e-ac3 to ac3 lfe problem

[Wile_E_Coyote]

Hi everyone. I've tried searching, but as you can imagine, there are lots of hits for the codecs.
I've been using ffmpeg for years, most recently for e-ac3 to ac3 in .mkv files.

ffmpeg.exe -analyzeduration 100M -probesize 100M -i Surround.ac3 -acodec ac3 -ab 640k AC3.ac3

being the simplified command line.

In general, there isn't a problem, but occasionally, I’ll get horrible noises from my sub during a bass heavy section of the file, which I’m assuming is linked to the way the .1 LFE channel is being handled in the conversion?
My AV receiver has been set up for the 6 channels using the in-built software, so as I say, normally everything is great, but short of diving for the off switch on my sub, I’m looking to see if there’s a better way of doing the transcoding as I’ve seen it mentioned that e-ac3 has embedded stuff that doesn’t come over.
I upgraded my AVR and (Panasonic) Blu-ray player last year, but the player throws an error saying it doesn’t support e-ac3, hence the need for the change to ac3. I’ve thought about an additional media player (I’ve got an old, cheap Android TV box), but the Zidoo and Dune ones that look like they do some of what I want, are pricey.
Any help would be appreciated.

[microchip8]

Can you explain more what kind of noises you hear? Also, what is your AVR maker/model? And how are you playing these files? Streaming or?

I have a Denon AVR and a Zidoo streamer and a Klipsch subwoofer. My collection contains 100+ movies that have E-AC-3 audio encoded by ffmpeg and I have never heard any strange things from my sub. Are you sure your sub isn't defective somehow?

[tebasuna51]

Upload a sample (source eac3 and wrong ac3 output).