February
2021

Country of Origin

Germany

Crossover

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo boost, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Audirvana 3, Qobuz Hifi, Tidal Hifi, Denafrips Terminator, Soundaware D300Ref SD transport & USB bridge; Preamplifier: Vinnie Rossi L2 Signature with WE VT52/300B or Elrog 50/300B; Power amplifiers: LinnenberG Audio Liszt monos; Headphone amp: Kinki Studio; Headphones: Final D8000; Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Aurai Audio M1 [on loan]; Cables: Complete loom of Allnic Audio ZL3000; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, LessLoss C-MARC Entropic cords between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands; Sundry accessories: Acoustic System resonators; Room: 4 x 6m with high gabled beam ceiling opening into 4 x 8m kitchen and 5 x 8m living room, hence no wall behind the listening chairs
Second system: Source: Soundaware D100Pro SD transport; DAC/pre: COS Engineering D1; Amplifier: Bakoon AMP-13R; Loudspeakers: Acelec Model One w. Franck Tchang magnesium 360° super tweeters, Zu Submission subwoofer, LessLoss Firewall for Loudspeakers; Power delivery: Puritan Audio Lab PSM-156; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Room: ~4x6m
Desktop system: Source: HP Z230 work station Win7/64; USB bridge: Audiobyte Hydra X+; Headphone amp: COS Engineering H1; Headphones: Audeze LCD-XC; Powered speakers: Fram Audio Midi 150
Upstairs headfi system: Source: Soundaware A280 SD transport; DAC: Auralic Vega; Integrated amplifier: Schiit Jotunheim R; Headphones: Raal-Requisite SR1a
2-channel video system: 
Source: Oppo BDP-105; DAC: Kinki Studio; Preamp: Wyred4Sound STP-SE II; Power amp: Pass Labs XA-30.8; Loudspeakers: German Physiks HRS-120; Room: ~6x4m
Review component retail: €3'249

spl Audio's Crossover is for users whose subwoofer either includes no low-pass filter because it's passive; or who wish to bypass what's built in for something superior. It's also for those who prefer full filtering to include their main speakers in the filter loop. Now their voice coils no longer heat up from attempting bass they can't do, thus don't drive up their impedance to choke the dynamic range higher up. It's why there's a matching high pass which can be set for 12dB/24dB/octave. spl's entire circuit is analogue to involve no redundant A/D/A conversion.

Because spl cross over from pro to hifi…

…their outputs are on XLR exclusively. You'll need matching balanced gear or XLR/RCA adapters.

The firm's trademark are their Voltair discrete operational amplifiers. They run on ±60V rails so four times higher than the standard ±15V. That's done for expanded dynamic range and lower distortion. It naturally relies on quality parts fit for such higher purpose. T+A also from Germany have their own take on the concept which they call HV for high voltage. It runs their low-level signals at up to 100V, the high-level signal in their power amps at up to 360V. The following video has spl's key talking points.

Below we see the Crossover's linear power supply with toroidal mu-metal shielded mains transformer; 2 x 4'700µF Epcos capacitors to stabilize the DC voltages; orange relays which are 18-carat gold plated and gas encapsulated; and, in the left photo, vertically installed Supra balancing and Supra operational amplifier cards plus an RK27 'Big Blue' Alps potentiometer for the subwoofer's relative volume.

In the upper right photo, we see the now installed top board. It splits into the low-pass filter with Panasonic PAM Gold series caps on its left, the high-pass filter with Styroflex capacitors on the right. Both filters use precision metal-film resistors and one each blue custom filter-frequency switch.