Differences in tube sounds: 6550 / EL34

I agree with Trelja on the tradeoff of a good EL-34 tube. I am using NOS Siemens EL-34's (12) in my Cary V12i. This amp also accepts other tubes including KT-88, KT-77, KT-66, or 6550. At the outset I was intent on tube rolling with others besides the EL-34. However, the Siemens NOS made me forget all about that. I'm sure the bass could be better, but its good enough for me and the mid-range and sweetness are exceptional.

I have just acquired an Audio Aero Capitole amp for demoing. It uses both EL34's and KT88's. I recently, today, changed out the KT88's for some 6550's. The 6550's do not have the base control of the KT88's but they do allow the sweetness of the EL34's to come through much more clearly, giving me the nearest to the C-J sound that I have lived with and loved for many years, only with much more articulation, detail, breadth and much else. Hope that helps.

I have to say that I very much like the EH 6550's that came in my Graaf GM5050. Good from top to bottom with excellent bass and a neutral midrange.