Linear Tube Audio - Aero DAC
Linear Tube Audio Aero DAC Reviews
- Stereo Times – by Terry London
- Twittering Machines - by Michael Lavorgna
- Stereophile – by Herb Reichert (measurements by John Atkinson)
- YouTube – by Steve Guttenberg
- 6moons Audio Reviews – by Frederic Beudot (currently a preview – review to come)
- Linear Tube Audio – Products - Aero - Digital-to-Analog Converter (DAC)
Linear Tube Audio Aero
The new Aero DAC by Linear Tube Audio has generated quite a buzz with respect to the level of performance offered for the (relatively affordable) list price of about $4K. The published reviews (linked above) have been universally positive, with a very enthusiastic review being written for Stereo Times by Terry London, who believes the sound of the Aero compares favorably (or at least competitively) with DACs selling for much higher prices.
I like the understated appearance of the Aero, which is a black box that doesn’t bring undue attention to itself, but includes enhancements being the calm yellow’ish LED lights indicating power, input, and sampling rate; the two round brass power and input switch buttons; and the two lighted 12SN7 tubes extending slightly above the top of the chassis (so you don’t have to take the unit apart to change tubes). As an aesthetic design feature, the chassis is wrapped on all sides by mitered solid aluminum plate of the same thickness that many companies use for their faceplate. LTA seems to have thoughtfully attended to every detail, including the very sturdy cardboard shipping box with conforming hard foam liner to protect the Aero enroute. The only thing I found aesthetically curious was the orientation of the output connectors on the back in that the right output is on the left side and the left output is on the right side. Of course, this would most likely be a non-issue for most owners who would not be connecting/reconnecting output cables to conduct DAC comparisons.
The LTA Aero is an R/2R NOS Ladder DAC, like the previously discussed Mojo Audio DACs. This describes the general method the DAC uses to convert a digital signal to analog, which is basically converting a finite-precision number into a physical quantity such as a voltage. Google is your friend for a more technical description of the meaning of R/2R and NOS but, in simple terms, the designation R/2R, or R2R, refers to resistors of two values, R and 2R, which are used to construct a ladder network of resistors resulting in a voltage output that is a fraction of a reference voltage. An R/2R network can be constructed from either discrete components (i.e., a bunch of resistors as in the Totaldac) or within a silicon chip like the AD1865 chip used in the LTA Aero. NOS indicates non over-sampling.
The function of a DAC (digital to analog converter) is to convert a digital input into an analog signal (i.e., voltage) that can be amplified by a preamp and/or power amplifier. It is my experience that DACs do sound quite different from each other so there must be differences in how they handle the conversion of the digital input and/or how they achieve the analog output. Some folks make a big deal about which DAC chip is used, and there are quite a few options out there. The Aero uses an Analog Devices AD1865 chip, which is the same as used in earlier versions of the Mojo Audio DACs and in their current Mystique Y DAC, as well as in some Audio Note DACs, and others. The chip is well regarded sonically, at least according to the 2012 DAC Chip List by Antonino Scozzaro at Soundbsessive.
The analog output stage of the LTA Aero is unique in that it is based on a Class-A ZOTL Output Stage, which provides an impedance-matched tube output stage to the loudspeaker without using an output transformer. Other design features include the attention paid to the power supplies, the discrete, active I/V stage, and the large 300K uF of storage capacitance. Additional technical information about the features and benefits of the LTA Aero can be found at the above link to the LTA website.
LTA describes the sound of their Aero DAC as delivering “crystalline realism, organic timbre, and an encompassing soundstage” and they believe that it has “unlocked that emotional involvement with the digital format”. That pretty much describes what I heard.
When I played the first music selection through the LTA Aero I thought, wow, this thing makes the music pop! The level of energy I heard made it seem that music was jumping out of my speakers, regardless of the volume level. That perception is not an easy trick to pull off but it does enhance the engagement level of listening to recorded music in your home. If I want boring, I can play background music through a transistor radio. The LTA Aero is definitely not boring.
Based on my listening, the LTA Aero not only gets most of the audiophile prerequisites right, it also presents the music with vivid presence and a dynamic sense of realism. The Stereo Times review alludes to this when Terry London wrote, “Blazing fast transients, extended accurate bass reproduction, and a sense of PRAT (pace-rhythm-and timing) that makes it difficult not to tap your toes to the music.” Herb Reichert at Stereophile commented on “the Aero’s extraordinary way with PRaT”.
