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I'm wondering if there is any particular point in using the low cut filter on my Sony PCM-M10; AFAICT it is purely a digital filter applied to the signal as it is recorded, and as such I should loose nothing doing this in post on the computer. Am I missing anything?

I never use low-cut. Better recovery afterwards.

In 99% of all cases I don't use the lowcut filter. But what I do often is to listen to the signal with the lowcut switched on in order to judge the sound without the low rumble you often get in urban areas

You can use later software EQ instead, at lower range, like 55-65Hz.

Thanks all. It did occur to me that the one tangible benefit would be in listening at the time of capture (and of course potentially less faffing later) but it seems technically better to do it later, with settings of course depending on the particular signal.

Depends where in the process the filter is applied. There are situations where low frequencies do negatively affect the recorded sound (effectively it takes away several dB of your dynamics). If the filter is applied between the mic and the recorder, chances are in these situations you will get a much better result than if you'd apply a low cut filter in post production.
If the filtering is done after the AD conversion, it's in some cases probably too late.

nemoDaedalus
Depends where in the process the filter is applied. There are situations where low frequencies do negatively affect the recorded sound (effectively it takes away several dB of your dynamics). If the filter is applied between the mic and the recorder, chances are in these situations you will get a much better result than if you'd apply a low cut filter in post production.
If the filtering is done after the AD conversion, it's in some cases probably too late.

Indeed, I was wondering about this in the context of my particular device, which is what prompted me to post. The manual doesn't explicitly say, but I saw a few things on Google say in passing that it is a digital filter, which seems quite likely. If it was analogue hardware I'd be more inclined to use it, otherwise I'd rather just have the device sample the raw data since as you say, if the signal is overloaded at the AD stage then such a filter can't help.

Maybe you can test it, if it has line in. Play a low frequency sound (maybe 20Hz sine, possibly lower) through your pc out into the recorder. See what effect the low cut has. If it's capable of getting rid of it, you can set it up so that the low freq sound is quite loud w/o low cut. Layer up some other sound with it. Play that. If w/o filter you hear the other sound clipping (which you could expect), turn on the filter. Is the sound still clipped, then the filter is too late. Otherwise, it's probably good.
I know there exist external low cut filters, I've used them with Schoeps M/S recording at the Filmschool. They're just a small XLR device (same size as male/male or female/female XLR connectors), hardly take up any space, and are placed inbetween mic amp and mixer/recorder. Don't know where to get them or at what price they come though. Simple stuff is usually expensive

You're right, I could test it. Having gone as far as discussing it here etc, I may as well really. Will do... if I get 'round to it.

I think we can guess the outcome.

Currently my recordings are either with the built in mics on the device (which are both better than any other mics I own and also obviously very convenient), or contact mics / hydrophones / binaurals connected by mini-jack. Of those, it seems like it would only really be the binaurals that might benefit much from an external filter. I might supplement my kit with something a bit more directed at some point.

Anyway, it doesn't bother me too much, I'd always assumed that the filter on the device wouldn't be of particular use, but thought about it as someone in a talk I went to mentioned in passing using the equivalent feature on their Edirol. In a sense I'm quite happy to do in post, although it is nice to feel that you've got as close as possible to the recording you want without needing any processing.