• BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

    Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

New to Bird/Wildlife Audio Recording :) - Gain/Trim & Fader and other basic settings to get started? (1 Viewer)

Joe94

Well-known member
United Kingdom
Good Morning, Hope everyone is well?

I have recently acquired a Zoom F6 Audio recorder with a Rode NTG5 shotgun mic (hopefully one day ill upgrade to a parabolic), which I'm hoping to learn the art of audio field recording; primarily of Birds & Nature/wildlife - with the plan of eventually using it to record the audio for my video work too, where ill then learn to sync the audio and video together in post.

However for now, whilst im focusing on the Audio side of things, I wondered if anyone could recommend a good Gain/Trim level to start with for recording Birds ect.. and where the Fader levels sit well? Also for bird/nature recording is there a sweet spot for the Bit & Sample rate to be used?

I appreciate these levels can be very subjective based on the individual listening, the gear and the individual noise a specific bird is making, but yeah any kind of general guid would be very much appreciated. Also any other audio recording tips for birds and wildlife, would be very very much appreciated : )

Thank you.
 

Jon.Bryant

Active member
As you say the gain levels will be partly dependent on the bird you are recording. The required gain will also be influenced by the mic you use (so the parabola you mention, would be different to the shotgun you have). The ideal gain also depends on circumstance (in particular how close you are to the bird - sound pressure is inversely proportional to the distance squared, so a bird 20m away is 4 x quieter than a bird 10m away and 16 x quieter than a bird 5m away - 1 over 400 compared to 1 over 100 and 1 over 25.)

For best recording, it is good to have a bird singing for a reasonable period of time from a song post at a fixed distance. You can then monitor and adjust the gain, then press record when you are happy with the levels. You don’t want to change levels mid recording. Ideally the meters should peak at about -3dB, so on most recorder meters, into the orange, but avoiding the red. By setting the gain to a good level, you avoid amplifying unwanted noise, which occurs when you raise the levels ‘globally’ in post production software, or by cranking up the volume when listening. You need to avoid going over 0dB (well into the red) as the recording would then be clipped and the sound distorted (unless you have a 32bit recorder).

In practice this ‘ideal’ recording level may be difficult to achieve. You may find the you end up pushing the gain too much, resulting in audible noise/hiss. I think with practice you will learn what levels to start at and how far you can adjust the gain while still finding the sound acceptable. I would suggest starting with some ‘well behaved’ subjects, and keeping a record of what works as a guide.

With regard to sample and bit rates, the bit rate determines the dynamic range (I.e the range between the quietest and loudest noise). I think for most recorders the maximum sound level remains constant, so the variations is in the lowest possible sound levels. This means that lower bit rates raise the ‘noise floor’. A lower bit rate could therefore raise the noise level above the inherent level of the equipment. Sounds complicated, but I would suggest using the highest bit rate possible. The sampling rate impacts the highest frequencies that can be captured - basically the highest frequency that can be recorded is 1/2 the sample rate. CD quality is 44.1K, so sounds up to 22kHz can be captured, which is more than enough for human hearing. If however, you recorded at 20kHz sample rate, you would not capture sounds about 10kHz - and a few birds sing at 10kHz and above. With the low price of memory cards, there is a trend towards recording at higher sampling rates - you can always later create a version of a recording at a lower rate, but you can’t create a version at at higher frequency rate and expect to regain high frequency data, not captured in the original recording. I would suggest that you record wav files at at least 44.1kHz. It is probably over the top, but I tend to record at higher rates and then render down to 44.1 later.

Hope this has not made things sound too complicated.

Regards

Jon Bryant
 

Joe94

Well-known member
United Kingdom
As you say the gain levels will be partly dependent on the bird you are recording. The required gain will also be influenced by the mic you use (so the parabola you mention, would be different to the shotgun you have). The ideal gain also depends on circumstance (in particular how close you are to the bird - sound pressure is inversely proportional to the distance squared, so a bird 20m away is 4 x quieter than a bird 10m away and 16 x quieter than a bird 5m away - 1 over 400 compared to 1 over 100 and 1 over 25.)

