What Questions about the tubes we sell.
What is your minimum order?
Minimum order is $5 excluding shipping.
What does NOS mean?
NOS means "new old stock." Old stock that is in new condition.
What does "like new" mean?
"Like new" means the tube has been used low hours, but still tests like a NOS tube. The "like new" tube might also have some scratches on the base, glass, or poor printing on the base or glass.
What is a "Kuhl-Tube"?
Pronounced (kool-toob). Tube World's cryogenic process takes select vacuum tubes and deep-chill anneals them in liquid nitrohen (LN2) for 36 hours at -193° Celcius / -320° Fahrenheit in our own cryogenic chamber, producing a superior sounding vacuum tube called a "Kuhl-Tube". Kuhl-Tube is a trademark of Tube World, Inc.
Am I going to receive the tube in the photo?
Yes, the tube (or other product) in the photo of the item you buy is the exact item you will receive. We take our own photos of the products before we list them.
If you see one (1) tube in the picture, you are purchasing one (1) tube. If you see two (2) tubes in the picture you are purchasing two (2) tubes, etc.
Where do you buy your tubes?
From hundreds of sources, all over the world.
Questions about shipping.
How do you pack and ship the tubes?
We package your tubes very carefully. We're proud to tell you that we have had very few instances of damage during shipping over the past 18 years. We ship primarily by USPS Priority Express mail, USPS Priority mail or USPS airmail. USPS Priority Express mail and USPS Priority mail shipments can be tracked at usps.com. Airmail shipments do not have a tracking number and therefore cannot be tracked at usps.com. Priority Mail Express is typically a 1-2 days faster service than Priority Mail. Airmail is the slowest option, typically 2 weeks. We recommend shipping orders over $200 by USPS Priority Mail Express or USPS Priority Mail. FedEx is also a shipping option. FedEx shipments have a tracking number and is the most expensive option, but also can be the fastest option and most reliable option. Delivery speeds will vary depending on the country you live in. This can be for a variety of reasons, but primarily because of customs delays. Packages can be held in customs for longer periods of time in some countries versus others.
When will my order be shipped?
Your order will be shipped typically within 24-48 hours after the receipt of your order. You will be notified by email on the receipt of you order and if any changes need to be made to your order. You also will be notified by email when your order ships.
Questions about tube testing.
Have you tested the tubes?
Unless stated otherwise, all tubes listed are tested.
How do you test the tubes?
We test tubes on one or more of the following pieces of test equipment:
- Amplitrex AT1000 Digital Tube Tester
- SOFIA plate curve tracer made by Audiomatica (tests for plate curve linearity and output (Iplate), will reveal gassy tubes)
- MaxiMatcher (power tube matching: Iplate and Gm)
- MaxiPreamp (preamp tube matching: Gm, Mu and noise testing)
- Space Tech Labs Canada custom headphone preamp (preamp tube noise and microphonic testing)
- VTV Dual Triode Characterizer: test for AC and DC section balance on 12AX7, 6922, 7308, 6SN7, 6SL7, 6FQ7, 5751, etc. test for noise and
- TV-7D/U military tube tester
- TV-10 military tube tester
Tubes are tested for:
- Audio power tubes are tested for: good idle current, linear and evenly spaced plate curve traces, transconductance (Gm) within specifications, gas, shorts, leakages, and instabilities
- Preamp tubes are tested for; (Gm) Transconductance, shorts, gas, leakages and manufacturers defects.