2-Bus 16-Channel Analog Passive Summing Mixer – 2 × 8 In / 2 Stereo Out – 1U Rack – DB25 In / TRS or XLR Out

2-Bus 16-Channel Analog Passive Summing Mixer – 2 × 8 In / 2 Stereo Out – 1U Rack – DB25 In / TRS or XLR Out

Hand-built 1U rackmount analog passive summing mixer with two independent 8-channel summing busses.

The summing circuit and attenuation are specifically designed around the customer’s outboard preamp or audio interface, providing the appropriate summing reduction for the available external makeup gain.

Dual Summing Busses

Bus A – -25 dB SUM BUS
• 8-channel balanced DB25 input
• 1 × balanced stereo output
• Stereo / Mono switches for channels 1/2 and 3/4

Bus B – -25 dB SUM BUS
• 8-channel balanced DB25 input
• 1 × balanced stereo output
• Stereo / Mono switches for channels 1/2 and 3/4

The two busses are completely independent, allowing two separate 8-channel mixes to be summed simultaneously.

Output Options

Each bus provides one balanced stereo output.

The output connector type can be selected according to the customer’s setup:

TRS or XLR — customer choice.

Custom Summing Reduction

The passive summing reduction is designed according to the customer’s downstream equipment.

The standard configuration shown here uses -25 dB summing reduction, but the circuit can be adapted when required to work correctly with the available outboard preamp or audio interface and its makeup gain.

Stereo / Mono Switching

Each bus includes two Stereo/Mono switches:

• Channels 1/2
• Channels 3/4

This allows selected channel pairs to be operated as stereo or summed to mono directly within the passive summing circuit.

Passive Analog Signal Path

The mixer uses a completely passive analog signal path.

No op-amps, buffers, amplifiers, digital circuitry or other active electronics are used in the audio path.

No power supply is required.

Technical Specifications

Format:
1U rackmount

Configuration:
2 × independent 8-channel summing busses

Inputs:
2 × DB25
8 balanced channels per bus
16 balanced input channels total

Outputs:
2 × balanced stereo outputs
TRS or XLR — customer selectable

Summing Reduction:
Standard: -25 dB per bus
Custom reduction available according to downstream equipment

Stereo / Mono:
2 × Stereo/Mono switches per bus
Channels 1/2 and 3/4

Signal Path:
100% passive analog

Power:
No power required

Custom Engraving:
Free custom name engraving — just let me know what name you would like on the front panel.

Build:
Hand-built in Hungary

If you need a different channel count, summing reduction, connector configuration or routing arrangement, I can build the unit according to your system requirements.

 

Frequency Response (Passive Section) +0, -0.1dB from 10Hz to 30kHz
Maximum level > +28dBu • Noise floor < -94.5dBu 22Hz-22kHz bandwidth
THD+N < 0.004% • IMD < 0.004%
Crosstalk rejection (Passive Section) > 110dB

Do not find your desired gear?  Ask to build Yours!

You can get as many channels and options as you want, so let’s build your gear!

Build time: 15 Working Weekdays after cleared payment

Enhance your digital ITB mixes with a touch of analog warmth! Uncover the hidden analog potential of your DAW interface and boost your mixes with depth and vibe. Experience a console-like sound with Passive Studio Summing Mixer that brings a new level of richness to your music. Warm up your mixes and explore the analog dimension in your digital workspace

Selected Studio grade VISHAY DALE military metal-film resistors
In/Out: Stereo Balanced Discrete path
Insertion input resistance: -15dB / -20dB / -25dB (order)
Output impedance 600 -1k ohms balanced
Frequency response: 0-500Khz
Crosstalk 1Khz: -95dB
Signal to Noise rate (SNR): -110dB
TRS wiring: (Tip:HOT/,Ring:COLD/Sleeve:GROUND)
Pure hand made! Hand wired and tested point-to-point!
Laser engraved massive aluminium alloy box