Acoustic Guitar Building ~ Summer Camp – On Sale Until DEC 26

An immersive experience in a fully equipped guitar building workshop… Build a beautiful acoustic guitar under the watchful eye of an experienced instructor. No experience necessary.   Questions? Please call us! 773-489-4830

Single-ended 2A3 Stereo Tube Amp

When I first heard a 2A3 pass signal I was floored. There seemed to be so much missing. So much information that didn't seem to belong was now gone. I felt as if a noisy refrigerator compressor that was running in the same room with my sound system just switched off and left me alone with the music.


It was at this point that I began to reconsider the use of nine pin tubes. They just seem so tiny and tend to go microphonic. Many worthy circuits utilize them, and they are still far better than their disposable solid state counterparts. But as far as current design efforts go, I am leaning squarely backwards to fewer pins and/or larger sockets, octals at least. Infrastructure is everything.

This circuit is a classic 6SL7 tube wired in series-regulated push-pull, driving a 2A3 directly heated triode for about 3 1/2 watts of output power per channel. The components are discreet. The topology is over the top. Turrets, no foils! That is a battle cry. I'll say it again. Turrets, no foils!

The same steel bar embedded in Martin's guitar necks and what made them famous is also used in Specimen amps to support the transformers and protect against inertial impact distortion. That means that when you drop the amp, the chassis panel doesn't bend and the transformers don't wind up in a trapezoidal shape with stretched windings, causing hum and failure. For twenty-five years people have been bringing me amps to fix, complaining of hum and failure. As they always say the best place to stop the bleeding is at the source.

Color Finishes:

The Specimen Single-ended 2A3 Stereo Tube Amplifier is made using the same Baltic Birch plywood as our horn speakers and can be finished to match perfectly. Presently we offer the following colors:

- Natural
- Dark Walnut
- Dark Green
- Dark Red
- Dark Orange
- Yellow
- Blue

*Opaque finishes are an additional $300 (e.g., black, white, or other custom opaque color)


Circuit: Single-ended pentode driven triode, Class A
Tubes: Two 6SL7 pre-amp tubes, Two 2A3 power tubes, GZ34 Rectifier
Power: 3-1/2 watts per channel
Inputs: Two RCA line-level
Dimensions: 16" deep x 11" wide x 8" high
Weight: 22 lbs.

Custom finishes to suit any decor are available as a special order.

8 - 11 weeks
see the full price list

Specimen Single-ended 2A3 Stereo Hi Fi Tube Amplifier

Specimen Single-ended 2A3 Stereo Hi Fi Tube AmplifierSpecimen Single-ended 2A3 Stereo Hi Fi Tube Amplifier

Specimen Single-ended 2A3 Stereo Hi Fi Tube AmplifierSpecimen Single-ended 2A3 Stereo Hi Fi Tube Amplifier