For the last thirty years I have been a staunch tube lover, but not for the reasons solid state aficionados would have you believe. The phrase I hear parroted by many personal audio buffs, which has its roots in solid state designers, is “that tubes make a distortion that is pleasing to the ear, and color the sound reducing harsh high frequencies”. It is this erroneous philosophy that has led many designers, especially in the personal audio community, to try to make solid state amplifiers that sound like tubes (usually to seriously degraded if popular sound quality), and many tube amplifier manufacturers to emphasis rather than limit the deficiencies of tubes. Contrarily, what makes a high performance tube amp sound better than an equivalent transistor amplifier is the inability of tubes to produce a specific distortion known as Transient Intermodulation Distortion (TIM or TIMD). The Tube’s relatively slow slew rate (which makes it unable to reproduce TIM) can also roll off the high frequencies in a poorly designed tube amp and this along with tube amps having generally higher measured THD (Total Harmonic Distortion which is significantly less audible than TIM) has brought about the above myth. TIM is what gives solid state gear that slightly metallic or harsh sound in the high frequencies which tends to obscure micro-detail, and it is this micro-detail that give tube amps their expansive and airy sound stages.
The holy grail of Tube amps is the Single Stage Single Ended Class A Triode. The drawback of this configuration is fairly low power output levels (generally less than 10 Watts), which severely limits loudspeaker selection (primarily to horn loaded designs). While 3 Watts may be a sub-optimal for loudspeakers it is more than enough for headphones making the Single Ended Triode perfect for personal audio.
Justin Weber of ampsandsound is an old school tube designer who believes in best practices manufacturing (IE: he employs classic designs, with the highest quality components and hand crafting). Rather than coloring and blurring the sound to make a “tuby” sounding product they “strive for a neutral, non-fatiguing sound, and demand that all our [sic] products be ultra-quiet in operation.” In pursuit of this, ampsandsound realizes that one of the most critical components in a tube amp is the output transformer, which they have custom hand wound by Transcendar for extreme bandwidth and linearity.
One of their newest offerings is the Mogwai, designed with an 8 ohm tap for use with loudspeakers and a 32 ohm tap for use with headphones. Counting on different tube configurations to offer subtle changes in presentation, the Mogwai’s auto biasing is designed to accommodate a large range of tubes including; 6L6GC, EL34s, KT66, KT77, KT88, 6550s and KT90s. The one I have is fitted with JJ Electronic 6CA7s, and Justin even offered to retrofit it for the 802 (a personal favorite).
The Sound: For the purposes of this review, Justin sent along a pair of Zu Cubes so that I could evaluate the speaker outputs. To this end, I set up the Mogwai and the Zu Cubes in my living room. After quite a bit of tweaking, I was able to arrive at a configuration for the Cubes (against the far wall, slightly off axis) that provided a reasonable soundstage. Using the Questyle QP1 as a digital source I listened to several of my standard test tracks and determined fairly quickly that not only could the Mogwai drive high efficiency speakers, but make them sing. But alas the Zu Cubes are not the speaker for me and even the Mogwai’s warmth and mystical midrange could not make them something I wanted to listen to. As an experiment, I connected my audio speakers to the Mogwai, and though the sound was heavenly, three watts was simply not enough power for them even in a near field configuration.
It was time to switch to headphones. My initial listening tests using the QP1 as DAC involved the MrSpeakers ETHER C Flow headphones and the HiFiMan HE-1000 headphones. While the two headphones have a slightly different sonic signature, both are extremely fast and detailed and were well served by airy resolution of the Mogwai. The tonal balance of the Mogwai is very linear with a slight uptick in the high frequencies and exceptionally deep and fast bass (which is frankly unusual for tube headphone amps) as was evidenced by “Can-Utility and the Coastliners” (Genesis Foxtrot 16/44.1). Michael Rutherford’s bass pedal enhanced sub-sonic bass notes were rendered with great authority without appearing boomy while the percussion expertly punctuated by Phil Collins was crisp and well defined. In contrast the Mogwai’s honeyed midrange wrung every bit of emotion from Peter Gabriel’s heart rending vocals.
