Sutherland Engineering Little Loco MK2 Trans-Impedance Input Phono Preamplifier
When you open the User Manual of the Little Loco Mk2, you are greeted with this welcome:
You are about to celebrate your new Little LOCO purchase. The direct experience of the Little LOCO in your system will transcend any discussions we could have. I wish I could be there with you for a ‘high five’ moment.
Ron Sutherland
A couple of minutes after switching it on, Ron’s choice of words become completely understandable. Make sure you have someone with you as you will need them for the inevitable ‘high five moment’.
Ron Sutherland has been making phono preamps for a very long time. By focusing almost exclusively on phono preamps, his design and circuitry has benefited from continued refinement and improvement over the years. All of those designs were based upon voltage amplification. The cartridge delivers a small voltage to the phono preamp input. This voltage is then multiplied to create a larger output voltage (along with RIAA EQ). A typical voltage multiplier of 1,000 can also be expressed as 60dB. One millivolt in → one volt out.
In recent times you may have noticed a new kind of phono preamp design, usually referred to as ‘current input’ or ‘trans-impedance’. Until recently, that approach has been very much in the background. However, many audiophiles are now switching over to this style of phono preamplification because it offers some serious benefits. The first transimpedance phono preamp released by Sutherland Engineering was the PHONO LOCO, which is an ‘all-out’ very high-performance design. Following the immediate success of the PHONO LOCO, there naturally followed a challenge to bring a big measure of that performance to a lower priced model. So finally we have a ‘technology trickle-down’ from the PHONO LOCO to the new Little Loco Mk2.
What is Current Input?
In short, the input signal comes from the current flowing through the cartridge, NOT the voltage from the cartridge. That current information is the input for a transimpedance gain stage (the input signal is current and the output signal is voltage). The connections on the back panel of the Little Loco Mk2 appear to be totally conventional. There is the usual IEC input for the power cord, a ground screw for grounding the turntable, and two RCA jacks for the input signal from the turntable. Finally, two RCA jacks deliver an output signal to your line-level preamp. There is, however, a requirement that both coil connections float with respect to ground. Turntable grounds and cable shields need to go to a separate ground wire. There must be no direct connection from either coil side to chassis ground.
Load Settings
There are no loading adjustments in the little LOCO. Your cartridge will see a load of zero Ohms. The input signal will be the current your cartridge produces into that virtual short. No need to worry about or fuss around with loading.
Gain Settings
The Little Loco Mk2 is factory set to medium gain which should work very well in most situations. The usual concerns about cartridge output voltage do not apply here. Cartridges of varied output voltage specs tend to supply about the same level of drive current to a short (higher output voltages usually have higher resistance while lower output voltages usually have lower resistance). Into a virtual short, most deliver about the same current signal. If your particular situation would benefit from a gain adjustment, you can change it.
According to a rapidly growing number of music lovers around the world, these new ‘current input’ or ‘trans-impedance’ design phono preamplifiers are attracting a lot of attention and respect because they have a unique ability to ‘dig deep into the music’ and ‘bring it to life’. They are dead quiet and very dynamic. The Little Loco Mk2 has most of the magic that has made the PHONO LOCO an instant classic but at a much reduced pricing level. Be prepared to be seduced
What are the Differences between the Mk2 and Mk2 Versions?
In 2023, Sutherland Engineering updated the Little Loco to Mk2 specification. The transimpedance input stage was improved and the shell of the RCA input jack is now at ground level. There are now no special requirements or concerns for signal interconnection to the turntable.
Videos
Reviews
Home Theatre & HiFi, Rick Schmidt, 2020
The Sutherland Little Loco Phono Stage competes way above its price point and delivers transimpedance intrigue along with the music, it is a different experience from conventional phono stages.
Product Specifications
Item
Phono Preamplifier
Operating Voltage
210–250 VAC (not universal and cannot be field modified)
Dimensions
432 mm (W) × 305 mm (D) × 57 mm (H)
Shipping Box Dimensions
559 mm (W) × 432 mm (D) × 229 mm (H)
Weight
6.8 kg
Shipping Weight
8.2 kg
Warranty
5 years parts and labour (transferable). Valid only for units that have not been modified or abused.
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