This is the other 12AX7 tube made by JJ and it is very different both in sound quality and construction from the previously reviewed JJ ECC83 S tube, with its’ frame-grid construction and compact, 6DJ8-style plate structure. This ECC 803 S long-plate 12AX7 variant is a recreation of one of the finest vintage 12AX7 tubes, the Czechoslovakian-made Tesla ECC803S. It is rumored that Tesla actually made many tubes which eventually were labeled, boxed, and sold as German Telefunken, and the ECC803 S is a prime example of this often-discussed practice. Setting aside our discussion of the history and provenance of the JJ ECC803 S for a moment, the review panel took several minutes to physically examine our review specimens. Like the other JJ 12AX7 variant, the ECC83 S, this tube also has a very solid, “weighty” feel which conveys a sense of quality. In the transconductance tester, the two internal sections of the JJ ECC803 S were fairly well balanced with each other in all tubes evaluated; most varied less than 10% from triode one to triode two (the 12AX7 tube is actually two individual triode tubes combined in one glass bulb).
We then installed the tubes into the test phono stage - a EAR 834P - and prepared for our listening/evaluation session by cueing up one of the most well-recorded LPs available, “Drinkin’ TNT and Smokin’ Dynamite”, the legendary performance by Buddy Guy and Junior Wells at the Montreaux Jazz Festival. Because the Rolling Stones happened to be recording in a studio located very close to this venue, their bass guitarist Bill Wyman dropped in to play for the sessions captured here and issued by Blind Pig Records. This recording is very useful for evaluating not just tubes, but audio equipment, and phono cartridges as well because it features a well-defined sense of “space”; in other words the echo and decay present when listening to a live performance in person is captured very well here, as are the audience noises and other subtle spatial cues. With the very best 1950s and early 1960s NOS-type tubes such as the Raytheon 7729 and square getter, longplate Genuine British Original Mullard ECC83 from the legendary Blackburn, Lancashire Mullard factory, it is possible to hear individual audience members shouting praise and requests from the back of the hall in between songs on this reference quality, all-vacuum tube recording. Likewise, when Junior Wells draws down deep to belt out a phrase or classic line, the listener can hear the faint echo reverberate and decay with tremendous precision. The JJ ECC 803 S longplate tube did perhaps less well than hoped at capturing the small details of this extraordinary recording. The fundamental notes were reproduced accurately and with natural timbre, but the complex harmonic swirl and 3-D imaging that are the hallmarks of a truly great 12AX7 tube were perhaps slightly lacking here.
The JJ ECC803 S was indeed successful at presenting a balanced, “tube like”, musical soundstage that had some elements of soundstaging and imaging present... but it was most certainly not the best in the areas of resolution and detail retrieval.
Strengths—Good imaging, natural sonic balance, “tubelike” presentation that hinted at the sonic performance of classic NOS 12AX7s.
Weaknesses: Less than excellent detail retrieval and only medium resolution.
Note: This review is actually from a multi-listener session of new production vacuum tubes. Notes were summarized by my good friend Chris James.