Hands On: Bob Carver Black Magic 20 Amp
Tube amps get expensive fast, but Bob Carver's Black Magic 20 is priced at a level that makes it a reasonable step up from mainstream solid-state products.
Robert Archer · January 28, 2013
Tube amps used to be considered unreliable, noisy and demanding to own, but times have changed. The quality has improved and fixed bias or auto bias technologies have taken the constant care out of owning a tube amp.
The Black Magic 20 is rated to deliver 20 watts per channel operating in stereo mode and 40 watts as a monoblock. In the input stage Carver employs a pair of 12AX7B tubes and in the output stage the amp uses
four EL84M tubes. On the right corner of the amp there is a volume control that can be used if source components are connected directly to the amp and like many modern tube amps, Carver utilizes an auto bias
feature to help maintain the power tubes’ proper operational parameters, as well as their longevity.
In addition, the hand-built, point-to-point hand soldered amp employs a screen voltage regulator and DC restoration circuit that is said to minimize crossover distortion and output tube dissipation. Other design elements include current and voltage feedback loops that are coupled with the amp’s 1.5 ohm output impedance to enable the amp to “listen” to its room environment via acoustic feedback from the connected speakers.
2 12X7 preamp tubes
4 EL84M power tubes
One set of RCA inputs
20 watts per channel in stereo mode
40 watts in a bridged, monoblock mode
Installing the amp is a breeze. After plugging in the input and power stage tubes I set the volume knob at its max level, ran a pair of Straight Wire RCA cables to a Bryston preamp that was connected to a NAD Masters Series M51 DAC and a Cambridge Audio phono preamp/Thorens TD-160 turntable.
From the outset, I loved the way this amp sounded uncolored and delivered lots of 3D texture. While breaking it in I listened to songs in a variety of formats including digital, vinyl and CD. On songs like The Police’s “Every Breath you Take,” Stewart Copeland’s drum kit was transparent with a nice amount of responsiveness. Sting’s bass had a nice sense of space within the image and Andy Summers’ guitar was presented with a huge amount of detail that allowed me to hear the decay in the amount of delay he used to accent his part within the song.
One trait that doesn’t get talked about with amplifiers often is dynamic response. Listening to the first CD in Led Zeppelin’s “How the West was Won”, I loved how the Carver was able to communicate Jimmy Page’s use of his guitars’ volume knobs to control the distortion and intensity of his guitar tone. When Page rolls back the volume on his Les Paul to clean up his tone the Carver is able to convey the differences in dynamics without losing any sense of musicality.
Tube amps get expensive fast, but the Black Magic 20 is priced at a level that makes it a reasonable step up from mainstream solid-state product products.
I love this amp and I’ll be really sad to send it back to the factory. And yet as good as it sounds now, I think there’s room for improvement. If I owned the amp I would ditch the Chinese preamp tubes (Chinese tubes are generally mushy sounding) and I would replace them with a matched set of European JJ Electronics 12AX7s.
Beyond the sapping of preamp tubes, the Black Magic 20 delivers everything a music lover would want out of an amplifier and more. My listening sessions revealed an amp that delivers all of the qualities that tubes are known for at a price point that is reasonable.
I didn’t hear any of the negatives that are sometimes associated with tube gear like a lack of bass control and a lack of frequency extension.
Bob is an audio enthusiast who has written about consumer electronics for various publications within Massachusetts before joining the staff of CE Pro in 2000. Bob is THX Level I certified, and he's also taken classes from the Imaging Science Foundation (ISF) and Home Acoustics Alliance (HAA). In addition, he's studied guitar and music theory at Sarrin Music Studios in Wakefield, Mass. Have a suggestion or a topic you want read more about? Email Robert at [email protected]
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