PRS Blue Sierra Dallas and Original Sewell

September 1, 2009

IT HAS BEEN A SUBJECT OF SPECULATION FOR some time as to when Paul Smith would launch a new line of guitar amplifiers. He’d tried it back in the early ’90s with a short-lived solidstate design, so it seemed plausible that Smith would eventually return to the amp arena with a tube-powered design. A few years ago, Smith needed an amp to perform with at the Dallas Guitar Show. Someone suggested he try one of the models made by Doug Sewell, who also was at the show. Smith played the amp, loved how it sounded, and before long, he and Sewell were designing amps that would ultimately bear the PRS name. In January 2009, two models— the Dallas and Original Sewell—were introduced at the winter NAMM show by Smith himself, who wore a suit for the occasion made from the same amazing looking paisley cloth that is used to cover the amps and speaker cabs. Five months later, GP received the first review samples of these amps, along with a new model called the Blue Sierra, which we promptly put to the test using a Fender Eric Johnson Signature Stratocaster, a Gibson Historic ’59 Les Paul Reissue, a Gretsch White Falcon reissue (equipped with TV Jones Filter ’Trons), a Hamer Newport, and two PRSs—a Custom 22 and a Modern Eagle II. The amps were primarily tested with a PRS closed-back 2x12 ($875), though we occasionally plugged into a Bogner 1x12 open-back with a Celestion Vintage 30 and a Bag End S12B rear-ported 1x12. (PRS also offers 1x12 and 4x10 open- and closedback cabinets.)

Before we get into the specifics of what each model delivers, it’s worth discussing some of the common aspects of these amps. All are class-AB designs that develop 50 watts in base trim, with a 100-watt option (four power tubes) available for an upcharge of $375. You can also specify EL34 or 6L6 tubes at no additional charge. Internal details include aluminum chassis, a glass-epoxy circuit board with handwired components; chassis-mounted pots, switches, and phenolic tube sockets; and an abundance of flying leads for the interconnections. In terms of workmanship, the circuitry looks very clean and built for hard use thanks to generous solder joints, heat-shrink reinforcement on critical cable connections, and silicon glue used to firmly secure the larger capacitors.

Tube biasing on all models is simplified thanks to external test points and a screwdriver- adjustable bias pot on the rear of the chassis. PRS recommends that you have a qualified technician perform this task when changing the power tubes, and while anyone with a digital multi-meter could theoretically do a re-bias, there is no information in the brief manual regarding this procedure. One bothersome thing from a servicing standpoint (or that of buyers who simply want to view the innards of their new amp) is that the four chassis bolts are threaded from the inside of the cabinet, making them—particularly the forward pair—difficult to access due to the limited space between the sides of the chassis. I had to pull some tubes in order to get enough room to swing the handle of my socket wrench, and once the bolts are removed, there’s barely enough room to scoot the chassis out without also removing a section of L-shaped metal that the tube chart is glued to. This is only an issue with the amp heads, of course, but if the head also has reverb (a $335 option), then the tank has to come out as well before the chassis can be freed. One solution would be to make the cabinets for the heads a little taller, so that the reverb tank would not be in the way of the transformers as the chassis is pulled out.


In PRS’ own words, the Blue Sierra, is designed to be “evocative of classic American and British amps, but with a distinct Texas attitude.” That description certainly covers a broad range of amplifiers, and the Blue Sierra is an ambitious design that can dish out a broad spectrum of clean to very distorted tones. Hit with a Les Paul’s bridge pickup, the Sierra’s clean range extends to about one-third up on the Volume control, yeilding nice sparkle with the Bright switch activated, the Treble and Mid controls about halfway, and slightly lower on the Bass control due to the bottom-friendly voicing of this amp. These tones cover the gamut for crisp Fender-style sounds, and the reverb’s rich, airy bloom and smooth decay adds a familiar sense of ambience and dimension. With single-coil guitars, the clean range extends to about 10 o’clock on the Volume knob and the tones exhibit more twanginess (I guess that’s the “Texas” part), while still remaining on the warm side of the tracks.

The Blue Sierra’s “British” persona is revealed as you start wicking up the Volume control. Pummeled with humbuckers, the grit is perfect for Peter Green styleblues/ rock with the Volume pushed a little past the halfway mark and the tone knobs set pretty much mid way with the Bright switch off. With the Volume control at three o’clock, Santana-approved sustain and touchresponsive feedback is available at will—yet it’s still possible to dial in a cleaner rhythm sound by rolling back the guitar’s volume. The Blue Sierra’s preamp section has a lot a gain, and the distortion can get a little flabby and unfocused as the Volume knob is twisted much higher. The power stage is a big part of the equation here too, and running the Master as high as possible in order to get the EL34s contributing their smooth, slightly compressed tonalities to the sonic brew is key to getting the truly hair-raising bluesrock tones from this amp.


