This paragraph from Linear Tube Audio’s website description of their new Aero DAC sets the tone for the story I’m about to tell. “After trying various options, we chose the Analog Devices AD1865 R2R DAC chip, which is sometimes called the ‘vinyl DAC,’ for its organic sound. It is a non-oversampling DAC, with no digital filters. The AD1865 is much-loved by audiophiles and is used by at least one hi-fi company in a flagship DAC costing over $150,000.”

Check the forums and you find that the AD1865 chip is also a heavy DIY favorite. Home brewers are attracted to this discontinued, “obsolete” 18-bit chip for its easy implementation and unprocessed, music-friendly sound.

Manufacturers of luxury-priced DACs love it, too. They don’t mind that it’s discontinued; they’ve already bought thousands of chips. The main thing they care about is that it sounds conspicuously musical and engaging. I’ve listened at length to at least three well-known, very expensive DACs that use this chip, and I would describe their pleasures as the type favored by long-playing record collectors. I’m friends with the designer of one of these “luxury-priced obsolete-chip DACs,” and when I asked him why he chose the AD1865, he told me, “We tried all the others, and this one sounded the most right.”

“After trying various options,” LTA owner-founder Mark Schneider and his Aero design team—Will Schneider-White, Tony N. Nguyen, and Jacob Knibb—apparently came to the same conclusion, but I think they thought they could do “most right” better at a lower cost than those luxury DAC sellers.

Description

I asked Nicholas Tolson, LTA’s head of sales and marketing, how LTA’s Aero DAC project got started. He replied, “The idea of the first Linear Tube Audio DAC spent years hovering in the background as a blurry sketch, being redrawn regularly. We knew that if we made a DAC, it needed to be deliberate and unique. Two years ago, the pieces started to come together, and we saw that we finally had something that could be the LTA DAC. Now the Aero enters production as a generational step forward for the company. It is the first ZOTL circuit in production that was not an existing Berning design. It is the first single-ended LTA circuit, the first balanced output stage in an LTA product, and the first LTA product without inter-stage coupling capacitors. Along with the Velo [headphone amplifier], the Aero takes a significant step forward in utilizing higher performance SMD components and PCB layout.”

Of course I asked about that “obsolete” AD1865 chip. “There is an undeniable kinship between out-of-production non-oversampling DAC chips and vacuum tube amplifiers. The best of these chips scale up in sound quality alongside the right implementation. They also do not add anything that then needs to be filtered or removed.” The Aero offers no digital filters, no oversampling. Likewise, there’s no DSD or MQA support and no LCD display.

LTA’s Aero DAC caught my attention with its twin GE 12SN7 tubes sticking out of its hood. The 12SN7 is the 12V heater variation of the venerable 6SN7 medium mu triode, a tube I have 40 years of experience with. I regard the GE version as one of the best-sounding, longest lasting voltage amplifier tubes ever made. Here, it is used to buffer the output of the digital processer and will probably outlast the DAC and its owners.

According to Schneider-White and Nguyen, “The Aero’s analog section begins with a discrete current mirror with a balanced output. This active I/V stage allows the DAC chip to work less hard; and it sounded better than passive circuits during our testing.

“The signal from the I/V feeds the four single-ended amplification stages that make up the balanced ZOTL output stage.”

When I installed the Aero, I noticed that its brushed-aluminum back panel is the same thickness and finish as the front and side panels, and its lettering is as nicely engraved. It was obviously designed to be admired as much as the front panel, or as little.

“The casework for the Aero was designed as a nod to classic wooden tube amplifier chassis, re-interpreted in machined aluminum,” Nicholas said. “As fewer people use standard equipment racks, especially for headphone listening, we moved away from the basic box-with-a-faceplate formula and created something that can stand alone as an object intended to be seen from all sides. We also wanted to make the tubes more visible than our previous products and allow users to change their tubes without removing the cover.”

Don’t laugh, but the instant I turned the Aero on, I smiled wide in appreciation for three tiny cream-colored LEDs that look soothing rather than aggressive. I cringe when I see aggressive—non-soothing—chassis designs.

The left brass button and its associated LED handled Power On; the second button and LED were for the Input Selector, choosing between OPT (TosLink), USB, and RCA (S/PDIF). The third LED scoots back and forth in a line just off-center, indicating sampling rates for the incoming signal: 44.1, 48, 88.2, 96, 176.4, and 192. All very classy and understated.

I got so excited when I spied those sweet, warm LEDs that I texted Nicholas asking who made that decision.

“Quite a bit of effort was put into the indicator LEDs. We use the same warm, natural color that you would want for a reading lamp, along with a carefully chosen diffuser-plus-filter arrangement to create the right glow without glare.” This is when I began noticing a pattern: LTA was basing design decisions around the quality of the user’s whole experience.

Next, I asked Nicholas and LTA CEO Mark Schneider’s team for some information about the power supply, which I already knew was a hybrid switching/linear design. He told me he was glad I asked, because “combined, there is over 300,000µF of storage capacitance in the Aero, which is a ridiculous amount for a line-level source component. Power amps often brag about having 1/3 that amount.”

I can’t swear to the exact sonic effect of this much capacitance, but during my auditions the Aero flashed surprising amounts of drive, dynamism, and clarity—traits I associate with well-engineered power supplies and more expensive DACs.

Perhaps this is a good time to remind readers that lab numbers don’t always line up with the character of a component’s listening experience, and that sometimes, if we listen to music with an open enough mind, we might discover how many of the things we thought were important turn out to be less important or maybe not important at all.

Starting up

I inserted two American-made NOS GE 12SN7 GTA tubes (supplied), connected an AudioQuest Cinnamon USB cable (connected to my Roon Nucleus+), a Kimber Kable D60 coax, and a pair of balanced Cardas Clear Beyond interconnects; then pushed the Power button and used the second button to select the USB input on the Aero’s front panel. My Aero DAC setup was done.

Qobuz recognized the “LTA Aero” immediately. Ten seconds later, I was listening to French violinist Ginette Neveu’s The Complete Recordings (24/96 FLAC, Warner Classics/Qobuz).

That’s plug’n’play digital. My preferred kind.

NEXT: Page 2 »

COMPANY INFO

Linear Tube Audio
7316 Carroll Ave.
Takoma Park
MD 20912
[email protected]
(301) 448-1534
lineartubeaudio.com

ARTICLE CONTENTS

Page 1
Page 2
Specifications
Associated Equipment
Measurements

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