U67 Build

[abbey road d enfer]

I have, possibly a rookie question... I'm looking at the 67 builds and they're asking for 400meg resistors, I've gotten everything else I need but am i dumb here? I've done a couple other builds but cant seem to find these values...

400Meg was a standard value before ISO introduced the E series (E6, E12...E96).
Anyway, you should know that this value was chosen conservatively by the designers.
Actually, the circuit may perform better with a 1G resistor, or not.
What prevents increasing the value is the fact that bias goes all over the place, particularly as the tube develops gas.
Designers had to choose a value high enough to provide good performance, aprticularly noise performance, and maintain proper bias all along the tube's life or replacements.
The 400Meg value may have been perfect for period tubes but newer tubes may withstand (or need) a different value.

 

[Khron]

400Meg was a standard value before ISO introduced the E series (E6, E12...E96).

... And back in that day, you might've been lucky to get 10% tolerance parts, unless you were military..?

If you can find any, 390meg would be the closest standard one nowadays. 470meg should be even more easy to find (TE Connectivity RGP0207 series), and less than 20% away from the "nominal".