Replacing 6550s with KT 88s

Hi Joe
Many thanks. It's advice and insights like yours that makes Agon such a
great resource and community. For a tube novice like me this is invaluable.
Enjoyed reading your blog and will post my impressions post acquisition of
a new set of pre and power amp tubes which should arrive ,hopefully within
the next 10 days.
Cheers
Pradeep

If you replace all of the tubes at once(pre and power); you won't know what tubes made what change, or to what degree. Just a thought: replace the preamp tubes first, and listen for a while. Put the old pre tubes back in, swap out the power amp tubes and listen for a while. If you are replacing the phase splitter and driver tubes: make that a separate/distinct step as well.

Rodman
Many thanks. You are absolutely correct.I intend to do this slowly and in phases to try and guage the effect of each tube. Am interested in your comments/experience of the NOS 6550s vis a vis the Winged C current production
Cheers
Pradeep

I had been purchasing NOS Sylvania 6550's, from Upscale, until his supply ran out. Went to the =C= and felt I was missing nothing(at that point). Those had over four years on them when replaced with the NOS GE 6550A octet. Thus- I can't offer a valid, direct comparison. It's my impression, however, that the GE's are a more dynamic, open & cleaner tube, than either the Sylvania or =C=(at the same bias setting). Once you have listened to your rig with the new compliment of tubes for a time: Try some NOS Siemens E188CC's or 7308's(direct replacement, identical in every parameter to the 6DJ8/6922), in your phase splitter and driver slots.

Rodman
Thanks that seems a sensible way to go as the price differential between NOS and current production for phase splitter and driver tubes, at least in Singapore , is much lower than the 6550 power tubes.
Will post my impressions post makeover.
Cheers
Pradeep