Luxman EQ-500 phono preamplifier
Maybe that's why high-end audio enthusiasts spend so much money on atom sharpeners and quantum-field fencing and other tweaks: In a world where D/A converters turn themselves on as soon as you hook them up to your computerand playback software updates itself while you sleepthe concerned audiophile has precious little to do.
Into that world steps the new Luxman EQ-500 ($7490), a stereo phono preamplifier that has eight toggle switches, three rotary switches with three positions each, another rotary switch with six positions, one potentiometer, two meters, three pairs of input jacks, three pairs of output jacks, three separate ground lugs, and an on/off switch. As a radio announcer of the 1930s was purported to have said after the end of a children's broadcast, that ought to hold the little bastards for a while.
And if you think I'm damning with faint or ironic praise: I'm not.
Measuring a full 17.2" wide by 3.6" high by 15.5" deep, the low-slung EQ-500 could be mistaken for a full-function preamplifier, integrated amplifier, or [gasp] even a stereo receiver. (I blame the meters.) Its hefty steel chassis is fronted with a nicely machined aluminum faceplate and enclosed in a texture-painted steel wrap, the whole weighing 27.5 lbs. Removing the wrap exposes an exceptionally well-finished interior, elaborately constructed with multiple partitions, presumably for shielding. The largest, most eye-catching item inside is an 8" by 11.25" plate of lacquered copper perforated with cooling vents and held in place with four copper screws; this covers the audio circuitry.
The main audio circuit board, which appears to be a star-ground design, is home to no fewer than 19 relays; these are used to implement the Lux's many and varied switching functions, described in detail below. Contained in steel cans are two step-up transformers per channelone each for low- and high-output moving-coil (MC) cartridgestheir wiring suggesting that each has but a single primary and secondary coil. Critical signal capacitors are M-Caps (Fritz Lang's favorites), and most resistors in the audio circuitry appear to be metal-film types.
Also tucked away under that copper cover are three dual-triode tubes per channel, for gain and buffering. Additional gain for MC cartridges is supplied by those proprietary step-up transformers, which are wound on Permalloy cores. In fact, when the EQ-500 is set for use with an MC cartridge, a step-up transformer is the first thing the input signal sees, after which the signal proceeds to two ECC83/12AX7 dual-triode tubes, configured in shunt-regulated push-pull fashion. Sandwiched between those tubes is a passive capacitance-resistance (CR) RIAA de-emphasis stage, implemented with just two capacitors and three resistors. From there, the signal goes to an ECC82/12AU7 dual-triode tube configured as a cathode-follower, then on to a proprietary output transformer, also wound on a Permalloy core.
The EQ-500 is equipped with three pairs of (RCA) input jacks, selectable via its rotary Input switch. Another knob lets you choose among low- and high-output MC and moving-magnet (MM) cartridges, respectively labeled MC Low, MC High, and MM. By determining whether the input signal goes to one of the two step-up transformers or straight to the first of the preamp's active gain stages, this switch also sets the input impedance: 2.5 ohms for MC Low, 40 ohms for MC High, and anywhere from 30k to 100k ohms for MM, adjustable by means of yet another knob, labeled Impedance: a potentiometer infinitely adjustable between those extremes, with 47k ohms at the 12 o'clock position.
Using the Gain knob, the user can adjust the amount of gain produced by the EQ-500's active stages: 36, 38, or 40dB, those figures describing the preamp's performance when set to MM. (The two MC settings result in higher overall gain, of course.) Also of interest to MM enthusiasts is the Capacity knob, for selecting among six capacitive loads ranging from 0 to 300pF.
Additionally, the EQ-500 has a toggle switch labeled Mode for selecting between Stereo and Mono, and a Phase toggle for selecting between a Normal output signal and one whose absolute polarity has been Inverted. Two more toggles, labeled Low Cut and High Cut, offer bass rolloff (a "rumble filter") and treble rolloff (a "scratch filter"). There's also an Output toggle for selecting between Unbalanced and Balanced output, the latter available via output 3, which has XLR sockets instead of RCA jacks.
There's yet another toggle: the EQ-500's Articulation switch. Flip this switch on and a dedicated circuit emits, through whichever input jack has been selected, a signal intended to demagnetize the phono cartridge in use. When doing so, the Articulation switch also automatically mutes the preamp's output so the user doesn't hear all kinds of crazy demagnetizing shit going on.
What do I think of this Articulation switch? I don't know. Once upon a time I bought a Sumiko cartridge demagnetizer, but wound up selling it because I was never sure that it was actually doing anything. So it went here: I tried the Articulation switch, and followed the instruction manual's advice to leave it on for 30 seconds. But I'm still not sure if it produced audible results: I think my EMT TSD 15 sounded less grainy after demagnetization, but if so, the difference was tiny. Nonetheless, I endure in thinking it's a pretty cool thing to have.
The EQ-500's power supply, built around a chunky C-core mains transformer, incorporates an EZ81 dual-diode rectifier tube supplemented by various solid-state regulators, most of the latter secured to heatsinks of generous size. Nice touches aboundprotective sheathing for otherwise fragile cables, and an elastomer pad under the rectifier tube, apparently to keep it from being damaged during installationand the overall build quality is superb.
There's a lot going on in this thing!
Installation and setup
Indeed, there's so much going on in this thing that it's taken me over 1000 words to get to the one thing that isn't going on, and that's ventilation to the outside. Looking at the EQ-500's exterior, you'd never guess there are tubes inside, because the case is completely sealed. (Luxman makes tubed products and solid-state products: before receiving the EQ-500 and reading its owner's manual, I had no idea which one it would be.)
On the upside, during its time in my system, the EQ-500 never felt hotjust warm. On the downside . . . well, maybe there isn't a downside: Luxman has been around since 1925, and I suspect they know their way around tubes. In any event, and in addition to all of the usual generic warningsdon't take this product into the bathtub with you, don't set it on fire, etc.the manual makes a point of stating that the user should take care to install the EQ-500 in a place where there is sufficient space around it, and where it will not be in direct sunlight. I observed those suggestions to the very letter.
Beyond thatwell, what can I say? I sat the EQ-500 on the middle shelf of my Box Furniture Company D3S rack, and connected it to my system using Shindo Laboratory and Audio Note interconnects (all single-ended: I don't do balanced). I applied to it no tweaks, used no accessory AC cords, and modified it in no way.
Listening When I first used the Luxman EQ-500, in place of my usual combination of Hommage T2 transformer plus the phono section of my Shindo Masseto preamplifier, I was by no means turned offbut I wasn't knocked out, either. The overall balance of the sound hadn't been tipped one way or the other, but there was less bass and midbass. (I checked to make sure the EQ-500's Low Cut filter wasn't on. It wasn't.) Also, the size of the reproduced soundfield had gone down a couple of notches: I'd been listening to "Lorraine," from saxophonist Ornette Coleman's Tomorrow Is the Question! (LP, Contemporary S7569), in which Coleman and trumpeter Don Cherry play an eight-bar melody in unison, Coleman panned to the right channel, Cherry to the left; through the Luxman, the distance between them decreased appreciably. Also, the textures of both instruments now contained an excess of seemingly artificial tizz, Coleman's alto sax sounding particularly spitty.
I decided to keep at it and see if things changed for the better.