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

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

For just over half a century, for almost as long as there have been transistor amplifiers in fact, there has been Sugden. The company moves to its own beat; it makes amps that don’t follow the trend, and makes products that sound truly lovely in the right systems. The Sapphire range is the latest from a brand that cycles its products about once in a generation.

‘Range’ is probably an ambitious way of putting things. There is a preamp and a stereo power amp. The DAP-800 preamplifier is designed as a bit of a one-stop-shop, with balanced and single-ended inputs, a built-in DAC… but no phono stage or network streaming capacity.

The key sections of the preamp (analogue and digital) are self-contained, each having their own power supply voltage regulation and circuit board assemblies, to the point where the analogue stage uses a toroidal transformer while the digital section has its own E-core transformer. This means the digital power supplies are totally isolated from the analogue stage.

The DAP-800’s analogue stage features what Sugden calls a ‘VCV’ (Voltage Controlled Volume) circuit, which first featured in its Masterclass amps, and is seen here in its latest and most developed form. This circuit has a high impedance input section and a current gain stage, which drives a folded cascode stage into a Class A output stage. The folded cascode circuit facilitates a wide bandwidth with maximum dynamics and low capacitive connectivity. The volume control does not attenuate the signal; instead it ‘informs’ the current gain stage of the correct volume level. This means the tonal balance is constant irrespective of the output level, as opposed to most potentiometers and even ladder resistor array active volume controls.

The DAC connects to the digital outside world through inputs for USB, and optical and coaxial S/PDIF signals. The actual DAC is a non-oversampling, digital filtering-free, DAC capable of 24 bit/96kHz precision and where the digital interface transceiver is a Wolfson Micro electronics device. The DAC also includes Post Conversion Filtering in the analogue output stage. The USB signal received is converted via a circuit including a Texas Instruments Universal IC whose
S/PDIF output signal is reclocked and dejittered by the Wolfson interface transceiver.

This DAC configuration has been adopted for Sugden’s digital processing after many many hours of auditioning of a wide sample of DSPs. It was first used in the company’s Masterclass DAC-4 processor, and – with Sugden no longer building the CD player to match the A21 – the DAC-4 and DAC built into the DAP-800 represent the company’s main digital ‘push’.


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.


Power amplifiers are not known for their functionality, but the FBA-800 is remarkably comprehensively specified. It has two buttons on the front panel alongside the big on/off switch. One switches between balanced and single-ended operation, and the other lowers the input sensitivty by -6dB. This allows the user to adjust the gain structure to better match the preamp and loudspeakers. This is a surprisingly useful addition, especially for those who want to look beyond the Sapphire preamp.

Let’s not beat around the bush here. The FBA-800 runs hot. 40W in Class A pumps out a lot of heat, a surprising amount given the eco-friendly nature of the world today. Of course when powered down power consumption isn’t an issue, but this amp could pass as a space heater. But, that’s the price you pay for good sound, and the FBA-800 sounds really, really good. But we are running away with the story here. Let’s start with the system and the preamp.

I used the Sugden combination with a variety of sources, but predominantly from my MacBook Pro through the USB input and via S/PDIF from a Naim Uniti Core server. Both balanced and single-ended connections between pre and power were tried, using Nordost Blue Heaven, Cardas Clear, and generic microphone cable, and the matching Nordost and Cardas cables were used in building the whole system. Speakers were either Chartwell LS6/f towers or Wilson Audio Duette 2s, although the Dynaudio Contour 30 did see some Sugden action, too.

The good news is that the amplfiers do not require extravagent cable wrangling. Differences between cables could be heard and provided advantages in system building, but the system was just as comfy with a set of microphone cables between the preamp and power amplifier. In listening, I moderately preferred the balanced operation, but unless you are using long cables, it’s a bit of a tie.

Now we can talk about the sound. Sugden is trying a tag line that says ‘Rescuing Music From Technology’ and it fits perfectly here. These are products that ooze musical enjoyment from every extremely hot pore. This is a sound quality that delivers the detail goods, but you never, ever notice because the overarching feeling is one of sheer listening enjoyment. There is nothing forward about the sound of the Sugden system, but there is nothing laid back about the sound either. Instead, it just draws you in. I am reminded of the A21SE by the same company, which I have used – off and on – almost since it was launched. OK, so the O-rings on the feet eventually fell off after about 15 years, and I had to superglue one of the grilles after about a decade of use, but that amp just keeps coming out of storage and being used, not because it’s a reference point but just because it’s like a musical homecoming. Music sounds right on that amplifier, but it sounds even more right here.