The soundstage was open, wide and deep with live tracks like Peter, Paul and Mary’s cover of “Blowin’ in the Wind” (In Concert DSD) presented with a true sense of theater. The musicality of the voices executed with spine chilling passion and a pinpoint imaging that creates an engaging and joyful realism.
As part of my review of the Noble Katana IEMs I connected my turntable and Audible Illusions preamp to the Mogwai, the results were transcendental. Johnny Winter tugged at my heartstrings with the sentimental melancholy of his blues guitar artistry (Still Alive and Well – Columbia USA – SQ).
The higher resolution of a true analog source brought out the best in the Mogwai, enhancing everything that was magical about the tube amp. Listening to “A Cold Old Worried Lady” by Triumvirat (Old Loves Die Hard – EMI Japan) the piano was deep and rich placing the Steinway Grand in a great hall accompanied by the silky despondent vocalizations of Barry Palmer.
Not only did the ETHER C Flows and the Katanas prefer vinyl transliteration, the Zu Cubes also enjoyed the benefits, becoming a little more emotional and a little less abrasive.
Since the majority of readers will be listening to digital, and since a world class amplifier deserves a world class DAC I moved the Mogwai into my office to connect it to the Questyle CAS192D True DSD/Current Mode Amplification DAC.
You have probably have noted from earlier articles that I use Classical Music to determine the accuracy and fidelity of any given piece of audio gear, in specific Igor Stravinsky’s “The Firebird Suite” (and in this case Reference Recordings Eiji Oue conducting the Minnesota Orchestra – DSD). So how did it sound, you ask, have you ever been to the Hollywood Bowl? Or the Walt Disney Concert Hall? That’s what it was like. Dynamic, articulate, with a strong feel of the room, the musicians placed as individuals adding to a cohesive sound. Each instrument imbued with its own unique characteristics, the oboe, the flute, the French horn, plucked violas and cellos, the crash of the tympanis and kettle drums, the ring of triangles, violins singing in unison, as well as the blare of the brass section.
As a pianist, the one instrument that brings it home for me is the piano, so I put on Billy Joel (“Piano Man” Piano Man – DSD). While the Mogwai’s true strength is the human voice, lovingly portraying the soul of Billy’s singing, the piano reverberates with deep chest and spritely sopranos in a large music hall, yet refuses to obscure the harmonica, according and mandolin.
Bryan Ferry’s crooning baritone sparked its own form of ecstasy as he sang “Out of the Blue” against a cacophony of virtuosic melodies (Country Life Roxy Music – DSD) taking full advantage of the 6CA7s. As did a crooner of a different era, Dean Martin belting out “Everybody Loves Somebody” (Dino: The Essential Dean Martin – 16/44.1) to a backdrop of lavish strings, piano and guitar.
Since I hadn’t as yet been able to truly enjoy the Mogwai in its role as a loudspeaker power amp, as a last performance test, I connected it to my home theater speakers which are about fifty years old and date back to a time when 25 Watts was a large amp. Finally, audio bliss had been achieved. Everything I had heard with the headphones was reinforced through the speakers, with the added benefit of floor shaking bass (when appropriate) and a completely three dimensional sound stage. While I’m used to normally feeding literally ten times as much power to my home theater speakers, there was no lack in dynamics or bottom end. A sampling of Liz Phair’s “Polyester Bride” (whitechocolatespaceegg – 16/44.1) confirmed that the satin luster midrange was also there in spades.
The Mogwai is a clear indication of why ampsandsound is one of the most respected tube amp manufacturers. It is incredibly versatile, with more than enough power to drive any headphone. I listened to the MrSpeakers ETHER C Flows, the HiFiMan HE-1000s, the Noble Katanas, even the Wolfson Digital Silence IEMs and none were not enriched by the sweetness of the Mogwai’s mellifluous midrange, with the caveat that 1.8 Watts is way too much power for extremely sensitive IEMs (if you listen primarily to IEMs, I would recommend the Leeloo which has about half the power of the Mogwai). And with careful speaker selection, the Mogwai can perform sorcery with loudspeakers also.
