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Quality

The foundation of Eurotubes is our quality control. All of our tubes start with a 24hr factory burn-in along with every bit of available factory testing, of which we pay extra for… Once the tubes have landed at our facility our in-house testing process begins. This starts with a visual hand inspection of every single tube. Trained eyes look for glass anomalies, coating inconsistencies, pin straightness, etc. After that the testing process is unique to the tube type.

Power tubes are tested and graded at high voltage real world operating points. All of our power tubes are matched into quads by hand in real time. Not spec’d and grouped at a later date. This allows us to see exactly how all four tubes in the set function side-by-side. The tubes are checked for their static match and then swept from their turn-on “knee” right up to max dissipation. If the match is good at all operating points, a noise and leakage test is performed before the tubes are declared saleable. This process often takes many power/heat cycles, which helps ensure that the tube is robust and there’s no glass stress/annealing issues.

Preamp tubes are tested in three unique test fixtures. The first test fixture is our custom built noise analyzer. This setup runs each tube near it’s book-spec test values and then allows us to see the tubes natural noise floor as well as it’s microphonic response. If the tube passes our stringent protocol it moves on to the next test which is a pass through one of our Amplitrex AT1000’s, or a custom built ROE tester. Either way the tube is run at it’s book spec test values and is screened for both static and dynamic characteristics, as well as grid leakage and HK leakage. The third and final test is a run through our custom gain tester. This is a specialized setup that runs both sections of the tube simultaneously under constant current conditions while a small signal is applied to the control grid. The output swing is recorded and the real world gain is calculated. Think of this as a dyno for your tubes, a completely real world functional test.

Rectifier tubes are also tested. They’re screened for forward/reverse voltages, leakage, and peak current handling (hot-switch and inrush current).

For more specifics on tube testing please see our FAQ and blog posts.

Why People Choose Us

Guaranteed Testing

Every single tube we sell is tested and inspected, by hand, one at a time at our facility in Milwaukie Oregon. This is done with state-of-the-art equipment by knowledgeable and passionate individuals.

Six Month Warranty

All of our vacuum tubes are backed by a minimum six-month warranty. We stand behind what we sell. Our goal is to work with you, never against you.

Customer Support

Whether its basic questions about a Fender Blues Junior or a Mesa Triple-Rec, a Dynaco ST70 or a McIntosh MC275, we have the experience to guide you. In a pickle? Burning through tubes? Problems with noise? Give us a buzz.

Reviews

From: Conrad Engineering 
Sent: Friday, June 22, 2012 5:30 PM
To: Eurotubes Support

Hello all Eurotube members of the Tube Hall of Fame :)

I purchased a Blues Jammer amp from a fellow who purchased it from one of my customers. When the amp came in I put the amp on the Oscope and I've never seen such a terrible wave form. The amp had been violated with a weird assortment of tubes namely 2-GE 12AX7's, Jan Phillips 12AT7WC, Sovtek 12AX7LPS, 2- Tung-Sol 5881, JJ 5AR4.

I First replaced all the preamp tubes. Much better but still had a weird wave form. Replaced the 5881's with JJ 6L6GC's – Yea, perfect. Improved performance and output swing. The only tube kept was the JJ 5AR4.

JJ all the way, baby!

- Conrad Sundholm Conrad Engineering, LLC