Here are some other Sylvanias I have used and liked as much as the metal base and are a little cheaper. The 1952 tall bottle ("bad Boys") and the 6sn7W tall bottles. Which are pretty much the same as the metal base only plastic base. You can get some general info one the 6sn7s at www.tubeseller.com
Also if you do a search on www.head-fi.org there is a huge thread on the 6sn7 tubes. Type in.... The reference 6sn7 thread...lots of good info.
Also if you do a search on www.head-fi.org there is a huge thread on the 6sn7 tubes. Type in.... The reference 6sn7 thread...lots of good info.