Review in Recording Magazine (US), Oct. 2003
By Matt Zlaten

SPL Surround Monitor Controller—Make your monitors sit up and perform

Sound Performance Lab claims that its Surround Monitor Controller (SMC 2380) provides surround and stereo routing and volume control, with “excellent audio quality.” The stated aim: To provide surround signal routing and switching without sound degradation, without VCAs or A/D-D/A conversions, at an affordable price. Lets see how it does at these jobs.

Rear connections
The SMC has several sets of inputs and outputs, providing multiple options for connecting active speakers, computers, mixers, and multichannel audio recorders and players. Feel free to follow along on the diagram to see what connects where.

The left side of the rear has the IEC power connection and the unit's power on/off switch. On the right side of the rear is the I/O. First there is a pair of D-Sub connectors providing balanced ins and outs. The D-Subs are configured to conform to the TASCAM standard for analog audio on D-Sub, and provide six channels for the 5.1 inputs (labeled Input A), and two for the balanced stereo input (labeled Input C).

The second D-Sub is labeled SLAVE OUT and provides direct output of the A and C inputs for connection to a multitrack recorder (a DA-88, ADAT or similar) and a stereo master recorder (DAT, etc.). To the right of the D-Subs are eight RCA connectors, the first two (labeled Input D) for a CD player or similar and the next six (labeled Input B) for connection to a DVD or SACD player.

The last set of eight connectors are balanced 1/4 inch and are used for the audio monitor outputs. There's a pair for connection of stereo monitors and then an additional six for a separate surround setup. The accompanying labels “Stereo Speaker Outs” and “Surround Speaker Outputs” should not be misunderstood—we're not dealing with power amp/speaker connections here; all signals through the SMC are intended to be line-level audio, and the monitors attached to these outputs need to be active ones with their own built-in amplifiers.

One neat little feature on the rear panel is that all connections are labeled rightside up and upside down, so that if you lean over the top of the box from the front to change connections, the labels are easily readable.

Front controls
The front panel is where the real action is. It is dominated by the large volume knob, which has a smooth feel and a solid construction that inspires confidence. The knob is labeled with increments of volume percent. It's unfortunate that the labeling isn't in dBs of gain reduction or boost, but that is a minor issue for all but the pickiest engineers. On the plus side for engineers who want to be sure to alternate among consistent monitoring levels: A white ring around the volume knob allows for pencil markings.

Also on the front panel is a series of buttons. The first group, labeled Source, provides switching between the four sets of inputs. The second group, Monitor Mode, provides many useful monitoring options, including mono summing of the left and right channels, mono summing of the left and right surround channels, a -20 dB pad for all the output channels, and a global mute for all outputs.

The final button group is labeled Speakers On, and it provides independent on/off control for all six surround channels and the stereo output channels. This is especially handy for calibration of a surround system from a calibration tape or tone/noise generator.

Does it work?
We connected the SPL SMC to a DVD player (with SACD), a CD player, five Alesis ProLinear 720DSP active studio monitors (see the review elsewhere in this issue) and a KRK S10 active subwoofer.

Playing back material such as CDs, DVDs, and SACDs allowed us to run the SMC through its paces. All the switches and buttons work as advertised, switch quietly and positively, and are easy to reach and distinguish. The unit overall is very robust and solid.

The SMC is strictly a signal routing box with global volume control, it does not provide any kind of bass management or tone controls. (For more on bass management and other surround issues, check David Kelln's article on page 32 of this issue.)

Among the stated design aims: To provide anyone, whether working from a DAW or not, with consistent monitoring levels and flexible monitoring control. It certainly achieves that. DAW users can avoid clumsy aux bussing schemes in software just for monitoring, when a quick button push on the SPL unit can provide quicker and cleaner A/B/C/etc. comparisons.

How does it sound?
The SMC's manual includes audio specifications that are pretty impressive, including Total Harmonic Distortion plus Noise of 0.01% and frequency response out to 100 kHz (-3 dB). While we weren't in a position to do our own measurements for this evaluation, we have no reason to doubt SPL's claims, as the SMC proved as transparent to our ears as anyone could ask. We didn't hear any funkiness or artifacts when using it. The volume knob provides even and continuous taper without zippering. The switches are popless. Overall the SMC provides clean performance with no coloration.

So...
The SPL Surround Monitor Controller provides versatile switching and routing control in a well-built, neutral sounding package. It's not designed to provide bass management, but if you've taken care of that elsewhere, you may find that the sheer practicality and the affordable price allow the SMC to fit in nicely into your surround studio.

Find out more about the SPL SMC