mbl 1611HR D/A converter & 1621 CD transport Page 2

Three LEDs on the right side of the main panel monitor the frequency accuracy of the incoming digital signal. As we are all aware, digital signals often arrive at the converter in less than perfect condition. Not only can the transmission be plagued with jitter (short-term variations in data word-clock frequency) but the source (transport, DAT, digital broadcast, etc.) actually can be operating at a slightly different data/clock frequency than is specified for its type. Both of these factors can affect the operation of the phase-locked-loop (PLL) circuits, which are responsible for capturing the signals. If locking is unreliable, the conversion process suffers and the recovered analog signal is corrupted. If locking fails, the conversion process is interrupted and analog output becomes sporadic. The top "out-of-range" LED indicates that the signal is out of the capture window of the 1611HR's PLLs for 32, 44.1, and 48kHz. Illumination of the middle "±4.00%" LED says that only the primary PLL can be locked, and that that conversion, although possible, will be at less than maximum quality. Illumination of only the bottom "±0.04%" LED is compatible with the highest-quality performance.

In the center of all these buttons and LEDs is a large convex display that boldly shouts "DAT" (for 48kHz), "CD" (for 44.1kHz), or "DSR" (32kHz) when a signal of the appropriate sampling rate is detected. This excessively large and essentially unnecessary display is the only less-than-gracious aspect of the 1611HR. If it is merely to inform us of the sampling frequency, then a number should appear. Otherwise, the LED associated with the selected input is sufficient.

The back panel is, if anything, more impressive than the front. Almost every conceivable connection is provided, usually in duplicate. There are two each of AES/EBU (XLR), S/PDIF (RCA), S/PDIF (BNC), ST glass, and TosLink digital inputs, each independently transformer-coupled at its input. There are BNC and RCA digital outputs. There are two unbalanced RCA and one balanced XLR output for each channel, both for the variable and the fixed analog outputs. And there are balanced and unbalanced analog inputs, which can be fed through to the volume control and the variable analog outputs.

Inside, the mbl 1611HR is fully modular, and the basic componentry, including the delta-sigma DAC stages themselves, is 24-bit–capable. This means that input processing, interboard communications, and noise levels are compatible with high bit-rate and high sampling-rate signals, and that any 1611 can be upgraded to accommodate 24/96 or 24/192 media, when those are standardized. However, the 1611HR would not lock to the CL-20's 96kHz output.

Listening to the mbl
Though I've had the 1611HR in my setup for several months, it never fails to evoke a response when I switch to it from another source. The words that come to mind include "transparency," "dynamics," and "liveliness." While the mbl has somewhat less palpable bass than the other DACs, it is not at all lacking in that quarter. Nor does the mbl seem to have the sort of tilted or peaky frequency response that creates the artificial illusion of "air and space." Nonetheless, recordings always seem to sound clearer and nearer, and to have greater dynamic contrasts than with other systems. (John Atkinson's measurements should confirm that the mbl's output is a bit higher than that of the other DACs. However, I used the Line 3's ability to trim input gain to level the deck outputs.)

I particularly liked what the mbl 1611HR did for jazz combos and the human voice. Aside from the usual female vocal-and-small-ensemble discs by Holly Cole, Diana Krall, and Rickie Lee Jones, all of which were revealed with a greater immediacy of voice and instrumental detail, the mbl was ideal for the bigger ensembles of opera and symphony. The astounding opening of Vaughan Williams' A Sea Symphony (Handley/RLPO, EMI Eminence EMX 2142, CD) made my hair stand on end. Not only was there power in the choral and orchestral outbursts, there were size and space that I hadn't suspected the PSB Gold i's to be capable of.

I next hauled out Zubin Mehta's now-classic recording of Puccini's Turandot (London 414 274-2), always an impressive spectacle, and was bowled over by the expanse of the stage and the depiction of individual voices across it. A more subtle, yet equally thrilling, moment occurs in the final pages of Mahler's Symphony 2 (Rattle/CBSO, EMI CDS 47962), when the soprano's voice emerges eerily from the rich choral tapestry. The mbl delineated the tone and placement of that voice more distinctly than I've heard before, without artificially displacing it into a separate acoustic space.

Switching over to jazz and pop, the sound through the mbl 1611HR was consistently closer to the stage. The plucked string bass on Cyrus Chestnut's Revelation CD (Atlantic 82518-2), had weight, string buzz, and fingerboard slap, as I've heard before. What the mbl also revealed was the plosive quality that one usually gets only at a front-row table. Drums and piano, too, were immediate and clear. The bigger ensemble on Dick Cary's Saturday Night Friends (Klavier 77024) benefited from the mbl treatment, which tightened the bass and permitted me to follow all of the arrangements' delicious intricacies.

