This month I am presenting a 9 pin miniature (Noval) medium mu twin triode. Meet the ECC88:
The ECC88 is one of the more popular tubes among tube amplifier manufacturers and has seen some widespread use. For example some Audio Research preamplifiers use this tube.Telefunken data sheet. I never really used the ECC88 much in any of my own projects. For my applications the amplification factor was a bit too low or the plate resistance somewhat too high. Or the available output voltage would not provide the headroom I wanted. But that doesn't make it a bad tube. In contrary, if the parameters fit the application I would not hesitate to use it. The ECC88 was made by all the major European manufacturers and also came in industrial or rugged flavours with enhanced life time, tighter parameters and other improvements. These were called E88CC or CCa. The American equivalent was the 6DJ8 which had an industrial variant as well, called 6922.
As always we start with a look at the plate curves. Datasheet curves above and measurement of an actual tube below.
A very linear tube, which explains the popularity.
Since I never really used the ECC88 I did not accumulate a large stock of them. Above is all I have.
Starting with what is probably the most sought after version, the Telefunken E88CC with embossed diamond logo in the base.
Made at the famous Telefunken factory in Ulm.