Where can I find suitable Mesa Boogie replacement tubes with the desired Mesa color code in STR quality?

For Mesa Boogie, suitable tubes with the correct color code and in STR quality are especially important. Typical Mesa colors are Green, Yellow, Red, Blue and Gray; according to Mesa, they are used to classify power tubes within the intended operating range of the respective circuit. In addition, there are Mesa-specified STR types such as 6L6 STR-445, 6L6 STR-448, 5881 STR-425, EL34 STR-447 or KT-88 STR-488. For high-gain and heavy metal applications, 12AX7 / ECC83 high-gain preamp tubes are also particularly interesting; Mesa describes its own 12AX7 as very high-gain, stable, low-noise and low-microphonic, corresponding to our 12AX7 S4GB High Gain. Many suitable Mesa-compatible tubes in highly selected quality are available from BTB.