Coda Technologies FET 07x Preamplifier

This is my first review for the Stereo Times website. I am honored to be writing for The Stereo Times and joining the staff of excellent reviewers. I now consider myself part of the “Chicago Crew” alongside Dave Thomas and Michael Wright. Both are dear friends and we all live and play in the Chicagoland area. I look forward to contributing at a high level to what I consider a great website, that offers insightful reviews on all types of equipment and informs the reader about some of the best sounding gear on the market today.
 

For the past fifteen years, I have used highly regarded tube-based preamplifiers because they provide a high level of performance to two very important sonic characteristics: beautiful tone color/timbre and three-dimensional imaging with a sense of space around and between the instruments. I had in-house for review numerous highly regarded solid-state and passive preamplifiers that offered great dynamics, lower frequency control and slam, micro-details, and see-through transparency. However, for my taste, they all fell short in that they made my system sound slightly “washed out” regarding tonality/color. Also, in the area of spatial dimensions, both in the individual images and overall “air” in the soundstage, it became more two-dimensional in its presentation.
 

Just about a year ago I wrote a review on one of Coda Technologies’ new generation of Continuum amplifiers, the No. 8, a superlative single-chassis amplifier that I purchased to use in my system.  I was very pleased to write that review because I’d had great respect for this company for years but never had the opportunity to review on one of their pieces.  Coda Technologies is located in California and has been in business since 1985 designing and hand building very high quality and stellar performing preamplifiers, phono-stages, and amplifiers for very reasonable prices compared to other US based companies. I consider Coda one of the best kept secrets in high-end audio, here in the states. They do very little advertising, are beloved in the Asian and European markets, and are a very successful OEM manufacturer for many other very well-known companies. They also build Class-A amplifiers that offer some of the highest levels of current compared to virtually any other amplifiers on the market. This means they can drive the most monstrous/difficult speaker designs with ease. Doug Dale, president/CEO and house engineer Eric Lauchli both were former members of the R&D and technical support staff of the legendary Threshold Corporation with Nelson Pass, before leaving to start Coda Technologies.
 

Doug had mentioned that he and Eric were very excited about the performance of the fourth generation of their FET 07x preamplifier ($6,500.00) and asked if I would be interested in reviewing it. I shared that I’m not normally enamored with solid-state preamps, for the reasons stated above, and that I might not be the right listener to judge their new reference preamp. Doug replied, “I trust your ears and taste, so I’ll send you one because I know you will give me an honest take on it.”  That’s how this review came to be and turned out to be one of the most extraordinary experiences I’ve had in over 30 years of listening to and reviewing high-end gear.

The FET 07x preamplifier that was sent to me for review came in a black finish with gold accents on the front button controls. The chassis just oozes first-class materials and build quality. The 07x preamplifier’s dimensions are: 18” x 9.75” x 2.5” (WDH). It weighs 14 pounds. Coda Technologies did a great job at developing terrific isolation footers for this preamplifier. When I used my go to Krolo Design isolation devices, which usually improves the sound quality of most pieces of gear, I heard no difference in its performance. On the faceplate are gold buttons that control input source switching for any audio processor, mono, mute selection, and bypass that drops the gain to unity. The volume control is silky smooth and is setup in 1dB increments making it easy to find the perfect volume level for every recording. All inputs and outputs, along with the rest of the preamplifier’s functions can be controlled through the remote control. Another feature that I found extremely useful was that you can change the over-all gain level to match either the source component or amplifier to always be able to get to the “sweet spot” on the volume control for optimum performance of your system. On the back there are pairs of both balanced and unbalanced inputs/outputs along with the IEC input and on/off switch. Desirable, the FET 07x should be left on at all times. Coda Technologies offers a 10-year full warranty on the preamplifier that covers any possible malfunctions that could take place in the field.

I have a close friend who is an electrical engineer who builds his own stereo equipment and has hardcore standards regarding the quality of parts, how circuits are designed (the shorter and the simpler the better), and the craftsmanship of the build quality. When he took a look at the internal guts of the FET 07x he was astonished that all of the above criteria were at a level that even surpassed his standards. He was particularly “tickled” by the superlative build quality and materials used to construct the double-sided gold-plated circuit boards used throughout the preamplifier. The name of the Coda preamplifier clearly states that it is a FET (Field Effective Transistor) based design. Here’s an explanation why they use these types of transistors in the FET 07x preamplifier. FETs are inherently transconductance devices, meaning that an input voltage controls an output current. Unlike conventional transistors, FETs have extremely high input impedance (about 10 megaOhms – similar to vacuum tubes). The FET “senses” the audio signal without drawing current from the source. This eliminates complex interactions with the source, allows maximum performance from each system element, and greatly reduces the chance of cable characteristics altering the sound. The absence of input current in FETs allows high-bias currents for linearity and speed without sacrificing DC parameters. I am not an engineer, but besides build quality could the use of FETs explain two virtues that I heard with this preamplifier in my system. First, the apparent and easy to hear two-fold qualities of color/tonality/bloom along with three-dimensional imaging and ambient space between these instruments which is the best of what tubes have to offer (Remember, FETs work and measure in a similar fashion like tubes). Secondly, regardless of what amplifiers, solid state or tube based, I used in the reviewing process for the FET 07x preamplifier, it was able to drive all of them easily with the same superlative results.
 

