The Bargain Class A Usher R-1.5 Stereo Amplifier
The Usher R-1.5 stereo amplifier is built like a tank. Its utilitarian industrial design bears a striking resemblance to the Threshold 300 Stasis designed by audio guru Nelson Pass, which should come as no surprise.
In 1972 Usher Audio's owner and head engineer, Lien-Shui Tsai, built the first Usher R-1.5 amplifier as a copy of the e300 Stasis amplifier whose patent expired, and its designer, the venerated Nelson Pass, had welcomed others to use it. It began as a fun project, however, it soon became a hit with customers and eventually many audio enthusiasts throughout Taiwan became proud owners of this phenomenal amplifier.
"Over the decades much has changed, especially the power supply because parts were not available then that are available now, especially at the quality level," Fred Kat, importer for Usher Audio USA says.
Usher has incorporated some updates, particularly in the input stage and biasing to produce the R-1.5 amplifier ("Usher R-1.5 Amplifiers," Audioreview.com).
"The output stage is the same as some of the Threshold," Nelson Pass wrote in a Do-It-Yourself audiophile forum, "but they look to have stuck an additional gain stage in the middle."
A Class A design, the R-1.5 employs massive heat sinks to cool the amp. As you may know, Class A amplifiers are generally considered the best amplifier design class primarily due to their superb linearity and high gain versus low signal distortion levels when correctly designed. However, they are seldom used in high power amplifier applications due to high thermal power supply concerns. Interestingly, the R-1.5 amp gets warm, but not overly hot to one's touch as one would expect, suggesting that it does not operate entirely in Class A. (Note: my reference amplifier, the Pass Labs X150.8, is a Class A/B design with large heat fins and a similar heat signature). I heard it surmised that in the balmy climate of Taiwan, a fully biased high-powered Class A amplifier would act like a space heater and would be highly undesirable. Who's to say?
Regardless, the Usher R-1.5 employs "Super Cascade" output stage topology using high-powered bipolar metal-encased power transistors designed by Motorola. It also utilizes a large low impedance high capacity EI power transformer (a core of laminated steel in E-I configuration inside bobbin windings) with a high capacitive filtering system and military-grade metal resistors. (Lee, Gary. "Usher Audio 1.5 solid-state Stereo Amplifier." The Sensible Sound. No. 108, April/May 2006. and "Introduction to Transformers and Standard E-I Construction." February 4, 2021. Talema.com). It enlists "ultra-low odd order distortions" to minimize listening fatigue (Lee, Gary). It also includes a Burrow-Brown OPA2134P Sound Plus Series op amp, a bridging switch to allow for monoblock operation, high-quality terminals that accommodate banana plugs or spades, and large handles on the front and rear panels of its chassis.
Massive heat sinks adorn the sides, and rows of vents line the top. At the rear are two more large handles, RCA (unbalanced) and XLR (balanced) inputs, a sliding selector switch for Balanced or Normal (Unbalanced), and a sliding selector switch labeled "Operating Mode" to select Bridged Mode (Mono) or Normal Mode (Stereo), right and left speaker cord outlets, an IEC connector inlet, and an amp fuse port. Underneath, four sturdy legs provide ample support.
Photo courtesy of Usher Audio
A Few Words About Usher Audio
Photo courtesy of Gibson's Steakhouse
A California Red
"The R-1.5 is made to be bridged easily with a flip of the switch in the back," Fred Kat says. "And when you have two R-1.5's to bridge, they will become a pair of monstrous 400 Watts times two into eight Ohms fully differential if using XLR inputs Class A monoblocks, further improving the openness, effortlessness, transient attack, and capability of driving any difficult loads you may encounter."
Their warm signature is intentional. Kat had told me several times that Usher loudspeakers liked tube amplification, thus it shouldn't surprise that their house amp, the R-1.5, has an aural affectation approaching tubes, but with the pace and slam of powerful solid-state.
Although the unbalanced (RCA only) inputs version of the Usher R-1.5 can be found listed online for $3690, the current price for the balanced version is currently $3990, however it will rise to $4390 in October 2022 (both the unbalanced and balanced offerings come with balanced XLR inputs, but in the lesser costing unbalanced design, the XLR receptacles are included in order to facilitate possible future upgrades). Usher USA is currently only importing the balanced version of the R-1.5.
"The reason for the price increase is that the cost of raw materials is continually increasing," Kat says. "In fact, the factory has already increased its price, but I want to give people an extended window of opportunity."
When I compared the Usher R-1.5 to my reference amplifier, the more expensive Pass Labs X150.8, I found it to deliver a more luscious, midrange-forward, and bass-rich presentation.
Far from dry sounding, the more expensive Pass Labs X150.8 ($7150) plays a few ticks to the warm side of neutral with a richness and wallop of its own, but strikes a more neutral and detailed balance by comparison.
The R-1.5 is jammier, it's sweeter; it's a McManis Petite Sirah to the X150.8's Cab Franc. When it comes to preference, as with wine lovers, it boils down to taste.
You Say Tomato, I say ToMAHto!
Beauty is subjective; for years, I have longed to own a brawny Humvee (the High Mobility Multipurpose Wheeled Vehicle used by the U.S. military from 1983 through the present), while Belle prefers the sleeker aesthetic of a Land Rover Discovery luxury SUV (she owned a white one when we first met).
