Restoration of Golden Age audio amplifiers

[sser2]

Here is comparison of 2E24 and 7408 characteristics:
S, ma/V 3.5..........3.7
mu g1-g2 6.5..........6.0
Rl SE, k. 5.5.........5.0
Pa max, W. 12...........12
Pg2 max, W. 2.5..........2.0
Ua max, V 500..........315
Ug2 max, V 200 ...........315
Heater 6.3V 0.45A...........6.3V 0.8A
Bias for A1, V -14............-12.5
As one can see, these two tubes have close characteristics. The most significant difference is lower maximum screen voltage of 2E24. That means the screen supply should be modified. Output tube sockets should be re-wired too. Otherwise, it is a drop-in replacement.

 

[huggygood]

Thanks for the comparison data.
an opinion about the 2E22 that I have in stock?

 

[Zung]

... As one can see, these two tubes have close characteristics...

More importantly, if you look at the plate characteristics of the 7408, page 2, you can see the typical "kinks" in the low voltage and current region. The 2E24 has none.
Btw, the forum software now supports tables: the right most icon, near the center.

 

[sser2]

Unfortunately, I have no experience with 2E22.