Sutherland Engineering Little Loco phono preamplifier Herb Reichert January 2022

Herb Reichert reviewed the Sutherland Little Loco Mk2 in January 2022 (Vol. 45 No.1):

Sutherland Engineering's Ron Sutherland has been building highly respected conventional RC-type phono stages since the first settlements at Jericho. But in 2018, on the urging of a friend, he developed a current-drive/transimpedance phono stage and thought it was crazy-good, so he called it the Phono Loco. As I recall, the Phono Loco arrived to a fanfare of praise and curiosity, but it cost a lot ($8200), and a lot of audiophiles were skeptical about its unusual (but not unprecedented) current-mode operation and its need for balanced tonearm leads. This latter condition was a deal-breaker for many (including me) who struggled to comprehend the benefits of current-drive and were already invested in and satisfied with voltage-amplifying phono stages and step-up transformers.

According to the Sutherland Engineering website, the Phono Loco, the less expensive Little Loco ($3800), and the least expensive TZ Vibe ($1400) are best suited for use with low-output, low-internal-impedance moving coil cartridges; high-impedance moving magnet cartridges are not recommended.

Brian Damkroger reviewed the first version of Sutherland's Little Loco in the October 2019 issue of Stereophile. Like the Phono Loco, the Little Loco required fully balanced wiring from the phono cartridge to the Loco's balanced-only XLR inputs. Happily for me, and maybe lucky for you, the new "Mk2" version has only single-ended inputs; it still works only with MC cartridges—the lower the output, the better—but now with no special wiring requirements. This flexibility should clear the path for more audiophiles to explore this alternative preamplification strategy.

Before I asked Mr. Sutherland for a Mk2 review sample, one of my cartridge-whisperer friends had already purchased a Little Loco and was raving about its "relaxed, nonelectronic" sound. He said it was "putting up a strong fight" against his John Curl–designed Vendetta Research SCP-2A, which he has been using continuously since 1990. That's high praise.

When I removed the Little Loco's top plate, the artist and amp-builder in me was impressed with the well-turned-out chassis and master-level circuit board design. Everyone knows how I feel about small power transformers and cheap, wave-soldered green-boards floating in mostly vacant bling-boxes; the Little Loco comes in a sturdy black steel box with an austere, brushed-aluminum faceplate with nothing on the front but a modest logo and a tiny Power On light. Inside, the orange and puce circuit boards are thick and properly hand-soldered.

Ron Sutherland describes the first stage of the Little Loco as a "transimpedance amplifier." A transimpedance amplifier is a current-to-voltage converter whose "gain" is directly proportional to the value (in ohms) of the feedback resistor connecting the output to the inverting input of an op-amp with its noninverting input shorted to ground. The output voltage of this transimpedance amplifier is equal to its input current multiplied by the designer-selected value (in ohms) of its feedback resistor (footnote 1). Ignoring a cartridge's—er—potential for voltage output while maximizing its current output (into a load resistance that is smaller than its own internal impedance) appears to solve the cartridge-loading issue.

The question for today is, how does the sound character of a transimpedance phono stage compare to that of a traditional voltage-gain phono stage and to that of a step-up transformer?

In the 1970s, my "I'm-cooler-than-my-friends" attitude led to my desire to own only British pressings of British-invasion music. After a score of years, that desire led to a need to hear British music on British labels played through British-made hi-fi. This weird, Veblen-esque desire led me down some un-Herb-like musical paths including this old-school audiophile chestnut from the Lyrita catalog: a trio of Walter Leigh compositions played by the London Philharmonic conducted by Trevor Pinnock (Lyrita LP SRCS 126). I've been playing this disc for decades, but I never play it for its musical content, which is forthright and benign to a fault (like the painting reproduced on its green-tinted cover); I use it to determine if my phono cartridge is "navigating the grooves" properly. If I can enjoy listening to both sides in one session, it means the stylus-rock is sitting just right in the LP's slot.

