Pine Tree Audio Earth Tones Amplifier by John Hoffman

Nirvana and Audio.

Nirvana is not the experience of bliss; it is a state where a person no longer feels desire or need. In this review, when listening to the Earth Tones SET amplifier, I felt complete sonic satisfaction without any desire for something more or different.  I will state up front that you need to have efficient speakers, as the Earth Tone will produce 5 watts of power. 

This is the first disruptive piece of audio gear I have experienced. Disruptive in that it delivers nirvanic sound at a very reasonable price (more on this below).  This is not a “for the price this amplifier is good” statement. Regardless of price, the Earth Tone produces a lush and detailed sonic presentation that is engaging and satisfying to my ears. 

This 5 Watt Earth Tones SET produces texture and tone that is realistic and substantial. Listening to cello, I hear the tension of the bow on the strings and, in my mind’s eye, can see the soundboard vibrating.  The soundstage is deep and wide with space between the instruments. There is a pristine tone that I have only heard in SET amplifiers. 

The limiting factor of the Earth Tones is that it requires sensitive speakers. My Devore O/96s did great, but to get room-filling sound in my space, I had the volume at -11db.  I did not hear any clipping or distortion at that output.

Pine Tree Audio

Pine Tree Audio is a husband-and-wife team located in Central Massachusetts. Pine Tree was founded in 2017 and produces/assembles all items by hand in their shop. Pine Tree states, “We have control over each step in the process of making our products and can offer you service and customization unlike larger manufacturers.”

Jesse Allain stated his goal with the Earth Tones was to create a 5-watt single-ended (SE) amplifier that meets the modern performance expectations and, importantly, retains a classic vacuum tube harmonic profile. Jesse chose toroidal transformers to meet his design specs to produce full frequency response, especially in the low register where many single-ended amplifiers struggle.  The measured frequency response of the Earth Tones is 18Hz-47KHz (-3dB points, measured at 1W into 8 ohms). 

A defining characteristic of this sonic performance of the Earth Tones is the use of only local feedback. This contrasts with global feedback amplifiers, which apply feedback from output back to input. The sonic difference is that the scheme used in the Earth Tones creates a natural, textured, lively sound with a very wide soundstage. From Jesse’s perspective, this allows the sound of the tubes and output transformers to be a part of the sound in a way that is musically engaging for the listener as well as rich in harmonic content.

The Earth Tones uses a single 12AT7 and two 6L6GC tubes, with an input sensitivity of 1VRMS for full power, making this amplifier very easy to drive. Because it is a pure power amplifier, pair this amp with a line-stage preamp or source that has built-in volume control.

Listening:

“Passione amorose (Arr for 2 Double Basses & Orchestra by Giovanni Veneri): 1. Allegro deciso” on The Giovanni Bottesini Collection by Thomas Martin and the London Symphony Orchestra. This is a great track to hear the Earth Tones produce impactful transients and dynamics, as the piece starts with the full orchestra thundering an introduction, followed by two double basses, and this is where the Earth Tones shine. I can hear the bow being dragged across the strings of the two double basses playing an octave apart.  The Earth Tones amplifier produces a pristine, realistic tone and separation of the instruments. When I switched to my solid-state amplifier, I noticed the texture was smoothed out and lost. Going back to the Earth Tones put me back in front of a real instrument.

A note on bass: I played the track “Scary Monsters and Nice Sprites (Phonat Remix)” on the Album More Monsters and Sprites EP by Skrillex to hear what the Earth Tones would do with bass.  The amplifier produced surprisingly clear, deep, and fast bass that was powerful and chest-hitting—the 5-watt Earth Tones produced as much bass as my 35-watt EL34 push-pull amplifier.

Another listening opinion.

Dear friend and fellow reviewer Terry London also had the Pine Tree Audio Earth Tones in his house to experience what this 6L6 SET-based amplifier offered in terms of performance.

“I totally agree with John’s take on this SET amplifier. Excellent overall dynamics, micro-details are revealed because of a very low noise floor, bass extension with precise control, and produces an airy large soundstage with exact location of individual instruments on this stage. As my readers know, the most important aspect of reproduction of music for me is timbres, tonality, and colors. This very inexpensive, yet very well built, amplifier yields beautiful, pristine, vivid timbres/colors/tonality that is at the same level as my reference amplifiers that cost thousands of dollars more. If you are interested in what a SET amplifier can bring to your listening pleasure for a very reasonable sum of money, give Pine Tree Audio a call.”

A note on 6L6 tube selection:

Jesse shipped the amplifier with Tung Sol new production but suggested I try JJ Electric 5881 tubes from Tube Depot. I got the 5881s Apex-matched, which is an accurate measurement to ensure both tubes’ output is the same.  I also experimented with vintage RCA 6L6 tubes.  With medium-low confidence (meaning I may not be able to pass a blind test), I felt the JJ tubes produced more clarity and resolution, whereas the vintage RCA 6L6 tubes were warmer and possibly less resolving. The Tung Sol’s that came with the amplifier were in the middle of these two places.

Conclusion

If you have speakers efficient enough to run on 5 watts, I suggest you consider the Earth Tones amplifier.  It has the disruptor qualities of wonderful, engaging sound at a very reasonable cost.

Specifications:
Price and information:
The Earth Tones amplifier sells for $1,295.00 at the time of this review.  It is available on the Pine Tree Audio website and is made in the USA.  
https://sites.google.com/view/pine-tree-audio/home

John’s Associated Equipment
Grimm MU2 Music player (Streamer/DAC/Preamplifier)
Plinius SA-50 Power Amplifier
Audio Note Kit EL 34 Amplifier
Pine Tree Audio ISO-Twist SPC (Silver Plated Copper) RCA interconnects
Pine Tree Audio Visceral Speaker Cable
Devore Fidelity O/96 speakers