please help to clarify the coding

[FYC]

Sorry may be I am asking something well understood already.

Nevertheless, I am preparing to build a PLH amp. Reading the schematics, I found the resistor value a bit confusing.

I see both 220 and 221. My first interpretation is that the last digit refer to the number of zeros, so "220" = 22 ohms, and "221" = 220 ohms. But this will make the code "392" equal to 3900 ohms, which I expect it be a 392 ohm if I want to set the bias of the phase splitter current to the correct value.

So apparently the last digit does not carry any special meaning but "220" IS 220 ohms while "221" IS 221 ohms. But then why not standardize to 220 ohms?

Please help me to understand this and forgive me if this issue was well explained before.

[medum]

Originally posted by FYC

So apparently the last digit does not carry any special meaning but "220" IS 220 ohms while "221" IS 221 ohms. But then why not standardize to 220 ohms?

220 ohm are standard in normal 5% resistors
221 ohm are standard in 1% resistors

try to google "resistors E24" and "resistors E96"
numbers refer to steps between values.

[FYC]

Thanks for quick and clear answer.