What's the point in digital level controls in portable recorders?

Ozpeter · 13th January 2009

Many or even most small location recorders these days seem to be equipped with digital level controls in addition to analog input sensitivity controls.

If you raise the digital level, you risk clipping in the digital domain. You could instead raise the digital level in post production for exactly the same result with no risk. Or if not using a DAW, just turn up the playback level at the amp of the playback system.

If you lower the digital level, you've probably done that because the analog input sensitivity is too high. So you're recording the analog clipping at a lower digital level, but it's not going to cure the problem.

So why are these controls provided? In my view, if they are provided, there should be provision in the recorder's menu system to bypass them. There should certainly be the means to set them accurately to zero gain.

Ideally it seems to me they should be done away with altogether.

Or am I missing the point?

Do they appear in upmarket devices (Nagras etc)? If so, do upmarket device users use such controls for purposes I've not envisaged?

staudio · 13th January 2009

I agree, digital trim controls are pointless and dangerous if doing live recording, but what if you are doing a simple transfer where you know what the peak level would be and want to adjust it on the destination recorder, I could see this as being potentially useful in doing digital to digital transfers, but really not a critical feature in my opinion. I like my gear simple and elegant.

loji · 14th January 2009

what about a digitally controlled analog circuit ... like the digital trim on the MOTU traveler and metric halo 2882?

Both use the onboard DSP to control the analog circuity in a very exact and repeatable manner (gain changes to 0.1)

This also has the added benfit of being able to locate the interface close to the mics (thier solid state so silent) .. and keeping the noisey computer far away yet still being able to enact level changes silently ....(try walking up to a recorder and changing a knob during a quiet passage)

remote recording meets remote control

staudio · 14th January 2009

Quote:

Originally Posted by loji

what about a digitally controlled analog circuit ... like the digital trim on the MOTU traveler and metric halo 2882?

Both use the onboard DSP to control the analog circuity in a very exact and repeatable manner (gain changes to 0.1)

This also has the added benfit of being able to locate the interface close to the mics (thier solid state so silent) .. and keeping the noisey computer far away yet still being able to enact level changes silently ....(try walking up to a recorder and changing a knob during a quiet passage)

remote recording meets remote control

I am all for digitally controlled analog, but I think the OP was referring to DSP trim control entirely within the digital domain, not digitally controlled analog.

Plush · 14th January 2009

One reason that the user (engineer?) might use the digital gain control is if he applied processing to the signal before recording it. The processing might boost the level of the program material and then it will be too loud or might peak or clip the system. Turning down the digital in solves this problem.

ghellquist · 14th January 2009

Personally I believe the reason is simply that is built-in to the chip used. Adds to feature list in ads. Useful or not, people are lured into things.

// Gunnar

just.sounds · 14th January 2009

Maybe it is because of -9dBFS standards on digibeta for television. You can use the entire range of the mic pre and AD and control the volume to the standard you want to use.
Otherwise you wont notice clipping but the video editor will!

And of course for monitor mixes internally.

Ozpeter · 14th January 2009

Quote:

One reason that the user (engineer?) might use the digital gain control is if he applied processing to the signal before recording it. The processing might boost the level of the program material and then it will be too loud or might peak or clip the system. Turning down the digital in solves this problem.

That makes sense - though recording with FX is of course not usually a good idea.

Having said that, I routinely use the R-44 MS 'effect' to record MS as XY - which the design of the R-44 requires one to do if you want to monitor in XY. It's a pity they don't provide effects on record monitoring, only allowing FX to be printed to the recording, or heard on actual later playback.

Audiop · 14th January 2009

Am I mising something here.. A digital VC work in the digital domain right? That would be after the analog signal has been digitized. If the level of the analog is to high it will clip the AD in the digitizing process hence it will be to late to adjust level in the digital domain.

I think it was mentioned in the first post of the thread:

Quote:

So you're recording the analog clipping at a lower digital level, but it's not going to cure the problem.

/Peter

Shadow_7 · 14th January 2009

I'm gonna assume analog level might be something like my DMP3 microphone preamp.

I'm gonna assume digital level might be like the mixer levels on my Delta 44 soundcard.

Under those assumptions, some analog preamps get really wacky when at their extremes. i.e. the knob goes to 11, but really only sounds good up to 9 or so. So to get a desired balance of color, noise, and distortion, you need both.

For my desktop setup, that means my DMP3 is AT it's LOWEST setting, and my Delta 44 soundcard is AT about 90% for any given input channel. For a relatively LOUD source recorded in CLOSE proximity. In my case a trombone with Avenson STO-2's at about 18" away. The advantage for me is that such a combination gives me the lowest possible noise floor from mics + preamp + AD converters on a loud source, without overpowering the soundcard or clipping.

