Myryad MDP 500 preamplifier-processor

In my February 2000 review of Meridian's multi-talented, multichannel, multi-kilobuck Digital Theatre system, I fumed about the lack of a medium for discrete multichannel music. Even more loudly, I railed against the irresponsible mastering of many Dolby Digital and DTS discs, which place the listener in the middle of an ensemble and swirl the voices around his or her head with little concern for musical or artistic coherence.

Now we are seeing the first offerings of SACD and DVD-Audio in discrete multichannel, as well as a growing awareness of the need for realistic acoustic perspectives for the appreciation of music. Although multichannel speakers and amps can be much the same as those for stereo, simply adding a new player and a few speakers will not get you to the Promised Land. The central element in a multichannel system is a preamp-controller-processor that, at the minimum, can provide input switching and volume control for two to eight channels. The VTL 2.5.1 preamp, used in my January 2001 Follow-Up on the Technics DVD-A10 player, does this. But you still will want a decoder for DTS and Dolby Digital sources, and it makes sense to incorporate these functions into the control center.

Myryad's sleek $2595 MDP 500 is just such a full-fledged preamplifier-processor. It is best described in terms of its inputs, its outputs, and what it does in between. It has nine pairs of analog stereo inputs and six digital inputs, for PCM, DTS, and AC-3. It has one 7.1-channel analog audio output fed from its processors and DACs, one digital output for an external DAC or other device, and three pairs of stereo analog recording outputs that are fed from analog inputs. The MDP 500 currently uses a Crystal Semiconductor CS 4226 A/D–D/A chip. This provides two ADCs and six DACs—all 20-bit/48kHz. The DACs are followed by second-order low-pass filters (located on the DSP module to keep any HF noise localized) that supplement the on-chip low-pass filters. The output amplifier uses Texas Instruments dual bi-FET op-amps with digitally controlled step attenuators in their feedback loops. Thus, the volume control and output stages are fully analog for all functions.

The MDP 500 also has what Myryad calls a "7.1-channel" input. This purely analog input bypasses all the digital sections and is fed directly to the analog volume control and output stage. It is intended for devices (such as present-generation SACD and DVD-A players) that do not provide full-resolution digital outputs, for future multichannel external sources, or, if you wish, for patching through your analog sources unscathed by digitization of any kind. Thus, the MDP 500 and its well-designed universal remote control are capable of handling nearly everything that's out there today (footnote 1).

And, of course, the MDP 500 has video inputs and outputs. Although our overriding concern at Stereophile is with sound, we cannot ignore entirely the encroachment of video sources and functions into modern audio systems. In fact, it has become nearly impossible to set up and use the latest generation of SACD and DVD players without a video monitor. The MDP 500 itself demands a video monitor in order to get the most out of it, even for purely audio enjoyment. This sure ain't your grandfather's preamp.

Button, button, who's got the button?
The recent trend of fewer buttons and knobs on front panels was almost exclusive to high-end stereo. However, while the MDP 500 is as complex and talented as those humongous A/V receivers that line the shelves at the big box stores, its front panel is not crowded with a multiplicity of knobs, pushbuttons, toggle switches, and LEDs.

The design is clean and unchallenging: A single recessed volume control is centrally placed with a crisp blue vacuum fluorescent display just to its left. To the knob's right are buttons for up/down source select, and three more for Tape Monitor, mode (Stereo, Mono, Pro Logic, Natural, Concert, Club, Party), Cinema EQ (removes excessive brightness from movie soundtracks), and the "7.1-channel" input (which bypasses the digital processing). To the extreme left is the Standby (power) button. That's it! If you plug your inputs into the similarly named ones on the back, you can operate the MDP 500 just like a regular preamp and never crack the manual.

Not bloody likely! First, stepping through inputs rather than directly selecting the one you want is a pain. Second, the clear and informative VFD display is too small to read from more than 5' away. Third, if you really want to understand, configure, and control what the MDP 500 is capable of, you'll be using a video monitor, and the placement of that monitor might not permit easy viewing within arm's length of the front panel.

I found that I almost never touched or even looked at the MDP 500's faceplate. Its remote can do more, better and easier, than the front-panel controls. For example, the remote has individual buttons for each input; single touches evoke video screens full of options and information.

I plugged in my sources and output devices—using some two dozen analog and digital cables—then sat down on the couch, put my feet up on the coffee table, opened the instruction manual and a beer, and entered the world of multichannel setup.

The Price of Admission
In order to make optimum use of the MDP 500—or, indeed, of any multichannel system—there are several setup procedures to perform.

First, you must associate the video sources with the correct audio sources (Source Setup), even though there are some reasonable defaults. This process also permits the user to adjust the input sensitivity of the A/D converter for individual analog inputs. Note, however, that current MDP 500s cannot make a fixed video association for the "7.1" input. This is no great hardship; a single button on the remote toggles in that audio input without affecting the video source.

Second, you must define the speakers and their placements. Begin with Speaker Setup, including bass management. From this menu, you tell the Myryad how many speakers (left, center, right, right surround, left surround, subwoofer) you have and whether they are Small or Large. Bass frequencies from channels with Small speakers can be routed to the Large speakers or the subwoofer (if any). This menu also lets you set the upper crossover point for the sub and the lower cutoff for the Small speakers (footnote 2). And there's an option for duplicating the Large speakers' low-frequency information in the subwoofer for more bass. (This can also be accomplished on the fly, from the remote.)

Footnote 1: 1 A major upgrade to the MDP 500 before the end of this year will require the fitting of a new internal plug-in DSP module. Myryad intends that the module be retrofittable into current production, and promises that, once the new module is installed, future software upgrades will be able to be made via the RS-232 interface port, which is currently usable only for control purposes. The upgrade will include 6.1- and 7.1-channel processing to handle DTS-ES and DD-EX material, plus "all-round" 24-bit/96kHz ADCs and DACs, as well as other software enhancements that have yet to be announced.

Footnote 2: This is a critical function. Many of today's systems, stereo or multichannel, employ small left and right speakers that require that the low frequencies in those channels be routed to a subwoofer, else they will be lost. DVD-Audio and SACD players, as a rule, use the subwoofer as a Low Frequency Effects (LFE) speaker and not, as is assumed for a normal satellite/subwoofer system, for handling the low frequencies of the left and right channels. In other words, such players lack bass management.

Myryad Systems Ltd.
US distributor: Artech Electronics, Ltd.
P.O. Box 455
Williston, VT 05495
(514) 631-6448