Sutherland Engineering Little Loco phono preamplifier

Descriptions of the sounds of products from Sutherland Engineering nearly always include "refined." While that word is certainly justified, it would be more apt to use it as a verb: Ron Sutherland spends more time than any audio designer I've known studying and fine-tuning and refining every detail of his work. I have the impression he knows those products so well that when he decides to design a less expensive version of his newest and best models, he knows exactly what to do.

The Sutherland Duo phono preamp I reviewed in August 2017 is a case in point. It sells for $4000 and comes within a hair of matching the performance of the $10,000 PhonoBlock Refined. It even betters it in a few ways. So when I heard that Sutherland was introducing a "trickle-down" version of the cost-no-object Phono Loco phono preamp, I muscled my way to the head of the line for a review sample.

Transimpedance 101
The Little Loco and the Phono Loco differ from Sutherland's other models in being current-mode designs, other examples of which include the CH Precision P1 (which Michael Fremer uses as a reference, footnote 1), the Channel D Lino C 2.0, and the Haniwa HEQA03-CI (see this issue's Analog Corner). But the technology is not as well-known as that of voltage-mode phono preamps, so the distinction bears repeating:

An MC phono cartridge can be modeled as either a voltage source or a current source; conventional phono preamps take the former view: The movement of the cartridge's coils through its magnetic field creates a small voltage that pushes a current through the internal resistive load of the attached phono preamplifier.

Current-mode phono preamps view the cartridge as a pure current source, ignoring voltage, and aim to impede that current as little as possible. A typical strategy is to use an op-amp to mimic a short between the cartridge's two terminals; the cartridge thinks current is flowing freely, but it is actually diverted through a feedback resistor connected between the op-amp's input and output terminals. The voltage drop across that feedback resistor is measured, amplified further, RIAA-corrected, and sent on to the rest of the audio system for conversion into music.

1019sutherland.bac Opinions vary, but there's general agreement that current-input phono stages have two advantages. One is inherently low noise: Because there's no voltage associated with the musical signal, it's immune to several vexing noise sources—for example, those that result from the mechanical and electrical weaknesses of phono cables. A second claimed advantage of transimpedance designs is their demonstrably faster real-world response at similar levels of effective gain; this difference provides better damping and allows a cartridge to respond more quickly and accurately to the smallest variations in a record groove.

On the other hand, a current-mode phono preamp limits choice in some ways. 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.

A little loco
The Little Loco shares its cosmetics, fit and finish, and build quality with other Sutherland models, which is to say, it's refined. I've never seen a Phono Loco, so I contacted Ron Sutherland to learn how the Little Loco differs from its big brother. "Everyone loved the Phono Loco, so I started thinking about how I could do it for less money. It's a challenge, but one that I really like. A lot of it was power supply and filtering. The Phono Loco has completely separate power supplies (for the two channels) and . . . separate power supplies and filtering for each gain stage." In contrast, the Little Loco has separate power supplies for each channel after the transformer, but not for individual gain stages.

Sutherland continued: "Because of the smaller power supply, I could use smaller boards and a smaller chassis. The Little Loco actually uses the same chassis as the [Sutherland Insight phono preamp], so I didn't have the expense of building a new one." I asked, "If you're reusing an existing chassis, why design a whole new power supply?" After all, you can buy cheap ones off the shelf, such as the one he used with the Sutherland Duo. His answer: "Oh, I just thought it should have a linear power supply."

Is it not for everyone?
In most manufacturers' product descriptions, "It's not for everyone" usually means one of three things: that the product is unreasonably expensive; that its operation is so convoluted that the effort required to play music becomes excessive; or that its sound is an acquired taste, appealing to a few but sufficiently odd to be considered a fail with respect to established criteria and metrics. In these respects, that phrase does not apply to the Little Loco.

The first two of these concerns are easily dispelled. At $3800, the Little Loco isn't cheap, but its price is in line with those of other products in its class. Second, its use could not be more straightforward, even if it isn't universally applicable. True: Your tonearm wiring must be fully balanced between cartridge and phono preamp, with no connections between any of the tonearm leads and ground. That means that the Little Loco won't work, for example, with your Rega arm, unless it's rewired. Yet there are no adjustable parameters, options to choose from, or controls of any sort— not even a power switch (footnote 2). You connect the input and output cables, plug it in, and play music.

1019sutherland.gainadjust

When I did that, the third possible interpretation of "not for everyone" vanished, too: Its sound was about as far removed from "acquired taste" as I could imagine. It was love at first listen.

Ah, but there's a fourth
So the Little Loco is reasonably priced, trivially easy to use, and sounds wonderful. But don't buy a Little Loco to use with a moving-magnet cartridge—"their performance is awful into a short," Sutherland says. And MMs aren't the only cartridges that won't work with the Little Loco.

I tried pairing the Little Loco with six cartridges: an Audio-Technica AT-OC9ML/II, Grado Statement Reference, Lyra Titan i, Benz Micro SL, My Sonic Lab Ultra Eminent Ex, and, just for fun, an Audio Technica AT-MO-NO3/LP. On paper, the AT-OC9ML/II, Titan, and Benz Micro—all moving coils—are very similar, each with an output of about 0.5mV, internal impedance around 10 ohms, and a dynamic compliance of about 10×10–6cm/dyne. The moving-coil My Sonic Lab Ultra Eminent Ex has similar specs for output and dynamic compliance but an impedance of only 0.6 ohms.

The AT-MONO3/LP has two coils that are built to respond to horizontal motion only, and the negative output terminals of those two coils are connected. Because of the connection, it shouldn't have worked with the Little Loco— and it didn't: All I heard was a loud, threshold-of-pain hum underlain by music signal at the limits of audibility.

The Grado is neither moving-magnet nor moving-coil: It's a moving-iron cartridge. The Phono Loco website says that moving-iron cartridges won't work with the Phono Loco, but the Grado Statement Reference sounded as good through the new Sutherland as through a more typical phono preamp—although it did not benefit from the Little Loco as much as the Benz Micro, My Sonic Lab, or Audio Technica AT-OC9ML/II did. I had to connect the ground lug of the Little Loco to the one on my turntable to eliminate hum, but that was all it took.

Ostensibly, my success with the Grado contradicts the Sutherland Engineering website, but it corroborates something Ron Sutherland told me: The Little Loco is unpredictable. "I want people to be comfortable that transimpedance (or current input) phono preamps have some frontier exploration aspects," he wrote in an email. "I suggest the potential buyer work closely with a dealer very experienced with Loco/cartridge matching."


Footnote 1: Published in Analog Corner in the April 2017 issue.

Footnote 2: You can adjust the gain by replacing two resistors inside the box, but I don't count that as a control.

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 :-) .........

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

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. :-)

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 the 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 large 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 ja 630mH we get: f(-3dB) = 303Hz!

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