Simaudio Moon 810LP Phono Preamplifier

A Statement Phonostage

Equipment report
Simaudio Moon 810LP
Simaudio Moon 810LP Phono Preamplifier

The 32-year-old Canadian firm Simaudio is one of those few companies with a decades-long track record of marketing nothing but great-sounding and beautifully made products at competitive prices. Although Simaudio isn't an entry-level brand by any stretch, I would call them a “high-value” brand, because many competitors routinely charge more for less.

The 810LP phonostage reviewed here is a case in point. The company’s flagship is its all-out assault on the state of the art in phonostages. It is designed and built with meticulous attention to detail and features lavish chassis work, yet is priced at $12,000. Yes, this is a lot of money for a phonostage, but not for a statement-level product with the sound quality I’m about to describe.

The 810LP is housed in a solid chassis that is built entirely in Simaudio’s factory. Simaudio is one of the few electronics companies with in-house CNC machining. It took this step to improve quality and reliability, provide customization options, and shorten lead times. Simaudio’s Web site offers a photographic factory tour showing metal parts being fabricated. The 810LP’s silver front panel (black is also available) is quite plain, with just a power button and a blue LED power indicator. Rounded aluminum “cheeks”—key elements in Simaudio’s visual design— flank the front panel’s left and right sides. The rear panel houses one stereo pair each of balanced inputs (XLR) and unbalanced inputs (RCA), along with balanced and unbalanced outputs.

The 810LP offers extensive adjustments for gain and loading via bottom-panel DIP switches. This location isn’t convenient for making changes on the fly, but was chosen to keep the signal path as short as possible (the switches are located in-line with the circuit). Gain is adjustable in 16 increments from 40dB to 70dB. A second bank of switches allows you to set the capacitive loading from no capacitance to 1120 picofarads (pf) in 16 steps. A third bank sets the resistance from 12.1 ohms to 47k ohms in 64 increments. Because the 810LP is a true dual-mono design, each bank of DIP switches (gain, resistance, capacitance) is duplicated for the left and right channels. Finally, another pair of switches selects between RIAA and IEC equalization. The bottom panel with its vast array of switches looks intimidating, but the outstanding owner’s manual makes everything clear.

Simaudio has pulled out all the stops for the 810LP, incorporating the best design techniques developed over its 32- year history. The power supply, a particularly crucial part of a phonostage, is a good example. The 810LP’s supply is housed in a sealed, 14-gauge-steel subchassis that consumes about 40% of the interior real estate. The DC voltages from this supply are then re-regulated on the audio board with multiple cascaded regulation stages of Simaudio’s proprietary design. Each regulation stage, located near the audio circuit it supplies, is built from a combination of ICs and discrete components, along with a large inductor. The result is ultra-pure DC that is isolated from the AC supply as well as from noise or contamination from the audio circuits. Simaudio calls this circuit i2DCf (Independent Inductive DC Filtering). The 801LP uses a whopping 24 of these sophisticated regulation stages. Simaudio claims that the 810LP’s DC supplies are as quiet and well regulated as the DC from a battery. Indeed, the noise floor of the DC supply is -150dB below 1V from DC to 100kHz. This is an astounding specification— and unprecedented in my experience in any product.

The audio circuit is a dual-mono fully balanced differential design. The transistors in the differential pairs are hand-matched, and the layout features very short signal paths. The four-layer audio board is mounted on a five-point, floating gel-suspension to isolate the audio circuits from vibration. Simaudio calls this suspension M-Octave Damping. To avoid compromising the isolation by connecting the floating board to the rear-panel, a dual- layer rear-panel is employed in which the outer layer is mounted to the chassis and the inner layer is connected to the audio circuit board. The two layers don’t come in physical contact with each other. To further isolate the circuits from structural vibration, the chassis sits on Simaudio’s custom isolation cones at each corner of the chassis. This attention to vibration isolation is even more crucial in a phonostage because of the very low-level signals the circuit is amplifying. Even tiny vibrations can contaminate the audio signal through microphonic effect, primarily of capacitors and inductors. That is, vibration is turned by these devices into tiny electrical signals that pollute the miniscule audio signal from the phono cartridge. Keep in mind that, as a phonostage amplifies a signal by as much as 70dB, any introduced noise is also amplified by 70dB.