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The Gudebrod Audio 3T12V Tube Preamplifier Strikes a Nice Balance

10-04-2019 | By Juan C. Ayllon | Issue 105

Arlington Heights, IL - The music swirled about the room like wine in a sommelier's mouth.

I'd first heard them in a packed Arlington Room at the Arlington Heights Historical Museum in February 2018. The frozen, yellow grass out front was thawing and inside, principals Eric Krupp and John Brunner were demonstrating their Gudebrod Audio 3T12V preamplifier and AC/120/3 line filters to the Chicago Audio Society with a pristine pair of Sonus Faber Amati Olympica 3 speakers.

"Initially, its presentation was a little softer in the highs—an affectation that some prefer," I reported. "But somewhere after the half hour mark, the team of Krupp and Brunner triggered a phase shift and—voila! Gone was the softness! New detail and a more forward presentation emerged. Miles Davis, Pat Metheny, more classical and soft rock—they all presented crisp, well-articulated, and compelling."

Eric Krupp, at left, with John Brunner, seen here presenting Gudebrod Audio to the Chicago Audio Society in February 2018.

Not too long afterwards, I was contacted by Mr. Krupp, who discovered my account of the event after Googling "Gudebrod."

I had just finished a pair of reviews of the VPI Prime Signature turntable and the PS Audio BHK Signature preamplifier, when Krupp dropped off his preamplifier, and a pair of line filters. I was excited about hearing this, the fourth preamplifier I have reviewed in little over a year in front of the Usher Mini Dancer Two DMD speakers that I've also been reviewing (which are very detailed and revealing). And their line filter also piqued my interest, as I was curious to hear its impact on my listening room.


​The Gudebrod Audio 3T12V Preamplifier has the following specs:

  • Unique direct coupled design (no coupling caps)
  • Choke - input power supply utilizing Lundahl chokes
  • Three separate transformers (high voltage, rectifier and signal tube filaments)
  • All audiophile film type polypropylene capacitors
  • Military-style turret board construction, utilizing silver solder and point to point wiring
  • Solid copper with gold-plated input and output connectors
  • Frequency response: 20Hz - 50Hz
  • Gain: 5x (15dB)
  • Non-inverting output
  • High input impedance, low output impedance
  • Auto-bias design (no adjustments ever needed)
  • Auto-channel balancing (compensates for aging tubes)
  • 5v 3amp rectifier filament supply can support; 5r4, 5u4, 5ar4, gz37, 5v3, etc...
  • Harmonic distortion: <.05% in normal operation
  • Power Consumption: 17ma (signal circuit)
  • Main voltage: 120vac - 50-60Hz
  • Inputs: 4 line
  • Outputs: 1 pair of single-ended and 1 pair of balanced outputs (xlr with Lundahl transformers)
  • Dimensions: 470mm wide x 385mm deep x 100mm high
  • Weight: 25 lbs

As Krupp suggested, I plugged all but one of my components into the Gudebrod Audio AC120/3 AC Audio Purifier (at $650, it features a polarity changing switch and according to its literature, removes unwanted EMI/RFI frequencies) and run the preamp for a day. It already sounds very good, but triggering the reverse polarity switch on their AC Purifier, its soundstage improves, taking on a more full-bodied tone. This is going to be fun!

Listening Session

Michael Franks. "Alone at Night." Passion Fruit.  ALAC 44.1 kHz.  Warner Brothers. 1983.

The 3T12V teleports you into the studio where Steve Gadd's drum kit, Will Lee's bass, Randy Brecker's muted trumpet, and Sue Evans' intermittent finger snap lay down the gauntlet for the late Hyram Bullock's guitar, Rob Mounsey's keyboard, and Pat Rebillot's piano to accompany Michael Franks' soft vocals through, organic and clear, in this 80s smooth jazz classic. The mix is full and crisp, and Randy Brecker's austere and mournful flugelhorn raises the goose bumps.

Anthony Wilson Trio. "Mezcal." Jack of Hearts.  DSD128 Native DSD download. Groove Note Records. 2009.

This sassy jazz gem by the longtime guitarist in Diana Krall's quartet ("Anthony Wilson: Guitarist, Composer, Arranger") shows plenty of slam with Jim Keltner's snare, crash, ride cymbals—and, yes, the cowbell, while Wilson's electric guitar is big, bold, and well articulated. Larry Golding's vintage Hammond B-3 lead riffs and background pads give it verve. And, when Wilson opens up, it's an intoxicating kickoff to an outstanding album that shines with a very analog and realistic presentation.

Vanessa Daou.  "Life on a Distant Star." Plutonium Glow - 1st Version.  MP3 44.1 kHz.  320 kbps. Daou Music / Oxygen Music Works.  1998.

Daou's luscious, effects-laced vocals are ethereal, floating through the air in this Indie chill-out gem. Rendered through the Gudebrod 3T12V preamp, it is pleasant and powerful, haunting and compelling.

Eden Atwood. "He's a Carioca." Waves: The Bossa Nova Sessions. DSD128 Native DSD download.  Groove Note Records. 2002.

Atwood's silky sultry jazz vocals shine and shimmer in this glowing rendition of Antonio Carlos Jobim's classic. Accompanied alternatively by Scott Breadman's congas, Bill Cunliffe's acoustic piano, Derek Oles' bass, Joe LaBarbera's lilting ride cymbal and Antony Wilson's acoustic guitar, her vocals and fill the room with wet, glistening notes floating through the air. With the Gudebrod in play, it's evocative, transcendent, and a bit intoxicating. 


In the world of high-end audio, transparency and accuracy are highly exalted. Nevertheless, audiophiles fall somewhere along the continuum in one of two camps:  One favors and prefers the use of valves—or vacuum tubes—while the second camp favors solid state components and extreme accuracy.

In its extreme side, denizens favor that classic, warm tube amp sound while, on the mild end, preamps such as the PS Audio BHK, are prized for their relatively neutral signal. 

Some denizens of the solid state aficionados are critical of the valve group, saying that tubes are outdated technology and introduce second order harmonic distortion; they view them like audio versions of white zinfandel—syrupy caricatures of what truly good sound should be.

​Looking back at some of the preamplifiers I have reviewed, I have to say that the Gudebrod 3T12v possesses a powerful, robust, and transparent presentation... just right of neutral with more than a hint of warmth and sweetness. It isn't the vintage warm tube sound, but certainly gives a 21st Century nod to it.

Compared to the Cypher Labs Prautes Headphone Amp/preamplifier, for example, it is more neutral, but set it up against the PS Audio BHK preamplifier and it's a different story. The BHK Signature is a French red wine to Gudebrod's California red; it's drier and more neutral than the Gudebrod, which has a warmer, wetter, more enriched presentation. 

Summed up, Gudebrod preamplifiers lean more towards a 1930s than 21st Century presentation, resulting in a fresh, full-bodied and transparent spin on vintage audio. That works just fine for me—and if you plan on attending AXPONA 2020 in Schaumburg, IL in April 2020, you should be able to find out for yourself, as they plan on showing there.

Gudebrod Audio's Eric Krupp (far left) and John Brunner (far right) with their friend, John Lumley, examine my Lampizator Lite 7 DAC in my listening room

3T12V Preamplifier

Retail: $5500

Gudebrod Audio