Reviewer: Srajan Ebaen
Source: Accustic Arts Drive-1; Zanden Audio Model 5000 MkIII DAC
Preamp/Integrated: Bel Canto PRe2 GenII; Eastern Electric MiniMax
Amp: AUDIOPAX Model 88
Speakers: Avantgarde Acoustic DUO; nOrh SM 6.9, Gallo Acoustic Reference III
Cables: HMS Grand Finale; Crystal Cable Reference; 2 x Stealth Audio Cable Indra; Z-Cable Reference Cyclone power cords on powerline conditioners
Stands: Grand Prix Audio Monaco four-tier
Powerline conditioning: BPT BP-3.5 Signature; Walker Audio Velocitor for source components
Sundry accessories: GPA Formula Carbon/Kevlar shelf for tube amps; GPA Apex footers underneath stand and speakers; Walker Audio SST on all connections; Walker Audio Vivid CD cleaner; Furutech RD-2 CD demagnetizer; WorldPower cryo'd Hubbell wall sockets; Musse Audio resonance dampers on DUO subs; Mapleshade 4" solid maple platform under BPT conditioner
Room size: 30' w x 18' d x 10' h [sloping ceiling] in long-wall setup in one half, with open adjoining living room for a total of ca.1000 squ.ft floor plan and significant 'active' cubic air volume of essentially the entire (small) house
Review component retail: $6.800/pr

The CIA asked me to issue a Conflict-of-Interest-Alert. Roger Hebert included this pen in his shipment of review amps and -- despite being a computer guy with foul handwriting -- I've accepted it for future check writing use when I grow up and get a real job. You're thus duly forewarned that what follows has been gratuitously influenced by this pen. There, I got that off my chest. Phew. All kidding aside, my prior encounter with Wyetech Lab's Coral preamp had prepared me for what to expect:
No-nonsense styling, lavender 14-gauge welded steel casings, perfectly balanced polished brass grab handles to move each amp's 33 lbs. Yeoman switches that will still work while my remains are pushing up daisies. Sorbothane-decoupled 3M rubber footers, cast-aluminum power tranny cover, in-depth documentation. Sensible features such as a lo/normal/hi switch for 20/25/30dB of gain and 2/4/8/12-ohm impedance-matching taps selectable via a combination of two switches to avoid disconnecting speaker leads. Did I mention a slow-start circuit to extend tube life and prevent in-rush current effects and cathode emission deterioration?

When you're dealing with Wyetech Labs, the real beauty of their designs goes far beyond surface considerations. In the case of the new and non-inverting Sapphire monoblocks with their quasi-paralleled TJ Full Music gold mesh plate 300B output tubes and a NOS 9-pin 5687 for voltage gain/driver stage, think custom wide bandwidth 12 lbs. Hammond output transformers. Add very large signal capacitors for a claimed frequency response of 6Hz - 43kHz +0/-3dB, or 11Hz - 28kHz +0/-1dB for an even tighter spec. Think toroidal power transformer with selectable 115V/230V 50/60Hz switch and full-wave rectification. Think auto bias at 78 volts DC that independently regulates each output tube which only connects via its plate/transformer connection to the other 300B while enjoying its own dedicated DC floating power supply. Think DC filtration on the driver/input tube filament for low noise. Think separate R/C filtered power supplies for the 400-volt input and 460-volt output stages. Think 185 watts of max power consumption per amplifier for pure Class A1 operation without any feedback. Think 10-year warranty if you return the registration card and proof of purchase within 15 days.

Now let's talk turkey - power. The Sapphires are rated for 18 watts RMS with an energy storage of 300 joules which requires 4 hours of dissipation before it is safe to remove the bottom plate. Depending on which gain option you select, input sensitivity drops from 1.28VRMS to 0.6 and 0.38 as you increase gain from 20 to 25 and 30dB. Input impedance likewise varies with gain setting: 55kohm/low; 50kohm/normal; 200kohm/high. Users with phase-inverting preamps can request in-built phase inversion for the Sapphires but the stock amps arrive with non-inverted polarity and are preset to normal gain. A quick removal of the bottom plate and a flick of a switch or the removal of a jumper can change the latter to suit your personal needs.

In case you're wondering about those heatsinks in the upper image and are thinking transistors - those are the 5-volt DC regulators for the 300B filaments. Wyetech Labs uses a separate bridge rectifier and a 10,000uf capacitor for each tube to filter the DC before passing it along to the regulator to arrive at a pure source of 5-Volt DC power for those critical Directly Heated Triodes. Those two rectangular white ceramic wire-wound resistors standing up next to the regulators are rated at 10 watts dissipation each. Roger Hebert uses two of them in parallel to form a 20-watt resistor. They are used in the biasing circuitry for the 300B and put out about 6.5 watts of heat. This would be considered overkill by any stretch of the imagination but was done for rugged reliability and to spread the heat around for better convection cooling through the side vents and up through the top vents.

Dimensions without tubes are 9.5" W x 16" D x 8.5" H. Weight again is 33 lbs and tubes are warrantied for 6 months. Each unit comes with a brass name plate and individually engraved serial number.

On their chassis top, each Sapphire sports a pair of top-grade WBT 5-way speaker terminals and a single RCA input on the left side of the power transformer and a mains fuse on the other. Just above the polished grab rails are the impedance selector switches with clear silk screen markings to indicate how to set for the four possible combinations. Just in front of the handles is a voltmeter input for each power tube in case you purchase replacements not from Wyetech. In that case, you should check that the bias current remains within 10% of what the circuit wants to see.

The front of the chassis top sports the green power LED in the left corner and the power mains toggle in the right, with high-quality tube sockets arranged in a triangle and clearly marked by a brass plate. All in all, the new Wyetech Labs Sapphire monoblocks are a smartly executed product with a unique combination of vintage looks and modern touches and an uncommon variation on parallel SET architectures for 18 watts of low-noise, wide bandwidth output power.

You'll notice in the left picture how bright the 5687driver tube lights up. Roger calls it a 6SN7 on steroids, with higher current capabilities and lower plate resistance than its more commonly used relative. He has thousands of them in stock and will be using them in future products.