Electro Harmonix EL34 / 6CA7 "Big Bottle" Audio Output Valve - Part # 6CA7EHElectro Harmonix Classic 6CA7 EL34 Audio Output Thermionic Tube. Part No. 6CA7EH. Manufactured by Electro Harmonix. Octal base. 34Watt output per valve. Designed to exacting specifications of a Philips 6CA7, this classic tetrode retains a high detail tone with military reliability as a direct EL34 replacement with higher headroom, etc. Larger bottle tube. Its a sturdy tube that can handle heavy use, excellent replacement for Marshall amplifiers, etc.