tctubes.com testing service

I wanted to recommend tctubes.com if you need tubes tested and matched. I recently won an auction on eBay for a dozen Tung Sol 1626 tubes from seller cooltubes. They were sold as NOS but were shipped in white boxes so I suspected they were used and sent off to tctubes for testing. You probably only need his standard testing service.

I opted for premium tests and here is an example of results from one tube:





Out of the twelve tubes I won at auction all tested as used. One was dead. Four were 90% of rated Gm. Five tubes tested between 80% to 90% so I was able to get several good matched pairs that should have some decent life left. Two were 70%. Tung Sol 1626 are almost impossible to find so you have to take what you can get at this point.

Link on how to interpret AT1000 test results. Tyler explains how sellers can use auto bias mode to produce test results that look better than they really are. Video of AT1000 in use:



I was using true NOS closely matched wartime RCA 1626 tubes in my Kenzie and even the used Tung Sol sound noticeably better. I am able to hear fine details I was missing, imaging and sound stage is improved and vocals are the most natural I have heard on my system. There is a reason Tung Sol 1626's are so hard to find

Maybe one of the experts here could explain why the Tung Sol's always sound better that the alternative 1626's. I am just enjoying listening more now as I have been without Tung Sol's for about 6 months since the last pair I had went bad.

 

How much for the service?
Could be useful for those with really expensive tubes.

 

Standard test -- $3.00 per tube ($40 minimum order)

Standard tube testing service includes the following:

• current draw (mA)†
• transconductance (Gm)†
• gas current (mA)
• noise/microphonics
• screening for shorts and leakage

† Not available for rectifier tubes.

Premium test -- $10 per tube ($40 minimum order)

• AT1000 data sheet
• characteristic curves

See this link for more info. Tyler uses a $3000 Amplitrex AT1000 tube tester. Testing takes about two weeks he stays busy. Great communication and tubes were packed very well on return. Will use his service again for sure and he also stocks some interesting tubes, all tested before sale.

 

Great info - thanks!

 

That is a reasonable fee considering the time involved. @allegro I have an old TV-7A (1955) but am pretty limited on tests. Mutual conductance, shorts, and gas. Thanks the link sharing his system protocol.