I’ll state right now that the Dallas is my favorite of the three amps. Besides being a convenient—albeit a tad heavy—thing to carry to a gig, this 6L6-powered combo is loaded with great sounds that are easy to dial in for pretty much whatever style you play—as long as it’s not something that requires tons of amp gain. The Dallas’ clean sounds are exceptional. Set the Volume at about 10 o’clock, the Treble a little left of center, the Bass a little right of center, and the Mids and the Master both at around two o’clock, and the rich harmonic shimmer that results is inspiring. Touted as being “reminiscent of classic 6L6 American reverb amps” (gosh, what could they mean by that?), the Dallas has more clean range in the preamp and a glassier, more Fender-like vibe overall courtesy of the 6L6s. That said, when the distortion comes on to any significant degree—say, with the Volume knob above two o’clock—you get that cool experience created by of lots of even-order harmonics crystallizing around your notes, allowing them to sing sweetly even at lower levels of sustain. At higher volumes, the distortion is more bright than buttery, but there’s an underlying foundation of warmth and roundness that creates a sort of best-of-both-worlds situation in terms of having an overdrive sound that cuts well but isn’t too skinny. The Dallas has impressive bottom for an open-back combo, but its response is so balanced that you may not even need to touch the Bright switch to get the slice you want— even with humbuckers. Single-coil guitars are a natural with this amp, eliciting ringing highs, silky upper mids, and taut lows. You’ll probably want to use a distortion pedal for super sustaining lead tones, but get one that doesn’t add a lot of midrange coloration so as not to mess with the delicious complexity that the Dallas’ middle frequency range has to offer. Factor in the Dallas’ sweet sounding reverb, its awesome covering, and its abundant volume potential, and this amp wins an Editors’ Pick Award.


While all of the PRS amps are minimalist designs in that they have only one channel, no footswitchable functions, and no effects loop, the Original Sewell cuts things down even further by having only Volume, Treble, Bass/Boost, and Master controls. Our test model doesn’t have reverb either, although it’s available as an option. In the company’s words, the Original Sewell is all about “recalling the complex tones and harmonics of ’50sera amps.” A sort of high-gain, EL34- powered re-think of a tweed-era Bassman, perhaps? That might describe some aspects of this amp, which offers a detailed sounding clean range that extends to about 10 o’clock on the Volume control with the Master turned up about halfway. Push either control much beyond those settings and a nastier attitude begins to emerge. This amp has a lot of natural sparkle, which necessitated a low setting of the Treble knob, the Bright switch off, and a healthy upward twist of the Bass/Boost control (which noticeably pumps up the lows when spun to two o’clock or more). And this was with humbucker guitars! Interestingly, the same settings sounded cool with single-coils too, which would seem to indicate that while the Original Sewell is the brightest sounding of the bunch, it’s still an easy amp to dial in—and one that you don’t have to re-tweak much when switching between different guitars.

The Original Sewell packs way more gain under the hood than any amp from the 1950s. Crank up a guitar with the amp’s Volume control at one-half or higher and you’re greeted by a cutting distortion voice with huge amounts of sustain available as the Volume is nudged to around 3 o’clock. You can hold a note forever in this mode, but the distortion also became somewhat unfocused sounding at these high settings, and had a razory edge that couldn’t be mitigated by switching to humbuckers or turning down the Treble—which was already at a very low setting. Thinking that a preamp tube change might be in order, I replaced the 12AX7 with a lower-gain 12AT7 in the first position and instantly noticed not only improved tightness and focus, but also a timbral change, as the edginess gave way to a warmer glow in the distortion. It’s common practice to experiment with lower-gain dual triodes—such as the 12AT7, 12AY7, and 12AU7—in order to optimize an amplifier for certain playing styles. And while the enhancement in this case may be partly due to the fact that the 12AT7 I used was one of the high-grade JAN (Joint Army Navy) Philips tubes from the Dallas’ reverb circuit, this simple change helped make the bridge pickup on our Fender Eric Johnson Strat sound meaty and badass though the Sewell— and there was still plenty of sustain for solos. Suffice to say, if the notion of having a onechannel amp that allows you to go from harmonics- infused rhythm textures to scorching overdrive with a sweep of your guitar’s volume knob, the Original Sewell could be your ticket to the tone zone.

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