re-tubing CJ LP70s

The cheapest route would be to change out the Telefunken 12AX7 tubes in the Calypso to something not has solid state sounding as the telfunkens. You could try Mullards, Amperex or one of the NOS 5751 tubes. That's what I did. If this doen't work then you could change out the tubes on the amp. There are many threads on Audiogon or AudioAsylum about changing the Calypso Tubes.

I have tried a variety of 6550 varients in my CJ PR 8A's from EH, Svetlana, NOS Tungsols and others and for the price, sound, and reliability the SED Winged Cs are my tube of choice as of a lot of other Audiogoners.

"...3D, liquid, sweet mids..." - not the 6550's strong suit; EL34, yes.

After the NOS GE6550A - CJ ran out of 'em during the middle of Premier 12 production - I'm with Bbro and SED Winged C 6550C.

Regarding the 6DJ8/6922/7308 driver - here's a good opportunity to have some fun tube rolling. I've yet to hear a contemporary member of this family that meets up with any of the better NOS. Amperex Orange Globes are a safe choice. From current tubes, the Electro Harmonix 6922 is worthy and inexpensive.

Thanks to you all.

For the 5751, there are many variations. I was looking at eBay, MDS, can you please elaborate which one it is? i know the 3 mica ones are the one to look for. then the black plate ... then I get confused.

The NOS tungsol is so $$$, that's completely out of the question. I will definitely go with the Winged Cs.

just a side question, how do you determine if an amp is underpowered for the speaker by listening?