For sale NOS EZ81 Tungsram tubes.
Both tubes are in very nice condition, as you can see in the photos.
The tubes were tested for each section on Ua:230VAC, through a load resistor, where the maximum Ia: 75/75mA (100%).
See measured values on the tubes!
Both tubes are perfectly strong and balanced.
The price is for one tube!
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About the testing
Most of my tubes are tested, but always pay attention to the description in the listing!
Vacuum tubes can be tested for a variety of attributes, but they are very rarely tested for everything. I usually test for the attributes I find most important with the specific tube.
I take responsibility for these measurements, but not for other attributes that I have not tested!
Also keep in mind that when measuring vacuum tubes with different test equipment there will always be differences in the results. However, these differences shall not be significant (usually within 15%), and when done right, won't show a bad tube as good, or a barely good tube as very strong.
If you are not sure what you need or how to choose, message me and I will try to help you make a decision that fits your needs.
Tests I do:
- Ia / emission test - is the most common test, which shows how strong is a tubes' plate current according to nominal catalog data. The tests are usually done on a standard operating point, and these values will be shown on a tag or in the description.
Usually above 80-90% of nominal we say it is Strong (or NOS), and above 60% it is still Good.
- S / transconductance test / or GM - is the second important attribute of a tube indicated as mA/V. These tests are carried out at the nominal plate current and will also be indicated on the test tags.
- Noise test - is made where it is indicated in the description. It means the tube has been tested for weird noises or microphony while playing music.
It will be shown on the test tag as a 
mark.
mark.Keep in mind that noise test does not guarantee any sound quality, which is always the product of a specific tube type, brand, Ia and S attributes, and the amplifier as a system. Noise test means that in a simple audio circuit the tube did 't make any disturbing noises, hum, and was not microphonic even when gently tapped.
(In an audio system many parts, or the setup can couse weird noises, but it is not necessarily coused by the tube, but by certain interferences.)
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Shipping
The tubes will arrive to you in a well protected package and will be shipped within two business days from payment.
The package will be sent with priority and a tracking number will be provided.
If you find other tubes in my inventory, I will gladly combine shipping, and the cost will stay as listed under 0.5 kg total .
For a package that exceeds this weight, we shall discuss the shipping costs.
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About me
I am a private seller located in the EU. I buy and sell vacuum tubes.
I'm dedicated to reserving this beautiful technology, and for that purpose I select, test and rate my tubes.
I build my own testers, work with them daily, and I know how they operate. I am also a test enthusiast who likes to learn more about tubes and tube testing.
I am dedicated to sell tubes as described, and believe these tubes will perform as they should be according to the description.