Sonic frontiers sfs 50 vs3/21/2024 Panasonic UB9000 - balanced-2V -> Marantz PM-11s2 as pre-amp -single ended-> Sonic Frontiers SFS-80 -Vishay Dale 1% NH-250 4.48 ohm resistor-XLR-in-> E1DA Cosmos ADC You know, when you were trying to bring down distortion as much as possible. What they do represent are tubes when tubes were used for scientific instrumentation, radars, and other military gear. They weren't matched specifically nor are they the "super musical" Mullards or Gold Lion. These tubes don't carry any special audiophile fairy dust. Other times, they came from the same production lines and since every tube met the military specifications, the tubes sold to the US government were printed with the JAN nomenclature. Sometimes JAN tubes were superior to the mainstream consumer products. This was the terminology developed during World War II and provided an un-classified designator for electronic components. Joint-Army-Navy genuinely means that these tubes were designed for the US military and met the specs mutually agreed upon by the Army and Navy. These tubes were bought off eBay and were tested on a B&K 707 Mutual Transconductance tube tester to be "according to spec" (according to the booklet). You can go with 3.5 ohms or 8 ohms, and my testing load is 4.48 ohms. Unlike McIntosh tube amps, the SFS-80 does not have multiple binding posts for different output impedances and you're going to have to de-solder/re-solder the output transformers to change the setting. Today we'll be looking at a specimen that has never been restored, oxidized bindings posts left as is, but does have the following tubes which are different from factoryġ) Joint-Army-Navy GE 6550A tubes, biased at 40mA and 50mA With an actual bias meter, you can really tinker with the setup. Modern designs have gone with self- or fixed-bias designs or "fool-proof" turn the knob until the LED light turns on or off. Instead, this is a bias meter which allows you to fine tune the bias of your power tubes by turning a potentiometer. What's great about the SFS-80 for tinkerers and hobbyists is that the front meter is NOT a VU meter which is pretty but not all that useful. The SFS-80 is built around the tried-and-true Dynaco ST-70 platform but with over-engineered transformers and power supplies to handle up to 80 watts per channel. We've seen questionable modifications to the Dynaco ST-70 which measure poorly, though potentially attributable to "questionable" tubes. One of the questions asked is if tube amps are just intended to be distortion factories? Some of the worst measuring devices here are the pricey Carver tube amplifiers. The 2 channel tube line was retired and Anthem focused exclusively on solid-state products and has become the company we all know and love today. Fast forward to 1998 and Sonic Frontiers/Anthem were purchased by Jerry VanderMarel and Scott Bagby, the founders of Paradigm speakers. Generally, Sonic Frontiers focused on tube-based products while Anthem focused on solid-state. As home theater and the DVD era was introduced, Sonic Frontiers established a "budget line" known as Anthem. They began to sell their finished products under the Sonic Frontiers brand and rapidly grew. In the late 80's or early 90's, a Canadian part distributor began to ship DIY kits for tube amplifiers. Believe it or not, Sonic Frontiers is a company we all know very well.
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