Question from a customer…….
We found the EL84X from testing/measuring/auditioning tubes – as our passion is vinyl, SET and full-range speakers. Just like how we came across the GE5670 premium family compared to the generic family of 6922s.
The EL84X is an almost equivalent to the EL84, mainly with higher ratings and with a somewhat better sound quality (at least in the Stereo 50 :atsmile:), compared to other current production EL84 tubes.
The sonic qualities of this particular brand/model of tube is down to the electrical parameters…for example, the peak cathode emission is higher than standard EL84, so higher peak current can be sustained. There are many other small aspects that make it in our book better than the rest.
In some EL84 amplifiers it can be just dropped in without changes, in some it does not. The Stereo 50 was designed to allow either tube (but please wait until the warranty has expired before rolling tubes).
For obvious reasons we scour the markets for tubes that are available in large quantities that offer good sound quality. This how we found this one. It is a military tube, not advertised or specified for audio use.
In practice it makes a swell “super EL84”, hence the EL84X moniker
For obvious reasons we prefer not to disclose the precise Tube number. Replacements are available from iFi and will be so for a long time, generic EL84s are fully-compatible with the Stereo 50 and who knows, sooner or later some factory may very well make an EL84 that sounds better than our EL84X.