Steen wrote:

Hi - I recently got an old (68-69) Teisco guitaramp.
Works great but I like to be prepared and have a set of
spare output tubes.

The amp has two 6L6 RCA tubes.

Are they labelled 6L6 only? Look on the tubes themselves - not on the
chassis.

If they are indeed RCA 6L6 tubes they are black metal tubes.

6L6 tubes can be replaced by any type of 6L6 tubes you can get. The
Russian 6L6GB equivalent (sometimes called 6L6GT) should work well, as
will the 6L6GC tubes from Sovtek, Svetlana or JJ. Have a look at
http://triodeel.com/ for good service and prices.

Best regards,

Mikkel C. Simonsen