Sugden Audio Sapphire FBA-800 Amplifier by Terry London

On a few occasions, either at audio shows or in personal systems, I have heard Sugden Audio’s amplifiers and have been quite impressed by their overall musical presentation. This company, located in West Yorkshire, England, has been in business for 59 years. From the very beginning, their integrated amplifiers and straight power amplifiers were highly regarded for being hand-built to very high standards in small numbers and for being among the best-sounding low-wattage pure class A solid-state models on the market. Recently, my dear friend, Mike Kay, owner of Audio Archon, located just outside of Chicago, has become a retailer for Sugden Audio, adding to the many fine lines, both solid-state and tube-based, that he carries in his store. I shared that I was quite interested in reviewing the FBA-800 40-watt class A amplifier that Sugden Audio considers their “most advanced power amplifier” that they build. Mike made all the arrangements, and within a short time, the FBA-800 arrived for this review.

The review sample was in the silver/gray finish. Its physical appearance spoke to high build quality and an understated, classic look for a hand-built amplifier that retails for $9,000. The front panel has an on/off button located dead center, flanked by two push buttons. One is a gain selector that can reduce the input by 6 dB. This is a great feature on the FBA-800 for matching the amplifier to whatever preamplifier I was driving it with. For my system, this meant the “sweet spot” between the lowest noise floor level without losing overall dynamics or bass control. The other button selects between RCA and XLR inputs. The FBA-800 is a truly balanced design from input to speaker terminals. Therefore, I only used XLR-balanced cables during my review.

The back plate is straightforward: you find one pair of high-quality speaker-cable terminals that accept either spades or banana plugs, RCA or XLR inputs, and an IEC input. The amplifier weighs 55 pounds. Its dimensions are height 8 inches x Width 17 inches X depth 18 inches. Because of its class A biasing, the FBA-800 runs relatively warm, but not as hot as other class A amplifiers I have used in my systems. Sugden Audio uses the following information to describe the topography of the FBA-800 amplifier: The floating-bridge design combines four 20-watt amplifiers into a single stereo chassis, providing several key benefits. Each channel consists of two voltage amplifiers that drive an output stage of bridged power transistors. Each device can produce 26 amps on demand. The advantages are a low noise floor, better power output relative to the voltage rails (x2), the fixed current of class A mode, low output impedance, and better load tolerance. I used five different speakers (Rosso Fiorentino Arno 40 and 20, Tekton Design Encore monitor, Musican Audio Knight V2s, Sonus Faber Auditor Ellipsa) with the FBA-800 amplifier, and it effortlessly drove them with very different efficiencies and impedance loads.

After listening to the Sugden Audio Sapphire FBA-800 amplifier to gain a thorough understanding, I started to collect my thoughts on how to write a review that would give the reader a contextual frame of reference for how the FBA-800’s 40 watts of class A presentation compares to other highly regarded single-chassis solid-state class A amplifiers. I have had the great pleasure of owning and reviewing in the recent past the Pass Labs XA-25, which retails for $4,900, and the Coda S5.5 amplifier, which retails for $6,400. The Pass Labs XA-25 differs from both the Coda S5.5 and the Sugden Audio FBA-800 in that it offers only RCA inputs, as it is not a fully balanced design.

SIMILARITIES:

All three amplifiers are relatively small and weigh about 50 pounds each. However, because of their very robust power supplies and high current loading, each amplifier can virtually drive any speaker without attenuating at high dB levels or distorting on musical peaks. I’m sure that someone who listens at insane high dB levels or owns a pair of speakers that are ridiculously hard to drive because of 2 Ohms or less impedance might find these three petite but powerful, rated at 40 watts into 8 Ohms, insufficient for their listening needs.

All three amplifiers are at the top of the list for eliminating grain/dryness in their overall presentation. I would use descriptors such as liquidity, silky, and ease/flow with all three amplifiers to describe the music.

The FBA-800, XA-25, and S5.5 are very linear and balanced in their overall sonic spectrum. Some amplifiers are tuned to present a bottom-up perspective or a mid-range hump, which brings the listener’s attention to mid-range details. Not these three amplifiers, like a great SET 2A3 or 211 tube-based amplifier, they keep a natural balance top to bottom, which leads to a natural overall balance that many find enchanting and engaging.
Because of their class-A biasing, each amplifier has a virtually nonexistent noise floor and offers see-through clarity, revealing the most subtle micro-details in the music. However, the three amplifiers never veer into being analytical or into listening to the music as if it were under a ‘microscope’.

