April 2019

World Premiere Review!
Audio Mirror Tubadour III Digital Analog Converter (DAC)
A study in subtlety.
Review By Ron Nagle

  In the October 2018 issue of Enjoy the Music.com I introduced to you the Audio Mirror Reflection monoblock amplifiers. On the heels of our World Premier Review, a print audio magazine reviewed it and loved it too. Always glad to have others follow Enjoy the Music.com's footsteps. And now we have a new Audio Mirror component. It is the Tubadour III, which is a digital to analog converter (DAC) that's unique in many ways. Instead of writing Audio Mirror many times I will hereafter refer to the company simply as AM. The new Tubadour III, we can assume the spelling of its name is a tongue in cheek reference to this DAC's internal tube circuits. The manufacturer refers to it as a "five digital input, non upsampling tubed Digital to Analog Converter".

There's a current trend of stuffing even more features into a single box so it can be marketed as a multi-functional audio component. Is more better? Not necessarily! There is a definite performance advantage when designing just a basic DAC. With no graphic display or upsampling ability and no Blue Ray streaming function with a Siri control. It seems like the Audio Mirror guys concentrated on getting just the digital conversion function right. So let us take a closer look. We start from the outside of the Tubadour III and then move the electronics inside. From the very first it was evident that the Audio Mirror people invested some time and expense fabricating the Tubadour III form factor. Like some lesser components this is not a "Slip-Case" economy of construction.

The Slip-Case is a relatively inexpensive way to fabricate a component cover. It is a metal sheet bent into a three sided upside down "U" shape. By contrast the Tubadour III has a black anodized aluminum case made from individual aluminum plates. They are fitted to a sub-frame and held in place with Phillips head screws.

The streamlined front panel of the Troubadour is finished in matte silver, the overall appearance is very attractive. The front panel measures 13" wide and the chassis body is 12" front-to-back and is 3" high. The black anodized body has two rows of slotted vents on the top surface. These provide ventilation for the circuit board dual triodes. The silver face plate sports two silver Dome shaped control knobs. The first is designated as power on/off and to the right of that is a source select control knob.

The Tubadour III front panel has five blue LEDs, when lit they indicate which digital source is active. Reading from the left to right, the leftmost LED has a different white color and it indicates if the DAC has locked onto the selected digital source. It only lights to indicate signals input via: Coax, Optical and AES inputs. It doesn't light up for USB and I2S inputs. The LED lineup counting from left to right is coax S/PDIF, TosLink optical, AES XLR, USB and I2S (optional). The review AM DAC came with only unbalanced RCA output connections. However the DAC can be ordered with an optional XLR balanced output jacks. And once again, each source is selected using that front right dome shaped knob.

On The Inside
The DAC is based on the Analog devices AD1865N-K flagship DAC chip. The manufacturer states, "This is one of the two best and most analog sounding DAC chips ever made". Reviewer Note: The AD1865N-K is an older style DAC. It's an 18 bit ladder DAC that uses some interesting techniques to derive the least significant bit (LSB). Reviewer Note: This might possibly make it more "analog-sounding" than more modern Delta-Sigma DACs says the manufacturer. The Ad1865 can convert 24 bits, if it uses a 74HC164D chip, which I have included, this will increase the rate by six additional bits.

Tubes used in the DAC are two 5977 sub miniature triodes, a pair in each channel. They use a special tube adapter, which is plugged into a regular 9 pin tube socket. You could unplug the adapter, which would then allow you to do some tube rolling. So you could substitute tubes like, 6DJ8, ECC88, 6N1P, 6922 and the Soviet 6H23 P. After experimenting with many tubes the AM team found that the 5977 were the best sounding tubes for this application. Second best sounding tubes are the 6N1P. But all of this tube substitution comes down to a matter of personal taste. All the nine pin based tubes mentioned will have twice as much gain. Therefore you will have twice as much output from the DAC, at around two Volts. That two Volt output is pretty much the standard maximum output specification.

Expected tube life for 5977 sub miniature tubes will be around 3000 hrs. The AM DAC has a build in slow ramp up high voltage (HT) supply to prevent shortening the tubes life. Due to this the DAC will perform with nearly full potential sound quality approximately 10 minutes after it is turned on. The manufacturer advises, to not leave the DAC on for long periods of time (24 hours or so) if you are not listening to music. This will only shorten the tube life.

System Integration
To evaluate the AM Tubadour III I used a variety of digital sources. Starting with Pandora blue ray feeding a Yamaha WXC-50 streaming Preamp. Also sourced was a stand-alone SSD drive containing a library of Hi-Res Music. Add to that a Sangean HDT-1 digital tuner for good measure. A Sony Blu-ray 5" digital disc deck. And by direct comparison I used my Music Hall 25.3 Upsampling DAC incorporating a substituted NOS Amperex 6922 Bugle Boy output tube. Note that this is not the original Yamaha tube. So in comparison the AM DAC and my Music Hall DAC, both have tubes in the output circuits. The output of the AM DAC was unbalanced cable feeding into my very versatile does everything Parasound P5 preamplifier.

The direct Output from my Music Hall DAC and my Sony DSD/CD player and the Yamaha XC-50 Streaming Amplifier each of the three sources had separate inputs to my Parasound P-5 Preamplifier. That in turn connects to my Roger Sanders ESL Mk 2 (drive anything) 400 Watt per channel power amplifier. My reference speakers for this audition were Aurum Cantus modified V30 M. These are a two way stand mounted monitor, with a super ribbon tweeter.

