Manley Labs Jumbo Shrimp Pre & Mahi Power Amplifier Review

Posted on 13th December, 2023

Manley Labs Jumbo Shrimp Pre & Mahi Power Amplifier Review

Chris Frankland feasts on this exquisite-sounding tube preamp and monoblock power amplifier combination…

Manley Labs

Jumbo Shrimp/ Mahi

Pre/ Power Amplifier

£5,299/ £6,999, respectively

Manley Mahi review

There's something fishy about US-based tube specialists Manley Labs. The company's naming policy pays tribute to underwater creatures, including the Stingray II integrated amplifier, Steelhead phono stage and Snapper II mono power amps, among other delights. Its range also includes more prosaically named products too, but they're no less exotic in their design or sound quality. This shouldn't come as a complete surprise, given the company's history…

Manley has been making valve amplifiers since the late nineteen eighties – when the breed was very much out of fashion – while gleefully proclaiming, “Tubes rule!” It started out as part of a company called Vacuum Tube Logic (VTL), and the current CEO, EveAnna Manley (then Dauray), began working for the production team in 1989. She then married David Manley and started to run the factory. VTL and Manley Labs went their separate ways in 1993. David moved to France, and he and EveAnna subsequently divorced, and she took over the company in 1996


Manley is proud to boast that its products are entirely made in California. Indeed, on the website, there's a photo of a beaming EveAnna wearing a T-shirt with the slogan “Not Made in China”. The original Shrimp dates back to around 2002. It is a line-level-only, minimalist all-tube design using two 12AT7 input valves, a pair of 5670 driver valves and a brace of 7044 output valves. The manufacturer says it delivers high bandwidth, low noise, low distortion and uses only modest local negative feedback.

Manley Jumbo Shrimp review

The current iteration uses a dedicated White-Follower output stage that provides a low 50 ohm output impedance, which is said to be, “much better than a boring, plain-old cathode follower”. As a nod to modern technology, it has a motorised ALPS volume potentiometer, allowing remote control operation. Inside, it sports MIT MultiCap polypropylene coupling capacitors. It is housed in a sturdy aluminium case with an attractive solid brushed gunmetal grey front plate and has nice-to-use metal rotary knobs to control volume, input, balance and on/off. All inputs on the rear panel are via gold-plated RCAs. No balanced inputs are provided.

The Mahi monoblock is also beautifully made and housed in a sturdy hexagonal case sitting on four large metal feet. Like the preamp, it has a large Manley illuminated badge on the front. After the introduction of the Snapper in 2002, Manley decided it was time to update the Mahi, and so it now has a triode/ultralinear mode switch as standard (more about that later) and German WBT binding posts.

Manley Mahi review

The Mahi mono power amplifier delivers a claimed 24 watts into 8 ohms in triode mode (standard feedback) from four EL84/6BQ5 tubes, driven by a 12BH7 (or 6414) dual triode driver and a 12A7EH input dual triode. There are two transformers at the back, mains on the left and Manley's own, in-house manufactured output transformer on the right. There are also toggle switches for different levels of negative feedback – standard (6dB), minimum (3dB) and maximum (10dB). The company says that feedback alters an amplifier's slew rate, or speed, and invites users to use their own ears to decide which they like best. It can make quite a sizeable subjective difference to the sound.

As mentioned, you can switch the output valves between triode and ultralinear modes. The former is when the screen grids are hooked up to the plates of the EL84s and is generally regarded as giving a sweet sound. Ultralinear offers partial triode operation, where the screen grids are connected to special taps on the primaries of the output transformer; this provides more power, with 40 watts quoted (standard feedback). The bias current for the four EL84 output tubes can be adjusted to keep the heater filament of the tube running at an optimal setting. Manley provides a digital multimeter for this purpose, and there's a video tutorial on the website showing how to set each valve to the optimum 250 millivolts. This should be checked every few months.

Manley Mahi review

Before getting started, I suggest you read the manual for the Mahi. Not only because it is jam-packed with extremely useful and important information on how to set up, use and take care of this amplifier but also because it is one of the best-written, most informative and most amusing manuals I have come across. The Troubleshooting section had me laughing out loud when it suggested that if your amplifier is humming, then “it forgot the words”, and if there is hiss, it must be “stray snakes in the room”, or if there is a balance problem, then “mom told you not to put anything smaller than your elbow in your ear”. Of course, it also gives sensible advice on how to deal with those issues should they arise, but you see what I mean.

