Audio Research SP-11 preamplifier Page 2

The level-change increments of the volume controls are quite large at reduced settings, becoming increasingly gradual as you turn them up until, near full-up, the increments drop to about ½dB per step. For this reason, at least one control (preferably the "Level") should be operated most of the time near its full-up position, the other turned down appropriately. Running both at about half rotation causes excessive incrementing, which will usually mean the volume setting you seek is halfway between one setting that's too loud and one that's too soft.

I should draw attention to the Mono position on the Mode switch. A boon to serious record collectors who still treasure many mono discs for their performances, this is a welcome inclusion on a preamp otherwise clearly aimed at people who play only the best, most recent recordings.

The "Impedance" switch isn't really that. It's a resistance switch, selecting different values of cartridge loading for MM cartridges and a variety of MCs. The preamp gain, by the way, is high enough, and its noise low enough, that it will work fine with any but the lowest-output MC cartridges, without the need for a signal-fouling step-up device. Thus, there is no sound quality sacrificed through one's choice of MC rather than MM cartridge.

The "Invert" switch is, of course, an absolute-phase (polarity reverse) switch. The Bypass switch throws out all circuitry except the minimal amount required to provide gain, volume control, and output buffering. Even the Balance control is deactivated. I assume that the Direct outputs eliminate even more circuitry, but I can't figure out what. It does make the sound a hair more transparent, but doesn't have as much effect as the Bypass switch.

The unit is extraordinarily quiet! With the moderately efficient Infinity RS-1Bs, and both volume controls all the way up (nothing plugged into the inputs), there is simply no noise from my listening seat. With my ear a couple of inches from the tweeter strip there was an exceedingly faint, smooth hiss—that was it. From phono, with inputs shorted, full up on both controls yielded a moderate amount of hum—primarily 120Hz, and a bit less muted hiss —at a volume setting that would blow the system apart with a 1 millivolt MC cartridge feeding it. Yet there was never any evidence of strain when feeding the preamp with a typical 5mV-output MM cartridge (the Shure V-15). That input stage must have truly astonishing headroom!

Okay, okay. So what do you really get for your almost-$5000? Does it sound like what $5000 should sound like? Oh boy, does it!

First, it must be said that the SP-11, more even than most other preamps, does not like a cold start. After 15 minutes' warmup, it sounds very good—ho-hum. After an hour it starts to pull ahead, sonically, of any of its known competition. After two hours, it is head and shoulders better than anything I have ever heard!

This preamp sounds like nothing! The high-level section is the closest thing to a straight wire with gain that I have ever encountered. (I've heard capacitors that degrade the sound more than the SP-11!) Processing through the phono preamp seems to add nothing more. The sound is just simply neutral. It is indescribable. I can only lamely say that everything you think is superb about your present preamplifier won't be when you hear the SP-11. Highs are unbelievably sweet, delicate and effortless, yet superbly detailed and focused. Surface noise separates out from the music and becomes one-dimensional, assuming a degree of unobtrusiveness that I did not believe possible.

Bass, through phono and line-level inputs, is unobtrusive most of the time, but positively awesome when the music calls for it. (My initial reaction was that it is a little weak. I was just accustomed to it being a little loose.) Bass drum, foot poundings on a stage, subterranean hall rumble, and the deepest organ pipes are reproduced effortlessly and with a sense of power I had not heard from my system before (except when feeding CDs directly to the power amp).

It's all there—remarkable depth and soundstage breadth, stable, pinpoint imaging, prodigious inner detail without the false edge that often passes for detail—the most breathtakingly musical sound I have ever heard from any preamplifier. (I have heard a direct comparison between this and the Audio Research SP-10. The 11 was noticeably better in every respect. I have asked myself this before, but I ask again: How much better can preamps, and power amps, get?) It somewhat embarrasses me, but to date I have not been able to find anything to criticize in the sound of this preamp.

Interestingly, while the SP-11 passes a bypass test so well it is impossible (for me) to tell which I'm listening to, it does not have any of the coolness or subtle dryness I have observed in other preamps that I have characterized as "mercilessly accurate." The SP-11 is both accurate and "musical," if you can imagine such a combination.

There are two bits of bad news, though. One is its formidable price. I have looked inside the SP-11, and I am damned if I can see why it should have to sell for as much as it does. $3000, yes; $3999, maybe. But $4900? Unfortunately, ARC is never going to sell enough SP-11s at that price to justify producing the LSIHs (footnote 1) that might effect a dramatic reduction in their production cost and thus their price (footnote 2). Nonetheless, I must admit that the SP-11 is enough better than any other preamp I know of—or have even heard of—to justify its purchase by anyone who can afford it.

The other bit of bad news is that, after about 12 hours of warmup, the damned thing sounds even better! Noticeably. Every time I listen to it, after it's really charged up, I get two consecutive gut reactions. First, my jaw hangs slack. Second, I get chills and goose bumps. Sometimes I stand up and wave my arms in time with the music and shout the way some well-known conductors are known to do. In a word, I get involved.

The reason this is bad news is that I cannot recommend leaving the SP-11 turned on all the time, as ARC implies (but does not come right out and recommend), because estimated tube life under constant-on conditions is about nine months, and replacement tubes will cost close to $70 if bought from ARC, which I strongly recommend. (Don't muck with success!) On the other hand, there's something to be said for the view that, if you can afford to buy this preamp in the first place, a new set of tubes is probably less than you routinely pay for a box of Havanas or a bottle of Scotch.

The Audio Research SP-11 is an incredible preamplifier, very probably the best preamp that any amount of money can buy today. If it does not sound as musical on some loudspeakers currently in my house than some other preamps I have, I am willing to blame that on the loudspeakers and look for other ones. And I don't usually make that kind of excuse for any product. This calibre of sound quality is what high-end audio is all about!—J. Gordon Holt

Footnote 1: Large-Scale Integrated Hybrid.

Footnote 2: Interestingly, sales of the SP-11 have been brisk since it was first introduced, making it one of ARC's best-moving products. I figure just under $1M sales for the first year, to the factory. The measure of the US's (and the world's) willingness to really shell out for the best has yet to be taken.—Larry Archibald

Audio Research
3900 Annapolis Lane North
Plymouth, MN 55447-5447
(763) 577-9700