Precision Mid Side MS Matrix Boards and Kits

Mastering Transfer Console Input-Gain-Filter-Output

Elliptic Equalizer for Mastering with 12dB/Octave Slopes
Mastering Insert Switcher, Passive, Fully-Balanced, Two Insert with Flip

Phono Transfer System

Stereo Width Controller Board

Dual Class-A II Line Driver and Headphone Amplifier Board

MS Matrix Schematics and Construction Information

Line Driver-Receiver and Other Alternative Applications for the MS Matrix Board

Using the Precision MS Matrix Encoder to Drive "A Mid Side Speaker Array For A Big Ambient Sweet Spot"

Visit The Pro Audio Design Forum

MS-II MatrixThe MS Matrix is Offered as A Bare Circuit Board, PC Board with THAT ICs, or Assembled and Tested Shown Above.

This is the new "MS-II" Matrix based on the original MS design published in the Pro Audio Design Forum and used by mastering facilities world-wide. The MS-II offers a number of new features including Mid/Side Gain Offset, Variable Width control, a Tilt Equalizer in Side and multiple Bypass modes.

The Precision MS-II Matrix uses THAT1240 and 1246 line receivers with resistor matching of 0.005% to perform high accuracy mid-side sum and difference functions. Encode/decode crosstalk performance is typically >55 dB across the full audio band.

The Precision MS-II Matrix provides simultaneous encode/decode capability. THAT1246 line receivers and THAT1646 OutSmarts
line drivers provide fully-balanced I/O for the encoder and decoder inputs and outputs.


The MS-II has a number of new features to make MS easier. For those wanting a quick look, the schematics are here.

Insert Gain Offset.

M/S processing can often create level challenges for both outboard gear and internal to the MS matrix itself. Side levels are often significantly lower than Mid. With highly-correlated elements Mid often has "mono build-up" producing level increases of 3 to 6 dB.

The MTC-MS-II addresses MS level challenges by applying switchable Insert Gain Offset between Mid and Side. The Encoder can operate with 0, 6 and 12 dB offset between Mid and Side. When gain offset is applied in the Encoder, the Decode gain is compensated to maintain the original M/S ratio.

Mid Gain Offset: Reduces Mid Encode Gain by -6 dB. Mid Decode Gain is automatically increased by +6 dB to compensate. Mid encode headroom is increased by 6 dB.

Side Gain Offset: Increases Side Encode Gain by +6 dB. Side Decode Gain is decreased by -6 dB. Side gain offset allows outboard gear to be driven hotter.

By using Mid and Side Gain offset together, an offset up to 12 dB is available.

Individual Encode and Decode Bypass.

The MTC-MS-II's Encoder can be bypassed to forward Left and Right into the Insert. The Decoder can be also be bypassed to forward Mid/Side to the final Left and Right Outputs or jumper-configured to forward the Decode inputs directly to the output.

By using Encode and Decode bypass together the Insert can be switched from Mid/Side to Left/Right processing.

Individual Insert Bypass.

Mid and Side have individual Insert bypass relays. Need to compress only Mid? Bypass the Side Insert completely. Processing both Mid and Side? Bypass one at a time to hear each processes' contribution. On-board relay logic is available to bypass Mid and Side Inserts simultaneously for instant A/B comparisons.

On-board Width Control.

The MTC-MS-II has on-board Width control ranging from 0 to 200% by varying Side Level from -∞ to +6 dB relative to an anchored unity gain Mid level. Control is smooth and predictable with a "feel" similar to the Width Controller using the LRS method. A potentiometer or stepped make-before-break rotary switch can be used. The Width Control is relay-bypassed.

On-board Tilt Equalizer Provides Frequency-Dependent Width.

A gentle tilt equalizer can be inserted into the Side channel to provide frequency-dependent Width. The range at 10 kHz is +/-3dB. As 10 kHz is boosted, 100 Hz is decreased by an identical amount with a "pivot" frequency of about 1.2 kHz. A 0 to 6 dB range in frequency-dependent Width is available from the 100 Hz to 10 kHz with either positive or negative slope. Width can increase with frequency or decrease with frequency. The Tilt Equalizer follows the overall Width control and is relay-bypassed.

Individual Mid and Side Mutes.

The Mid and Side channels have individual relay mutes to audition the processing of each insert. The Mid and Side channel mutes are placed in the return path rather than the Insert Send to eliminate "compressor recovery" artifacts from muting sends. When Mid is muted, Side is presented to the Left and Right outputs in their actual perspective similar to an "in place" Solo function. (Side is a "mono" single-channel signal. When presented "in place" the positive polarity is heard in Left and the negative in Right. This is how we hear it in the stereo image when recombined with Mid.)

Improved Encoder and Decoder Headroom.

Mid Side encoding is well-known for Mid "build-up" on highly-correlated material.

The MTC-MS-II eliminates Mid build-up and the resulting headroom reduction with Mid Gain offset. Internal encode headroom in Mid is increased by 6 dB.

Though not fully-appreciated Mid Side decoding has additional gain build-up during Left and Right reconstruction. When M+S is added to M-S to produce "L" the actual result is 2L. The MTC-II avoids L and R buildup by using the THAT1240 and 1246 line receivers to provide summation without gain.

By switching the THAT1240 in a unique way its gain can be varied from -6, to 0 and to +6 dB. This provides the opportunity to provide switchable gain offset with high precision without the requirement for additional stages that would add differential phase delay to one process path but not the other. High frequency crosstalk performance is maintained.

To learn more about the MS-II Precision MS Matrix visit the Pro Audio Design Forum.

The Precision MS Matrix is sold as either a bare PC board, a "kit" including THAT1240, THAT1246, THAT1646 ICs and an OPA2134, or an assembled and fully-tested module.

A Mouser Electronics Project Manager bill-of-materials is available for DIY builds of the Precision MS Matrix.

In Stock!

Bare PC Board
$69.95 US

Bare PC Board Including THAT ICs for MS Matrix
(6 each THAT1240, 1246, 4 1646, OPA2134.)
$129.95 US

Assembled and Tested MS Matrix PC Board Including All ICs

$599.95 US
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