For best recording, it is good to have a bird singing for a reasonable period of time from a song post at a fixed distance. You can then monitor and adjust the gain, then press record when you are happy with the levels. You don’t want to change levels mid recording. Ideally the meters should peak at about -3dB, so on most recorder meters, into the orange, but avoiding the red. By setting the gain to a good level, you avoid amplifying unwanted noise, which occurs when you raise the levels ‘globally’ in post production software, or by cranking up the volume when listening. You need to avoid going over 0dB (well into the red) as the recording would then be clipped and the sound distorted (unless you have a 32bit recorder).

In practice this ‘ideal’ recording level may be difficult to achieve. You may find the you end up pushing the gain too much, resulting in audible noise/hiss. I think with practice you will learn what levels to start at and how far you can adjust the gain while still finding the sound acceptable. I would suggest starting with some ‘well behaved’ subjects, and keeping a record of what works as a guide.

With regard to sample and bit rates, the bit rate determines the dynamic range (I.e the range between the quietest and loudest noise). I think for most recorders the maximum sound level remains constant, so the variations is in the lowest possible sound levels. This means that lower bit rates raise the ‘noise floor’. A lower bit rate could therefore raise the noise level above the inherent level of the equipment. Sounds complicated, but I would suggest using the highest bit rate possible. The sampling rate impacts the highest frequencies that can be captured - basically the highest frequency that can be recorded is 1/2 the sample rate. CD quality is 44.1K, so sounds up to 22kHz can be captured, which is more than enough for human hearing. If however, you recorded at 20kHz sample rate, you would not capture sounds about 10kHz - and a few birds sing at 10kHz and above. With the low price of memory cards, there is a trend towards recording at higher sampling rates - you can always later create a version of a recording at a lower rate, but you can’t create a version at at higher frequency rate and expect to regain high frequency data, not captured in the original recording. I would suggest that you record wav files at at least 44.1kHz. It is probably over the top, but I tend to record at higher rates and then render down to 44.1 later.

Hope this has not made things sound too complicated.

Regards

Jon Bryant
Hello Jon,

Thank you so much for this! As you say it can certainly get complicated haha but I have to say everything you have said makes sense to me and really does help answer some of the questions I have.

If I may, I do have a follow up in regards to the Gain/trim side of things. So what you have said make total sense and I appreciate every scenario can be different, but your tips around good places to start and aim for is really helpful.

However if my understanding is correct gain is set first and effects the input noise, whereby you would then use faders (my F6 has fader knobs on the front - gain is done in the menu) to then fine tune the output noise - whether it be a stereo track or just the mono track? So if im on the right lines, how would I use the faders? Also my recorder has 2 headphone options I believe - pre fader and post fader - for bird recording is it best to hear the noise pre fader (while setting gain) or post fader?

As for sample rate and bit rates, that also really makes sense and in that case I will aim as you say to record higher sample rate and then if needed reduce in post - again with that in mind are you able to recommend some good post software? I have been looking at reaper... seems to be reasonable price yet can do really top level things - I would rather learn the basics in software that can also do bigger pro stuff for when im ready to say create track for video ectt.

Again Thank you for your help and support with the Jon, very much appreciated : )
 

Mono

Hi!
Staff member
Supporter
Europe
The Zoom F6 you have is a multi-input recorder where the gain and faders are used for different things. A normal workflow when dealing with multiple inputs would be to monitor each input separately with the the fader at 0dB and then adjust the gain so that at maximum source volume you are not clipping. Do that for each input separately then you can turn down the faders, on the fly, to create the mix that you want with knowledge that you won't clip.

The post fade and pre fade listens can be used to monitor your different sources. The pre fade option removes the fader from the path so you hear the source at maximum volume, but you are still recording at the post fade level. The post fade option allows you to listen to the levels as they are being recorded.

All this is of course moot if you are just using a single source, but then if you are just using a single source the F6 is a bit of a sledgehammer to crack a nut.
 

Jon.Bryant

Active member
Hi Mono,

Thanks for the specifics about the F6 and the work flow. I didn’t realise this was a multi-track recorder with four mic inputs when I made my initial reply.

