October 2002

The Manley Labs Shrimp Pre-Amplifier
A Second Look And Listen

Review by Dick Olsher
Click here to e-mail reviewer

  For months now EveAnna Manley's "little crustacean" has been simmering on my "BBQ." Dubbed after an aquatic creature in keeping with Manley Labs' new naming convention, the Shrimp is touted as an entry-level line pre-amplifier. Anecdotally, its initial working name was Anchovy, something which EveAnna apparently enjoys on pizzas and Caesar's salads. But since many do not share her love for anchovies, the decision was made to go with shrimp. Be forewarned that a medium-priced pre-amplifier called the Prawn is in the plans, followed by the cost-no-object Lobster. Lord, not since the days of Charlie the Tuner has anybody in audio had so much fun with sea life.

All kidding aside, and despite its whimsical name and affordable price, the Shrimp is much more than an entry-level pre-amplifier. It most definitely can swim in the company of the big fish. Seasoned to perfection, I now take a second look at a product our own Tony Maresch recently found most addictive.

Kudos to the Shrimp design team (EveAnna Manley, Mitch Margolis, and Baltazar Hernandez ) for a job well done. In contrast with the Stingray, the looks are more understated, yet refined. The finish inside and out is exceptional for a product in the under $2K price point. The front panel is dominated by a "Manley" sized volume knob - almost the size of a church bell. The knob, it turns out, operates a Noble stereo volume potentiometer, which is followed in the circuit by a Noble balance control.

The size and perspective of the chassis gives no immediate visual clue that this is a tube powered pre-amplifier. There are actually a total of four tubes lurking under the hood: a pair each of 12AT7 and 7044 twin triodes. The trick is that the tubes are mounted horizontally. The 12AT7 type is sourced from the Ei factory in the former Yugoslavia. These new production tubes are tested in-house to ensure quality and reliability. The Ei is a great sounding tube and I would like to publicly acknowledge the effort made by Manley Labs to make this tube available to its customers.

You might also wonder why with so many triodes on hand, the voltage gain is only a factor of about four (11.8 dB). Let me first state categorically that I consider a voltage gain of about four to five to be ideal for a line pre-amplifier. Many line stages out there offer a factor of 10 or more in gain, making it difficult to advance the volume control beyond 9:00 O'clock. In addition, more gain is synonymous with greater noise and a poorer signal to noise ratio. The reason for the low gain is inherent in what I consider to be an extremely elegant and effective circuit topology. The input stage consists of a 12AT7 operated in a common cathode configuration. Its advantages are significant: high input impedance, low output impedance, and no phase inversion. Its only downside, and not really an issue for this application, is low gain. This is the only gain stage in the circuit. The output stage is a buffer, which provides low output impedance and wide bandwidth. Rather than use a standard cathode follower circuit, Manley's choice of a White follower affords greater overload margin, less distortion, and an exceptionally low output impedance of 50 Ohms. As a rule of thumb, reject any line stage whose output impedance exceeds 500 Ohms, as cable and equipment interactions become an issue at higher impedance. The Shrimp can sink a fair amount of current and thus power into al low-impedance load like 600 Ohms. That makes it ideal as a headphone amplifier. Curiously, no headphone capability is provided.

High-grade polypropylene film-and-foil capacitors (Re Cap MultiCaps) are used for signal coupling. The one exception is at the output stage, where two monstrous 30 uF metallized polypropylene MultiCaps are used to maintain an extremely low bass cutoff frequency. This is a really nice touch and definitely not in the category of entry level. Note that MultiCaps are notorious for requiring a long break-in period. Plan on a minimum of 24 hours of break-in before any serious listening.

The Sound

The first thing you will ooh about is the amazingly low noise floor. It's like taking a bungee cord jump to the depths of the music's foundation. The decay of ambient information was remarkably well resolved. Nuances in a multi-track mix such as vocal overdubs were easily resolvable. Individual instruments remained distinct during complex passages. In general, the level of clarity was competitive with that of any line stage at any cost.

This Shrimp was a fast swimmer: a sense of speed permeated the music. Plucked instrument and piano overtones unfolded with excellent attack. Treble transients were voiced naturally without emphasis or edginess. Some of the credit for this must be laid at the feet of the low output impedance and exceptional current drive of this design. It is guaranteed not to be impacted by weird cable impedance or power amplifier input impedance interactions.