To recap, the Mogwai is exceedingly linear, with a fast deep bass extension that you just don’t expect out of a tube amp, yet it retains all the air, resolution, detail and musicality one demands from an audiophile quality single ended triode.
Input impedance is 10K ohm with alps pot, .5v for full power. Input Sensativity 800mV peek for full power out.
32ohm power: 1.8watts RMS @ 1khz, 7.6VRMS Frequency bandwidth 20hz -1db to 20khz -3db @ 500mw output Frequency bandwidth 20hz -1db to 14khz -3db full power Noise on 32ohm tapp @ 580uV
8ohm power: 3watts RMS @ 1khz, 4.7VRMS Frequency bandwidth 20hzhz -3db to 17khz -3db @ 2watts Noise on 32ohm tapp @ 340uV
Mogwai Headphone amp – $1,850 with tube set.
A New Record Day review doesn’t end on a more positive note than this and its for a dang good reason. Amps & Sound is here, they have already arrived.
Both the Casablanca’s and Stereo 15 have the highest recommendation that I can possibly give. Both amps offer a soundstage that is true tube magic and anyone searching for holographic goodness wont be disappointed with their purchase. Using the AVA ABX Comparator, I was able to A/B both amps with the press of a button. Spending some time and comparing my notes with what I heard in my A/B tests, I feel extremely confident my impressions are spot on with both offerings. I think the Casablanca’s might throw a wider stage and offers a noticeably blacker background. There were times when swapping back and forth I could hear a noise floor drop, leaving you alone with instruments piercing the leftover silence. Does this make the Casablanca better? Not really and if I’ve left you confused on which one to buy… I apologize but I’m in the same boat. I think the choice of amplifier could come down speaker sensitivity and whats sound signature you are hoping to achieve? Demanding loads or looking for a classic tube experience? Go with the Casablanca’s. Higher sensitivity reaching the mid 90s or want to tame a hotter top end? The Stereo 15 would be my pick. Either way folks, a New Record Day review doesn’t end on a more positive note than this and its for a dang good reason. Ampsandsound is here, they have already arrived. Both the Casablanca’s and Stereo 15 have the highest recommendation that I can possibly give.
I've been interested in high-end audio since the mid 1970s, maybe even before that, certainly before anyone used the term High End Audio. This was mostly due to my love for music, and happening to have a few school friends and acquaintances who parents had really good systems. It wasn't until I was in college (starting in 1975) that I actually walked into a real high-end audio dealership. What struck me then, was how often the salesmen in the shops talked about how many of the manufacturers were really one or two guys building gear in their kitchen or garage. This was usually part of an explanation about how dedicated these guys were, how they weren't supporting a building full of employees or spending large amounts on marketing or PR. The line was usually that all the money went into R&D, and building the best product possible for the price. Of course, if the product mentioned was at another dealership, the comments about small one or two person operations weren't always so positive.
However, ever since then, I found many of the products I've really liked, one way or another, came from either one of these small businesses (often started as a hobby) or from companies that at least started that way, and grew to a larger size afterwards. Unlike some people I know who look for comfort in large companies, or fall for big advertising campaigns, I've often been willing to seek out the little guy, the tinkerer or maybe just the new guy.
And boy, does the Internet, non-existent in the good old days, make finding these small companies much easier.
And so it was through chance and circumstance (and Facebook) that I discovered ampandsound (like conrad-johnson, it apparently isn't capitalized, though they aren't totally consistent with that on their website). I found that ampsandsound founder Justin Weber and I shared several friends on Facebook, and seemed to be on the same side of a lot of non-audio related discussions. I then saw he posted photos of some very sweet looking tube amps, and after checking his Facebook page, realized that he was the builder.