I cannot say which design decisions went into the Aero that allow it to present this level of excitement compared to what I hear from most other DACs, but the Aero never sounded dull on any music I threw at it. After much listening, I suspected there may be a slight emphasis on the leading edge of notes and/or on the upper midrange and presence regions (from about 2K to 6K Hz, and maybe a touch higher). I also don’t hear quite the same level of tonal warmth and power in the lower midrange/upper bass region that I am familiar with from the Mojo Audio DACs. This goes back to how I hear different voicings from different DACs.
As I ran through my list of music selections, the commonalities I heard from the Aero included the clarity of the high frequencies, tonal richness, and a high level of dynamic expression (i.e., the ability of the Aero to quickly go from very soft to very loud). You would never mistake music through the Aero as “background music”, regardless of the volume level. This DAC can make familiar selections more exciting to listen to and many will appreciate the ability to listen at low levels without a loss of realism.
On recording after recording, the sound from the Aero demanded my listening attention. Female vocals by Astrud Gilberto, Dominique Fils-Aime’, and Sara Bareilles were well-served and fun to listen to through the Aero. Less complex presentations such as James Taylor’s Steamroller Blues highlighted the clarity of James’ vocals supported by his and Danny Kortchmar’s guitar work and the horn section that rolls in later. The projection of the upper mid to high frequencies of Sara Bareilles’ vocals were dynamically expressed through the Aero, and her crescendo at about 3:30 into the song Gravity from her Variety Playhouse live album was emotionally and beautifully presented. Even the harder rock tracks on my test selections including Smells Like Teen Spirit by Nirvana and Outside by Staind were hard-hitting without any evidence of break-up when things really got rocking. Neil Young’s high tenor vocals on Cortez the Killer seemed to have just the right tone and bite. Based on the selections I played, it seems the Aero should sound good with all types of music.
This was a difficult write-up because the Aero does so many things well that I want to convey that IMO this is a really good sounding DAC, yet my subjective preferences favor a couple of the (2x to 3x) more expensive DACs that I have here. I will make the distinction that I am not saying those more expensive DACs are inherently better, but I do like some aspects of how they sound because they more closely align with my sonic preferences. Therefore, I urge folks reading this to consider the many positives offered by the Aero such as the rich tonal qualities and dynamic presence that few (if any) DACs I have heard can match at its $4K price. I can envision many buyers will be perfectly happy to live with the Aero DAC in their systems for a long time.
What could be improved? In my listening, the slight emphasis on the upper midrange to high frequencies that I perceived sometimes resulted in a slightly forced presentation in those regions and a touch of hardness to certain recorded material. I can envision others saying that the Aero is simply providing a level of clarity and detail in those regions that I am not used to hearing. I would not argue with them, but the overall presentation to my ears doesn’t quite achieve the same level of refinement I have come to enjoy from my Mojo Audio DACs. This doesn’t reduce the musicality of the Aero, but it does suggest the overall presentation is more energetically focused, which Robert Harley referred to as, “athletic boogie factor”.
I looked through the linked reviews and found a couple of subtle observations by the reviewers that seem to be similar to what I sometimes heard, including:
“the LTA Aero DAC …imparted a bit of hardness and thinness from the upper midrange (on up) to the Unison/DeVore system…Switching in the more costly totaldac illustrated, immediately and obviously, that the Aero DAC was responsible.” – Michael Lavorgna, Twittering Machines
and
“To my surprise, LTA’s DAC shifted the energy emphasis from the bass and midrange—the bottom octaves of Waits’s voice—up to the midrange and treble, presenting Waits’s vocals with considerably less weight and texture. With the Aero, the song’s lyrics were clearer to my ear but less gnarly, gritty, and attitude-rich.” – Herb Reichert, Stereophile
I also found an interesting observation about the Analog Devices AD1865 chip used in the Aero, compared to the AD1862 chips that are used in the two Mojo Audio DACs that I have here. It sort of describes the basic differences I hear between the Aero and my two Mojo Audio DACs. The statement below was written in a review of the Mojo Audio Mystique Y DAC, with respect to Mojo Audio’s use of the AD1865 chip in their new Mystique Y DAC compared to their using the AD1862 chip in their Mystique X SE DAC.
“The sonic differences between the two chips are subtle but noticeable. The 18-bit (AD1865) chip sounds energetic and exciting, while the 20-bit (AD1862) chip sounds more harmonically dense and liquid.” – Ken Redmond, Tracking Angle
In conclusion, the LTA Aero is a very nice DAC, nice to look at, musical and fun to listen to, built by a really nice group of folks at Linear Tube Audio, and a no-brainer for a test-drive by anyone interested in a DAC at a price range of around $4K or higher. These things always come down to personal preference, and I have no doubt that many will find the LTA Aero DAC to offer a perfect musical solution.