High – Low Output Power
A peculiarity of the Stella series products is the High Power switch. Through a simple but clever circuit the amplifier can operate at 50% of the nominal output power. All Stella amplifiers are designed with a pure Class A triode operated power output stage. One of the advantages of class A is lower distortion but this comes at a price, namely power consumption. Being that valves are conducting even in absence of an input signal, substantial power dissipation occurs at all time regardless of music being played or not.
You can save unnecessary power dissipation by operating the Stella at half of its nominal power. The bridge-circuit output provides indeed high current that drives speakers with authority even at half power. In both modes, full or half power, the class of operation doesn’t change.
Important Note. When turning on the amplifier make sure the High Power switch is deselected. This will guarantee a longer life to the output tubes. Same recommendation before turning off the amplifier, if in High Power mode then deselect the High Power switch and wait few minutes before turning the amplifier off. Doing so the thermal stress to the tube glass will be reduced with consequent benefit for their functional integrity over time.
Double Output Transformers
A characteristic of the output stage is the seldom seen double output transformers configuration. Based on a bridge-circuit output also known under the trademarked “Circlotron” name, the power output stage uses two transformers to provide best driving performance:
· minimum negative feedback
· high current output
· high stability even with demanding loads
Such topology mastered by just a few designers while not economical can guarantee if done properly outstanding results.
Additional flexibility is provided by the possibility to control both volume and input gain. Source voltage level (line level) actually varies from device to device and one can find himself/herself in a situation where volume is practically utilized for only one third of its range. At the other end of the spectrum one may need to get to 5 o’clock to have the desired sound level.
The Stella preamplification stages have generous gain to deal with a wide range of source levels. Thanks to the Gain and Volume knobs it’s possible to find the sweet spot for a specific audio set up.
In audio the most highly regarded method to connect components is point-to-point wiring where each component is directly soldered to another or by a ”point-to-point” wire. Angstrom audiolab uses PCBs (printed circuit boards) of very high standards in other series, but for Stella just the best was chosen. All the wiring is Teflon insulated according to military specs. Some customers prefer PCB based circuits, like in the Angstrom Zenith series, but connoisseurs will surely appreciate the more traditional and refined point-to-point wiring. Again nothing is for free, such approach implies a remarkable amount of hours of skilled work for what we consider a work of art.
Angstrom audiolab’s philosophy about component selection is to choose what available from well-known producers without any shortcut on quality.
In quality vs. hype Angstrom choses quality proven in more than three decades of experience. You may not find esoteric components in our products, not because they’re not good, but because we weren’t able to establish a clear advantage in our design.
Inputs (configuration can be customized)
- 2x XLR
- 3x RCA
2x 100 Watt (8 ohm) in full power mode
2x 50 Watt (8 ohm) in half power mode
Output stage in pure Class A, Push Pull triode operation (both full and half power)
Two Output Toroidal Transformer per Channel in Circlotron Connection
Total Power Output Transformers: 370 Watt
Pure Symmetric Balanced Circuit
Current Output Driver
Zero Feedback (we mentioned before in the “double Transformer output” that we had minimal negative feedback…)
6 Independent Power Supplies
2 Amorphous High Current Chokes (one per channel)
6x EL34 Output Tubes per Channel (12 total)
4x Ecc82 Input/Driver Stage per Channel (8 total)
Balanced 1M Ohm
Single Ended 470K Ohm
Hum & Noise
less than 2.0 mV rms 88dB
PS Energy Storage
Power Consumption At Max Power
1000 Watt (370 in Idle)
W 45.5cm, H 20cm, D 41cm