I would refer to Pieter Snayer's painting of the Battle of White Mountain (images
from it are here), at which (I think?) he was personally present. Bavarians seem to be wearing Spanish style tabard cassacks (some dark blue), while officers wear buff coats with dark blue (almost sea blue) sashes. This
specific picture is supposed to Bavarian and Imperial Reinforcements fighting at the Battle of White Mountain. There is also a closeup video animation of part of the painting here
. However the balagan wargaming website says Imperialists and Bavarians at the battle wore white sashes. It says that the Imperialist and Bavarian sashes
were white until 1631, when they changed to red, which makes me wonder a bit about whether Snayer was at the battle.