NEW! ALL TUBE Aural Thrills Audio Serenade II

New!

Serenade II

Many Upgrades available. I can build it from mild to wild! You choose.

Building on the legend of the original TAS product of the year "Serenade" I am introducing my latest version. I have been working on this design for over thirty years. I am a 24/7 kind of guy. My mind is always thinking of design considerations if I am awake. Yes, I need to get a life. But on the good side, I believe I have achieved success. I am a builder of tube amps. A typical day for me is to design, build, and listen to ideas I have had. If you look at my test amps they are full of all the different holes from trying new ideas. I listen to each component and remember their sound for future designs. I can tell you the sound of resistors, caps, solid state, tube rectifiers, etc. It is then a matter of mixing and matching, through trial and error listening, to  come up with the sound I want. If this does not sound possible please look up Kodály methodology of musical education. Toughest class I have ever taken!

The Serenade II uses the same great amplifying board as the original but I have completely downdated (is that a word?) the power supply. In the early days of tube audio the only capacitors available were very small. Devices called chokes were used to make up for the smalll capacitors. They add their own sound as every component does. Problem is that they are expensive. The solution today is to use solid state circuits or the large value capacitors that are now available. I have designed a tube recitied circuit as it would have been done in the thirties. The result is the rich, detailed, quiet sound that I remember as a kid. Combined with the detailed and dynamic amplifying board the combination is magic. Here is what TAS thinks:

Here is the complete "The Absolute Sound" review

Every once in a while a product comes along that totally defies expectations. Consider the Serenade, an all-tube phonostage with sufficient gain and signal-to-noise ratio to accommodate a moving-coil cartridge. This shouldn't be possible at this price point, but leave it to Aural Thrills Tom Kenny to pull off the impossible. OK so I would hesitate to hook it up to a cartridge width less than 0.4 mV output, but even so,  pulling 60dB of gain cleanly from a pair of 12AX7's with feedback-type RIAA EQ is a tricky task. Most designers opt for 45 dB of tube gain and throw in either a solid-state gain stage or a step-up transformer to generate the extra mc gain. I had auditioned an early version of this design, and it was prone to  hum and noise. According to Kenny, the culprit was the original Analog Metric PC board. The new board, sourced from Lite Audio. is used in conjunction with an improved power supply featuring both voltage and current regulation. Kenny points to the Hitachi 2SK350 current regulator as a key ingredient in the design's quiet noise floor. His recipe for success also includes proper routing of cables, layout, grounding, and attention to detail borne of many years of experience.

Kenny has been at it for over a decade. Phonostages are very special to him since he has a large record collection and never made the transition to digital. In some ways I'm envious of a man who has been totally faithful to vinyl, avoiding the trials and tribulations all of us have had to endure on a road littered with the carcasses of many DAC's in order to fulfill the digital promise.

The circuitry is a bit unusual in that the mc gain stage consists of a single 12AX7 triode section connected as a grounded-grid amplifier. This type of mc gain stage has been bandied about in Asia, mainly in DIY circles, and has ben enthusiastically endorsed by seasoned constructors. The grid is grounded while the signal is coupled to the cathode and the output is taken from the plate in the usual way. Since the cathode is shielded from Miller-effect capacitance by the grounded grid, high-frequency response is much improved over the common grounded cathode circuit. Its other characteristics are good gain, no signal phase inversion, and a low input impedance roughly equal to the cathode impedance.

As you might expect, the grounded-grid amplifier has seen expensive use in radio designs but can be categorized as a rare bird in audio gear due to its low impedance. Of source, you wouldn't want to use this circuit as a linestage, but in the context of a mc it makes perfect sense. Typical mc internal impedance is well under 100 ohms, so it seems logical to operate the cartridge in a low impedance circuit for significantly reduced susceptibility to RFI relative to a high impedance input stage. A DIP switch bank (one per channel) on the circuit board provides for adjustment of the input  impedance and mc/mm gain. One of several resistors (100, 500,1.2k, 1.8k ohm) may be connected in parallel with the cathode resistor. However, in my experience an mc cartridge loading of 100 ohms is usually optimal. For example, my Clearaudio da Vinvi V2 MC's internal impedance is 32 ohms, so that the voltage transfer into a 100-ohm loading is decent while still allowing for a respectable current drive. I realize that such a view is controversial, and that some insist that it's all about maximizing voltage transfer, and that the loading should be about ten times the cartridge"s internal impedance. To my ears, however, such a load results in an upleasantly bright listening experience.

