Audio Tubes Valves, 12AX7 ECC83 EH, JJ Tesla, Shuguang.

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Voc Rock Guitars Audio Reviews on ECC83 12AX7 Pre amp tubes.

Essentially there are only 3 major tube manufacturers remaining in the world today.  We decided to put the 3 most popular tubes manufactured by these plants to the test.  Audio tests were carried out firstly in a Rivera 100W 212 combo and then in both driver and pre-amp stages of a Leak 20/20 Hi Fi amplifier.  

Electro Harmonix (Russia).  First up is the Russian ECC83 from Electro Harmonix.  We found these tubes, on average to have the highest gain of the 3 types under test.  Clean, the tube seemed reasonably balanced with a tendency in High frequency emphasis but not brittle in any way.  In our Hi Fi amp test we noticed the cymbals and stringed instruments projected really clearly.  When overdriven in our guitar amp the tubes broke up nicely and relatively easily compared to the other tubes under test.  Driven more and the tube sang with a sweet spot around the upper mid frequencies.  Definition was good but not the best of the 3 tubes under test using severe overdrive.  These tubes produce a classic 'Marshall' sound.

JJ Tesla (Slovakia ~ Europe).  Second tube under test is the European JJ Tesla ECC83s.   This is a relatively modern design and has been recently upgraded to include a humbucking heating element.  The idea of using a anti phase spiral heater is to reduce the mains hum cross talking onto the valve plates hence giving a much quieter tube at high gain.  This tube was warmer than the Electro Harmonix.  The mid range was amongst the smoothest we have heard to date when played clean.  Driven into crunch the tube breaks up nicely.  Driven hard we found that instrument definition retention was amongst the best.  The tube did not display quite as much bass as the other tubes under test but was really refined in the mid range.  This tube would work well in taming down those harsh and brittle amplifiers offering a classic warm tone.  Fantastic clean and very quiet in overdrive and high gain settings.

Shuguang (Chinese).  Third and last tube to be tested is the Chinese 12AX7B.  These tubes have undergone many design changes over the last few years and the Chinese plant has invested heavily in new tooling and materials.  The 12AX7B is one of the latest generation tubes to come from the chinese Shuguang factory and we feel is one of the best produced by them.  Despite Chinese tubes having a bad reputation over the years we feel this latest tube is excellent.  We found that the tube was very well balanced right across the frequency spectrum with little colouration noted in any part of the frequency curve.  These tubes worked the best in our Leak 20/20 Hi Fi amplifier where a very articulate and well balanced sound stage was noted.  In our guitar amp we were surprised yet again.  Clean the tube sounded neutral and the true tone of our Strat and Gibson 355 was faithful.  Driven into crunch these valves sounded really bluesy with a massive bottom end.  At high gain the tube was not as quiet as the other two tubes tested but this did not cause problems and was only apparent at extremely high gain settings.  The overdrive was smooth and detailed producing pleasing harmonics and overtones.  We liked these tubes and was surprised at how well they actually performed. particularly clean in Hi Fi and Crunchy blues.

Well That's it from all at Voc Rock for now.  We hope you found this guide to preamp tubes helpful. If you want to browse tubes we stock please feel free to follow the link. at

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