A portable Single-Ended Triode for Everyone Everyday
Sassy is designed for every enthusiast and audiophile who enjoy sound of SET amp while demands more portability and practicality. Sassy as 2nd member of portable headphone amplifier (PHA) series has inherits many technologies and advantages developed for PHAntasy, the bigger sibling. One may immediately notice Sassy’s extremely compact and light-weighted ever seen for a tube amplifier. The secret is elimination of output transformer and choice of high efficiency subminiature tube. A newly developed full-discrete solid-state output stage replaces costly output transformers, which is capable of delivering precise and powerful energy into headphones no matter what impedance and sensitivity.
The Heart of Sassy, JAN6418
At the center of Sassy are a pair of JAN6418 tubes, each one responsible for major amplification of left and right channels. JAN6418 is a triode-connected filament type pentode in Sassy. The main amplifier topology is Single-Ended Triode (SET) from input up to voltage gain stage to preserve sound signature of Directed Heated Triode (DHT) followed by solid-state output buffer. A triode is unique as gain device that tends to generate more even harmonics than odd ones if any. The result is music sounds airier, smoother, and richer than other type of devices. JAN6418, a directly heated tube, instantly enters working condition after power on and provides intimacy and lifelike sound stage more than none filament type tubes. Hand selected JAN6418 driven by smart filament bias has extensive lifespan. There is no obvious degradation of tube performance for 5 years.
High-fidelity solid-state output stage
The biggest difference sets Sassy apart from traditional SET amp is solid-state output stage. The effort is beyond imagination and takes much longer time to come up a viable solution with satisfactory performance. The challenge is to make it stable and consume extremely low power, while faithfully delivering SET signature of sound and plenty of energy on demand. The efforts have finally paid off. Sassy is capable of up to 20V and 1A output that is something never been done in such a small form factor. Sassy meets the balance of both worlds with sweetness of Single-Ended Triode and precise slam of power transistor. Sassy’s overall tonal balance and driving capability are comparable to best amplifiers either desktop or portable formats.
Simple and Elegant
Sassy is a pure analog and full-discrete design. We make Sassy as pure as possible by doing the best in analog domain and leave the freedom to users for choice of front end as concept in hi-end stereo. Disregard the simple connectivity and control, Sassy can handle plenty energy dynamically for any types of headphone. Users can choose whatever they prefer without concern of impedance and sensitivity, A small form factor forges Sassy’s simple and elegant look in aluminum enclosure and machined panels, yet the inside complexity and technology.
Pure and Smart Power
Sassy is capable of playing music over 10 hours on battery (*1). This is unprecedented achievement for a tube amplifier. Instead of using two batteries like PHAntasy, there is only one cell in Sassy to supply both filament bias and amplifier. A filter in front of filament supply ensures the purity of power. Careful ground planning and layout topology guarantee minimum interference between blocks. And, as always, we adopt USB port as DC 5V charging supply for best convenience and true portability.
(*1) the actual time depends on type of headphone and sound level of playback
From the beginning of project, we intend to design a simple yet high performance amplifier for daily life without concern of control manipulation, trouble of carrying adaptor, choice of suitable headphones, etc. We are proud to say the goal has achieved. By leveraging the sweetness of tube and power of solid-state devices, Sassy is able to deliver touching and powerful music anytime anywhere. Following the adaptive nature of smart design, Sassy eliminates all the unnecessary switch and control. It is so much more comfortable to use Sassy without hassle, just plug and play.
Current Dumping Output Stage
Valve/Solid-State Hybrid Design
Driving All Impedance Headphone
DC 5V Rechargeable
Frequency Response: 10 Hz – 100 kHz
Output power: 180 mW + 180 mW (300 ohm); 1000 mW + 1000 mW (30 ohm)
Headphone impedance: 30 ohm – 600 ohm
Power supply: 5V/1A via micro USB port
Operation time (on battery): Approx. 10 hours (depends on headphone impedance)
Charging time (>1A supply): Approx. 3 hours
Dimensions: 119 mm x 93 mm x 23 mm
Net weight: 270 gram
Phatlab Phat Sassy
USB A to Micro USB B Charging Cable