Sidebar 4: Measurements, SimAudio Moon W-5 A full set of measurements of the SimAudio Moon W-5 was made using its unbalanced inputs, with selected measurements repeated in the balanced mode, as noted below.
Following its 1/3-power, one-hour preconditioning test, the W-5's heatsinks were hot, though not to an unusual degree. The W-5 is noninverting from its unbalanced input; pin 2 of the balanced input is positive. DC offset measured a very low 0.9mV in both channels.
The W-5's input impedance measured 49.9k ohms (97.2k ohms balanced). The output impedance measured under 0…
The THD+noise percentage vs frequency curves are plotted in fig.8. The levels here—quite typical for a good solid-state power amplifier—rise slightly (but not alarmingly) as the load impedance is reduced and the frequency increased. The waveform of the distortion at 2W into 4 ohms is shown in fig.9. It is heavily second harmonic, with indications of higher-order components that become a bit more obvious into a 2 ohm load (not shown), plus the inevitable noise. Fig.8 Moon W-5, THD+noise vs frequency at (from top to bottom at 10kHz): 4W into 2 ohms, balanced; 4W into 2 ohms,…
Fig.11, the output spectrum with a combined 19+20kHz signal at 167W into 4 ohms, indicates the intermodulation products resulting from an input signal consisting of an equal combination of these two frequencies. Visible clipping is present above 167W into this load with this input signal. The IM here is quite low—a maximum of -69.4dB, or just over 0.03%, at 18kHz. The result into an 8 ohm load for the same test (at 94W) was virtually identical and is not shown. Fig.11 Moon W-5, HF intermodulation spectrum, DC-22kHz, 19+20kHz at 167W into 4 ohms (linear frequency scale).
The…
A Follow-up review by Kalman Rubinson appeared in May 2001 (Vol.24 No.5): Like everyone else, I go to the January CES to see and hear what's new. I was greatly interested in Simaudio's new multichannel amplifier and their new analog FM tuner, but Lionel Goodfield, their director of media relations and marketing, cornered me: he wanted me to do a Follow-Up report on the $4795 Moon W-5 amp, which I'd reviewed in the March 1999 Stereophile. After all, he said, the many changes and improvements that have been made to the amp over the years justify such a re-examination.
I could see…
Kalman Rubinson followed up on the Moon P-5 preamp in July 2002 (Vol.25 No.7): I approach a Stereophile Follow-Up as a reality check, and the return of Simaudio's Moon P-5 preamplifier to my system was a big one. In re-reading my review of the Simaudio W5 power amplifier and the P-5 in our March 1999 issue, I saw that I had found both to sound sleek and powerful, but ever so slightly velvety and dry at the top end compared to, say, the Sonic Frontiers Line-2 with its more silky treble. Aside from that, I had found little to distinguish the sound of these two excellent preamps.
So…
In the past few installments of this column I've promised to talk about another subwoofer equalizer system. Now I'm going to pull the old switcheroo and discuss a different subwoofer EQ. The SMS-1 is a new, standalone digital equalizer system from Velodyne, based on the EQ built into their DD-series subwoofers. Larry Greenhill went gaga over the Velodyne DD-18 in the June 2004 Stereophile, particularly because of the ease and sophistication of the EQ system. Apparently, one of the Velodyne sales guys asked the obvious: What about making the EQ available separately for use with other…
But subwoofers were not invented to reproduce recordings of the solo violin. Regardless of the number of voices and instruments, real and otherwise, that were playing, the bass on the Polyphonic Spree's newly EQ'd Together We're Heavy (DVD-Audio, DTS Entertainment 69286-011189-9-1) was now nimble, and defined in ways I had not suspected. Electric guitar and bass on B.B. King and Eric Clapton's Riding with the King (DVD-A, Reprise 47612-9) had a powerful kick that remained focused both tonally and spatially. Organ-pedal notes were now tubey and reedy, with discernible fundamentals, even when…
Sidebar: Records in the Round
GERSHWIN: An American in Paris, Catfish Row, Promenade, Rhapsody in Blue, Cuban Overture
Jeffrey Siegel, piano; Leonard Slatkin, St. Louis Symphony
Mobile Fidelity UDSACD 4007 (SACD)
Yet another spectacularly successful transfer by Paul Stubblebine of Nickrenz-Aubort master tapes to SACD. If you like this music and you're over 40, you probably have these performances in their original releases or on Classic Records DAD 1018, but you ain't heard nothing yet. In 4.0 channels, the orchestra is more coherent as an ensemble performing in a real…
It's a common audiophile failing to remember the past as being much better than it actually was. (Though, of course, some things were better.) I remember the first time I heard a pair of Acoustic Research LST loudspeakers, in 1974 or thereabouts. Compared with the Wharfedales I used in my own system and the various Goodmans, Celestions, and home-brews I heard at friends' homes, the sound of classical orchestral recordings on the ARs was about as close to the real thing as I could imagine. And the AR ads reinforced my experience, telling me that musicians such as Herbert von Karajan also used…
Sound
One of the advantages of a sealed-box woofer loading compared with reflex is the slower rate of rolloff below the system resonance: 12dB/octave compared with 24dB/octave. With the response in a small room typically rising at 4dB or so per octave in the bottom two octaves due to boundary effects, a sealed-box speaker can have impressive bass extension for its size. The big-bottomed 303 does low bass better than any other $1200/pair loudspeaker I've heard. Whether it was classical pipe organ or the synth bass on Annie Lennox's new Medusa CD (Arista 25717-2)—check out the awesomely…
