Need advice on Unico 12AU7 tube rolling

I like the sound of Brimar 13D5 tubes in my Unico. They are a 12AU7 type tube and are NOS, which stands for New Old Stock. You can find them on ebay, but a more reliable source might be Tubemonger.

As noted by another poster, "NOS" stands for "New Old Stock." These are tubes manufactured years ago by well regarded companies, many who are no longer in the tube business. Some people regard these old tubes as superior. In fact, there is a dirty little secret in that some dishonest people are actually relabeling modern tubes with old labels such as GE, Mullard, Telefunken and so on. Buy NOS tubes only from a reliable source.

(Tubes have zero deterioration in storage as long as they are not physically damaged. A 50 year old tube that has never been used is as good as the day it was made.)

Many well known manufacturers of tube got out of the business years ago and almost all modern tubes are now made in Russia, China, Slovakia and the Czech Republic. There are a very few American made tubes but they tend to be specialty, broadcast or military items.

I also own this cd player. If you want detail and clarity I highly recommend Radiotechnique and RFT tubes. In terms of transparency and detail I haven't found a better tube than the Radiotechnique in my system. It may sound a little lean in your system though depending on your other components. If you want a little more body to the sound with most of the transparency of the RT & RFT then try a pair of Amperex Bugle Boys. Have fun, this player is very responsive to tube rolling.

Thanks a lot for all your nice inputs. This motivates me to do some tube rolling. Will try Radiotechnique, RFT, Amperex Bugle Boys, Brimar or Telefunken after doing some more reading. Good to know that the player responds to tube changes.

Also are there any recommendations for more authentic and popular tube sources which are reliable ?

Thanks in advance

2 Tube retailers that come to mind are Tube World.com and Upscale audio.Both are well established and reliable.Welcome to tubes.You are gonna have a lotta fun!!