 For pentodes, it is higher, about (5-7)/"g"m. Tubes with high "g"m thus tend to have lower noise at high frequencies.For example, it is 300 Ω for one half of the ECC88, 250 Ω for an E188CC (both have "g"m = 12.5 mA/V) and as low as 65 Ω for a tride-connected D3a ("g"m = 40 mA/V).In the audio frequency range (below 1–100 kHz), "1/"f"" noise becomes dominant, which rises like 1/"f".