Questions about NOS 6550 tubes vs New stock

[Ern Dog]

One (out of 4) of my nos Tung sol 6550 power tubes went out. Since the new stock ones are less expensive, is there a big sound quality difference between the new stock Tung sol 6550's and the NOS ones?

Also, if I get 4 new stock, is it better to remove all my old tubes and replace them, so they are all the same? Or is ok to have 3 NOS and 1 New stock?

[TroyD]

Back when I had the CJ MV-75, I went through three quads of Tung Sol (new) tubes...each one had a bad tube. Could just be me but I went in a different direction.

BDT

[187CAM]

Replace the old with the new matched quad. However, I have used 2 old tubes, one for each channel and added 2 new, one for each channel and not noticed a difference. This being said your amp should require bias of all tubes. Personally I have never had a problem with the Tung Sol 6550's and found them to have a better bass responce than most tubes. If looking to go with another brand check the SED Winged "C" 6550's. Or possibly find a quad of GE 6550's. I also like both of these.

PS..I got your PM and responded.

[bikerboy]

I have been using SED winged C 6550 tubes in the jolida 502 I use and like them better than the stock tubes it came with. I will try a set of the reissue gold lion kt-88 next. I've read lots of good things about them. Nickolas really likes them. Reliablility of 6550 tubes seems to be a problem in general. The Shuguang KT88 is said to be very reliable, at least my local tube amp repair guy thinks so. He repairs guitar amps for the most part. As far as NOS I have only used preamp types and they have been very hit or miss. Let us know what you go with and what you think of them.