Nice example of a CBS-Hytron true 7025 made in 1959, two years before the great CBS tube manufacturing experiment ended, sadly.
This example has retained almost all of its white ink. Gm, Gain, and Noise are balanced across the triodes, and noise and microphonic profiles are especially good.
I’ve tested lots of the CBS 7025’s, and I’m still not sure on the signal tubes what the white and red inks were designated for, as it’s unrelated to the timeline of the company.
I’ve tested 58’s in red ink, 59’s and 60’s in white, and 61’s in red again. The only difference I’ve noticed is the gauge of the getter horseshoe being slightly thicker in one over the other. The red labels are almost uniformly higher in Gm. Very high, but higher in noise. The white labels, in my experience, have always been lower in Gm, high in Gain, and very low in noise and microphonics.
Both are wonderful sounding tubes, fed signal, but there is a marked difference in the two CBS 7025’s that is simply something I notice every time I test one of these. And I’ve only noticed it in the 7025’s.
Are you bored yet? All apologies. This is why it takes me so long to post tubes. Too many words.
TV-7 and MaxiPreamp bench test results can be found on the box in the last photo. Full voltage V1 test was played through a 6G10 Harvard with resulting in the CBS having “well behaved character” written on its report card.
