In the digital domain, the data word length is inexorably tied to the ultimate level of the noise floor. The longer the word, the lower the noise, with an approximate increase of 6dB in the system S/N ratio every time the word length…
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Before I discuss the results of my auditioning, I'll present the measured results. These were all taken in the digital domain using an Audio Precision System One fitted with the DSP option. The Meridian 518 was fed a data signal from the AP's AES/EBU output, set to a 20-bit word length. The 518's AES/EBU data output was looped back to the AP's digital input.
The Meridian offers seven different noise-shaping algorithms, shown in Table 1. The spectral effects of each on the noise floor, hence the ultimate resolution, are shown in figs.8 through 14. (All of these were made using our old friend, the 1kHz tone at -90.31dB.) Which will be optimum depends on the nature of the original signal, the playback situation, and individual taste. For example, I ended up using Shape A on the Concert CD, which was originally recorded on analog tape. For Festival, for which I used a Nagra D 20-bit digital recorder, I used Shape C. And the late recording engineer…
Glitches: Any recording engineer using A/D converters with better than 16-bit resolution but storage media restricted to 16 bits—CD, CD-R, DAT, etc.—owes it to their sound-quality-conscious customers to use a Meridian 518. However, I did have one operational problem using the 518 in that I could not get my Panasonic 3700 professional DAT recorder to lock to its output, even with the channel bit set to "P" for "Professional." For the Festival project, I used a Meridian CDR as an interim storage medium (footnote 1), as this would lock onto the 518's data output with the channel bit set to "C"…
Sidebar 1: Description
Specifications: Digital processor, with infra-red remote control, capable of operating in three modes: "Type 0," Digital Control Center with digital source selection and digital volume control (1dB step size); "Type 1," Digital Resolution-Enhancement Device with user-selectable input/output data-word lengths, gain, and dither/noise-shaping (five algorithms available); "Type 2," Digital Mastering/Multimedia Processor. Digital inputs: three electrical S/PDIF (RCA); one S/PDIF optical (TosLink); one AES/EBU (XLR). Digital outputs: one AES/EBU (XLR); one S/PDIF (RCA).…
Fig.1 D/A Processor with 20-bit resolution, waveform of undithered 1kHz sinewave at -90.31dBFS (16-bit data, 120µV/vertical div.).
Fig.2 Meridian 518, spectrum of undithered 1kHz tone at -90.31dBFS, with noise and spuriae, 16-bit precision.
Fig.3 Meridian 518, spectrum of 1kHz tone at -90.31dBFS, with noise and spuriae, 20-bit precision.
Fig.4 Meridian 518, spectrum of 1kHz tone at -90.31dBFS, with noise and spuriae, 16-bit precision, calculated from 20-bit data with 518 set to "20C16" using the "Shape B" noise-shaping algorithm.
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Fig.8 Meridian 518, spectrum of 1kHz tone at -90.31dBFS, with noise and spuriae, 16-bit precision, calculated from 20-bit data using the "Flat TPDF" noise-shaping algorithm (linear frequency scale).
Fig.9 Meridian 518, spectrum of 1kHz tone at -90.31dBFS, with noise and spuriae, 16-bit precision, calculated from 20-bit data using the "High-Pass TPDF" noise-shaping algorithm (linear frequency scale).
Fig.10 Meridian 518, spectrum of 1kHz tone at -90.31dBFS, with noise and spuriae, 16-bit precision, calculated from 20-bit data using the "Shape A" noise-…
Letters in response to this review appeared in March 1996 (Vol.19 No.3):
Goodbye
Editor: Thank you for a fun half-decade of sheer delight! It has been most enjoyable indeed. But I have purchased the Meridian 518 processor JA reviewed in January, some sound cards and music software for the ole PC, and am generally flying the flag of the Computer Camp. I'm not kidding myself, it's not hi-fi...yet, but it's one fun sandbox to play in! Anyway, it's not goodbye. I'm sure that I'll be seeing you guys again in five years when a fair portion of your advertisers will probably be selling…
John Atkinson wrote again on the Meridian 518 in July 1996 (Vol.19 No.7):
Reader Gregory Comnes of Tampa, Florida took exception to my January 1996 review of the $1650 Meridian 518 Digital Audio Processor (Vol.19 No.1, p.249): "Shame on you for missing the point..." he thundered. "You allude to Meridian's claim that, when used as a digital preamp, the 518 can sound 'frighteningly good,' but you didn't have time to use it as a preamp! How long could it have taken to hear what for most of is the most compelling reason for CD-only users to own this piece: the elimination of a compromising…
"Rarely, if ever, can this densely written sonata have been presented so lucidly with each note precisely in place...the dramatic and lyrical aspects were never slighted or taken for granted."
—Peter G. Davis, writing in the New York Times about Robert Silverman's New York debut in 1978, when he performed the Liszt B-Minor Piano Sonata in Alice Tully Hall.
—Peter G. Davis, writing in the New York Times about Robert Silverman's New York debut in 1978, when he performed the Liszt B-Minor Piano Sonata in Alice Tully Hall.
If you listen in order to the sounds of the three previous piano recordings I have produced—Anna Maria Stanczyk performing Chopin on the first Stereophile Test CD, Robert Silverman performing Brahms on Intermezzo, and performing…
And even when things are optimized for two omni mikes, the imaging is never better than vague. We had not had a choice with Concert, as explained in the article that appeared in the liner notes. However, the sense of "bloom" on this recording was the best yet. I therefore wanted to stick with the spaced B&K omnis for Sonata, yet I wanted to reinforce them with a centrally placed microphone array. I hoped then to be able to have my cake and eat it too: combine the true tone colors, extended low frequencies, and sense of ambient spaciousness captured by the pair of omnis with the more…