Tung-Sol Matched Pair (2) 6550 Beam Power Pentode AT1000 TESTED Vacuum Tubes 3-hole 3 getters premium 1963-1970

This listing is for a Matched (10% in plate current) Pair (2) of Tung-Sol-made 6550 Beam Power Pentode vacuum tubes in the ST (Coke bottle) tube shape. They have a nickel collar around brown micanol octal base, smooth grey plate, and 3 halo getter.

7% match in plate current. RCA labeled tube is also made by T-S.

These tubes have been selected to match one another for optimal performance! Matching is based on plate current for power tubes, voltage drop for rectifiers, and transconductance (Gm) for other tubes.

Your tubes have been fully tested on a computer-regulated, USA-made Amplitrex AT1000 on Fixed Bias setting with used good results. They have also passed shorts and gas tests. The tubes might have mechanical wear or have the label rubbed off - these are very old! Tubes that test like new (tNOS) are available in a separate listing. Every tNOS or Used Good tube you receive from Sound By Doc is guaranteed against failure for 60 days after purchase, an industry extreme!

These photos are not stock photos. You are looking at the actual tubes you will receive. If a box or boxes are in the photos, you will get them. If test results appear in the photos, look close, because those are the test results of the tubes you will receive! SKU 6L6-6550-322ump. Please note that matching is nearly always possible for us from stock that is inventoried but not yet listed. If you need a matched pair or quad etc., please use the make-an-offer feature through Reverb. Matching requires an extra burst of effort, so please add $5 per tube to your offer for 10% matching and $10 per tube for 4% matching. [Matching is based on plate current for power tubes, voltage drop for rectifiers, and GM for all other tubes. If you also require the label or internals to match, please specify that in your offer.]