The three amplifiers are reference-grade in creating, if it’s on the recording, panoramic soundstages with precise layering and the position of individual instruments. They give you the soundstage, along with the sound place (the ambience of the venue where the music was recorded), in a very natural manner.

These three amplifiers are extremely adept at rendering timbre, color, and tonality. They don’t “color” the music; they produce rich, intense timbres with high purity.

THE DELICATE AND SUBTLE DIFFERENCES BETWEEN THE AMPLIFIERS:

Please remember that the following differences are extremely subtle but real, and can be distinguished with careful listening, giving each amplifier a very subtle “seasoning” that is neither right nor wrong. Personal taste and the synergy with your speakers are the factors you consider when choosing an amplifier for your system.

The Pass Labs XA-25 amplifier adds a smidgen/pinch of overall warmth in its overall presentation. It also very slightly rounds the leading edges of the notes, creating a sense of image density, much like a tube. The top-end frequencies are detailed, but not as airy or open as those of either the Coda S5.5 or the Sugden FBA-800. Its speed and transient response are quite good. However, both the S5.5 and the FBA-800 sound quicker, with more “aliveness” in their overall presentations. If you have a pair of speakers that are somewhat bright/forward-sounding, think Focal/KEF, the XA-25 amplifier would be a great match.

The Coda S5.5 amplifier is neither YIN nor YANG; it’s very neutral in its overall presentation. It is not cold or steely at all. However, it renders pristine timbres and colors. It is also extremely transparent, so you can easily hear all the nuances of the music. The top end of the CodaS5.5 has a breath-taking sparkle/shimmering quality, with all the details/decays that never turn harsh or hard. One of the great systems I have heard recently was using the S5.5 to drive a pair of Spender speakers. So, if you team up the Coda S5.5 with Spender/Harbeth/NSMT, this would lead to great musical pleasure.

The Sugden Audio Sapphire FBA-800 amplifier combines the best sonic virtues of both the XA-25 and S5.5 amplifiers to produce one of the most enjoyable and engaging listening experiences I have had in my home systems recently. One of the sonic aspects I noticed immediately during my audition process was the FBA-800 amplifier’s spatial attributes. The height, width, and depth of the soundstage produced one of the greatest illusions of a full-sized orchestra spread out before me, transcending my listening space. The amplifier had a complete effortlessness/liquidity/ease in its overall presentation, yet when it was time to explode with speed and dynamics on music crescendos, the FBA-800 scaled with a pressurization of my large listening space. It’s hard to believe that the FBA-800 produces only 40 watts into 8 Ohms, given how it scales in dynamics and maintains total control of the speaker across all frequencies. Lastly, the FBA-800, like the other great class A amplifiers, delivers an overall purity/intensity in color and tonality that charms you like many tube-based SET amplifiers. As I stated earlier in the review, I paired the FBA-800 with five different speakers, and the amplifier performed beautifully with each. If you’ve always wanted to try a class A amplifier, consider adding the Sugden Audio Sapphire FBA-800 to your audition list for the reasons stated above.

Specifications

Price: $9000

– Input Sensitivity: 735mV for full output
– Power Output: 40 Watts into 8 Ohms, both channels working
– Frequency Response: 0dB 20Hz-80kHz
– Bandwidth: 6Hz-113kHz
– Signal to Noise: >96dB
– Distortion at 1 Watt 1kHz: >0.05%
– Gross Weight (packed): 25kgs
– Dimensions: 206 x 430 x 460mm
Power Output: 40 watts into 8 ohms
Website: https://www.sugdenaudio.com/fba-800-class-a-stereo-power-amplifier

TJ’s Associated Equipment

Source:
Reimyo DAP-999EX Toku DAC
Pro-Jet reference CD transport & LTA power supply
Amplification:
Coda S5.5
AricAudio balanced custom 5751 tube preamplifier
AricAudio Super SET 300B amplifier
Naiu Labs Ella MKIII amplifier
Plinius SA-50 amplifier
Loudspeakers:
NSMT System Two
Tekton Design ULfberth
Music Design Knight V2
RF Arno 40
Sonus Faber Auditor Elipsa
Accessories:
Vermouth Audio XLR Black Pearl MKIII interconnects
Vermouth Audio reference speaker wire
Jena Labs reference AES/EBU digital cable
Krolo Design reference rack & footers
Puritan Audio power conditioner & grounding system.
Vermouth Audio reference power cords