Uploaded May 2018 | Updated September 2026, 1 week ago
In this video, we'll compare 10 different EL84 brands in a JCM800 using the Yellow Jackets® YJS. The JCM800 typically uses EL34 tubes, but Yellow Jackets® allow EL84 power tubes to be used in place of most common guitar amp power tubes, providing a "self-bias" Class-A configuration for the EL84 so that no bias adjustment is required.
The first sound demoed is that of the EL34. There is a dropoff in volume when the EL84s are demoed due to the YJS's substantial reduction of maximum output power. This allows you to find that sweet, warm mix of preamp and power amp distortion at a lower volume.
The YJS used in this video is the pentode version, which reduces the output power by roughly 50% to 70%. The triode version of the YJS reduces the output power even further, from roughly 70% to 90%.
The YJS is also available in a shorter version, YJShort, for amps that have low clearance. To find out which Yellow Jackets® model is right for your amp, you can find more info on the Yellow Jackets® website:
yellowjacketstc.com
Yellow Jackets® also offer a convenient list of recommended models for common amplifiers:
yellowjacketstc.com/amplifier-recommendations
To purchase Yellow Jackets® directly, visit:
amplifiedparts.com/taxonomy/term/693
Amplified Parts also offers an EL84 sampler set if you would like to try out various EL84s in your amp, with or without Yellow Jackets®:
amplifiedparts.com/node/41576
In this video, we'll compare 10 different EL84 brands in a JCM800 using the Yellow Jackets® YJS. The JCM800 typically uses EL34 tubes, but Yellow Jackets® allow EL84 power tubes to be used in place of most common guitar amp power tubes, providing a "self-bias" Class-A configuration for the EL84 so that no bias adjustment is required.
The first sound demoed is that of the EL34. There is a dropoff in volume when the EL84s are demoed due to the YJS's substantial reduction of maximum output power. This allows you to find that sweet, warm mix of preamp and power amp distortion at a lower volume.
The YJS used in this video is the pentode version, which reduces the output power by roughly 50% to 70%. The triode version of the YJS reduces the output power even further, from roughly 70% to 90%.
The YJS is also available in a shorter version, YJShort, for amps that have low clearance. To find out which Yellow Jackets® model is right for your amp, you can find more info on the Yellow Jackets® website:
yellowjacketstc.com
Yellow Jackets® also offer a convenient list of recommended models for common amplifiers:
yellowjacketstc.com/amplifier-recommendations
To purchase Yellow Jackets® directly, visit:
amplifiedparts.com/taxonomy/term/693
Amplified Parts also offers an EL84 sampler set if you would like to try out various EL84s in your amp, with or without Yellow Jackets®:
amplifiedparts.com/node/41576