At first flush, you’ll tend toward playing relatively gentle music. It’s like you need to get through your Vaughan Williams  phase on the Sugdens. You do this because it’s so rewarding, the sense of layering to the music, the sheer charm, and effortlessness to the sound is perfectly expressed in slightly flowing, gentle music designed for a pastoral mood. It’s like night-birds listening to ‘Sailing By’ at the end of the Radio 4 broadcasting day to reset their calm levels.

That feeling is temporary, however. Pretty soon, you are trawling through the meatier end of the collection, often through jazz and into rock. These Sugdens can handle every type of music you throw at them, but there’s an in-head process you go through. It’s a voyage of musical redescovery. I found myself listening to some very well-trodden musical paths, even to the point of listening to all of Kind of Blueby Miles Davis [Columbia]. Like practically anyone who has listened to an audio system, or has eaten in a restaurant, I know that album backwards. There’s no tread left anymore… except I found myself listening to that album in full through the Sugden combo, and loving every minute of it.

There’s a temptation to equate warm electronics with warm sound, and there is a kernel of truth to the connection. But that warmth doesn’t come at the expense of leading edge delivery and it doesn’t just make a huge soundstage as some kind of crowd pleaser. In fact, the combination – but especially the power amp – are extremely good at presenting the leading edges of music in a way that preserves timing information but doesn’t swamp the tonality or musical enjoyment at the same time. It’s the way the sound is just pulled together in one effortless gestalt that matters, and that’s what the Sugden amps do so well. You don’t tend to focus on elements of the sound because the music is so overarching, but if you force yourself to break up the sonic performance into bite-sized pieces, all those pieces are at or close to the top of their respective games. So when listening to Laura Marling singing ‘Take the Night Off’ [Once I Was An Eagle, Virgin], you not only have the stereo separation of voice and guitar, the detail and vocal articulation, the microdynamics of string noises, and the dynamic range of her singing rising out of the aether, but you get the added bonus of all of those things working together.

This shines through with the non-oversampling DAC, although I can’t help feeling this is a good and musical DAC in an otherwise fantastic system.


Actually, I’m about 8/10 with the DAP-800. I like its overall performance, and what could be thought of as a limitation in the DAC actually turns out to be the star of the preamp show. It’s a flexible and good sounding model and a keenly priced one at that. But it’s not the FBA-800. That’s something really special. It’s good with its Sugden brother, but it would really shine on the end of a superstar preamp, the kind that people talk of in hushed tones and are willing to spend tens of thousands owning. If I’m 8/10 on the DAP-800, I’m at about 11.5 out of 10 for the FBA-800. It’s best in balanced mode and that might keep away those who went from ‘purist’ to ‘puritanical’ but forget the connections, and even forget the 40W power output – these are some of the nicest watts you’ll ever hear. This isn’t just a world-class power amp, it sounds like home. If you can relate to what I mean by that, you are on the way to owning a Sugden Sapphire.



  • Inputs: Four line level inputs, one balanced input, bypass
  • Digital Inputs: Three S/PDIF coax, two S/PDIF optical, one USB type B, Word length up to 24bit 96k
  • Outputs: Two line level outputs, one balanced output, tape output
  • Volume Control: Motorised remote control (analogue) RC5 compatible
  • Mains Power Switching: Separate for analogue and digital circuits
  • Input Sensitivity:120mV for 1 Volt out
  • Maximum Output: 9 Volts
  • Frequency Response: 0dB 15Hz–98kHz
  • Bandwidth: 8Hz–125kHz
  • Signal to Noise: >85dB
  • Distortion: <0.05% @ 1kHz, 1 Volt out
  • Dimensions: 120 ×430 ×340mm (hwd)
  • Gross Weight (packed): 10kgs
  • Price: £4,635


  • Type: power amplifier
  • Inputs: Stereo line level, stereo balanced
  • Outputs: Stereo pair multi-way locking binding posts
  • Front Panel Gain Selector: 6dB input attenuation
  • Front Panel Input Selector: RCA or XLR
  • 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%
  • Dimensions (H×W×D): 21 ×43 ×46cm
  • Weight (packed): 25kgs
  • Price: £6,635

Manufactured by: Sugden Audio

URL: sugdenaudio.com

Tel: +44 (0) 1924 404088

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