The day I installed Sutherland Engineering's Little Loco Mk2, I played that Leigh-Lyrita recording twice. Both sides. The sounds from this famous disc flowed from my DeVore Fidelity Orangutan O/93 speakers with creamy ease, delicacy of detail, and no spatial congestion. Sutherland's Loco presented the Leigh-Lyrita's delicate air and dramatic spatial layering as dominant features. I could "see" the sturdy, morphing forms of its spatial constructions as I washed dishes in the next room. Also obvious from the next room was the solidity and focus of the Loco's bass octaves. The Koetsu Rosewood Signature Platinum–Loco combo reproduced bass and space with more "obviousness" than my reference, John Curl–designed Parasound Halo JC 3+ phono stage.

Realizing that the Little Loco Mk2 had something special going on, I tried a record I only play for the excitements of its musical content: Cheap Thrills by Big Brother & the Holding Company (Columbia LP KCS 9700). In contrast to those audiophile-approved Walter Leigh creations, this record is "Approved by Hell's Angels – Frisco"; it says so right on its R. Crumb–painted cover. You know you got it/If it makes you feel good.

With the Koetsu's 5 ohm impedance driving the Little Loco, this super-iconic album sounded more like Janis circa 1968 and less like a slightly annoying, heavily doctored Columbia studio album, which is what it usually sounds like. The added crowd noise was obvious but less annoying than usual. With the Loco, the only genuinely live part—Janis singing "Ball and Chain" at the Winterland ballroom—made it through my system with all its strutting wow and mind-altering Thrills intact.

While they cost about the same, Sutherland Engineering's Little Loco and Parasound's $3000 JC 3+ phono preamp are not in direct competition. The JC 3+ is a fully adjustable phono preamplifier that works equally well with any moving coil, moving magnet, or moving iron phono cartridge (footnote 2). The Little Loco's transimpedance input makes it more of a specialist product. Its raison d'être is to make some (perhaps many) moving coil cartridges sound more appealing than they would or could with a conventional voltage-amplifying stage like the Parasound.

During my leisurely back-and-forth comparisons, I noticed that the Little Loco preserved greater and denser amounts of low-level atmospheric information. Images were thicker and more three-dimensional. With the Loco, the back areas of the projected soundspace were filled with more "stuff" to examine. But that's just audiophile fluff-talk. What made the Loco "crazy good" was how it wrangled every ounce of dynamic mojo out of every recording. The Little Loco's easy-flowing dance'n'sing talents made the JC 3+ sound staid and ministerial.

Naturally, current-mode phono stages partner well with low-resistance cartridge coils because they generate less voltage but also resist current less. I enjoy low-impedance moving coils because the reduced mass of their fewer-turns coils recovers more small-signal spatial and atmospheric information than their heavier, more-coil-turns counterparts. (Those counterparts, though, trade some nuance and air for greater drama and dynamics.)

A perfect example of a low-impedance, low–moving mass cartridge is the $6995 My Sonic Lab Ultra Eminent Ex, which I described in Gramophone Dreams #25. The Ultra Ex is my behind-the-scenes music-listening favorite because in my system, it recovers more of what I imagine is in the grooves than the Koetsu does. I've said this repeatedly: My Sonic Lab's Ultra Eminent Ex reaches so far into all-analog black discs that I can hear the magnetic tape passing over the recorder's heads.

According to the Ultra Eminent Ex's designer, Y. Matsudaira, My Sonic Lab's signature SH-µX magnetic core material allows him to make cartridges with minimal coil-turns while still generating a reasonable, 0.3mV output. As a side effect, the Ultra Ex's low-turns coils permit an unusually low 0.6 ohms internal impedance, which should make it a perfect match for the Little Loco.

When I reviewed the Ex, I used the My Sonic Lab's Y. Matsudaira–designed Stage 1030 step-up transformer. Since then, I've used the Ex with a variety of high-quality SUTs and several transistor phono stages loaded at every setting between 14 ohms (with the HoloAudio LCR-1) to 400 ohms (with the Parasound JC 3+); none of these options sounded as right and satisfying as the Stage 1030.

But now, with the Ultra Eminent Ex driving Sutherland Engineering's Little Loco, I never want to change cartridges or phono preamplification again. These two phono products seem made for each other. The Little Loco makes the Ex's quiet spaces quieter, its deep spaces deeper and easier to see into. Transimpedance loading seems to enhance the palpability of the Ultra Eminent Ex's output. When playing orchestral music, the Ex–Loco combo emphasizes the physical character of instruments, the materiality of wood and metal. Rich inner details, like the tautness of drum-head skins or the decay of cymbals, are not submerged in the larger mass of orchestra and hall sounds.

