Quad bias probe. and extra bias probes if a person wanted a quad of probes for their power tube quad. '''It's for showing bunker research not conducting it. Bias voltage is like a control valve that regulates the current through the power tubes, by applying a DC voltage to the tubes' control grid. Tests EL84, 6BQ5, 6P14 etc. It allows guitarists, amp technicians, and hobbyists to safely and accurately check tube bias while adjusting the bias control of an amplifier. €134,99 including VAT 19% , [plus shipping] Qty Add to cart Add to wish list TAD Bias Master BM2 Kit of a bias probe for indirect measurement of the quiescent bias current of a tube. Build your own bias adapter with our Bias Scout kit and you'll save money every time you set the bias on your amp. Includes 4 probes and english/german operation manual. Unlike other bias probes on the market the “Pro One” Bias Probe is designed to allow you to play the amp while the probe is installed. The Bias Master™ allows you to monitor the bias current safely and easily. rhjn ihushw egqreym xeef qmacc ycqh uiubo ivkrx wiyff slrspd