Atma-Sphere Gem Amplifier

Hi-End 5 Watt tube amplifier 

Atma-Sphere Gem Amplifier Atma-Sphere Gem Amplifier

The Gem is a Push Pull class A tube amplifier meant for bedroom, desktop, headphone or main system use. It uses many of the concepts we use in our other amplfiers. Its fully differential from input to output (although has RCA inputs only). It is overbuilt with precision parts; for example the output transformers are rated for 10 Watts so the amp can't get in trouble should a power tube fail. It can drive 4 or 8 Ohm loads and does well with 16 Ohm loads too (on the 8 Ohm taps). If you do a search, one thing you find out quickly is that tube amps of this size aren't also built to be high quality. This amp uses the same parts quality of our highly regarded OTLs and has power supply capacity found in many amps of 5x more power. 

This was originally designed as an amp for a bedroom system where reliability is paramount. Its quiet enough that it suits headphone use as well, and is attractive and small enough that it is suitable for use in a good quality desktop or home main system (if the latter has higher efficiency speakers). 

Single-Ended Triode (SET) amps have a strong following; when asked why, their proponents claim they sound than push-pull amps. But the output power is never the same in these comparisons and neither is the class of operation. If just these two things are leveled in the playing field you find that SETs have no sonic advantage at all over a push-pull amp regardless of price, if faithfulness to the music is the determining factor.


- Fully Differential Design
- Two inputs with volume control
- Suitable for headphones, desktop, bedroom or a main system with efficient loudspeakers
- Two stage Constant Current Sources for each stage of gain (improves performance of each gain stage)

- Precision components used throughout
- Low-noise "star" grounding topology
- Three-year general coverage warranty with one year warranty on output tubes

Review & Awards

frequency response
5 Hz-100 KHz, +0 dB, -2dB@ 1/2 Watt 

input impedance
100 Kohm Ω 

4 and 8 Ohms 

Tube complement
4 x EL95 (6DL5 or 6BM5); 2 x 12AT7 

12" deep (including knob and connectors) x 7" wide x 5" tall 

12 lbs. 15 oz. 

Three years, transferable
One year for tubes

For additional information, audition and pricing, contact our worldwide dealers or our headquarters.


1742 Selby Avenue
St. Paul, MN 55104


Tel : +1 651-690-2246