Anticipation
OK, the DAC's tubes have a gradual warm up, then after about 10 minutes the tubes should be ready to go. Knowing that the manufacturers recommended break in occurs after 50 or 70 hours of playing time. I still could not resist giving the AM DAC a brief listen. I decided to use my Sony UHP-H1 universal 5" digital disc player. I loaded one of my reference recordings, Nils Lofgren, Acoustic Live on SACD [Analog Productions CAPP090 SA]. And even though not broken in the Tubadour III DAC's presentation was appreciably better than my Music Hall DAC. I could hear much better separation between the individual layered elements in the music, the word for that is, Delineation. Also unmistakably in evidence was the softer smoother sound of tubes. Flowing from my boundless curiosity I decided to try another comparison. (I do not claim this to be anything other than a subjective test).

For this comparison I routed the Sony output playing Nils Lofgren into my Music Hall 25.3 DAC. But then I connected the Music Hall out put into another devise, my iFi Audio Micro i Tube Expander and Tube buffer. This little component has dual purposes. First, it will use the internal tube to mitigate any residual digital artifacts. In other words the iFi Audio has a smoothing effect. Second, at the same time it also provides a switchable sound stage expansion feature. At this juncture with the iFi Audio providing a smoothing effect and sound stage expansion. The sound of the Nils Lofgren and his Acoustic Guitar did became pleasantly warmer and more dimensional. However, it still did not separate and delineate the individual elements contained in this performance. When in a direct comparison with the Sony, am playing Nils Lofgren directly into the Tubadour III DAC. This unit has the ability to elicit all the small nuanced timbral details that breathes a sense of its happing now reality to this live stage performance.

Conversion
The digital Output from my Sony SACD Player as it plays a DSD compact disc is not a true DSD Delta Sigma Modulated digital output. Native DSD has a sampling rate of 2.8224 MHz, or 64 times the sampling rate of Red Book specification. The DSD is a digital stream of single bits, either a one or a zero. Question: Can the Tubadour III play this format? The answer is yes it can. Like most every consumer CD/ SACD Deck the digital DSD/SACD signal output as transmitted on a coaxial S/PDIF. The Sony licensing requirement has us convert the SACD output to a PCM rate of 16 bits at 44.1kHz. And as you would expect when a playing a standard Sony Red Book 16-bit/44.1kHz encoded CD it is unchanged. To get true pure DSD signal decoding, time was you would have to use expensive Pro equipment. Now you can download DSD files direct from the internet.

Another Listening Session
I estimate I put 50 Hours on the DAC just playing back ground music. Manufacturers advisory: Although the Tubadour III DAC has a break in time of between 50 to 70 hours. The most noticeable improvement in sound will be in the first 5 to 10 hrs. I suppose that's well intention advice. However I believe it was in the first 10 to 20 hours that the AM DAC began to love music more. At that juncture I could hear a noticeable improvement in the sound. Of the many hours and recordings I listened to let me refer to just one other CD. However I should apologize for referring to another recording you probably do not own. But I would like to recommend it to you. This is one of my flea market sidewalk purchases: It is Elton John's CD One Night Only [Universal CD 44001 30502]. This is a one night sold out concert in New York's Madison Square Garden, which was back in October 2000.

The sound of Elton John's voice was amplified to death in this cavernous arena. But a clearer more grain free depiction of the performance still survives pulled out of the background hash by the Tubadour III. It manages to save a bit of warm intimacy derived from this DAC's glass heart. The audience sound and the great hall ambiance painted by Tubadour III lend a quality of vast airy spaciousness. Let me repeat, I mentioned this CD so that if you are an Elton John fan this is a recording you should own.

The Bottom line, The Audio Mirror DAC is a study in subtlety. It deserves to be connected to every system with high quality cables. It brings a nuance of fine details that can be obscured by a cheap set of interconnects. I tried several different brands and types of wiring and was able to A / B the Tubadour III output to my preamplifier with a remote control from across the room.

If I did a comparison between copper coax and silver wired coax, the silver wiring invariably won. I was sorely tempted to push the limits of the audition and swap the internal 5977 tubes for some NOS miniature triodes. But once again that would not be playing fair. Because you will most certainly not have the exact same tubes. There are some nice bells and whistles included within the stock Audio Mirror Tubadour III DAC for only $1500.

The optional balanced output and I2S input are at extra cost. If you opt for these connections please refer to the manufacturer website, as of now price not determined. I highly recommended it for its overall musical performance and price. And I recommended it for the sound shaping flexibility only Vacuum Tubes can offer you.

Remember to enjoy the music and from me Semper Hi-Fi.

Specifications
Type: Digital to analog converter
Sample Rates:
    S/PDIF, AES , 44.1 to 192kHz
    Optical/TosLink , 44.1 to 96kHz
    USB, I2S, PCM , 44.1 to 384kHz
Bit Depth
    Up to 24 bit over S/PDIF, AES, TosLink
    Up to 32bit over USB and I2S
Options: XLR balanced output and optional I²S input
Dimensions: 13" x 12" x 3" (WxDxH)
Price: $1500

Company Information
Audio Mirror
7236 Ticonderoga TRI.
Eden Prairie, MN 55346

E-Mail: contact@audiomirror.com 
Website: www.AudioMirror.com