Meridian 263 D/A processor & 200 CD transport

Whoever invented the adage "Good things come in small packages" wasn't into high-end audio. Most high-end products are huge and heavy, with massive power supplies, thick front panels, and battleship build quality. This dreadnought approach is justified if it directly affects the unit's sonic performance (as in the Mark Levinson No.31 transport, for example). In some products, however, the massive build can reflect a shotgun, overkill approach by the designer, or a mere fashion statement.

But can flyweight products hold their own musically with the behemoths of the High End? This question was on my mind after opening the $895 Meridian 263 D/A converter and the $1495 Meridian 200 transport. There is very little inside them in terms of mass and weight. Indeed, the 263's single printed circuit board, consuming the rear third of the chassis, is about 4" by 5" with very few parts mounted on it. Moreover, the 263 doesn't sport a large toroidal transformer and rows of power-supply regulation stages as do many digital processors. Instead, it has a relatively small transformer bolted to the chassis bottom near the front panel, and just three IC regulators.

But looks can be deceiving. The 263 and 200 are filled with design innovations and tweaky techniques to optimize their sonic performance. There are many clever tricks inside them that don't require sheer bulk to achieve design goals. As we shall see, intelligent engineering can triumph over pure muscle.

The 263 technical story
The 263 shares a common appearance with other Meridian products. It's a simple black box with front-panel glass. In fact, the 263 looks nearly identical to its predecessor, the very successful 203 digital processor. The rear panel holds a pair of RCA jacks (analog outputs), a single RCA jack (digital input), an IEC AC jack, and a power on/off switch. No Toslink or ST optical inputs are provided. The front panel has four LEDs: Power On, De-emphasis (which blinks randomly when no input is connected), Lock, and one marked "44.1kHz." This last indicator hints at the unique technology inside the 263; it comes on only when "double-locked" to the incoming digital data stream. I'll have more to say about this later.

The secret of the 263's apparently minimalist design is the use of Crystal Semiconductor's surface-mount devices (SMD). These are much smaller than traditional components with leads that fit through holes in the pcb. In addition, only two primary chips are needed; the CS8412 input receiver and CS4328 DAC. The CS4328 has an on-board 8x-oversampling (8fs) 18-bit digital filter and a 64x (64fs) sigma-delta DAC. Meridian has abandoned Philips Bitstream DACs in all Meridian products in favor of Crystal Semiconductor parts from Texas.

Only five additional chips (again, all surface-mount) are required for housekeeping and glue logic. The reduction in parts count and tiny surface-mounted devices provided by the Crystal chipset account for the 263's small pcb. This is the same chipset (but not in the SMD package) used in the California Audio Labs Sigma converter I reviewed in October 1992. Unusual for an inexpensive product, the 263's pcb is a four-layer type.

The power supply consists of a bridge rectifier and three regulation stages. There are three 5V rails—+5V to the digital circuits and ±5V to the DAC and analog stage—compared with the usual practice of supplying the output stages with ±12V or ±15V. Two very large (15,000µF each) Nichicon Muse caps, an electrolytic type designed specifically for audio, provide filtering and energy storage. These caps are each bypassed with a large Solen polypropylene type.

As with other Meridian designs, the 263's output stage uses the NE5534 single op-amp chip (one per channel). Unlike other Meridian products, however, the 5534 is followed by a discrete class-A stage; it is this discrete stage that drives the outputs. Resistors in the output stage are metal-film types, and capacitors are primarily polystyrene. The active de-emphasis circuit is part of the output stage and is switched in by JFETs. Rather than mute the output with a relay when the unit isn't locked to a digital source, the 263 uses a clever trick: The DAC is held in "Reset" mode until released by the PLL, when it achieves lock. This technique was so effective I was able to connect and disconnect a digital input without the slightest trace of noise or clicks.

Now, about that "double-lock" feature. Rather than use the Crystal CS8412 input receiver in a standard topology, the 263 employs an innovative dual Phase-Locked Loop (PLL) to reduce jitter in the recovered clock. As discussed in "The Jitter Game" (Vol.16 No.1), a digital processor's input receiver generates a new clock with a PLL which is based in the incoming digital signal. This technique results in sonically degrading jitter being introduced into the processor's master clock.