One of my go to albums for both my listening pleasure and reviewing is tenor saxophonist Ike Quebec’s Blue Note album Bossa Nova/Soul Samba. It has a rich, warm, and overall luxurious sonic quality that adds to the beauty of this Latin-tinged jazz. The FET 07x preamplifier was able to exceed the quality of my benchmark 6SN7 based preamplifier’s reproduction of tonality with even more pure and pristine timbres and colors that make up the signature of Quebec’s tenor saxophone. Another aspect that was quite striking is that I had never had a solid-state preamplifier in my system that could create the image palpability/density with air around each individual that my tube-based pieces could deliver. In this case, the FET 07x preamplifier caste a life size holographic image of Quebec and his band members spread across a realistic studio soundstage.
 

Another of my favorite tenor saxophonists is Scott Hamilton, who has carried on the tradition of the great swing players in his fruitful and long career. His 2018 trio’s album Live at Pyatt Hall [Cellar Live] was recorded in Canada. It dramatically captures the size of the hall, where the band members were located on the stage, and the ambient cues that make you have the illusion that you are in the hall itself. Through the FET 07x preamplifier this hall’s acoustic signature was nailed to such a high degree that if you shut your eyes you could be fooled into thinking you were there.
 

To address how the FET 07x would handle the sonic parameters of high-end extension/air, micro-details, bass extension/control and overall micro-dynamics/slam, I put on an album by The Bill Holman Band, which is an audiophile quality recording, called Brilliant Corners, which is totally composed of music by the legendary Thelonious Monk. Regardless, of how loud the band roared on its peaks the FET 07x preamplifier effortlessly delivered room shaking taut bass, the upper frequencies were detailed, yet never became harsh or hard, and the smallest details of each band member’s unique quirks, like moving in their seats or turning over their sheet music, could be heard through the mix. I believe that the FET 07x preamplifier is the quietest linestage I have ever had in my system because of the ease of hearing the smallest details in the music. These micro-details never became annoying because the overall presentation of the FET 07x is extremely organic and natural, again very tube-like.
 

Based on the details shared in this review you can now understand why I selected the Coda Technologies FET 07x preamplifier to put on The Stereo Times “MOST WANTED COMPONENTS OF THE DECADE” list. It is the best synthesis of what solid-state has to offer (transparency, clarity, low-frequency extension, control, micro-details, and slam/speed) and of what tubes have to offer (tonality, color, holographic imaging, three-dimensionality, and soundstaging with a sense of air around individual instruments) that I have heard in over thirty years of listening to scores of preamplifiers. Add on the factors of impeccable build-quality, a design that has been honed to greater levels of performance over time, great ergonomics, and a very reasonable price for a terrific hand-built US benchmark product, and you now know why I purchased the review sample. Highly recommended!
 

 terry london

Associated Equipment

Digital Front End

Mhdt Lab Orchid DAC

Lab 12 DAC

Threshold DAC 1e

Jay’s Audio MK-II CD transport

CEC MK3 CD transport

Amplification

Coda NO. 8 amplifier

Coda 07x preamplifier

Pass Labs XA-25 amplifier

Triode Lab SET 2A3 amplifier

Threshold 550e & Threshold SA-4e

Threshold FET 10 preamplifier

Linear Tube Audio reference preamplifier

Loudspeakers

Tekton Design Ulfberth & Perfect SET-NSMT Model 100/ Cabling-Full looms of Black Cat Coppertone wires Accessories- Krolo Design reference rack & Krolo isolation devices-Dignity Audio PPT-1500 isolation transformer-Audio Archon power cords 

Specifications
Price: $6,500 USA 

Coda Technologies FET 07x Preamplifier

Frequency Response: -3dB @ 5Hz to 200kHz

Distortion: 

Gain: Unbalanced Output: 12dB @ 1kHz Balanced Output: 46db @ 1kHz

Maximum Output: 10V peak

Noise:  Input Impedance: 20kÙ

Output Impedance: 50Ù non-reactive unbalanced 100Ù non-reactive balanced

Crosstalk: 90dB @ 20kHz

Dimension: 18” W x 9.75” D x 2.5” H

Address

Coda Technologies

7850 Cucamonga Ave #34

Sacramento, CA 95826