I also listened to a lot of chamber music with the 1611HR; the Jan;aacek string quartets with the Stamitz Quartet (Bayer 10051) are a good representative. The rendition was consistently engaging and often gripping, focusing my attention on the dramatic music. Long listening sessions were never fatiguing, but the mbl's focus and intensity made it less suitable for background listening. With all the music sources I tried, it brought out the best in the PSB Stratus Gold i, a speaker that I otherwise found a bit reticent and unengaging.

The 1611HR also sports a superb analog-domain volume control and a single pair of analog inputs. Almost invariably, sophisticated DACs implement gain control in the digital filter, since most modern filters provide this facility. However, whether due to a loss of resolution as bits are lopped off or to suboptimal use of dither in the reconstitution of the bitstream, only the Z-systems rdp-1 seems to have succeeded in doing wide-range digital-domain gain control without compromising sound quality. The otherwise superb Burmester 970 fails in exactly this area. [The Wadia DACs' digital volume control is also well implemented.—Ed].

The much less expensive Camelot Uther 2.0 DAC succeeds by implementing a stepped, remote-controllable analog control, but the mbl 1611HR's buttery-smooth rotary control does even better. Switching from the main outputs to the volume-controlled outputs imposed no constraint at all on the sound of the digital sources. To take greater advantage of this analog stage, mbl has added a line-level analog input, selectable from the front panel or the remote and fed through the volume-controlled outputs. When I piped my tuner or preamplified turntable signals through this input, I thought the 1611HR to be as good as any line preamp I've used.

Against the Burmester & Mark Levinson
The mbl 1611HR is yet another 5dB$ more in cost (footnote 1) than the Mark Levinson No.360, and that increment buys great elegance in design and much sensual pleasure. Its unusual signal-analysis facility holds the upstream components to high standards of performance. The mbl's sound is certainly more lively, forward, and spacious than the Levinson's, the Burmester's, or even the dCS Elgar's, but not as obviously so as the Arcam 9's. I think of the mbl as offering vivid reproduction in both dynamics and harmonics. Alone among these components, the 1611HR consistently sounded like a topnotch analog source. You'll know from the first audition whether the mbl's presentation is appropriate for you, the rest of your system, and your room acoustics; if so, the extra 5dB$ is a worthwhile investment in your musical enjoyment.

In consideration of that "investment value," one cannot ignore that the 1611HR includes a superb analog gain control and line driver along with its multiplicity of digital inputs. Although all of these DACs are upgradeable in one way or another, neither the Levinson nor the Burmester offers a comparable potential of becoming the centerpiece of a no-holds-barred complete system. Down the road, the 1611HR will be able to handle the input from your preamplified turntable completely undigitized, as well as all imaginable digital sources.

The mbl 1611HR is one of the most involving components I've come across. Its extraordinary dynamics and lively presentation suggested the attributes that vinyl devotees, the single-ended triode set, and the devoutly horn-loaded tout for their preferred devices: striking midrange clarity, precise micro- and macrodynamics, and the resolution of extreme detail across the spectrum. Like those devices, the 1611HR isn't for everyone.

And like only the best of those devices, these characteristics of the mbl 1611HR are very subtly distinctive. I emphasize them only in the interest of making a clear distinction between the mbl and other fine equipment. One could argue that, in the hierarchy of other DACs (Camelot Uther, Levinson No.360, dCS Elgar, Burmester 970), it is hard to justify spending a lot more for the small incremental performance differences. However, one cannot deny that the unique performance of the mbl 1611HR sidesteps such relativistic considerations and rewards the listener with its vivid presentation. And don't forget: The analog input and volume control are as good a preamp as you need. How's that for added value?

Footnote 1: Since we are dealing with exponential differences in price, I conjured a new unit of measure, the dB$, to help my deliberations. The dB$ is equal to 10log(price1/price2). I used a multiplier of 10, not 20, because money is power, not merely potential. So, if we make the MSB LinkDAC our reference, the Levinson No.360 is +11dB$, the mbl 1611HR is +16dB$, and the Burmester 970 is +20dB$. Note that the Levinson is merely 1.8dB$ more than the Camelot Uther, and the Burmester is less than 4dB$ more than the mbl! These dB$ values seem to offer a better perspective on the nonlinear relationship between performance and price.—Kalman Rubinson
MBL-Akustikgerate GmbH
US distributor: mbl of America
8730 E. Via de la Luna
Scottsdale, AZ 85258
(602) 991-8001