You are here

Vacuum Tubes - Frequently Asked Questions

The getter flash on my tube looks unusual. Does that mean it’s bad?

If the getter flash has a milky white color, then it means air has leaked in and the tube is bad. Other discolorations are usually just due to differing speeds and temperatures at which the flashing was done and do not mean the tube is bad.

My tube has an unusual glow. Does that mean it’s bad?

A blue glow on the surface of the glass, mica, or metal is fine. A blue or violet cloud within the tube structure is bad.

An orange glow from the filament or cathode in the middle of the tube is normal and can vary from very bright to very dim depending on how it is covered from view by the surrounding structures. A red or orange glow on the surface of the plate is bad and is referred to as “red-plating.” This is caused by setting the bias of the tube too hot.

Can you match new-old-stock vacuum tubes?

We can match new-old-stock vacuum tubes if we have ample supply. If you request matching and we are unable to do so, we will contact you.

How do you match your power tubes?

We match current production power tubes based on plate current and transconductance and consider them matched if they are within 2% of one another. We charge an additional $1.25 per tube for matching.

Due to the difficulty of finding NOS tubes that match brand and ratings, NOS tube matching is $2.50 per tube. They are matched for transconductance and, if possible, we also match them for plate current.

Do you match tubes like the 12AX7?

We do not match dual triodes or other such preamp tubes, nor do we test for microphonics. We can match power tubes. If requested, there is a per-tube fee for matching.

Where do you find your new-old-stock vacuum tubes?

We are constantly searching for new-old-stock vacuum tubes, and they come from a variety of surplus sources. One of our sources is our customers. If you have vacuum tubes that you would like to sell us, please request a bid list from our contact page

Can I request specific brands of new-old-stock vacuum tubes?

For an additional $1.00 per vacuum tube, you can order specific brands of tubes. Please list any brand preferences in the comments section of your order. If we cannot fulfill this request, we will let you know