Where does this remarkable current-sucking device fit into the larger schemes of audiophile-quality phonography? If you are committed to high-output moving magnet/moving iron cartridges, it doesn't fit in at all. However, if you are a well-seasoned audiophile that's getting bored with that expensive low-impedance moving coil you once thought was purity and excitement personified, you might reconsider how to amplify its output. At their best, active tube or JFET head amps add an aura of Tesla-lab electric-shock excitement to the output of moving coils. Many are the times I've switched from a JFET head amp to an expensive step-up transformer and been disappointed by the loss of those arm-hair–raising excitements.

But more frequent are the times when I've switched from passive SUT gain to active head-amp gain and been disturbed by the loss of the SUT's radiant, understated, low-fatigue naturalness. But now my months-long auditions of Sutherland Engineering's Little Loco transimpedance phono amplifier indicate that it might give jaded phonophiles the best of JFETs and SUTs. Without the disappointments. Highly recommended.—Herb Reichert


Footnote 1: Details here.

Footnote 2: Although some certain moving iron cartridges work best loaded at about 10k ohms, a rare setting not found on the JC 3+.

COMPANY INFO
Sutherland Engineering
455 East 79th Terrace
Kansas City, MO 64131
(816) 718-7898
ARTICLE CONTENTS

COMMENTS
Anton's picture

If it weren't for streaming, I would have never engaged with a computer to interface with my Hi Fi. Download, Winn this AFLAC that...I was never gon' do it.

Now, this carn sarned complicated stuff hits me right in my 12 inch!

So, to use this preamp, I need a random cartridge, chosen in the hope that maybe it will work with my system, perhaps, and also get a different wiring set up for my tonearm...as you say: "The shield and ground of the phono cable must be isolated from the plus and minus conductors, which eliminates certain cables and tonearms from consideration. There's nothing a user can adjust to optimize the circuit for a certain cartridge—no adjustment of load resistance, in other words. You're almost entirely limited to moving-coil cartridges, and apparently, even among moving-coils, some combinations don't work at all. Got a cartridge you want to use? Plug it in, hold your breath, and see what happens."

That is so inconvenient, I don't know how us vinyl aficionados can resist!

Whole new layers of inconvenience, expense, and complexity.

Sign me up!

I would buy this if it were plug and play...can we beg a primer on how the Hell to get a system ready to install this crazy thing?

Ortofan's picture

... caliber should settle for nothing less than the CH Precision P1/X1 combo. It has both voltage and current mode type inputs, so that you can switch back and forth between them in search of the ultimate sound quality until you drive yourself silly.

https://www.ch-precision.com/en/products/source/p1
https://www.ch-precision.com/en/products/extra/x1
http://ch-precision.com/images/reviews/1704_Stereophile_P1.pdf

Bogolu Haranath's picture

The Rolexs of phono pre-amps .......... CH Precision and Soulution (see TAS review, Soulution 755) ......... Swiss Precision :-) ...........

Bogolu Haranath's picture

"Drive yourself silly" and get into a nervous breakdown :-) .........

Michael Fremer's picture

I own the P1/X1 and it's far more costly than the Little Loco...it's an unfair comparison.

Bogolu Haranath's picture

Parasound Halo JC3+ phono pre-amp ....... $2,995, Stereophile Class-A :-) ...........

Anton's picture

Think you'd be able to tell them apart by listening?

Saying something like "Nagra BPS: $2459 phono preamp, Stereophile Class A :-)" is meaningless.

Bogolu Haranath's picture

I don't know ...... You can read the reviews and decide ......... JC3+ provides several user adjustments in the back panel ....... It would be nice if, Stereophile did a comparison review :-) .........

Bogolu Haranath's picture

HR said " ... best commercially available phono pre-amp, I have used - Period" about JC3+ :-) ........

Anton's picture

Did you buy it?

Bogolu Haranath's picture

I no longer listen to any analog playback gear (sad!) ........ I was trying to make some helpful suggestions to fellow comrades (audiophiles) :-) ........

JRT's picture

The transimpedance amplifier provides extremely low load impedance at its input.

