Sonic Frontiers Model Power 2, All Tube Amplifier, Amazing Musicality

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For your consideration is a super-clean Sonic Frontiers tube amplifier model Power 2 made from 1997-1999.

We've been running this all week in our listing area and have not thought of turning it off or swapping it out for a new arrival once. It just sounds *SO* good. Streaming Sonos, Hi-Res Tidal, and playing CD's sounds perfectly WARM.

Big, heavy, and incredibly well-built. Happiest sitting on the floor since it's likely too big for most racks. Beautifully finished in a stainless steel and black powder coating.

Currently running on strong 6550 tubes but can be altered to utilize others including KT120's.

The overall topology of this 110W x 2 push-pull amplifier comprises of an input cathode follower (6922) and two differential plate-loaded voltage amplifiers (6922's) in cascade, followed by a driver cathode follower (5687WB) that is direct-coupled to the output tubes (6550's).

The amplifier is fully balanced throughout including the output transformer. The input voltage amplifier configuration allows balanced as well as single-ended inputs, and balanced feedback to be used. 

Tested super clean to 110W (manufacturer full rated power), starting to show some distortion as we got all the way up to 140W.

A great value considering its construction, attention to details, and sonic qualities. Very hard to beat at this price.

The included manual is a printed copy of the PDF manual.

This amplifier can be internally switched for 8, 4, or 2 ohm loads. It's currently configured for 8 ohms but we can switch it to the loading of your choice before shipping.

SkyFi Tube Notes:
• All output tubes are Svetlana Gold Label 6550
• All 6922 tubes are current production Sovtek
• Both 5687 are vintage Tung Sol

For full specifications please see the linked manual below or our last photo:

Sonic Frontiers Power 2 Stereo Amplifier - Manual

The SkyFi Testing Process for Tube Amplifiers:
We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and tubes are inspected for signs of stress overheating or cracking.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If it all looks clean we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier the remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will also be tested.

We also test all tubes for output gain and leakage on our calibrated B&K 747 tester against the original manufacturers specifications. If needed, the tubes will be replaced from our vast NOS (New Old Stock) vintage or modern inventory.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.