FabFilter User Forum
Pro-C 3 not catching transients like Pro-C 2 and other compressors
I'm getting some weird behavior with Pro-C 3. I am compressing a plucky arpy pattern, and no matter what settings I dial in, Pro-C 3 let's some very large spiky transients pass through. Even with .005ms attack, and 20ms lookahead. It happens on all modes.
I pulled up Pro-C 2 as a sanity check and do not get these spiky transients. Even with slower attack settings. I also don't get them on Ableton's Compressor or Glue Compressor. Not sure what's going on here.
Mark D — Mar 25, 2026
Alright I realized I was only setting the "max" lookahead, not adjusting the lookahead itself. With a high lookahead, the problem is resolved. However, I'm still confused why Pro-C 2 and other stock compressors are able to catch these transients without lookahead and with a slower attack, but Pro-C 3 requires shorter attack and lookahead.
Here's a comparison of what I'm seeing in Pro-C 2, versus Pro-C 3 no lookahead, and Pro-C 3 with 2ms lookahead.
imgur.com/a/t73TZMt
I find it intriguing how Pro-C 3 requires a more nuanced approach to handling transients compared to Pro-C 2 and other stock compressors. The need for shorter attack times and the adjustment of lookahead settings to effectively catch those spiky transients suggests that Pro-C 3 has a different algorithm or processing style. While it's great that I've resolved the issue by adjusting the lookahead, I still wonder why other compressors can manage transients effectively with slower attack settings. It raises questions about the design philosophy behind Pro-C 3 and how it interprets dynamic range compared to its predecessor. This experience highlights the importance of understanding each compressor's unique characteristics to achieve the desired sound.
web-games.io
Hi Mark,
What styles did you use in the images you posted? Is there any character mode applied? Could you please send over a screenshot so we can see if we can reproduce?
Hi Ralph
I am using the "Clean" style on both. No character mode. Thanks for helping.
Here are screenshots. As far as I can tell, I dialed in the same settings on both, except shortened the attack on C3 to a minimum- and still get those transients
imgur.com/a/jHx6Zlk
I don't think the style has much to do with it either. I typically work into MiniMeters and have a visual of the waveform, and I feel like in general, ever since I switched up to Pro C 3 I notice those spikes passing through regardless of what settings I dial in (besides a very large lookahead). This didn't happen with Pro C 2.
I'd be surprised if it was a bug but I don't know what I'm doing differently. Also, for reference, I did turn off the graphics acceleration for FabFilter plugins because I was getting occasional freezing and that resolved it. Unsure if that would have anything to do with the audio though.