Phono cartridges have an optimal load impedance for flat response to high frequency. Jim Hagerman provides a good explanation at the following link.

http://www.hagtech.com/loading.html

Stereophile has provided an industry profile of Jim Hagerman at the following link.

https://www.stereophile.com/content/industry-profile-jim-hagerman-hagerman-audio-labs

JRT's picture

https://www.electronicdesign.com/analog/whats-all-transimpedance-amplifier-stuff-anyhow-part-1

JRT's picture

https://www.passdiy.com/project/other/zen-i-v-converter

Mökö Koo's picture

http://www.hagtech.com/loading.html

Sadly mr. Hagerman makes an error. Formula for Ropt should be:

Ropt = √(L/C)/2.

Without the divider 2 we get peaking frequency response with ringing in the time domain.

Graham Luke's picture

...The cleanest industrial design chic yet!

JRT's picture

As an alternative, one might try using a Bob's Devices Cinemag Sky to step up the voltage and provide impedance matching between a moving coil phonograph cartridge and a moving magnet phonograph preamplifier.

https://www.bobsdevices.com/product-page/sky-cinemag

Similar:
https://www.stereophile.com/content/bobs-devices-cinemag-1131-phono-transformer

JRT's picture

RIAA filter ... phono equalization

http://www.hagtech.com/equalization.html

Reference inverse RIAA filter

http://www.hagtech.com/pdf/riaa.pdf

Ortofan's picture

... buy a well-designed phono preamp that works with both fixed and moving coil type cartridges.

https://www.lehmannaudio.com/phono-stages/black-cube-se-ii.html

https://www.lehmannaudio.com/assets/products/black_cube_se_II/reviews/EN_review_Hifi_News_02_2010_SEII_screen.pdf

https://www.analogplanet.com/content/lehmann-audio-black-cube-se-ii-mmmc-phono-preamp-reviewed

Bogolu Haranath's picture

Lehmann Audio Decade phono pre-amp ($2,099) was better rated Class-A by Stereophile :-) .........

Ortofan's picture

... only a 3% increase (according to Hi-Fi News) in sound quality, then by all means be my guest.

tonykaz's picture

Everyone can have an Opinion.

The above Summary Opinion needs qualifiers:

Best $3,800 Analog Money Spent for folks that can spend $50,000 a year on audio hobby purchases. ( about $4,000 per month considering Sales Tax )

Circuits like this demand an appropriate Transparent Audio Cable costing near $5,000 for the entry level priced one.

Well, dammit, this Circuit makes ALL phono Cartridges sound wonderful, even cheap ones statement reveals the reviewer's system deficiency, despite the extravagant costs of the gear.

Superb Phono Cartridge transducers have their own unique voice which is beautifully revealed thru well chosen Pre-Amps, is this review suggesting that Today's Pre-Amps with Phono are no dam good?

I'll suggest that it's the Vinyl being played is not so good. ( along with the Pre-Amps being offered )

Superb Vinyl Analog is super Pricy ( and a pain in the Schiit'r ).

Tony in Venice

Anton's picture

Didn't you used to be the world's biggest seller of Monster Cable?

No way I am gonna believe you, dude, You sold your credibility!

;-D

He didn't say it made all transducers sound the same, he said it appeared to allow them to sound better than they did with the other type of phono preamp.

If you found an amplifier that lowered the noise floor of a system, would you say that it made all preamps and sources sound more engaging, or would you think it made all other components sound the same?

I am wondering if you read the review: did you interpret what he said to mean that it made all cartridges sound the same? try it again and read to the end.

tonykaz's picture

Monster's early days. I bought in Deep

You make good points about these things. He does suggest compelling results.

I checked the Sutherland Company's engineering report to find them a detail oriented Vinyl Playback optimiser .

I too worked with optimizing Vinyl playback and had a range of Phono Step-up transformers and amplification devices and circuits.

So, these guys are making MC circuits as did Electrocompaniet ( the best of my era ) , Audio Research and Conrad Johnson, Ortofon with their thousand dollar transformer for their top of the line MC transducer. All the above plus many more Manufacturers going deep into Low output MC step up circuits.

Vinyl now is populated by an obsessive cult ( which I was once a member ).