Designer Bob Stuart has added a second PLL to produce a recovered clock with virtually no jitter. The first PLL can be rather "sloppy," accepting a wide range of input frequencies—assuring that the 263 will lock to any transport. The second PLL has a very narrow acceptance window, taking the first PLL's output and acting as a huge digital flywheel. Just as a mechanical flywheel resists any change in its rotational frequency, an electronic flywheel resists any change in its signal frequency. To further reduce clock jitter, the PLL's crystal oscillator is shielded by a can on the pcb.

If the transport's output has very high jitter or is clocked at a frequency departing from the standard 44.1kHz sampling rate, the second PLL won't lock. A front-panel display shows the lock status of the two PLLs: the "Lock" light indicates that the first PLL is locked, and the "44.1kHz" LED comes on when the second, high-precision, PLL is locked. An internal switch automatically selects between the two PLL outputs; the first PLL will lock to virtually any source, the second to most good transports. Note that the second PLL won't lock to sampling frequencies other than 44.1kHz.

The result of this technique is reportedly nearly complete immunity to jitter in the S/PDIF interface (the primary source of jitter) and much better sonic performance. The second, high-precision PLL takes about a second to lock to the output of the first PLL. Although the 263 will behave as any other converter—locking instantly to the data source—it won't sound its best until after it double-locks to the transport (footnote 1).

The 263's compact, efficient design explains how the 263 can sell for $895 in the US, even after the cost of importing has been factored in. This is $100 less than the price of the Meridian 203, a converter that set a benchmark level of performance for under–$1000 processors.

Build quality and appearance are excellent. Potential purchasers should be aware of the 263's simple design: only one input, no polarity switching, and no provision for adding glass fiber input (this last feature may be moot; see the jitter measurements later). The 263 is the kind of processor you connect and forget.

The 200 transport technical story
The 200 transport, which is the cosmetic and electrical companion to the 263, has a unique two-chassis construction. Each half is a standard Meridian size, the same width as the 263 DAC. The left half is the transport mechanism itself, the right houses the decoder, control circuits, and digital output electronics. The rear panel holds the 200's coaxial (RCA jack) and optical (Toslink) jacks, plus a communication port for interacting with other Meridian products. The front panel features two rows of small illuminated rectangular buttons. These provide the usual CD control and programming functions. A green display above the buttons indicates track number, track time, and other familiar CD functions.

The 200 features a unique drawer mechanism: The entire transport assembly is brought out for disc loading. A Philips CDM 4 mechanism is mounted in a large drawer that consumes fully half the 200's front panel. This design is said to offer the technical and sonic advantages of top-loading without the inconvenience of a manual disc clamp. Once the drawer closes, an automatic clamp descends on the disc from above. The mechanism is mounted on Sorbothane, and the drawer's top cover is suspended from the drawer to damp vibration in the mechanism.

This is a much more expensive method of transport construction: Moving 3.3 lbs of mass with high precision requires a heavy-duty mechanism. It has several advantages, however. Once closed, the drawer forms a chamber that isolates the disc from acoustic, electromagnetic, and mechanical interference. Meridian has found that a CD's mechanical resonant frequency range is between 500Hz and 3kHz. They thus concentrate the acoustic and mechanical isolation across this frequency band. The two-box construction also helps to isolate the mechanical and electronic portions of the transport.

Footnote 1: The 263 review sample double-locked to the following transports: Mark Levinson No.31, Proceed PDT 3, Marantz CD-11 Mk.II, Marantz CD-94, Museatex CD-Deck, and a JVC XLZ-1010. During our DCC listening tests at the Stereophile High-End Hi-Fi Show in San Francisco in March 1993, the 263 didn't double-lock to the Philips PASC encoder's output until the digital cables were rerouted. Apparently, the digital interconnects were picking up some noise that prevented the second PLL from locking.
Meridian Audio Ltd.
North American Distributor: Meridian America Inc.
351 Thornton Road #108
Lithia Springs, GA 30122
(404) 344-7111

Ortofan's picture

... Bob Stuart's engineering expertise?
If so, maybe you'd rather get the player that JGH would have bought:

Indydan's picture

Meridian gear has always been over priced and under performing.