“Good enough’ is rarely good enough for SPL, as this thoroughly over-engineered preamp testifies!” Hugh Robjohns
“On review here is the company’s latest eight-channel mic preamp, the Crescendo, which is a substantial piece of kit… From the user’s point of view, it’s very straightforward, just as a preamp should be, but it features some interesting technology that sets it apart from most mainstream preamp designs.”
“It doesn’t take long to comprehend the facilities and features of the Crescendo, and there’s little need to consult the brief but well-written user manual.”
“Apparently the SPL engineers used critical listening sessions to identify and select the best-sounding components (transistor types, resistors, capacitors and so on) to use in production. Inter stage coupling capacitors have been avoided where possible, with active DC servo circuitry to eliminate any DC offsets. The output driver stage is a variation on the standard SUPRA design that operates as a Class-A current amplifier running a relatively high (6mA) quiescent current, and
this enables it to drive long cables with ease. Although quite complex, the entire construction is beautifully engineered and inspires confidence.”
“Other manufacturers use discrete op-amp stages, of course, but SPL’s approach differs dramatically in their use of unusually high power-rail voltages: the circuitry operates on symmetrical ±60V power rails, an arrangement which might be expected in a power amp but is very unusual within a preamp. The Crescendo is not the only SPL product to work with such elevated power rails; the same engineering approach is used in several of the manufacturer’s high-end headphone amps, their phono preamp, several power amps, a D-A converter, the Neos console and, of course, all of their mastering console product range. So the technique is well-established, and the SUPRA op-amp modules have now been developed into a fifth-generation design.”
“The significance of the power-rail voltage is that it effectively defines the largest audio signal the circuitry can accommodate: the higher the voltage, the greater the audio headroom.”
Conclusion:
“This attractive and very well-built eight-channel mic preamp employs an unusual circuit topology to provide massive internal headroom and dynamic range capability.”
”…the preamps always sounded wonderfully open, crisp, full-bodied, and effortlessly transparent – a large part of which must be down to the massive internal headroom and dynamic range. ”
“In summary, then, SPL’s Crescendo is an impressively-built multi-channel mic preamp which espouses the art of the discrete transistor op-amp operating on high-voltage rails, and that unusual design approach pays off in its graceful and natural sound quality.”
Find the complete review in Sound On Sound magazine (edition May 2019) or purchase a PDF version online at Sound on Sound.
