Akarakrit Uamkruea, blogger and audio gear maker who passionate in vacuum tube, audio & music.
Producing electronics projects since high school. Seriously upgrade and modify vintage audio equipment for “Real Sound” concept.
He is a co-founder of Soundaries, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Thursday, December 30, 2021

Hard to Find Information Tube : LS7/CV1660

 I will try to measure vacuum tubes and post here frequently about tubes that hard to find information especially characteristic curve.

Hope this will help many people to discover good and reasonable price tubes on worldwide markets.

First is LS7/CV1660, Directly Heated Triode tube from England, ST shape with brown base.

Can make good sound small power amplifier or preamplifier.

Vf = 4V

If = 0.15A

Va = 150 Volts

Vg = -6 Volts

Ia = 10 Milliamperes

Mu = 12

Rp = 5,000 ohms

Gm = 2,400 Micromhos

Happy New Year 2022 to all of you.



  1. Hi and thanks for these very useful curves. The LS7 direct heated triodes are completely underrated due to the lack of information. Will make a very nice line preamp and I am currently testing these tubes, along with LP2/CV1166,on a 20K transformer. Thanks again. Fred

  2. Hi Fred,

    I'm so happy that heard what I do can be useful like I always watching your amazing blog.

    Oh I'm working with LP2/CV1166 & LS7/CV1660 too.

    Plan to post detailed characteristic curve in my blog this week ;)

    Hope it will help you too ^^