Sugden Sapphire DAP‑800 preamp and FBA-800 power amplifier

Solid-state power amplifiers,
Solid-state preamplifiers,
Digital-to-analog converters
Sugden Audio Sapphire DAP‑800,
Sugden Audio Sapphire FBA-800

The choice of on-board DAC is intriguing. As discussed, it’s a 96kHz, 24-bit non-oversampling design, built for performance, not for the numbers. That’s an aproach more commonly seen on Audio Note and 47 Laboratory DACs and the occcasional tweaky models that periodically spring up and vanish soon after – not from a brand better known for making products that stay in production for decades. Actually, that sort of fits. Those seeking the Best Of The Moment in the numbers and acronyms arms race need not apply, as this one is for the listeners. On the other hand, those who buy in an unfaddy manner will appreciate something that doesn’t follow this arms race, and are likely to limit their music to ripped 16/44 CDs and similar-level offerings online. My concern here is that those with 24/192 files from high-res providers will not find their files supported as there is no downconversion option. So long as that’s known up-front by potential DAP-800 owners, that possibly is no big deal. Regardless, a DAC that only works to 24/96 precision will invariably result in a host of ‘No DSD… count me out’ comments, often from people who have no DSD files and no intention of owning any DSD files. Those who go searching for reasons why they don’t need to buy have found a reason without ever having to take the trouble to dig further. Consider this a service rendered to the measurebators and spec-freaks – this is not for you, and you can go about your business untrammelled by Sugden’s really rather good sounding DAP-800 preamp.

Similarly, a 40W power amplifier – even though it’s pumping out those 40W in pure Class A – will turn people away. There are some who might have legitimate call to be turned away here. You might have a loudspeaker that has the efficiency of a marble pillar and want to play those speakers at PA levels in an aircraft hanger. However, a surprising number of listeners will never get much past the first one or two watts on an amplifier, and it’s here where the FBA-800 shines.

The FBA-800 gets its prefix because it is a ‘Floating Bridge Amplifier’. And yes, I too am trying not to whistle the theme tune to Monkeyas I wrote that. Floating Bridge Amplifier is actually extremely descriptive as the amplifier operates in bridged mode with the output earth floating. Each channel consists of two amplifiers working as voltage amplifiers driving an output stage of bridged power transistors. This means the amp works in pure balanced operation from input to output if you select XLR connections. The advantages are a low noise floor, better power output relative to the voltage rails, and – with the fixed current of the Class A mode – low output impedance and better load tolerance. 

The Power amplifier is DC coupled, with a servo lock, and features a full DC protection circuit. This circuit is statically switched using extremely low impedance MOSFET switching devices. This circuit also acts as a soft-start switch. The FBA-800’s power supply is a low impedance design with a single custom made bi-filar wound transformer with four separate windings. Its main smoothing capacitors for the output stage are specially developed for professional audio applications with excellent ripple characteristics and long life. These ultimately feed to the four power transistors per channel in the output stages. These are multi emitter devices with an output capability of 26 amps per device.

There’s a sense of overbuild here, but not to excess. For example, although the amplifier is rated at 40W per channel, the transformers are specced for 350W use. Like all Sugden amps, the circuit boards all use plated-through-hole PCBs and the company eschews surface-mount devices. As there are reports of tiny components and greater potential for tin whiskers (solder forming its own dendrites in an EM field) over the decades, this might not be a bad idea.

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