UV-1 (UltraViolet) basic preamplifier/headphone power amplifier 
The UV-1 (UltraViolet) preamplifier is based on a circuit that we have used for many years, but not marketed before. About 40 years ago, Ralph Karsten began developing his own circuit for use for friends on a budget but with high end audio aspirations. It was originally used as a modification to the venerable Dynaco PAS-3. Over a period of decades, the circuit has seen a lot of refinement. It is a simple circuit (and obviously a complete departure from our other products), based on a very capable and refined 6SN7-based line section with a simple phono section based on 12AT7s. We have seen this preamp best preamps costing up to five times more; when we say 'refined', we mean it!

We never really considered marketing the preamp as it is so different from the rest of our product line. But friends and associates convinced us that we had something special, especially for its price so here it is.

The preamp is available in four forms: a basic line stage, a headphone power amp that also works as a line stage, a full function preamp with high output MM capability, or with the addition of a set of Jensen stepup transformers works with any low output moving coil cartridge as well.

The headphone version of the UV-1 uses the full tube complement of the UV-1. It has four inputs and can be used as a line stage as well. This version does not have a phono section.
  • Simple zero feedback line section
  • Cardas RCA connectors used thoughout
  • standard dual output connections, optionally reconfigurable
  • Shunt-style balance control
  • heavy-duty seamless aluminum chassis
  • Precision components used throughout
  • Low-noise "star" grounding topology
  • Three-year general coverage warranty with one year warranty on tubes

Line stage frequency response

2 Hz-200 KHz, +0 dB, -2dB

Line stage gain

15 dB

Line stage input impedance

100 Kohm Ω single-ended

Line stage output

12V; 17VRMS at clipping

Output impedance

400 Ohms from 2Hz to 100KHz

Phono stage input impedance

47 K Ω,

Phono stage input overload

500 mV

Phono stage gain

70 dB (Low Output Moving Coil version)

Phono bandwidth

5 Hz-90 KHz within ½ dB

RIAA accuracy

Within .1 dB

RIAA Phono sensitivity

( for 0.5 V @ 1 KHz ) 0.15 mV

Tube complement

2 x 12AT7 phono
2 x 6SN7GT line section


15 3/8" wide x 7.5" deep x 5." high


7 lbs.


Three years, transferable
One year for tubes


Owner's Manual
For support requests or any questions about your Atma-Sphere product, contact us directly at (651) 690-2246 or send us an email.

Available as full function with phono or line stage only.
Contact your local dealer for pricing information.
Contact Atma-Sphere tel.: (651) 690-2246 or email