The Fifth Element #71 Page 2
Luxman MQ-88 tubed power amplifier
Luxman's MQ-88 ($8000) is a classic push-pull tetrode design based on the KT88 power tube; the small-signal tubes are pairs of 12BH7s and ECC83s. Luxman claims for the MQ-88 an output at 40Wpc into 8 ohms, an input sensitivity of 420mV, an input impedance of 100k ohms, a total harmonic distortion at 1kHz of 1.5%, a frequency response of 5Hz90kHz (+0/3dB), and a signal/noise ratio of more than 101dB at 1kHz (IHF-A).
The MQ-88 has several distinctive features. The first is that, for a 40Wpc amplifier, it's massively builtat 55 lbs, it's the heaviest 40Wpc amplifier I have had experience with. The next is that it's hand-wired, point-to-point, and all internal circuit components are suspended from its 15mm-thick top plate, which Luxman claimed is a vibration-tuning measure. The weight of the transformers and top plate is carried down to the footers by internal pillars. Luxman claims that the MQ-88's vibration- and resonance-control design was arrived at by critical listening. The MQ-88 comes with a finely perforated tube cage that I removed for my listening. In front of each power tube is a small recessed button, pressing which engages the centrally located bias meter. Next to each button is a recessed slotted shaft for adjusting the tube's bias with a screwdriver. On the top panel is a recessed on/off button.
The MQ-88's industrial design is simple and refined. Everything is where you would expect it to be; complication has been reduced to a minimum. Instead of multiple loudspeaker terminals, to take into account varying speaker impedances, there is one set of positive and negative speaker terminals per channel. All the switchgear and connection hardware is of very high quality. There are both fixed and adjustable inputs, to allow direct connection of a line-level source such as a CD player, but no balanced inputs. The volume control is on the front panel under the top plate's overhang, but there is no provision for remote control.
In use, the MQ-88 was glitch-free with a variety of speakers, from Vivid's B1 and K1 through the Rogers LS3/5a to Direct Acoustics' Silent Speaker II to several amateur DIY projects-in-progress a friend brought over. It was very quiet in operation, in terms of both the lack of noise radiated by its transformers into the listening room, and of the very small amount of "tube rush," or hiss, which I could hear only when I placed my ear very close to a tweeter.
Two things stood out about the MQ-88's sound. First, it sounded much more powerful than a 40Wpc ampmost visitors guessed it was 65Wpc or more. The MQ-88's ability to fill the room with the sound of a pipe organ or orchestra was as surprising as it was satisfying, and underlined once again that the rated number of watts is only half the storyoutput current is as important, and for certain speaker designs, more important. In my experience, the oomph factor, especially in a tube amp, requires very large transformers, which by some law usually translates into a much higher retail price. The MQ-88 had oomph in spadesby any measure. (More listening impressions and two recommended recordings are found above, in my comments on Luxman's D-05 SACD/CD player.)
The other thing that stood out is that, unlike some contemporary designs (one that comes to mind is Ars-Sonum's Filarmonía SE, which I wrote about in October 2007), the MQ-88 is "a tube amp that sounds like a tube amp" (the Ars-Sonum not so much, but it still sounded great to me). I think that's the heart of the MQ-88 story.
I have previously expressed my exasperation at manufacturers that don't take steps to make their product lines even minimally comprehensible to people outside the company; eg, those who offer two different speakers, both priced at $5000/pair. Therefore I was glad when Luxman importer Philip O'Hanlon volunteered that, for $8000, the buyer of an MQ-88 gets "the next level up in midrange liquidity" from Luxman's top-of-the-line solid-state integrated amplifier.
The MQ-88 is about enjoying the vacuum tube experience in the most fuss-free way possibleits glory is in its delectable midrangebut it is not an amplifier for all seasons. As I noted in my review last June of the Direct Acoustics Silent Speaker II, the MQ-88 did not do a great job of controlling its bass (and was marginal in output power). In direct comparisons with Ayre's entry-level solid-state integrated amplifier, the 60Wpc AX-7e ($3500), and using a variety of speakers, the Ayre did a better job of resolving power and bass extension and of controlling and organizing the soundstage. But the Ayre's midrange was not as beguiling. By the way, the combination of Luxman's D-05 SACD/CD player ($5000) and the Ayre AX-7e was remarkably synergistic; the total price of $8500 strikes me as a best buy in mid-upper-tier electronics.