Shortly after that, at THE Show Newport this past spring, visiting the Chapman Audio room, I saw that Chapman's new T-5 Custom Tribute Edition ($7495) speakers were driven by Weber's $2800-the-pair Casablanca power amps. I've always liked the sound Chapman produces at shows, but this was maybe the best I had ever heard them. Justin and I chatted, and after looking over his line, I asked if I could review the Stereo 15 Special Edition.
Headphonemania! Headphones hold top five slots in global audiophile charts!
Well, that's what the headlines should say. Headphones, headphones everywhere, and now I see headphone ads from the same companies that used to make my plasma TVs. Even the President is bumpin' his Beats, although that may be just a farewell finger to his non-Beat buddies across the aisle. The bosses of electronics, eying potential sales and a new demographic (praise God almighty, they're here at last!), are taking time out from making surveillance servers and refrigerator filters to sell headphone gear to all comers at all prices.
All to the good, I guess, but I'm of the mind that the best personal listening gear is still being made by specialized companies who want to make both money and cool headphone products. Marquee players like Audeze and Cavali Audio draw crowds at headphone shows and generate well-deserved praise. This demonstrates once again that single-minded focus and a head start go a long way when you're trying to outrun giants.
The only problem is, all of these headphone choices now flooding from headphone conglomerates and artisans make me feel like I'm standing in a Tijuana mercado, looking at Baja hoodies and trying to decide which one to get. All the hoodies look the same, so who knows which one stays scratchy and falls apart, and which one softens up and lasts forever? Aloha Mr. Hand, indeed. Fortunately, I'm lucky to have chums who will test the waters for me. The ampsandsound Kenzie headphone amplifier featured in this column was originally referred to me by chief headphone scout (tribal seer might be closer to the mark, if you're following his Occupy HiFi vision quests), the irrepressible Michael Mercer.
Local Southern California builder Justin Weber runs a small company, ampsandsound, which produces a fine line of reasonably priced tube amplifiers and high efficiency horn speakers. His $1800 Stereo 15 Special Edition is one of the best sounding affordable tube amps I've ever tried. Utterly silent background levels with superb dynamics and tone. Ultralinear configuration with a pair of low cost EL84 tubes per channel, tube rectified and beautifully finished. Can be custom ordered for either 4/8 or 8/16 ohm speaker connections. Just make sure you mate it up with speakers that can be driven adequately by 15 watts. I used the amp mostly with Tekton or Fritz speakers and the sound was gorgeous in every case.
For the longest time, I’ve been a “tube-guy”. I’ve had tube based amplifiers in my rack in various forms for over 20 years. I’ve really enjoyed the ability to “tune” the amplifier to my personal preferences. The ability to get the “perfect” sound for a pair of headphones or speakers is one big advantage that tube-based amplifiers can offer. But that can lead one down the “rabbit hole” of constantly trolling the internet for older and rarer NOS (New Old Stock) vacuum tubes from the 1930s and 1940s.
But once you get the tube combination “right”, the magic that a well-designed and built tube amplifier can offer is very special indeed. I would make the comparison of digital audio vs. vinyl when comparing solid state to tube amplifiers respectively. Tube amplifiers can offer a very natural and musical sound when compared to the usually more clinical approach solid state based amplifiers. Now for the past 3+ years, I’ve gone over to the “dark side” (literally as my solid state amps no longer have that great warm glow given off by the vacuum tubes) and have gone all-solid state in my setup. So when the opportunity to review a new tube headphone amplifier came up, I was more than happy to oblige and see what I’ve been missing for the past number of years.
This amplifier was designed and built by Amps & Sound; a company located in California, USA. The company was founded by Justin Weber and he is the lead designer for all of his products. In my discussions with Justin, his passion for amplifier design and tube amplifiers really came through. He certainly was very knowledgeable of many different approaches to designing amplifier circuits and while his first products released were focused on 2 channel full speaker setups, he has made the foray into personal audio with the release of the new tube-based headphone amplifier: The Kenzie.