Low cutoff filters?

S

Scottdvx100

Veteran
Here's an odd thing:
Roland Low Cutoff Filter values are 100, 200, 400 Hz
Tascam Dr-100 mkii Low Cutoff Filter values are 40, 80, 120 Hz
Zoom H4n Low cutoff filter values of 80 to 237Hz (11 settings)
Mackie uses 75Hz since that's low enough not to cut into male voices

20 to 140 hz seems to be the normal for higher end gear.
In theory you set the minimum level to get rid of wind noise and other low rumbles without affecting the voices.

Just seems like the Roland values are a bit out of place compared to others and don't provide the granularity required.

Any thoughts on Roland values?

Are people using low cutoff filters? If so are you using the one built in to a mic or the one on the recorder?
 
I would probably never use a low cut that is 200hz or higher. I rarely go above 100hz, but that's just me.
 
From my own experience, a low cut of 100 or lower is pretty safe in that it doesn't affect most voices (some dark male voices might, but probably not by much). There's very little reason not to use it for film since it's mainly the dialogue we are interested in, and the rest would be removed in post anyway. I generally don't want to go above 130-140 since that's where I start to hear a clearly noticable loss (mainly male), but if the wind/low rumble is very bad I wouldn't hesitate to go a bit higher if it gave a good improvement. I'd probably draw a line around 160 or maybe 180 though.

As for your last question, I always use low cut filters on a boom since it helps remove handling noises (never heard a setup yet that I didn't think needed at least a little), but rarely lavs and plants unless they sit on something that vibrates or there's much low frequency noise around. Regarding low cut on mic vs recorder/mixer, that is an interesting question that I've asked before too. The main concern is that the low cut should be analogue and preferrably be placed before the preamp in the chain. This is because low frequency content usually has a lot of energy and can overload the preamp or analogue to digital converter, making it distort. Most low cuts on low- to mid budget recorders have a digital low cut that doesn't protect from overload in any way, so I don't use them (maybe the new Fostex DC-302 is different?). This is one of the reasons I don't want to be without a proper mixer, if only for one channel. Regarding low cut on the mic, this is something that many preach as preferrable to the one on a mixer or recorder, as it can be placed before the mics own preamplification. Some claim that many don't sound very good though, so I guess it's up for everyone to judge. I know of some who use both if one isn't enough (I do too on sensitive mics like an oktava MK012).
 
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Roland tend to have more experience of music kit so that is why their frequencies are different, most of my kit has two 14db per octave cut-off's fitted at 80hz and 160hz and they seem to do the job for most dialogue or effects depending how much traffic or wind rumble there is.

The 100hz on the roland is useful but 200 and 400 are too extreme for most dialogue and effects.

All my mics have 80-100hz roll off filters and I tend to use them all the time but the ones on my P2 camera I only use for the camera mic. I only switch the mic LF filters off if I am recording music but as that may also involve removing traffic rumble I would rather record it clean with the filter on and add a little 150hz in post if I need to warm it up a bit.

Most mic LF filters and -10db pads are in circuit between the mic capsule and the mic amp within the mic so it is good to have them in circuit as it prevents any overload at the source end.
 
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The Mix Pre's are at 80 and 160. I use the 80 90% of the time and very rarely use the 160. There is not much that you won't hear the 160 cutting into so it's one of those lesser of two evils kind of things. I have a hard time thinking of a situation where I would use 200 or 400.

I don't have the inline filters for the Oktavas so most of my field mics don't have a HP filter available. not sure I would use it anyway just because it's a lot easier to change at the mixer and you can A/B the results.
 
I prefer to put the LF rolloff as early as possible in the circuit chain so it will help in avoiding overloads all the way down the line, especially in the mic head itself and the first preamp stage. So a LF cut feature on the microphone itself is preferable, as long as it doesn't introduce any artifacts of its own. I use 80-100 Hz. 200 Hz would cut the lowest formant of most male voices, and if you get up to 400 Hz, that's well into the range of "telephone sound" special effects -- nobody's voice would sound normal with that rolloff.

- Greg
 
Thanks for the responses. Open to others if people have some thoughts.
It does confirm for me that the Roland R26 has downsides. Still have to put it through sound quality tests but there's an incredible amount of handling noise if the internal mics are used for anything, even to gather room tone. Also Tascam DR-100 should easily beat it for phantom power time since Tascam has the chargeable battery pac along with optional battery plugin unit.
 
The Roland freqs are there for other instruments that dont have much information below that, not just specifically for human voice. depending on the situation I have had to cut certain instruments in a musical recording as high as 650hz to make them fit in better in a mix.
another variable there is the slope of the cut-off. most cut offs are sometimes variable as in 6db per octave or 12 or 24 , then you have different curves which behave a bit different at the cut off freq, such as Linkwist Riley or Butterworth curves.
even tho they are unusually high , they do have their purpose for some one.
 
Since I'd be mainly using it for dialogue recording with external mics these high settings don't seem to provide me much value compared to Tascam's and other devices meant for film recording.
 
I was exploring a few other recorders. Among those is the Marantz PMD661. It has low cut and high cut filters that can be turned on. Yet there are no settings for these and no where does the manual or product listing provide the hz being filtered. i would have assumed all vendors would provide these basic specs but it seems not. It seems strange the higher you go sometimes less control you have. Does anyone know what these values are?
 
Scottdvx100 said:
I was exploring a few other recorders. Among those is the Marantz PMD661. It has low cut and high cut filters that can be turned on. Yet there are no settings for these and no where does the manual or product listing provide the hz being filtered. i would have assumed all vendors would provide these basic specs but it seems not. It seems strange the higher you go sometimes less control you have. Does anyone know what these values are?
Click to expand...

Funny you should say that I was testing a marantz PMD670 I bought cheap off e-bay yesterday and noticed that it had high and low roll off available, must be to narrow the band for the radio guys but as you say no mention of the frequencies in the manual.
 
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