Roland M-1000 Digital Line Mixer

A digital audio stream consists of two components, the word clock and the digital data, and if various sources' word clocks are not identical, their digital data cannot be mixed together - or even coexist - on the same digital bus. The Roland engineering team has developed an elegant solution to this problem in their new M-1000 ($695), and it saved my ass big time on a remote recording session recently in NYC!
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One built-in shortcoming of just about every digital mixer is its inability to mix different stereo digital sources (such as keyboards, samplers, CD recorders, DAT machines, etc.) within the digital domain-even if they're all supposedly at the same sample rate (say, 44.1 kHz). A digital audio stream consists of two components, the word clock and the digital data, and if various sources' word clocks are not identical, their digital data cannot be mixed together - or even coexist - on the same digital bus. The Roland engineering team has developed an elegant solution to this problem in their new M-1000 ($695), and it saved my ass big time on a remote recording session recently in NYC!
Product PointsApplications: Digital studios, keyboard rigs, remote recording setups - anywhere one needs to connect lots of different pieces of digital gear.

Key Features: 24-bit; digital line mixer with four stereo pairs of digital inputs; built-in sample rate converters; 56-bit internal processing; USB and word clock I/O; stereo analog and digital outputs

Price: $695

Contact: Roland at 323-890-3700, Web Site.

Plus

+ Can synchronize (and digitally mix) four completely different digital inputs

+ Word clock or 44.1, 48, or 96 kHz sample rates

+ Good sounding 96 kHz stereo DAC

Minus

- No provision for dithering 16-bit sources.

The Score: I know I'm not supposed to call anything a "Swiss Army Knife," but if this isn't one, I don't know what is! I've found it to be absolutely indispensable in my studio.
Features

A single-rackspace unit - with platinum front panel, colored knob inserts and rows of multicolored LEDs for level and clock source - the Roland M-1000 packs an awful lot of digital mixing and sample rate conversion technology into a very small package, only 6 5/8 inches deep. From left to right on the front panel are an analog input level pot with -10/+4 dB sensitivity switch and four digital input level pots mapped to the four S/PDIF coaxial rear panel inputs; the first knob's section also includes a fiber optic TOSLink S/PDIF input, and a switch for selecting between the two. With those four digital input controls, one can not only input the digital data, but also fade it appropriately; there is no gain, but the level can fade all the way down.

Next, roughly in the middle of the front panel, is a master output level control with a concentric balance pot. This controls the analog output level, the digital output level, as well as the USB feed to a computer. Although the digital output is another coaxial RCA jack on the rear panel, here on the front one finds a parallel Toslink output as well. Next comes a TRS headphone jack and its associated level control, followed by two vertical columns of seven multi-colored LEDs for showing level - four greens, two yellows, and a red "clip" one on top. Finally, we come to another column of seven LEDs (with two more off to the side) which show clock source, sampling rate, and lock condition. The power switch completes the front panel.

The rear panel is a little sparser, with a multivoltage IEC AC connector, a pair of word clock BNCs (with 75-ohm termination and thru on/off switches), and the USB port. The rest is just standard I/O jacks- a pair of balanced TRS jacks at +4 dB for monitor out, a pair of balanced XLRs for main master out, and the aforementioned coaxial RCA digital output. Finally, we come to the four RCAs for digital input, and a pair of unbalanced 1/4-inch analog inputs.

For the spec-conscious, the ADC is done at 24-bit, 64X oversampling, the DAC at 24-bit, 128X oversampling, and the internal processing is 56-bits fixed. The unit can be set to 96 kHz, 48 kHz and 44.1 kHz internal clock, but can accept external clocks all the way down to 32 kHz, as well as 88.2 kHz. Digital Input 1 can accept varispeeded rates and pull-ups/pull-downs, while inputs 2, 3, and 4 will lock only to the standard fixed sample rates.

The USB connection is supported by Windows XP/2000, Windows ME/98, and the Mac OSs OS X down to 8.6. "Advanced Mode" and "Standard Mode" USB drivers are supplied on a CD with the M-1000.

In Use

So what happened at my big classical recording session last week that made the Roland M-1000 such a lifesaver? Well, the short story was that the Digital Audio Denmark ADDA 2408 (which I was using as a multichannel monitor DAC) - just like all other digital mixers which accept eight-channel digital inputs - didn't want to allow me to audition playback of my Superscope PSD-300 CD recorder through a stereo pair of its four AES/EBU inputs. The problem was that the other three AES/EBU inputs were being fed from six channels of my DTRS recorder, and my Danish review unit lacked its separate AES-S/PDIF I/O expansion card - that would have enabled multiple separate digital stereo monitoring scenarios. I really wanted to check the quality of the CDs I was making for the artist through those wonderful upsampling Danish DACs.

But then a light bulb went on I my head. What if I were to clock the Roland (at 88.2 kHz) from my Crane Song Spider mixer (which was the system clock on my session), input the digital output from the Superscope recorder into the Roland, and then send the Roland's sample rate converted output version of the CD-R playback to the Danish unit's AES/EBU input 4? Presto; it worked great! I know there were several other ways to skin that cat, but the Roland was there, and it did the job perfectly - just like a Swiss Army Knife is supposed to do.

Back at the studio, I was able to use the M-1000 in a more typical fashion. I filled its digital inputs with playbacks from my Sony TCD-D10 DAT recorder, that Superscope CD recorder, my Kurzweil K2600XS keyboard, and the stereo output from a Fostex VF-160 multitracker I had on hand for review, and its sole analog input from my Sony NS999ES SACD player. We're talking different sample rates, bit rates, analog - the whole nine yards.

I fed the Roland's digital output to my 96 kHz stereo master recorder (an old Sony PCM 800 with an Apogee PSX-100 and Spectral Translator Plus wrapped around it), its master analog output to a pair of Dynaudio BM-6A powered monitors, and its monitor output to my control room monitor preamp. Everything "sunk up" perfectly, and the sound of the Roland was quite nice. Perhaps I should point out that its built-in SRC circuits enable easy "upsampling" of 44.1 kHz CD and DAT playback to 96 kHz, and the M-1000's DACs sound very good. The sound of the Miles Davis classic Kind of Blue, as played back from the SACD, resampled into PCM at 96 kHz and converted back to analog in the Roland's output section - while certainly not identical to the source - was definitely more than acceptable.

The only caveat I noticed was that if one feeds the M-1000 with wide dynamic range 24-bit digital material, and connects its digital output to a 16-bit device like a DAT or CD recorder, the Roland's lack of dither and/or noise-shaping circuitry produces the typical truncation artifacts. But these days, most engineers are aware of this problem, and have learned to dither before reducing 24-bit material.

Summary

So what's not to like about this versatile little gadget? It does things that nothing else in my studio does, sounds good, and is reasonably priced. I might even say that I can't live without it!