Tube Amp Doctor EL84-CZ Power Tube
The EL84-Cz is the most powerful EL84 tube we ever heard—big tone and very dynamic.
Recommended when powerful tone is what you're looking for. EL84-CZ gives most amps an extra powerful bass response compared to the russian EL84 options. Be careful with amps that already do have a fat bass or if their speaker can handle the increased bottom end as it might be too much then.