Space is the final frontier. It defines the setting for the final battle for supremacy between tubes and transistors. When it comes to 3-D palpability, the sensation of being able to reach out and touch someone, tubes stomp the sh$t out of transistors. It's a question of image focus and soundstage layering. In terms of conventional engineering specifications, silicon-based designs appear to be near perfection. But they typically lack the affect and spatial conviction of tubes. This is a perfect example of specs failing to tell the whole story. The enjoyment of reproduced music hinges on perception. This was clearly understood 50 or more years ago when the ear was taken as the final arbiter of musicality. Some technoids dismiss this as nothing more than wine tasting, and miss the essential point: listening to music at home is all about enjoyment. I would no more buy a fine wine on the basis of chemical tests than I would a piece of audio gear solely on the basis of specifications. I'm in no way suggesting that the Shrimp measures badly - it does not! But the differences in focus and depth perspective between the Shrimp and a $5K solid-state preamp are shocking. Early solid-state managed no better than 2-D perspectives, with image outlines at times appearing as cardboard cutouts within the soundstage. And after 40 years of trying, ultra high-end solid-state pre-amplification at best squeezes out a 2.5-D perspective. In contrast, the Shrimp goes all the way. Given appropriate supporting ancillary gear, image outlines snapped into tactile focus. In addition, image placement was precise and rock solid. It felt as though a bright searchlight was aimed at the inner recesses of the soundstage making for exemplary transparency.

Tonally, the Shrimp's presentation was lightweight and airy. Right out of the box, there was a slight brightness to the sound that diminished over the requisite break-in period. However, it did not disappear entirely until I slipped the Ensemble Tube Sox over the entire tube complement. It sort of looks like a condom, but they're not ribbed for pleasure. They're in fact more clever than meets the eye. Woven with strands of Kevlar and pure copper, Tube Sox fit snugly to dampen tube microphonics - while still providing for heat conduction from the glass envelope. And they worked effectively in this instance. The upper mids were infused with sufficient sweetness to conserve the sheen of violin overtones and the patina of soprano voice. On the other hand, the lower mids were not quite my cup of tea. I like a full-bodied, gutsy sound, what you might expect from a 6SN7 based pre-amplifier. The 6SN7 sound might be described as vintage and possibly romantic, and clearly soulful and bluesy in character. It's an interpretation that might be labeled as slightly euphonic, but pleases my musical sensibility. That the Shrimp did not do. Its tonal center of gravity was shifted toward the upper midrange, making the tonal character leaner and less vintage like. If neutrality is defined as a perfectly balanced teeter-totter, then my preference is for a slight imbalance, along the lines of what I experience in a concert hall, tilting up in the lower octaves. Unfortunately for me, the trend in modern designs is for exactly the opposite tilt that is emphasis of the upper octaves.

The Shrimp moved up the food chain considerably with its nifty handling of dynamic nuances. Imagine a fine Swiss watch movement unfolding a time base with great precision. That's exactly how the Shrimp uncoiled microdynamics, progressing up the volume ladder without missing a rung. The music's emotional content ebbed and flowed freely. One of my main criteria in this regard is the passionate reproduction of human voice. I know of audiophiles who would accuse me of being dyslexic in this regard, when I put microdynamics before macrodynamics. If my objective were to reproduce Tchaikovsky's 1812 Overture without compression, they would be right. But when it comes to voice, the magic is in the small details. It is critical for me to resolve the subtle volume and pitch inflections that convey feelings. I am happy to report that I completely enjoyed the Shrimp's ability to convey the passion of a solo voice in full flight.

Conclusion

The Shrimp pre-amplifier is an absolutely engaging sea critter. Its clarity, detail resolution, and dynamic conviction work together to give it a healthy dose of Zen. It is one of those rare components that allow the listener to commune with the music with little effort. Forget all the nonsense about this being an entry-level pre-amplifier. The only thing entry level here is its price. A must audition at any price point. Go ahead, taste it. I think you'll agree that without a doubt, this Shrimp is one scrumptious sonic treat. Bon Appetite!

Specifications

Tube compliment: two 12AT7 and two 7044 
Inputs: five RCA line level
Featrues: Mute switch and warm-up muting delay 
Accurately tracking NOBLE volume control 
Center detented NOBLE balance control 
Record Output 
Two sets of unbalanced RCA main outs 
Gain: 11.8dB 
Frequency Response: 10Hz - 80kHz 
S/N Ratio: typically 95 dB A WGT 20-20K 
Input Impedance: 250 Kohm 
Output impedance: 50 ohms 
Dimensions: 19" x 11" x 3 1/2" (WxLxH) 
Shipping weight: 15 lbs.
Price: $1,880

Company Information

Manley Laboratories, Inc.
13880 Magnolia Ave.
Chino, CA 91710

Voice: (909) 627-4256
Fax: (909) 628-2482
Website: www.manleylabs.com