Audio Research • LS17 SE Line Stage
One of the decisions a vinyl-spinning audiophile must make when contemplating a new preamplifier is that of an integrated preamp (complete with phono stage) vs separate phono and line stages. The integrated approach certainly has its benefits, namely less space requirements and a (usually) smaller price tag (especially if one includes the sometimes not inconsiderable expense of an extra power cable and an extra pair of interconnects). It was partially the latter of these that drew me to choose an Audio Research SP9 as my reference preamp a few years ago. Assuming space is not an issue, one can always add an external phono stage later as funds allow (this is what I have done). Space and cost considerations aside, though, there’s no denying that if sound quality is one’s highest priority, separate phono and line stages are arguably the way to go.
As I recount in my review of the Audio Research PH8 phono stage, my receipt of the LS17 SE review sample was a happy side benefit of reviewing the PH8. Simply put, I didn’t want my SP9 to compromise the PH8’s abilities. As good as it is, at the end of the day the SP9 was Audio Research’s entry level integrated preamp, and cost about one-third the PH8 does now (excluding the effects of inflation).
Technical Details
The LS17 SE is the entry-level model in Audio Research’s quartet of line stages, its bigger brothers being the LS27, the Reference 5 SE, and the recently introduced two-chassis Reference 10. It has two pairs of balanced inputs and four pairs of single-ended inputs, and two pairs of balanced outputs and one pair of single-ended outputs (there are also a set of single-ended record and monitor inputs and outputs). One pair of single-ended inputs is a unity gain home theatre bypass, labelled Proc. This allows the LS17 SE to be used in systems that are both stereo and multichannel; in the latter, the front left and right channel outputs from one’s surround sound processor would be connected to the LS17 SE’s Proc inputs with the former controlling the volume level.
The back panel houses the plethora of gold-plated RCA and XLR input and output sockets, and a 15A IEC mains socket. There is also a 12V trigger output for controlling other components.
Like other ARC gear, the front panel (which is made from a 6 mm thick sheet of machined aluminum) is available with either a natural or black anodised finish; the purchaser can also specify the finish of the front handles (natural or black anodised). The default is for the handles to match the front panel, but I find black handles with a natural faceplate rather fetching (this is probably a holdover from my appreciation of the older Audio Research aesthetic). In addition to the handles, the front panel is also home to a display which uses LEDs to display the current input source and volume setting (there are also LEDs for mute, processor, and monitor).
Flanking the display on either side are a pair of control knobs. The left knob adjusts the volume (in 104 steps), whereas the one on the right selects the input. Below the display are four round aluminum buttons which control the power, monitor, processor, and mute functions. Although the buttons are perfectly serviceable and make sense in the context of a remote-controllable device, I really missed the silky feel of my SP9’s clunky toggle switches when operating the LS17 SE’s buttons. Ah, such is the price of progress, I guess!
The front panel controls are duplicated on the included remote control, although each input has its own button rather than mimicking the sequential nature of the front panel’s input selector. I’m obliged to mention that I think the plastic remote control, like that which comes with the PH8, feels a bit cheap for a product in this price category and quality aspiration. Fortunately, this feeling doesn’t extend to the LS17 SE itself, which exhibits a very fine build quality.
Inside the case we find a single large circuit board. About one third of the circuit board implements the power supply, the remainder being used for the audio circuitry. The solid state power supply features a custom transformer, multiple stages of regulation, and a fairly generous capacitor bank. Each channel of the non-inverting Class A audio circuit is built around a JFET-based front end and a 6H30P dual triode, and high quality components—including Teflon coupling capacitors—are used throughout.
The differences between the SE and non-SE editions of the LS17 are essentially the updated cosmetics to the front panel (bringing it in line with other contemporary Audio Research models), and upgraded coupling and Teflon bypass capacitors. Non-SE LS17s may be factory upgraded to the SE; interested owners should contact their Audio Research dealer for more details and pricing information.
Setup and Listening
The first thing one must do when setting up the LS17 SE is install the two tubes, which are safely packed in foam for shipping. After removing the top cover (and its attendant 14 screws), the tubes are inserted into their sockets. The tubes and sockets are clearly marked, so this is an easy task for even the most wary tube neophyte.
What Audio Research giveth with one hand, they take away with the other: although the LS17 SE sounds fine out of the box, it doesn’t sound its best until it is fully broken in. There’s nothing unusual with this (pretty much all gear doesn’t sound its best until it has been broken in), but Audio Research recommends a full 600 hours of break in time! This is primarily due to the Teflon capacitors, whose dielectric takes a notoriously long time to form. The sound quality during the break-in period is bit up and down. At times the sound was good, at other times not so much: the sound became darker at times, and less involving. The key point is if you’re evaluating a LS17 SE and considering a purchase, make sure that it is fully broken in. To help speed up the break-in process, I used Granite Audio’s excellent burn-in CD. Note that Audio Research caution against leaving the LS17 SE permanently powered on, so I only used the burn-in CD when not actually listening to music until I went to bed for the night.
As with the PH8, I evaluated the LS17 SE in two phases: the first by inserting it into my system in place of my SP9 using my usual Allnic H-1200 phono stage, and the second by using it in conjunction with the PH8.