Two additional Class A gain stages follow the input stage. The fourth and final triode section is configured as a cathode follower so that reasonably long cable runs can be safely used. For a moving/magnet cartridge input , the grounded grid input stage is bypassed via the DIP switch bank and the input impedance is set to 47k ohms. The Serenade worked nicely with one of my favorite mm cartridges. an old "Grace F8E. But there are plenty of affordable mm tube phonostages out there so the primary reason to own this phonostage would be for its ability to interface directly with an mc cartridge.

Apparently Kenny focused all of his resources on the internals of the phono stage. At its advertised list price, a basic no-frills chassis is provided and the unit ships with JJ Electronic new production tubes and no power cord. Kenny does offer custom touches, a fancy chassis can be had for $300, premium connectors for $200, and a on/off indicator light for $50. I'm not a fan of the JJ Electronic 12ax7 (or of most Russian brands). I think we can all agree that the JJ Electronic 12AX7 runs quiet but its lack of tonal color saturation and coarse textures makes for a rather dull presentation. My suggestion is that you bypass the stock tubes and aim for NOS alternatives. I rolled in a pair of Siemens ECC83s and a pair of vintage Ei 12AX7s. The payoff was immediately obvious. The treble range opened up and textures much sweeter. The Siemens ECC83 is one of my favorites, and I would have been happy to outfit the Serenade with nothing but, but unfortunately a single pair is all I had on hand at the time. A word of caution, be sure to clean the pins of any NOS tubes you plan on using really well, a lesson I learned the hard way. Oxidation buildup is quite common and when the input pin is looking at a fraction of a millivolt that oxidation will definitely cause a problem.

The Serenade's signature sound cold  be summed up in two words: transparency and clarity. Soundstage transparency was such that every recess was well lit up within an expansive spatial presentation. It was easy to point a finger at specific image outline and locate individual voices in a large chorus. Transient response was both quick at the point of attack and well controlled all the way down to the recording's noise floor. As a result, plenty of low-level detailed was discernible . even in complex passages. At no time did I feel short changed when it came to retrieval of microdynamic nuances. The Sernade was capable of dishing out plenty of passion and fire too. This is an attribute that tube preamps seem to capture more cogently than solid estate designs do, and I think is most responsible for their continued longevity in a transistorized world. They may not always excel at the frequency extremes, but the midrange is delivered gift-wrapped for the sheer enjoyment of the music. The macrodynamic range from soft to loud was reproduced with conviction, and only a hint of compression was evident when pushing the envelope from loud to very loud. The Serenade didn't do much wrong. I did note a slightly lightweight bass balance, extending perceptually from about 100Hz into the deepest bass. Harmonic textures while definitely tube like lacked the ultimate in textural liquidity. I would rate liquidity as an 8 on a scale of 1 to 10. Ditto for tonal color saturation. Only an 8 again, but the comparison here is against far more expensive products.

Audio reviewers are tasked with deconstruction the sound of a particular component into its individual attributes. and we often don't say much about the grand picture, the holistic nature of the product. The Serenade managed to meld its sonic virtues on all of my favorite albums to make for a terrific first impression. It's the sort of sound that first and foremost appeals to the right slice of the brain in control of our artistic and rhythmic senses. It consistently evolved the music's verve with convincing drive. This phonostage can boogie with the best of them. I would have been happy with the sound quality even at four times the Serenade's asking price. As it stands, the Serenade is an insane value and a wonderful entry point for rediscovering the analog experience. It has given me a long and blissful respite from digital sources.