The 6948 is an ultra low microphonics and low noise sub-miniature tube originally developed for high altitude missile guidance systems during the Cold War.
These indestructible beauties were some of the most stringently tested tubes ever built by Philips/ECG. Designed for operation at altitudes of 80,000 feet where high mechanical shock, vibration and high temperature are the norm, the 6948 is considered to have extraordinary freedom from intermittent short circuits from within the tube and little intermittent leakage.
Testing of the tubes included fatigue frequency response measurements between 30hz and 3khz and back to 30hz over 3 minutes whilst under an acceleration pulling 10g's! As well as, white noise tests consisting of subjecting the tube to a white noise vibration spectrum test between 100hz to 5khz at level when traveling up to 15g's. Other tests included impact acceleration tests up to 450g's and high radiation dosage tests.
And now in 2019, these little pencil tubes have been re-purposed for some 21st century musical love and hard wired forever in our new pedal LOVE BOMB.