I suppose that I over-reacted with the reviewer's claim of best $,$$$ spent. ( an extravegent exaggeration , in my opinion )

I'm suspicious of the worshipful Wilson people, wondering how their claims could be relevant for everyman Stereophiles.

I could regret even reading that Sutherland Review, considering my outspoken position against all things Vinyl. The best money spent claim triggered my angst.

Sorry, Mea Copa

Tony in Venice

Michael Fremer's picture

"Vinyl now is populated by an obsessive cult ( which I was once a member."

Olivia Rodrigo fans bought 268,000 copies of "SOUR" last year. Are you saying they are part of an "obsessive cult". Vinyl sales today are driven by young people who enjoy the experience sonically and otherwise.

i find your characterization of a large group of people you do not know quite pathetic. I won't say "offensive" because I'm never offended by foolishness.

Characterizing people you do not know with such a broad brush is best described as a character flaw.

Why you felt it necessary to bring Wilson into this is another character flaw. Sabrinas for instance are within the means of a large percentage of "Stereophiles."

tonykaz's picture

Sour's 286,000 are Album Equivalent Units , not Albums. Most of that number were Digital Downloads.

Sour was an Awards Winning Album

Tony in Florida

Anton's picture

This is all good natured ribbing, of course.

You know the difference between a cult and a religion?

The number of members.

As of this year, vinyl is a bigger 'cult' than CD.

Vinyl is a fun part of the audio hobby, why denigrate it? People enjoy vinyl at all price levels.

Do you troll auto enthusiast forums and admonish people that driving really fast costs millions of dollars so they and their street legal car cult should shut up and shut down their obsession?

Do you whine at wine forums that the finest wines cost tens of thousands of dollars per bottle, so they should quit with the cultish talk about finding great 50 dollar bottles?

Well, maybe you do, but you shouldn't!

;-D

Sit back, enjoy some nice copa and cheese, pop open a fine bottle of wine in your favored price range, and get off the vinyl whiner train.

Or, better yet, do us a big favor....go mewl on the digital review posts about the cult of digital and those 15,000 dollar CD players and 80,000 dollar DAC stacks.

Go tilt at the 50,000 dollar amps, while you are at it! Take down the entire hobby, man!

We all have our points of price ridiculosity. There are times I will agree with you, too! Sometimes, I read show reports that list prices and just shake my head. For fun, watch the show videos and pay extra attention when a manufacturer is asked the price of his piece of kit...there is always a pregnant and embarrassed pause, as if they are wondering if the interviewer will laugh, be outraged, or ask who he's kidding. If these guys were playing poker, we'd own them. They know it's silly, too.

Cheers, man.

Bogolu Haranath's picture

"Music and passion were always in fashion at the Copa .... Copacabana" :-) ..........

misterc59's picture

I may have missed something in these comment sections over time, but I have never seen anyone troll digital on this site. Good luck getting your point across to you know who. I, probably like yourself, listen to most if not all musical mediums (there's a term for what I just said, but don't know what!) Anyway, happy listening, even if it's through a paper 6x9 speaker in a '57 Chevy!

Cheers,
Terry

rschryer's picture

Yep, it's: "polyphonical".

Feel free to use the term liberally. :-)

Michael Fremer's picture

That emission!

Mökö Koo's picture

Using the current-mode in phono amp means that all the cartridge current is sinked by the short circuit in amp's input leaving no current to run in the cable capacitance. As a result the filter that acts on the cartridge signal is now of LR type instead of the usual RCL type. So, what mostly limits the choise of cartridges is the corner frequency of this filter which must be high enough. It is calculated by the formula: f(-3dB) = R/L/(2π), where R,L = resistance and inductance of the cartridge coil. E.g. for Ortofon Quintet Black whose R and L are 5Ω and 6.2µH we get: f(-3dB) = 128kHz. By contrast, for Ortofon 2M Black which is MM cartridge and whose R and L are 1.2kΩ and 630mH we get: f(-3dB) = 303Hz!

Michael Fremer's picture

For a MM cartridge? Not applicable for current mode phono preamps.

Mökö Koo's picture

Well, I just wanted to show why current-mode concept is not working for MM cartridges. Maybe somebody would be interested in the math related.
Greetings from Finland.

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