Vintage Digital & Analogue Studio Effects

Vintage Digital

Ursa Major MSP-126

Ursa Major MSP-126 Multi-Tap Stereo Processor

The Ursa Major MSP-126 is a stereo tapped delay digital delay line with a 20kHz bandwidth, eight pre-programmed processing modes and more. The Ursa Major MSP-126 is a signal processor that creates a whole range of interesting effects inlcuding great balanced stereo with flat response from any kind of program material.


William Blake coined the phrase “to find a universe in a grain of sand.”  The Ursa Major MSP-126 has a seemingly narrow province: 370 milliseconds of memory, with one input and two multi-tap outputs. This is far simpler than my other digital processor designs optimized for reverberation synthesis, yet it contains a fascinating world of possibilities.

The 12 tap algorithm of the Ursa Major MSP-126 is more complex and, to my mind, far more interesting than that most popular of delay devices, the digital delay line or “DDL” . With only one tap, the DDL is unable to achieve convincing stereo perspective.

However, with two groups of six taps, the Ursa Major MSP-126 delivers rich, full stereo in all its signal processing modes. Although all listening experiences are stereo, in modern recording, broadcasting, film sound recording, and even musical composition and performance, the closely miked or purely electronic sources are severely monaural. I believe that a richer, more natural kind of stereo ambience is vital in all these media. That is why I’ve based my Ursa Major MSP-126 design on a stereo time delay algorithm with multiple taps.

Even in the Ursa Major MSP-126’s effects modes, where the sound processing is deliberately dramatic, the result is satisfyingly stereo. I believe you will find these modes new, exciting, and extremely musical.

Ursa Major MSP-126 Inputs
Stereo or mono Input Modes, switchable by rear panel switch.  In stereo Input Mode, the processor is fed from the sum of left and right inputs, and with Bypass “on”, the left input feeds the left output and the right input feeds the right outputs. In mono Input Mode, the processor is fed from the left input only, while with Bypass “on” the left input feeds through to both left and right outputs.

The inputs are electronically balanced (differential amplifier): Pin 3 high, Pin 2 1 old, and Pin 1 ground. In stereo Input Mode, input impedance of pin 3 is 11K ohms and pin Z is 21K ohms. In mono Input Mode, input impedance of pin 3 is 5.5k ohms, pin Z is 10.5k ohms. Recommended source impedance is ohms or less. Maximum source voltage before input stage overload is +17dBV (7Vrms). Minimum input for operation of ‘0 LED” (Input Level fully clockwise, input frequency 100Hz, mono.

Input Mode, left input only driven), is -10dBV (.316Vrms). In stereo Input Mode, with both inputs driven in phase, sensitivity rises to -16dBV (.159Vrms). Connectors are XLR-3 female.

Ursa Major MSP-126 Outputs
Stereo outputs, active differential circuit. Pin 3 is high (100 ohm source resistance), Pin 2 is low (100 ohm source resistance), and Pin 1 is ground. Minimum recommended load impedance is ohms. Maximum output level ( Input driven so that “0 LED” flashes occasionally, Output Level full clockwise) is +12dBV nominal. Output stage maximum level is +17dBV feeding an unbalanced load, and +23dBV feeding a balanced load. Connectors are XLR-3 male.

How the Ursa major MSP-125 Works
The Ursa Major MSP-126 is a digital audio delay system. It converts sound into a digital format and writes it into memory. It reads signals from 12 different memory locations and creates a left output and a right output, each consisting of six delay signals. The time delay, phase (+/-), and amplitude of each tap are all set by firmware stored in EPROM’s.

Three front panel switches allow you to select from many pre-programmed possibilities stored in the EPROM’s. The Mode switch has the highest priority and sets up the ‘menus” of choices for the other two switches. Parameter 1 accesses 16 variations of the time delay placements for the taps, while Parameter 2 accesses 16 variations of the amplitude/ phase values.

The left and right inputs are summed internally (but when the Input Mode is set to mono, only the left input is used) and fed into the RAM (random access memory). A 16K RAM and our sampling rate of 44. 1kHz permit time delays up to 37Bms. The 6 left taps are read out with time delay values T1L…T6L, and subjected to gains g6L…g6L, and the right taps are similarly read out. The two groups of taps are then summed and fed to the Ursa Major MSP-126 outputs.

Many new and useful audio processing functions are possible with this technique. If all the time delays are short, the effect will tend ±o be audible as frequency If the delays are long, the taps will response changes. The Ursa Major MSP-126  would be easier to be heard as echoes. explicate if this technique were more generally utilized commercially, and thus more familiar to sound engineers. Sound engineers have grown up with a variety of reverb devices, which produce a very high number of echoes quickly and sustain them for several seconds.

They are also familiar with DDL’s, with only one tap and a very limited number of echoes even when used with feedback. But the MSP-1Z6 is in a world of its own, and it Will require some reading of the material in this manual and several hours of experimentation before most sound engineers reach the point of saying, “Ah hah! I hear what, you mean.



Quantization: 16 bit
Sampling Frequency: 44.1kHz
Frequency Response: > 20Hz – 20kHz
Dynamic Range: >80dB
THD: Unknown

Dimensions: 480(W) x 44(H) x 280(D)mm
Weight: 5.5 kg

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