SonarLatentOperationNoise

SonarLatentOperationNoise is a latent operation that injects noise into the latent during sampling, using whatever custom noise chain you give it. If you've ever wanted "add a burst of colored noise at the mid-point of denoising" or "inject a bit of extra structure into the initial latent," this is the node. It's the pack's noise machinery rebuilt as a LATENT_OPERATION - a pluggable thing that slots into the pack's operation-based nodes (like SonarLatentOperationAdvanced, SonarLatentOperationFilteredNoise, or the CFG-apply nodes) rather than running standalone.

How it works

• custom_noise - the noise chain to inject. Anything the pack can generate.
• scale_to_sigma - scales the noise to the current sigma when enabled. This is the setting that makes the injection behave like the sampler's own noise: stronger early, weaker late. Leave it off and you get a flat-strength injection regardless of where you are in the schedule.
• normalize - default true, normalizes the injected noise.
• cpu_noise - default false, so noise generates on GPU by default (faster), with the pack's usual caveat that this can change seeds across GPU models.
• lazy_noise_sampler - default true. This caches the noise sampler between calls and only rebuilds it when necessary, which is a big speed win during multi-step sampling. The tooltip is admirably honest: there's no 100% reliable way for a latent operation to know when sampling starts and ends, so if the heuristic gets it wrong you get non-deterministic generations. If you notice results varying between identical runs, disable this before anything else.

Output is LATENT_OPERATION, which feeds a consumer node - commonly SonarLatentOperationAdvanced (to schedule when it runs) or one of the pack's apply-operation CFG nodes.

Why you'd use it

Stock ComfyUI gives you one noise injection point: the very start of sampling. A latent operation gives you the ability to add noise at chosen points in the schedule - the classic trick being a mid-sampling noise bump to rescue a generation that's collapsing, or adding detail-enhancing structure at low sigma. The README's FreeU-Extreme and Wavelet-CFG sections are built on this same operation machinery, so if you've seen those in the wild, you've seen this concept working.

Gotchas

The lazy_noise_sampler non-determinism warning is the one to remember - it's the author explicitly telling you "if results get weird, turn me off." And since injected noise scales with sigma when scale_to_sigma is on, a tiny factor difference in your noise chain can have outsized effects mid-schedule. Change one thing at a time.

Install

ComfyUI Manager → search "ComfyUI-sonar" → Install → restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/blepping/ComfyUI-sonar

No models, no extra deps. For pairing with this node, the author's ComfyUI-bleh pack adds more blend modes to SonarLatentOperationAdvanced, but nothing here requires it.