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Is she closing permanently?

It seems to me that Mullard made the EZ81 for many different brands - is it possible that you can identify them by looking for the lines/creases on the top of the glass?

Do you think that godkänd 83/03 means that it was retested then and found fully functional?

The code on the glass in black at the bottom of the tube I think indicates Blackburn/Mullard - maybe March 1966.

I my old amp I always found the older Hungarian made Tungsram EL3N to sound dull and unpleasant. However, I found the small Tungsram signal tubes to sound very good.

There are Telefunken straight glass EL3N tubes out there but I haven’t heard them - always wondered how they sound. It also seems to me that there also exists Telefunken EL3N ST type tubes.

In my old amp i felt that the 6F8G sounded better than the 6C8G but that was in general - don’t have a TS 6C8G to compare with. However, always trust YOUR ears. My ears are 10% older than yours but I still trust them. The tube prices have climbed through the skies for popular tubes - the trick...

Some people think that the NU 6F8G is the best sounding of that type, but YMMV depending on amp and synergy with other tubes. Many of these tubes were rebranded and if you learn how to tell which manufacturer it is, you could find better prices. I have a NU labeled PHILCO and a TS labeled...

Those tubes were manufactured during the height of communism. If you did not produce a great product there were severe consequences… Did anyone figure out the purpose of the bulging glass?

Yes, you are right - you could use a single 6SN7 dual triode as a driver. As you point out, you would have to make the adapter yourself since nothing is available commercially.

Ask Eric what he thinks of an amp using 6528/6336 tubes with 12AV7?

With all due respect, RaynFox asked about the compatibility of 6SN7 as driver tubes - IMHO it will not work. As power tubes the 6SN7 work fine with adapters. '74 TVR 2500

As I recall you cannot use 6SN7 tubes as drivers in the Little Dot MKIII because they draw 0.6A each and the combined 1.2A exceeds the allowable current draw for drivers in the LD MKIII.

The budget champion of these tubes is the Shuguang 6C8P and surprisingly it is very good sounding and can easily hold its own against the famous names. Around $5 each on AliExpress including shipping.