Like the PH8, the LS17 SE is sensitive to power conditioning. After careful evaluation, my observations matched Audio Research’s recommendations: i.e., the LS17 SE is best used without a power conditioner (or, perhaps more precisely, without the Furman 15PFi; YMMV with other power conditioners).
Listening
My first impression of the LS17 SE was that it was not spectacular, in that it doesn’t shout “Here I am!” in a hi-fi sense. Lest I be misunderstood, let me be clear: this comment is not a slight against the LS17 SE, rather it is a compliment. The LS17 SE is polite, unobtrusive, and gets out of the music’s way.
Its noise floor is very low, allowing instruments and voices to fully form out of the blackness. The decay of bells and the like is longer, by which I mean that they’re audible for longer because they’re not being truncated by noise and other artifacts. This was something which I noticed not by the sound of noise from my SP9, but from its absence with the LS17 SE.
The LS17 SE’s transparency to the source means that little details, the likes of which I hadn’t heard before, are revealed as if for the first time. An example of this is can be heard in Mike Oldfield’s Tubular Bells [Virgin Records V2001]: just before he starts playing the acoustic guitar after the gongs prior to the finale’s intro, you can hear his fingers on the guitar’s fret board as he gets ready to play. Remember that I’ve listened to Tubular Bells countless dozens of times—it has been one of my references for years—so I find new details being revealed to be very impressive.
After Tubular Bells I switched to another (relatively new) favourite of mine: Prokofiev’s Lieutenant Kije [Classic Records/RCA Victor LSC-2150]. This is one of the records I use to test how well a component images, and in this department the LS17 SE is no slouch. The opening trumpet is clearly off stage to the left, but the reverb from both it and the opening snare drum (which is also stage left) can be heard from the rear right of the stage. This gives the listener an insight into the recording venue’s acoustic envelope.
Sticking with imaging, it was easy to locate the various instruments in the sound field: violins in an arc near the front, brasses to the right and behind the strings, woodwinds towards the centre, and so on.
Another audio attribute I test for using Lieutenant Kije is bass weight and dynamics. The drum whacks in the first and third movements should have a visceral, almost palpable, quality to them, but they didn’t have quite the weight and didn’t engender a “jump out of your skin” reaction with my usual phono stage. I’m inclined to attribute this more to the phono stage than the LS17 SE: the H-1200 is a good phono stage, but not a great one.
Thinking that I had identified a trend, I put Kate Bush’s The Kick Inside [EMI EMC 3223] on the platter and listened to Wuthering Heights. The tell-tale goosebumps I get when everything is just so were hinted at, but didn’t appear. Again, I’m disinclined to blame the LS17 SE, which was just reproducing what it was fed from further up in the audio chain. It was time to up the ante, so I replaced my usual phono stage with the PH8. Coupled with the PH8, the LS17 SE’s strengths were (if you excuse the pun) amplified, but rather than repeat myself here, please read my PH8 review for a description of how the two components sounded together.
Verdict
The Audio Research LS17 SE is a fine-sounding, moderately-priced tube line stage which benefits from being used with the finest ancillary components. Its excellent build quality, enough inputs and outputs for all but the most complex of systems, and nifty features such as remote control, and a pair of balanced inputs and outputs only add to its value proposition. I have no hesitation in recommending the LS17 SE to prospective purchasers, and can only imagine what its bigger brothers can accomplish!
Specifications
Description Tube line stage.
Frequency response +0, -3 dB 0.5 to 200 kHz.
Gain 12 dB (balanced), 6 dB (single-ended), 0 dB for tape output and processor input.
Distortion < 0.01% at 2 V RMS balanced output.
Noise 1.7 μV RMS residual IHF weighted balanced equivalent input
noise with volume at 1 (109 dB below 2 V RMS output).
Input impedance 120K Ohms balanced, 60K Ohms single-ended.
Output impedance 600 Ohms balanced, 300 Ohms single- ended.
Output polarity Non-inverting.
Maximum input voltage 20 V RMS balanced, 10 V RMS single-ended.
Crosstalk -80 dB or better at 1K Hz and 10K Hz.
Tube complement Two 6H30s in the gain stage.
Dimensions (whd) 470 mm x 132 mm x 305 mm.
Weight 5.9 kg.
Finishes Natural and black anodised aluminum.
Serial number of unit reviewed 91103702.
Price $3,995.
Warranty Three years non-transferable (90 days for tubes).
Manufacturer
Audio Research Corporation
3900 Annapolis Lane North
Plymouth, MN 55447-5447
USA
(763) 577-9700
www.audioresearch.com
Associated Equipment
Analogue source Forsell Air Reference Mk 2 turntable and arm.
Phono cartridge Lyra Atlas.
Phono stage Allnic Audio Labs H-1200, AUdio Research PH8.
Preamp Audio Research SP9 Mk 2.
Power amplifiers PrimaLuna ProLogue Sevens.
Speakers MartinLogan Spires.
Cables Phono: Nordost Frey. Interconnects: Nordost Frey. Speaker: Nordost Frey. AC: stock.
Accessories Target and SolidSteel equipment stands; Mission Isoplat; Furman Elite 15-PFi power conditioner; Audio Physic cartridge demagnetiser; Acoustech carbon fibre brush; Last record and stylus cleaning products; Audio Additives digital stylus force gauge; Spin Clean Record Washer Mk II.