You’ll see great reviews for the Electro-Harmonix 12AU7 all over the web, but my experience tells a different story. While it’s certainly not a “bad” sounding tube, we have to ask ourselves: when we’re investing huge amounts of money into high-end tube equipment, is “good enough” actually enough? I don’t believe so. To be honest, I didn’t care much for this tube at all; it feels boring and leans far too close to a solid-state (SS) sound profile.
While it does offer a larger soundstage than most solid-state amps, the transparency and imaging simply cannot compete with the top-tier 12AU7 options. The high frequencies roll off much too early and carry a distracting metallic tone. On a positive note, the construction is excellent—reminiscent of Sylvania Gray Pinched Plates with old-style micas. I actually prefer the build quality of EH over ShuGuang, as there is clearly a lot of care put into the internal structure.
While it wouldn’t be fair to compare a $10–$12 tube to legends such as Telefunken, Amperex, or Mullard, the price point isn’t the primary issue. The real problem is that even an RCA Cleartop or a standard 5814 will outperform this tube in every category—including reliability—despite costing half as much in some cases.
Final Verdict: Despite the solid build quality, the lackluster performance and rolled-off highs make this a “pass.” I would not recommend it when better, cheaper vintage alternatives are readily available.
Wow. Great reviews of the tubes, but mostly from stores. See our reviews…
So this is where my tube rolling started. I bought a Cary Audio SLP-03 Pre-amp that had 4-EH 12AU7’s in it. The rest of the reference system includes a Chord DAC, Krell Evolution Amplifier, B&W Diamond Speakers, and pure silver solid core wiring throughout.
At the time I had no idea I could swap out tubes.
Initially the set-up had loads of grip, plenty of definition and detail, adequate soundstage between the speakers, and enough “umph” to keep me and others thoroughly impressed.
Then I started to tube roll. The first matched quad to arrive were the Sylvania JAN-CHS 12AU7’s at $20/tube. This is when I realized my high’s were “rolled off”, I had no extension, and the system was very “solid state” sounding. I was missing tube magic, but had the ultimate Pre-Amp to showcase the uniqueness of new tube to come….
Electro-Harmonix 12AU7 – 3 Stars