The MESA® 5U4GB Rectifier Tube is our very best overall 5U4 and our rectifier tube of choice in the production of all new MESA amps featuring this tube. This tube produces a "traditional vintage sag" with the most elastic and compressed feel of the two 5U4's that we offer. Amazing feel and exceptional overall quality make this our factory favorite.
Based on classic 1950s technology, the 5U4GB is a vastly improved 5U4 design that is extremely reliable and consistent, as well as more compact compared to original “Coke Bottle” 5U4Gs (3 3/4" from bottom of base to top of glass).
It is similar in size to a 6L6 power tube so please take special care to install them in the correct tube position(s), especially when replacing 6L6's at the same time. 5U4GB Rectifier Tubes are used in MESA Amps like the Dual and Triple Rectifiers®, Road King®, Roadster®, Stiletto Ace™, Deuce™ & Trident™.