Graham Slee Solo Ultra-Linear Diamond Edition Headphone Amp
The Magic of Tubes Captured in Solid State
The Solo Ultra-Linear Diamond Edition is a brand new type of solid state device, one we're exceptionally enamored with. Graham Slee has finally unlocked the secret of the glorious sound of tubes and has figured out how to get a solid state device to sound just like a tube amp.
"It's been my intention to recreate the original valve sound for years as they always "told the story" better! Our Ultra-Linear technology is the result of two years almost solid research, exhaustive development and testing. We researched how to mimic all the valve’s sonic characteristics to improve our products. We found a number of op-amps (integrated circuits) which could be made to perform just like valves!"
– Graham Slee
So what is the secret to the Solo Ultra-Linear DE's incredible sound? Well, there are many, but for one its distortion characteristics are quite unlike any other solid state headphone amp. Generally speaking, solid state distortion increases in proportion to frequency, so when there's lots of high frequency information distortion increases and this is highly noticeable when playing complex music.
"Graham Slee products with Ultra-Linear technology feature significantly wider bandwidth just like the best valve amps. We call this innovation Ultra-Linear because that was the tag used to describe the great performance of the best sounding valve amps from the mid 1940s."
– Graham Slee
The distortion from the Solo Ultra-Linear remains consistently low throughout the audio spectrum, because it has exceptionally wide bandwidth! Most solid state headphone amps have limited bandwidth and use negative feedback to not only fix distortion and noise but also to widen the bandwidth of the device. All this really does is add distortion in the form of glare to the high frequencies, affects bass and mid frequencies by smearing the leading edge of the note. If highs are distorted much of the fine detailing in the bass and mid frequencies is also lost. By linearly improving distortion throughout the entire audio band the sound stage comes alive as you've never had before.
Like most headphone amps except for the ridiculously expensive, the Solo Ultra Linear is basically a pair of transistor assisted op-amps, but these are no ordinary op-amps! Graham Slee chose one of the very few op-amps which feature one of the best output stages ever designed. Featured in Wireless World in 1969 and authored by J L Linsley Hood this circuit remains the most musical of all output stages and runs class-A. To these Graham Slee adds their proprietary open-loop bandwidth widening technique and the difference is staggering.