I suppose that if I had higher end gear, or lived in a perfect world, that there would be no difference between 1 and 10 other than level. And setting 1 on the digital and 10 on the analog would be the same as 10 on the digital and 1 on the analog. But I've yet to find a device or get results like that from a device. At least when the device(s) were turned on. In my case, if I set the DMP3 at a volume > 10% on the knob, I get clipping on my soundcard at any level. And if I change mics, there's a completely different manual on what works and/or works best.

13th January 2009	#1
Ozpeter Lives for gear Joined: Oct 2008 Posts: 624 Thread Starter	What's the point in digital level controls in portable recorders? Many or even most small location recorders these days seem to be equipped with digital level controls in addition to analog input sensitivity controls. If you raise the digital level, you risk clipping in the digital domain. You could instead raise the digital level in post production for exactly the same result with no risk. Or if not using a DAW, just turn up the playback level at the amp of the playback system. If you lower the digital level, you've probably done that because the analog input sensitivity is too high. So you're recording the analog clipping at a lower digital level, but it's not going to cure the problem. So why are these controls provided? In my view, if they are provided, there should be provision in the recorder's menu system to bypass them. There should certainly be the means to set them accurately to zero gain. Ideally it seems to me they should be done away with altogether. Or am I missing the point? Do they appear in upmarket devices (Nagras etc)? If so, do upmarket device users use such controls for purposes I've not envisaged?

14th January 2009	#5
Plush Lives for gear Joined: Jul 2003 Location: EARS/Chicago Posts: 4,274 2 Reviews written	One reason that the user (engineer?) might use the digital gain control is if he applied processing to the signal before recording it. The processing might boost the level of the program material and then it will be too loud or might peak or clip the system. Turning down the digital in solves this problem. __________________ Atelier HudSonic, Chicago EARS-Chicago (Engineering And Recording Society) visit me at https://public.me.com/hudsonic1 to hear recordings and ephemera

14th January 2009	#7
just.sounds Gear addict Joined: Sep 2005 Posts: 390	Maybe it is because of -9dBFS standards on digibeta for television. You can use the entire range of the mic pre and AD and control the volume to the standard you want to use. Otherwise you wont notice clipping but the video editor will! And of course for monitor mixes internally. __________________ "Music" Just a combination of sounds.

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13th January 2009	#2
staudio Lives for gear Joined: Oct 2005 Location: New York City Posts: 1,333	I agree, digital trim controls are pointless and dangerous if doing live recording, but what if you are doing a simple transfer where you know what the peak level would be and want to adjust it on the destination recorder, I could see this as being potentially useful in doing digital to digital transfers, but really not a critical feature in my opinion. I like my gear simple and elegant.

14th January 2009	#3
loji Gear maniac Joined: Jun 2008 Location: Brooklyn Posts: 229	what about a digitally controlled analog circuit ... like the digital trim on the MOTU traveler and metric halo 2882? Both use the onboard DSP to control the analog circuity in a very exact and repeatable manner (gain changes to 0.1) This also has the added benfit of being able to locate the interface close to the mics (thier solid state so silent) .. and keeping the noisey computer far away yet still being able to enact level changes silently ....(try walking up to a recorder and changing a knob during a quiet passage) remote recording meets remote control

14th January 2009	#6
ghellquist Gear addict Joined: Jan 2006 Location: Stockholm Sweden Posts: 416	Personally I believe the reason is simply that is built-in to the chip used. Adds to feature list in ads. Useful or not, people are lured into things. // Gunnar

14th January 2009	#10
Shadow_7 Banned Joined: Aug 2007 Posts: 595	I'm gonna assume analog level might be something like my DMP3 microphone preamp. I'm gonna assume digital level might be like the mixer levels on my Delta 44 soundcard. Under those assumptions, some analog preamps get really wacky when at their extremes. i.e. the knob goes to 11, but really only sounds good up to 9 or so. So to get a desired balance of color, noise, and distortion, you need both. For my desktop setup, that means my DMP3 is AT it's LOWEST setting, and my Delta 44 soundcard is AT about 90% for any given input channel. For a relatively LOUD source recorded in CLOSE proximity. In my case a trombone with Avenson STO-2's at about 18" away. The advantage for me is that such a combination gives me the lowest possible noise floor from mics + preamp + AD converters on a loud source, without overpowering the soundcard or clipping. I suppose that if I had higher end gear, or lived in a perfect world, that there would be no difference between 1 and 10 other than level. And setting 1 on the digital and 10 on the analog would be the same as 10 on the digital and 1 on the analog. But I've yet to find a device or get results like that from a device. At least when the device(s) were turned on. In my case, if I set the DMP3 at a volume > 10% on the knob, I get clipping on my soundcard at any level. And if I change mics, there's a completely different manual on what works and/or works best.