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TL;DR Tisbury Audio Challenge Amp 1 Review: The CA-1 is a British reference grade desktop headphone amplifier with the most beautiful design and sound quality. Primarily sold direct through their website and eBay the CA-1 is smooth, detailed, and dynamically tame, and excellent value for money. Review Preface Opening their doors in early 2014 with their first product, the ‘Mini Passive Preamp’, it was clear from day one that young London born Tisbury Audio aimed to please with elegant ‘old skool’ analogue designs that cut out the middleman and became obtainable for an not-so extravagant price. Saying this it is important to note that, where applicable, Tisbury Audio try to source all of their components from British manufacturers or suppliers. Now, building upon the success of their first foray, Tisbury Audio has released a charming desktop headphone amp named the Challenge Amp 1, and today we shall explore this elegant, somewhat organic, design. Please note that Tisbury Audio sell their product on their website and on eBay for a current retail price of £349.00. Tisbury Audio are so confident in their product that they offer an unbeatable 30 day money back satisfaction guarantee. In addition the Challenge Amp 1 comes with a comprehensive three year warranty in the unlikely event of electronic malfunction. Unboxing, Design Features, and Technical Aspects Situated inside a plain white Tisbury Audio branded box with a cocoon of grey low density foam, the Challenge Amp 1 appears to be well protected against the elements. Upon opening you are greeted with a separate box for the 12v wall-wart power supply, a basic instruction manual, and separate A4 design notes sheet. The purpose of using and external power supply is that the main unit doesn’t have to sport an expensive integrated power circuit that needs to adequately isolated from the signal path, removes potential interference, and eliminates various mains issues. Therefore, the Challenge Amp 1 is immediately more cost effective and passes this affordable benefit down to the consumer. Furthermore, Tisbury Audio have opted to use a reputable Stontronics switch mode supply with a cable length of 1.8 meters to allow the CA-1 to be placed in far reaching locations, although arguably a ferrite core bead on this cable would have added a higher degree of protection from radio-frequency interference. If we now refer back to the main man, the Challenge Amp 1 is clearly a well built and relies on a beautiful yesteryear design. Tisbury Audio have crafted the faceplate, backplate, and top U-Shape case from a 3mm thick brushed aluminium panel with punch engraved detailing, which naturally stops radio frequencies from penetrating the outer casework. The product measures 8” x 5 ½” x 3” and for aesthetic reasons, the CA-1 features left, right, and baseplate sides which have been lovingly hand crafted from 10mm waxed black American walnut. The carpentry is second to none, and Tisbury Audio have internally lined the wood with a copper foil to, again, inhibit penetrating radio frequency interference. On the faceplate Tisbury Audio have opted for simplicity by including only a single ¼” headphone output, output power level flick-switch selector indicated by High and Low, an aluminium potentiometer cap, and an dual LED indicator which shows as green when the power protection is on (during startup), and illuminates as a baby blue when the amplifier is fully operational. Unfortunately the power on flick-switch is located on the rear of the unit, next to the standard power input instead of conveniently being located on the faceplate. However, Tisbury Audio have opted to use high performance solid copper, gold plated, CMC (Charming Music Conductor) 816-U protruding RCA posts which is a positive point. As these posts have 20mm of clearance you are able to use premium interconnects with wide terminals by the likes of The Chord Company, if you so choose. Please note that the package does not include any RCA leads as standard. On the whole the CA-1 is beautifully built, is of moderate weight, and includes four elevating rubber feet to protect the surface that it may sit on. Strangely enough we often associate weight with quality and, whilst this is the most ridiculous point to pick up on, please forgive me, the Challenge Amp 1 is on the light side. This concludes the exterior presentation. Internal inspection of the Challenge Amp 1 clearly indicates exceptional engineering capabilities, understanding, and attention to detail. In fact the CA-1 is fanless and sports a precision engineered surface mount PCB with clear tracings and excellent clearance to eliminate any possible crosstalk, whilst premium components are expertly silver soldered and trimmed. Tisbury Audio have gone to great lengths to create the Challenge Amp 1 and, as such, have only used premium components, which include; Panasonic capacitors, Susumi Thin Film resistors, a Neutrik connector on the ¼” output, and finally the brilliant Japanese ALPS ‘Blue Velvet’ potentiometer. No expense has been spared, no corners have been cut! However, also employed within the Challenge Amp 1 are two relay switches to protect your headphones from possible damage during startup, shutdown, and if an incorrect power supply has been connected. Obviously these protection features come as standard at this calibre, although still notable. Evidently with the Challenge Amp 1 Tisbury Audio spent