Up for sale is a world-class, exceptionally well-matched quad set of four pieces (4 Pcs) of vintage original Ken-Rad 71A power triode vacuum tubes. Highly sought after by custom low-wattage amplifier designers and audiophiles for high-end preamps, headphone amplifiers, and high-efficiency speaker drivers, these classic USA-made triodes are legendary for their organic tonal purity, rich imaging, and exceptional micro-detail resolution.
These premium specimens showcase the iconic Ken-Rad / Made in U.S.A. base branding. Meticulously manufactured in the USA during the World War II era in 1942, they feature the matching V2 date codes, heavy-duty Black Plate structures, and pristine Black Base configurations. Each valve comes housed inside a fresh, clean protective white box.
Testing & Verification: Every tube in this quad set has been strictly processed and tested on our industrial Amplitrex AT1000 analyzer under factory conditions. Measured against standard baseline operational factory specifications for the 71A triode class, this set displays superb full-strength performance and exceptionally balanced transconductance tracking across all channels.
| Sr. No. | Test Triode | Parameter Ip mAdc | Result Ip mAdc | Percentage Ip | Parameter Gm uMhos | Result Gm uMhos | Percentage Gm |
|---|---|---|---|---|---|---|---|
| 1743812 | Triode | 20.0 | 24.2 | 121% | 1700 | 1690 | 99% |
| 1743805 | Triode | 20.0 | 29.2 | 146% | 1700 | 1740 | 102% |
| 1743801 | Triode | 20.0 | 22.4 | 112% | 1700 | 1700 | 100% |
| 1743802 | Triode | 20.0 | 23.2 | 116% | 1700 | 1700 | 100% |
We are specialized suppliers of high-grade vintage vacuum tubes and valves, maintaining an industry lineage established back in the 1970s. With an extensive inventory of nearly 300,000 components, we serve high-end audiophiles and vintage equipment restoration collectors worldwide. Every tube is strictly evaluated using calibrated industrial testing instruments such as the Amplitrex AT1000 to guarantee absolute transparency.
Note: Note: Custom Duties and Taxes are the Responsibility of the Buyer in their Country
NOS Audio Tubes — Mumbai, India