency response is 15 Hz – 75 kHz (-3 dB), and distortion is 0.05% at 1 kHz and 0.5% at 100 Hz. Input impedance is 32Ω, and the retailer-listed size is 103.5 x 36.5 x 86.5 mm. With a DSP's de-equalizer in the chain, any non-linear response caused by mixing already-filtered channels is compensated.

Ideal For / System Fit

• Factory systems with separate amplified tweeter and midrange/woofer channels
• Extending the input count of an Audison bit processor or Forza bit amplifier
• Installs where only two inputs are available on the processor

Not an active mixer or amplifier: it only mixes signals passively, and it works best when a de-equalizing processor follows it.

Installation Note

When an SPM4 is used with Audison bit processors (bit One, bit Ten, AP bit), the ART function is disabled, so use channels 1 and 2 of the processor on the head-unit high-level outputs that are not connected to the SPM4.

What's Included

1 x Audison bit SPM4 4-channel stereo passive mixer (confirm the supplied accessories with your supplier)

Precautions

• Do not exceed the 25 W RMS / 50 W peak maximum input power
• The ART (automatic remote turn-on) function is disabled when the SPM4 is used with Audison bit processors
• Try the phase of the inverting input to find the best mixing result
• Professional installation and tuning are recommended

Audison bit SPM4 vs. Active Mixing

Frequently Asked Questions

What is the Audison bit SPM4 used for?
It mixes separate midrange/woofer and tweeter channels from a factory system into a single mid-high channel.

Does it need power?
No. It is a passive, unpowered mixer.

How many inputs and outputs does it have?
4 inputs and 2 outputs (stereo).

Why does it have an inverting input?
Mixing often works better when one of the two channels is phase-shifted by 180°.

What power can it handle?
25 W RMS and 50 W peak at the input.

Which processors does it suit?
Audison digital processors and amplifiers with built-in DSP that use a de-equalizer.

Does it affect the ART function?
Yes. ART is disabled when the SPM4 is used with Audison bit processors.

Is it an amplifier?
No. It only mixes signals and adds no gain (output gain is -3 dB).

Product Specifications

Make factory multi-way systems work with your Audison processor — order the Audison bit SPM4 today.