When Belle first spotted the Usher R-1.5 amplifier atop our Simpli Home Skylar 60" Hardwood and Metal TV Stand, she scrunched her nose, and said that it was too bulky and the blue "ON" indicator light was too bright detracting from relaxation time in the family/AV room with the lights down low. Instead, she preferred the cleaner lines and the understated designer look of the Pass Labs X150.8 (with softer blue lighting) that I use in my reference system.
In all fairness, placing the Usher down lower or inside a media console cabinet with slatted or vented doors, rather than in the open at eye level, might reduce the irritation of a bright indicator light, but when it all boils down, it's a matter of taste.
A Hit With The Boys
After 15 to 20 minutes of playback, I transferred the XLR and speaker cables from the Pass Labs amp (which are tethered to the Pass Labs XP-12 preamp) to the Usher. Everyone was bowled over by the boost in presence, warmth, and bass that the Usher R-1.5 imparted to the room.
What's interesting to note is that when swapped back and forth, some preferred the Usher to the more expensive Pass Labs amp, others weren't quite so sure, and yet others preferred the greater detail, neutrality, and nuance of the X150.8.
For example, Bob an audiophile, drummer, and mechanical engineer who works for Motorola, was initially floored with the Usher R-1.5, but when I A/B'ed the Usher and Pass Labs amps playing the John Mayer Trio's rendition of "I Got a Woman," Bob noted that with the X150.8 he could clearly hear the impact of Steve Jordan's wrist turning technique when striking the snare drum, but not so much with the R-1.5.
Joe Jurzec, a software consultant specializing in Computer Maintenance Management system applications and a partner in Purity Audio Design (who builds OEM vacuum tube line stages), preferred the sound of the Usher R-1.5 in my room. However, when he borrowed the R-1.5 and auditioned it with one of his prototype tube preamplifiers, he was surprised.
Would You Like That With A Side Of Tubes?
"It's probably best to use the Usher amp with a very detailed or neutral solid-state preamplifier like your Pass Labs," he concluded.
Interestingly enough, Usher Audio's reference preamplifier, the Usher P-307A Mk II is a solid-state line stage. Imagine that?
Either way, mating the R-1.5 amplifier with a solid-state line stage sounds right to me, but again, it could be tailored to a person's taste. Tomato, ToMAHto!
An Enchanted Listening Session
Jimmy Vallance's spare, sustained single taps on keys and Tom Howie's synth-tinged vocals, "And after all, it's love we've found/well, you being 'round", dissolve and segue into hypnotic, thumping electronica, transforming my room into a top tier dance floor in Bob Moses' "Love We Found" (Bob Moses, Desire. Qobuz FLAC 44.1kHz, 24-Bit, Domino Recording Co., August 28, 2020). And the Usher R-1.5 amplifier delivers this luscious electro-pop concoction of the Native Instruments Maschine, MFB drum machine, Ableton Live, Dave Smith Prophet 5 and Nord Lead synthesizers with ample power, punch, and presence (mixdownmag.com.au).
The R-1.5 spotlights Patricia Barber's low alto vocals supple and often served dry with a touch of melody and warmth lustrous against a black backdrop when she covers Rodgers and Hammerstein's "Shall We Dance" (Patricia Barber, Clique! Qobuz 174.6kHz, 24-Bit. Impex Records, 2021). Together with Patric Mulcahy on his resonant plucked double bass, she enchants with a delightful duet before her swinging piano, John Deitmyer's drums and Jim Gailloreto's tenor saxophone join them on the dance floor. The nuance, articulation, and depth of voice and instruments are luscious, vivid, and compelling as rendered by the Usher amp in this classic American standard.
The string section joined by woodwinds and brass is rife with textures as it crescendos twice, the tympani drum serving as an exclamation point, during the opening moments of "Menuetto, Allegro Molto e Vivace" (Yannick Nezet-Seguin / Chamber Orchestra of Europe, Beethoven: the Symphonies. Qobuz FLAC 192kHz, 24-Bit. Deutsche Gramophone, July 15, 2022). Woodwinds and strings navigate passages that are delicate one moment, and powerful the next as the entire orchestra asserts itself in the refrains. This pattern repeats itself: swirling strings trading leads with woodwinds in quiet moments, followed by surging orchestral swells. The precision, the mathematic orderliness and brilliance of this performance at Germany's largest opera and concert house, the Festspielhaus Baden-Baden, is outstanding, and the Usher R-1.5 delivers it with a freshness and palpable presence.
As mentioned earlier, it's probably best matched with a solid-state preamplifier possessing a very neutral, detailed or sharper signature, as using a warmer tube line stage may yield a presentation that's too buttery and a tad soft on linearity.
That said, getting a reference level, Class A design oozing so much power, presence, and finesse at this price point is a bargain (remember, it was designed to drive any consumer speaker) and worthy of serious consideration.
As a reviewer, I rely on the extra bit of detail, resolution and neutrality afforded by the X150.8 in order to properly assess the gear that I am reviewing. However, if that's not a concern, at $3990, the Usher R-1.5 amplifier is an overachiever and one that I can heartily recommend.