No returns, exchanges or refunds. Buy at your own risk.
We bought these highly desirable tubes about 15 years ago in pristine condition. However, all of these test below reject range on a tube tester. That does not mean the tubes are dead. These still play fine.
So for the price of 3 cups of coffee you can savor the fine sound of 1950s Holland production tubes.
MINT NOS 1957-58 Amperex/Philips ECC82 Long Plate tubes with D-Foil Getter. Heerlen Holland Production Date Code k63 revision and 47L or 48A (first letter 4xx 4=delta or left triangle for Heerlen Plant). One of the most musical and desirable tubes in the 12AU7/ECC82 family.
*Heerlen plant tubes were sold with different labels like Amperex, Miniwatt, Philips, Bugle Boy and also relabeled by various Philips associates or companies owned by Philips like Valvo, Mullard, La Radiotechnique RTC, Siemens, Adzam etc. Etched date codes tells the origin of the tube.
However, all of these test below reject range on a tube tester. That does not mean the tubes are dead. These still play fine.
Here are some points to consider:
- Even high testing NOS tubes can go south at random. MTBF for NOS tubes cannot be predicted on the test scores alone. These are complex devices with hand/machine assembled mechanical components with coated materials and chemical processes involved in the production.
- Too many factors can cause early demise or defects. Special materials, quality and purity of materials and a whole lot of electro-mechanical factors come into play.
- So called typical new value in mmhos for 12AU7 is a number given by RCA in design books. A typical brand new batch of 12AU7 from the same date/lot can vary anywhere from 25-35% from that arbitrary number.
- A typical NOS Tesla ECC802S, which is a premium ECC82 tube tests 30-35% below the RCA spec. That does not mean these tubes will sound bad or dull or last fewer number of hours.
How a tube decays depends a lot on the materials, quality/purity of materials and the manufacturing processes. Cathode poisoning, leakage, mechanical integirty etc etc are factors that can make a brand new tube go kaput.
Tubes tend to decade in chunks. They donít die until they do.
There is a good chance that these low testing tubes will sound better and last longer than some of the other NOS tubes you have.
Since there are not many early European desirable tubes around, these can be a great introduction to the classic 1950s Philips sound.Single Tube = $15.