By Carlos Garza
Originaly Published in Pro Audio Review.

DACS (Digital Audio & Computer Systems) has been producing hand-made products in the UK for more than 10 years. The DACS MIDI Patch Bay ($275), one of its oldest products, was recently re-engineered and is now available in the US through Independent Audio. The company set out to design a unit with simple visual feedback of signal path and high-performance specs.


The DACS MIDI Patch Bay concept owes more to audio patch bay design thanconventional processor-based MIDI patch bays. Each of the single-rack-space unit’s 10 identical blocks house rear connectors for MIDI inputs and outputs as well as front panel patch points for routing the signal between blocks. Here’s the cool part: the front panel patch points are standard 1/4-inch two-pole audio jacks!  The signal is converted to Transistor Transistor Logic (TTL) format for it’s journey over two conductors.



Each block on the front panel has a pair of MIDI outs, a MIDI in and a MIDI thru. Patching is accomplished by attaching a 1/4-inch cable from one of the MIDI outs to the MIDI in of another block. Each block can drive only two other blocks directly, but the MIDI thru in any block provides a copy of its input signal that can be sent to an additional block. The active circuitry is powered by the MIDI signals flowing into the unit from the MIDI outputs of your devices. You need to connect a MIDI output for each MIDI input that you attach to the unit or it will be underpowered.

Optionally, an external 6.5V power supply can be used in lieu of matching the number of MIDI inputs and outputs. Individual blocks can be normalized to other blocks by soldering a wire between a “normal” pad on the top PCB to another pad labeled “in” on the bottom board. The MIDI Patch Bay has an open construction with exposed PCBs on the top and bottom. Some of the I/O labeling is on the PCBs.

In Use

My only real gripe with the unit is the shallow depth. I installed it in my Anvil rack between a Furman power conditioner and an AKAI S2000 sampler. The Furman reaches about halfway back into the rack and the AKAI goes all the way back. With the Patch Bay installed in the rack (and no gaps), I was not able to get my hands between the surrounding units to make the MIDI connections.

My studio environment is oriented around a Power Mac for sequencing and recording. My dilemma in testing the unit was figuring out how to integrate it with my existing MIDI interface. My fear was that repatching my modules through the DACS would make obsolete the OMS studio setups in the Mac. I attached my three AKAI S2000 samplers and a pair of controllers to the DACS. I also attached a few MIDI in/out pairs of my Opcode Studio 64 XTC MIDI interface. In a rehearsal scenario, I found that I could quickly and easily patch either controller directly to any module or several. For sequencing, could easily route either controller to the computer, back to the DACS, and on to any sound module. The visual feedback of the patch cables kept things clear.

I tested the speed of the thru circuits by daisy chaining a controller signal from the first block through every other block and finally into the Studio 64. I recorded several test sequences and I was not able to measure any latency between the DACS “delayed” signal and a parallel signal from the same controller (Kurzweil PC88MX). The test was conducted in Studio Vision Pro at 500 BPS and a resolution of 480 PPQ.


The DACS MIDI Patch Bay solves many common patching problems. My earlier gripe about the difficulty in making connections is somewhat mitigated by the fact that rear connections are not expected to change very often in a studio patch bay. On the other hand, making connections for transient equipment could be easier if the unit had a set of MIDI connectors on the front. Then again, you could just leave a couple of long MIDI cables attached to a block for visitors. For band rehearsals, it is nice to change MIDI routing without having to power up the Mac and launch OMS. Studios that use MIDI for automated mixing or effects patch changes may like the ease of swapping control signal sources and destinations.

The DACS would also be useful in environments that rely on rapid patching of multiple controllers to multiple modules (such as classrooms). Even environments with limited but frequent re-patching will benefit from the simplicity of a dedicated high-performance MIDI patch bay.

Contact: Independent Audio at 207-773-2424, www.independentaudio.com.

(c) 2002 Carlos Garza