I am a big fan of valve amps and so was particularly keen to hear what this legendary US brand could bring to the table, as this would be my first review of one of the company's products. I slotted the Jumbo Shrimp preamp and Mahi monoblocks between my Audio Note TT3/Arm Two/Io1/S9 vinyl (using a Puresound phono stage as no Manley model was supplied for review) and Audio Note CDT-Five and DAC Five Special CD front ends, playing through RussellK Red 120Se loudspeakers. The two Mahis proved to have more than enough grunt to drive these speakers, with their 86dB sensitivity. For those with big rooms who want to listen really loud, higher-efficiency speakers from the likes of Klipsch, Heco, Tannoy and Audio Note would be worth considering.

Manley Jumbo Shrimp review


This high-end pre/power amplifier combination delivers a seductive and musical sound that makes your favourite recordings a pleasure to play. In this respect, it's typical of really high-quality tube amplification – where the music is unfettered and beguiles the listener. It carries great emotion yet never shouts at you. It has delicacy allied to drama – with tight and snappy rhythms and oodles of inner detail. By separating out the strands of the music so well, it shows you how vocalists and instrumentalists can shape every note of a song – so that the contribution of every musician can be appreciated and enjoyed.

With feedback set to standard and in triode mode, all of this was clear from the first few bars of A Place for Skipper from Larry Carlton's Discovery album. I was struck by this pre/power amp combo's sheer lusciousness of sound. There was superb definition, making clear the guitar work's inner detail while conveying the bass line's weight and movement well. Cymbals and drums were also tight and snappy yet had delicacy and rhythm.

Manley Jumbo Shrimp review

Likewise, the Manley combo's handling of Sunny Side of the Street from Ben Sidran's Enivr d'Amour album instantly pleased me, with these amps capturing the artist's distinctive delicate vocal style while not losing the sparkle and detail on the accompanying Yamaha DX7 synth. At the same time, the bass line drove along with appropriate impetus and verve. I then reached for Linda Ronstadt's superb Hasten Down the Wind album and played the lovely ballad Lo Siento Mi Vida. The Manleys imparted the raw emotion in her voice and allowed her powerful vocal to soar without ever glaring or shouting. The track is packed with emotion, as was the performance of this pre/power amp combination.

There is no shortage of power from the Manley amplifiers; there's never any sense that the electronics are struggling for breath or labouring under the weight of the music. For example, with I Can See Clearly Now from Peter White's Groovin', the song drove along with gusto, showcasing the nuances of playing in the powerful reggae-style bass line. At the same time, instrumental separation further up the audio band was excellent; it was good to be able to make out details, such as the accordion playing, which was nicely separated. With The Bright Side from Dave Koz's excellent The Dance album, this pre/power combination imbued the saxophone with fine body, detail, articulation and fluidity. At the same time, percussion work was conveyed with subtlety and finesse.

Manley Mahi review

After extensive listening, I came down on the side of leaving the feedback set to standard – as it just seemed better balanced. 'Minimum' sometimes gives a bit more leading edge to notes but can sound thinner, so my vote is for standard. I personally found the ultralinear mode to be less convincing than triode mode; I thought it lost definition on instruments and vocals, and sounded more forward. It is useful to have, however, should the user ever need more power – it gives a claimed 40W versus 24W into 8 ohms. Yet for normal listening, triode worked better for me.


Although not inexpensive, this Manley Labs Jumbo Shrimp/Mahi pre-power amplifier combo makes a great case for itself. Never less than dynamic, detailed and tuneful, it is a compelling music maker. Anyone still hanging onto the old cliche about valve amps having soggy bass and a warm but bland midband and treble will rethink things after hearing this. So, if you have this sort of budget to spend on your next amplifiers, then do not leave this fishy combination off your shortlist.

Visit Manley Labs for more information


    Chris Frankland's avatar

    Chris Frankland

    One of StereoNET’s most experienced reviewers, Chris has written for a multitude of hi-fi magazines, from Hi-Fi Answers and Hi-Fi Sound, to The Flat Response and Hi-Fi Review. A regular concert-goer, his quest continues to find hi-fi that gets as close as possible to conveying the raw emotion of live music.

    Posted in:Hi-Fi Amplifiers Power Amplifiers Preamplifiers
    Tags: manley labs  manley laboratories  scv  scv distribution 


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