Prautes – Desktop Headphone Tube Amplifier
The PRAUTES is a vacuum tube headphone amplifier that also functions as a line stage amplifier and low power speaker amplifier, thus providing great flexibility in limited spaces. It was created as a heritage piece—something that can last for decades. Some of the parts (like the switches) are sourced from military aircraft, made to withstand high stress. All the external case and knobs parts are custom-made only for our products.
The PRAUTES uses a 12AU7 tube gain stage to drive a pair of 50L6 or 25L6 tubes in push-pull mode. The serial number on the back will indicate which tube type is used. This provides for more power than needed for almost all headphones—and can drive high efficiency speakers with about 2 watts. Five separate output impedances are provided to match listening equipment including 8 ohm speakers, standrad headphones, high impedance headphones and In-Ear-Monitors.
Each of the four inputs are independent. Connect your line sources such as CD player, TV, or iPod to any of the four inputs. Since there are no digital switches (which can degrade the audio signal), it is recommended that unused devices connected to the PRAUTES be turned down or off.
Allow about five minutes of warm-up to let the tubes settle. Leave the ground lift switch on normal unless there is a ground loop hum in your setup. Turn the PRAUTES amplifier off when not in use to increase tube life.
The headphone outputs and speaker outputs are independent. Only the selected output is used. High efficiency 8 ohm speakers work best. See our website for recommendations.
The line output is appropriate for powered speakers, power amplifiers, or any other device with a line input that has an input impedance of 100K ohms or greater. Used to supply a line output to another amplifier, the PRAUTES amplifier acts like a pre-amplifier. It is appropriate to connect a turntable the the PRAUTES amplifier and then connect to a power amplifier. Short cables are best.
Volume: This heritage quality finely manufactured potentiometer controls the headphone, speaker and and pre-amp line outputs
Input Switch: Selects one of four line inputs
Input impedence on each input is 100KΩ
Tip: Use the ‘Mute’ position when changing input cables
Impedance (Ω) Switch: Headphone and speaker settings
300 Ω: High impedance headphones like Sennheiser 800.
100 Ω: Standard for many Studio headphones
32 Ω: Standard consumer headphones
8 Ω: Speakers or very low impedance headphones.
Bass Boost Switch: Provides approximately 3dB boost with a variable roll-off point
The bass boost circuit is a subtle increase in bass response. This control eliminates the high phase shift that occurs with typical tone controls. The boost amount is the same for all settings, but the frequency point of the boost ranges from 47Hz to 31Hz. This allows for very fine tuning of the bass response. Match this setting in coordination with the Impedance Switch to match the selected headphone, type of music chosen and your preferences.
Output Switch: Selects output type
SPK: Output to rear speaker jacks—use 8 Ω impedance.
XLR: Output to balanced XLR jacks
Mute: No speaker output—use for independent line output mode.
1/4″: Output to 1/4″ (6mm) Headphone jack.
1/8″: Output to 1/8″ (3.5mm) Headphone jack.
Line Stage: approximately 16dB
Headphone power: > 1 Watt, depending on load
31, 36, 41, or 47Hz boost of approximately 3dB (6dBm)
No extra active circuit elements are engaged!
Ground Lift Switch:
Use only if there is ground loop hum in your AC supply wiring.
Four 50L6 tubes are supplied for the output stage
Two 12AU7 tubes are supplied for the input/line stage
Annodized tube shields are provided to cover the tubes. The use of the tube shields is optional.
20Hz to 20KHz .2dB to -.75dB into matched resistive load
Note: Can vary slightly based on tubes installed
12 ½” D x 7 ¾” H x 9 ½” W / cm D x cm H x cm W
16 pounds / 7.3 kilograms (not including AC power cable)
Depending on destination country the PRAUTES amplifier voltage setting is preset at the factory for 120v or 240v operation.
What makes the PRAUTES unique?
– The PRAUTES is a tube-based analog amplifier. It is powered by a small, custom made, internal regulated semiconductor power supply— thus allowing single box construction.
– The PRAUTES is hand assembled entirely in the U.S.A at Coffman Labs with point to point wiring—it should last decades. All contact points are mechanical as well as electrical.
– The PRAUTES is electrically rugged and meant to last.
– The PRAUTES chassis is a 100% machined (not stamped metal) and able to take abuse. All chassis parts are interlocked in specially designed machined slots so that only four bolts per side are required to keep the structure intact.