I got a quartet of 6B4Gs on ebay pretty cheap (less than $10 a pop). They are Sylvania JAN date coded 7452 (i.e. late 1974). I ran across this add:
http://www.boiaudioworks.com/index.php? ... a35035fd37
They state:
6B4G JAN NOS Philipps ECG $10.00
TRIODE, POWER
Wait, wait. Before you get too excited, please read the following first!
This is not a directly heated 6B4G, but a 6B4G replacement. It is pentode that is triode connected internally. The tube has the same pinout as DHT 6B4G, and works quite well as a 6B4G. Recommended for DYIers.
So is it really a 6B4G, or a tube that electrically does the same work? I wonder what it will sound like.
Insight appreciated