a significant amount of time to research and develop exactly what would make it one of the most competitive headphone amplifiers around. This painstaking process led the team to employ a chip and buffer configuration which, consequently, is the same process as used in reference grade headphone amplifiers designed for the record production and mastering industries. Tisbury Audio did not want to settle on seemingly ‘lower tier’ technologies and settled on an highly reputable, up-to-fate, and very well known Texus Instruments LME49720 operational amplifier (aka. ‘chip’) and LME49600 current buffer. As a result of the amplifier design, the Challenge Amp 1 has undisputed luxuriously clean ‘poreless’ characteristics, a low signal to noise ratio which is virtually inaudibly quiet at -110dBV, and a very low distortion (0.0003%). Sound Quality Before we progress it is important to highlight some of the basic assets that make the CA-1 a very competent headphone amplifier. It is reported within the notes that the Challenge Amp One, on the high gain setting, is able to pump 945mW of power into a pair of 36Ω headphones, 225mW into a pair of 300Ω headphones, or 115mW into a pair of 600Ω headphones. Clearly this is more than enough to drive tricky planar magnetic headphones and Tisbury Audio have performed tests on the Challenge Amp One to prove that it can even drive a pair of notoriously difficult HiFiMan HE-6’s to 113dB. During our own testing we can confirm that this headphone amplifier is easily capable of driving headphones of 250Ω and 600Ω’s. As the Tisbury Audio have designed their headphone amplifier with two varying stages of gain, the volume can be used to suit all headphones from IEM’s to thirsty over ear headphones. I have to say that I do really love what the Challenge Amp One manages to achieve. Without rehashing what has already been mentioned, I stated that the Challenge Amp One is luxurious. I mean this with all seriousness. It is all too often that we come across the ‘reference grade’ prefix thrown out to the fore of marketing materials. Subsequently these hastily positioned buzzwords have left low to mid-tier consumers accepting that flatline frequency (1dB increment) responses yield an inherent unexciting, prickly, and crystalline tone. Actually this is so far from the truth, but unfortunately the technology is currently too expensive to unlock what true ‘reference’ is to the masses. However, the Challenge Amp One doesn’t follow the forgettable aforementioned characteristics. The Challenge Amp One is liberating. Tisbury Audio clearly understand what reference really is and they have done this without pretentious prestige pricing. They have succeeded in producing a technically ‘flatline’ headphone amp that is silky, suave, refined, and engaging. During the entire time that I spent with the CA-1 I never encountered any distortion issues and found the headphone amp to be whisper quiet to the point that it was absolutely not audible. If we dissect the broad magnificent statements of the above the Tisbury Audio CA-1 is one of the most ‘fluid’ headphone amps within its class. Transient detailing across the frequency range is not overly critical and remains natural and fairly consistent across the frequency spectrum with the only exception being the ‘true’ midrange. ‘Pointed’ crunchy vocals, heavy guitar riffs, and explosive snares appear to be more defined in this area which, in turn, creates an excitable performance for the ear. Treble frequencies extend well and there is never any evidence of sibilance that would otherwise appear sharp, instead this area of interest is best described as sounding ‘full’. Again the midrange is well controlled and silky, however it does sound like the lower mids are ever so slightly forward, but saying this it is most likely as a result of the flatline frequency response. Bass is sufficient, rich, and present without overwhelming any other frequency and on the whole the synergy is outstanding. Again the term ‘natural’ can be used to describe the soundstage. Across a broad range of headphones the CA-1 managed to produce a sudo-personal experience that was highly agreeable and appropriately positioned the air within the mix to create a three dimensional experience. Positioning ‘air’ may sound like a strange descriptive, however air has to be well clean and well maintained in order for production processes, such as reverb tails or other decays, to compliment an experience that can be considered natural, and the CA-1 does this perfectly. In this department the CA-1 doesn’t artificially thicken this space, instead it leaves to to be populated by the music and does not hype certain elements that would otherwise leave the presentation sounding either sparse or overwhelming. The resulting soundstage is simply ‘natural’ and I, personally, find this area of performance exciting and the accuracy judged correctly. Live tracks sound phenomenal! Review Conclusion Tisbury Audio are onto a winner with their Challenge Amp One. A classy yesteryear design has been championed with exquisite engineering to create a sure fire reference grade hit for hefty headphone users. Fear not in spending £349, as soon as you hear the CA-1 you will be left with the biggest grin on your face. The Pro Audio Web Blog not only intends to hand the Challenge Amp One with an incredible four and a half star rating, but also our coveted ‘outstanding’ award.

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