Perhaps to some extent owing to the fall of the US dollar, and in large part to its being made in a high labor-cost country like Japan, Luxman's MQ-88 is more of a premium-priced near-luxury product than an affordable one built to a price point. I think the best way to look at the MQ-88 is as a cost-no-object, artisanal maxing out of classic 1950s push-pull tubed power-amp design. If the MQ-88's particular virtues (which I find extremely attractive) appeal to you, and if your speakers and room are likely to be synergistic with classic tube sound, the MQ-88 is well worth checking out.
Luxman C-600f preamplifier
Luxman's C-600f is a solid-state preamplifier ($9000) housed in a standard component-racksize chassis measuring 17" wide by 5" high by 16" deep and weighing 29 lbs. Its casework is of very high quality, and its industrial design reminds me of a bank vault. It has a full complement of five single-ended and two balanced inputs, two single-ended and two balanced outputs, and a tape-processor loop, but no phono stage. Its bass and treble tone controls are, unusually, operable from the remote control, as are phase inversion and channel balance. The C-600f can be put in Standby mode by pressing a button on the supplied, all-metal remote control.
Luxman states that the C-600f incorporates technology also found in their flagship C-1000f preamplifier ($32,990). The C-600f's volume-control knob is counterbalanced to mimic the feel of a conventional volume control, but it doesn't control the volume in the usual sense; it only sends a signal to a CPU that selects the current switches in the preamplifier module. The C-600f's control circuit converts audio voltage into current, then attenuates that according to the volume setting, then reconverts the current into voltageall in the analog domain. This is claimed to maintain a high signal/noise ratio and low distortion regardless of volume setting, and also makes possible remote volume control without a motorized potentiometer. In similar fashion, the C-600f's source selection is electronic. The manufacturer claims that these features will provide longer trouble-free operation than do mechanical controls.
The C-600f arrived as a replacement for the tubed CL-88 preamplifier ($6000), which suffered from FM-radio interference. The CL-88 is smallerabout half a rack space wideand its height is minimized by positioning its tubes horizontally, entirely within its chassis. The CL-88 is not remote controlled. Replacing the CL-88, whose notably sweet, tubey sound I really enjoyeddespite sometimes getting a little "Hey, Soul Sister!" mixed in with my Mahlerwith the C-600f resulted in an immediate lowering of the noise floor, accompanied by gains in overall neutrality and dynamics.
The C-600f's sound with the MQ-88 was transparent and open, with a wonderful balance of detail and warmth. But if I had to choose among virtues, I'd say the openness was somewhat more apparent than the transparency, and the warmth slightly more apparent than the detail. Had I been told that the C-600f was full of priceless New Old Stock tubes, nothing I heard would have made me suspect I was being fooled. I enjoyed my time with it immensely. If the price of Luxman's flagship C-1000f puts it out of reach but the C-600f's $9000 price does not, by all means arrange an auditionI think you'll be charmed.
Ah, the poor DEQ2496always a bridesmaid, never a bride. I have held this over long enough, so brevity must be the soul of my wit. Behringer's DEQ2496 ($653.99, but often available for under $300) is an entry-level professional, rack-mount suite of digital audio signal-processing functions, from dynamic EQ through reverb through digital room correction. Though it's far more than a DAC, I think that most Stereophile readers will want to know simply whether the Behringer DEQ2496 should be on their shopping list when buying a DAC for $500 or less. Absolutely. Yes.
Right out of the box, the DEQ2496 sounded cold, thin, and forward. Both break-in and daily ministrations with Ayre Acoustics' Irrational, But Efficacious! System Enhancement Disc, Version 1.2 cured most of that. Indeed, the DEQ2496 is the one component that seems to have benefited most from treatment with this disc.
The Behringer's essential sound quality in Bypass (DAC only) mode was clear, fast, and lean, with good bass and dynamics. For a sub-$500 DAC it had impressive resolving power, and indeed did sound like gear with a professional pedigree. Over the course of days, however, that leanness got to be a bit too much for me, so I engaged the DEQ2496's Graphic Equalization function and put a shelf in the midrange of +2dB from 160 to 800Hz. That did the trick, with no ill effects from signal processing that I could hear.
And there you have the DEQ2496's appeal: If the idea of digital EQ doesn't make you run screaming from the room, the DEQ2496 is an amazing bargain, and might very well be the cheapest way to solve some problems in system matching or room acoustics. It lacks a USB input, but it does accept S/PDIF via TosLink, so it's a viable computer-audio solution, at least for Macintosh owners. Its electrical digital input is AES/EBU on XLR, but that is switchable to S/PDIF via the setup menu. Analog outputs are balanced on XLR, so custom cables or adapters may be needed. All in all, the DEQ2496 might be too complicated or tweaky for many audiophiles, but for those willing to read the manual and follow the learning curve, it might be just the ticket. Recommended.