Croft Twinstar Amplifier & Charisma II Preamplifier Review

Croft is a British design and manufacturing company operating under the name of eminent audio uk, and is named for Glenn Croft who has been active in his business for about 30 years.

He became a force to be reckoned, as he produced amps and preamps for the proverbial "song" with a high-end sound. Croft sold them via word-of-mouth, as marketing seems to have been unimportant to him. More recently, croft has designed and produced truly high-end electronics and improved visibility with more advanced marketing procedures. The components under review are second from top of the line of four amps and four preamps currently available, which bring us to the....

APPEARANCE:

The preamplifier's original design sports a wooden face-plate, which actually looked quite attractive. However, the face plate has been redesigned and now offers the much snazzier look of polished steel. Nothing interferes with the components' immaculate frontal layout which accommodates two small brass knobs in the centre which operate the selector switch on the left and the volume on the right. The company logo is located under the two knobs. Also on the (far) right a small toggle serves as the on/off switch.

The external power supply is connected to the main unit and, strangely, doesn't include the AC cord which is attached to the main unit. The rear of the unit accommodates only four inputs (including phono) which reflect Croft's minimalist outlook: less is more (than enough to provide a connection for a cd player, a tuner, a spare and a mute control).

The amplifier matches the appearance of the preamplifier and sports only the on/off toggle on the unit's right front and the company logo in the centre. The relatively new look of these components will appeal to refined taste as they are quite attractive with a touch of urbanity.

TECHNOLOGY:

The Charisma II preamplifier is a true vacuum tube unit with few bells and whistles. The main features include a tube regulated external power supply with a 500Va dual capacity toroidal transformer.

The output stage is directly coupled to the inputs thus using bare minimum components in the signal path. Where applicable, wire wound resistors are employed and hand wiring is accomplished d with high purity copper conductors.

The vacuum tube complement includes five 6SL7GTs, one ECC83, one 6080 and one 85A2. Everything inside is hand-and-hard wired providing an immaculate layout and a straightforward signal path arrangement.

We understand that this unit is available with dual volume controls for left and right channels.

The Twinstar power amplifier is what croft calls a transvalve design, which hints at the hybrid topology employed here. It features a unique input stage powered by two 6sl7 tubes and solid state Mosfet output devices. The se are hard wired directly to the amplifier's output stage, omitting transformers, capacitors and resistors resulting in what is known as OTL (Output Transformer-Less) and OCL (Output Capacitor-Less) design. The amplifier features a pure class A input stage and zero feedback. Where necessary in the input stages, croft employs paper in oil coupling capacitors. The Mosfets are carefully selected for tight tolerances and according to the designer, provide similar sonic characteristics to those achieved with excellent vacuum tubes. The amplifier delivers 46 watts/channel, enough power to drive medium efficiency loudspeakers with sonic finesse of a good single ended tube design as we shall see when we get to....

THE SOUND:

For our auditioning sessions, we used the Gershman GAP's, as well as the Mead Song Lab ribbons (both reviewed in this issue). The Audio Aero Capitole CD player (reviewed in our last issue) served as our component and wiring was done with the XLO Limited Edition (reviewed in our last issue) as well as the Nordost Valhalla cables. All peripheral components had been previously auditioned and their sonic character was well known to our listening panel. To ascertain compatibility and/or synergy with additional electronics, we connected the amplifier to our in-house amplifiers - the Bryston 7B SSTS (reviewed in vol. 15#1) and the Wytech Labs Onyx monoblocks (reviewed in vol. 13 #4) for some of our sessions. For other auditions, we connected the croft amplifier to our in-house Wytech Labs Opal preamplifier, as well as the Audio Aero Capitole player which sports its own preamplifier section.

First, we used the amplifier with our in-house Opal preamplifier which quickly established the "sonic signature" of the Croft power amp. The first and foremost sonic element of this amplifier is its ability to "charm" listeners, as its musical proficiency far outshines its unpretentious appearance. Though we expected smooth flowing highs, we didn't anticipate the effortless blossoming of high frequencies combined with perspicuity. Pure midrange information, while demonstrating similar sonic attributes to the highs, did short fall of perfection as it "romanticized" the sound of the brass and other hard sounding instruments. This was more apparent when we used the Gershman speakers and, in all fairness, didn't detract from the amplifier's "musical" quality. In other words, hard-sounding instruments didn't sound severe enough to be labelled as realistic, but were gratifying enough to provide listening pleasure.

THE CHARISMA II PREAMPLIFIER IS A GREAT COMPONENT ALLOWS FIRST-RATE REPRODUCTION

Without a doubt, the most difficult test for the amplifier was with the meadow song lab speakers, when we used it first to drive the subwoofers and later the ribbons. Attached to the sub, the amp demonstrated surprisingly rich and low resolute low bass without, however, allowing even minute slacking of control by the drivers - proof of excellent bass. The stability of the amplifier was challenged by the ribbons, which tend to reveal shortcomings throughout the midrange and high frequencies. However, none of these potential problems were evident as the ribbons reflected the amplifiers mid-range bloom, smoothness and sophisticated high frequency information. All in all, this is a superb amplifier with considerable musical proficiency coupled with technology which brings its performance to a satisfactory and natural conclusion.

The preamplifier offers a phono stage which we didn't test, although we heard it in operation at the spring audio show in Montreal. There we listened to a couple of cuts of an lp and noted the quiet, naturally flowing information that is what a good turntable/cartridge combination does best. Back in our listening studio we tested the preamplifier with in-house power amps, including the Bryston 7B SST monoblocks, the Wyetch labs onyx monoblocs as well as the sibling Croft Twinstar. With our in-house amplifiers, the Charisma II quickly revealed its strength and its weakness. The strength was its musically gratifying disposition which included ripe, sonorous lower midrange and bass. Pure midrange had that undeniable vacuum tube quality with blossoming information achieved without masking the program materials inner detail, indeed revealing instruments texture and gradation.

The highs were accomplished, finishing upper extremes very well, but failed to conclude with maximal resolution. Some panellists felt this to be characteristic of vacuum tube designs and quite pleasing to the ear. Others thought that, although not being a big issue, the highs were "too polite". The editor stated that this attribute will match well with many loudspeakers and should not really be considered a weakness; rather, it should be viewed as the unit's personality which will please many listeners. As this trait doesn't diminish the unit's musical proficiency, on which we all agreed, the solution for potential buyers is, as always, to listen before you buy.

Imaging, focus, detail, rhythm and time/space elements combined with attributes of superb design make the Charisma II a high-end contender quite compatible with amplifiers of different makes.

SYNOPSIS & COMMENTARY:

In business, far too many consumers are worried about the science of audio, its technology. While science is interesting, it is perhaps more intriguing to learn why audio designers are predisposed towards a particular technique, a method which results in the interpretation of music via electronics. It is safe to assume that, while all designers have the same goal, they may choose quite different techniques to reach it. Here we have an amplifier design which, in its basic layout, varies somewhat from the Futterman OTL's of years past. It works extremely well, and we dare say, is much more reliable and affordable. Most of the OTL's we have examined are much more expensive as one of the problems is matching parts and tubes - a time consuming chore. Croft's Twinstar amps perform beyond expectations and far above the run of the mill amplifiers currently available.

Additionally the Charisma II is a great component that allows first rate reproduction and, ultimately, a view into the art form itself - the music. The Charisma/Twinstar combination won the respect of everyone who listened to the system as synergy was achieved and the loudspeakers we used acted as though the electronics were made for them. It is obvious that Glenn Croft is a gifted designer - an old dog with new tricks - who has taken the audio industry's standards up by a few notches - Good Job.

 


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