Looking at the F6 manual signal flow paths, it looks like the faders are on the LR mix to SD and that tracks 1-4 can be recorded to SD direct, but without fade control. Do you know if this is correct? When I started using a different multitrack recorder I found faders really difficult to understand at first - a recording session twiddling knobs with no impact. Then a look at the routing diagram and a quick question to SoundDevices made things a lot clearer.
 

Joe94

Well-known member
United Kingdom
The Zoom F6 you have is a multi-input recorder where the gain and faders are used for different things. A normal workflow when dealing with multiple inputs would be to monitor each input separately with the the fader at 0dB and then adjust the gain so that at maximum source volume you are not clipping. Do that for each input separately then you can turn down the faders, on the fly, to create the mix that you want with knowledge that you won't clip.

The post fade and pre fade listens can be used to monitor your different sources. The pre fade option removes the fader from the path so you hear the source at maximum volume, but you are still recording at the post fade level. The post fade option allows you to listen to the levels as they are being recorded.

All this is of course moot if you are just using a single source, but then if you are just using a single source the F6 is a bit of a sledgehammer to crack a nut.
Thank you Mono, this definitely helps my understanding of how the recorder works and the grain vs fader side of things. As for the post & pre fade, your explanation makes it really clear and with what you have said, I presume its better to listen to the output track whether it be one or multiple mic's either way?

In regards to the mic, I do apreciate for a single mic then the F6 could be a little over thank needed, however although I did not mention it in my OP for bird recordings, I also have a pair of Condenser mics and another mic to have ago at some other multi track recording/mixing too :)
 

Joe94

Well-known member
United Kingdom
Hi Mono,

Thanks for the specifics about the F6 and the work flow. I didn’t realise this was a multi-track recorder with four mic inputs when I made my initial reply.

Looking at the F6 manual signal flow paths, it looks like the faders are on the LR mix to SD and that tracks 1-4 can be recorded to SD direct, but without fade control. Do you know if this is correct? When I started using a different multitrack recorder I found faders really difficult to understand at first - a recording session twiddling knobs with no impact. Then a look at the routing diagram and a quick question to SoundDevices made things a lot clearer.
Apologies Jon, being new to the device and audio recording as a whole aha I didn't realise having the 6 mic inputs changed things :)

From what I have understood the knobs on the F6 control the fader level of either the LR stereo track or just the single input track if only recording a mono track and then the gain is set via the menu.
 

Jon.Bryant

Active member
Hi Joe,

I don't think things are that different if you are using a single mic. If this is routed to the LR recording and the balance is set to centre, then you will record two equal tracks (in effect dual mono). The trim and gain will them work as Mono described very well above.

The same is also true if you add additional mics and create a LR mix in the field. In this case you can set the balance for each mic (to adjust the ratio of signal split between the left and right tracks). The trim and fades would then control the mic levels. In this case you probably will want the main subject to be as close as possible to -3dB, but other parts of the mix to be substantially lower (so not as to drown out the main subject).

Setting the trim based on the maximum sound levels and fading down is easier when you are recording instruments or voice and can do sound checks. In the dynamic and transient world of wildlife recording, I tend to 'guess' a trim level than use the faders in the field. If you try to set trim and then adjust fade when you find a subject, it may well have stopped vocalising of moved by the time you finish adjusting settings!

The slight complexity with my recorder (not an F6) comes if I want to record multiple tracks but do not want to combine them in a LR mix in the field. As I understand you are only using the one mic for the moment, it is probably best to ignore all the blurb below for the moment. With my recorder, if I am recording to separate tracks, then I can set the trim of the mics, but the faders don't work. Looking at the block diagram for the F6, I think this may also be true for your recorder. The diagram below is from the F6 user manual and shows that the trim (yellow) is on all lines, but the TR1-6 Faders and LR Fader (both green) only affect the LR tracks and the Line Out and Headphones. Tracks 1,2 and 5 and 6 do not have fader control. As Mono described, the headphone monitoring can either be pre or post faders, as highlighted in blue. Pre-fader would allow you to check the source and post fader to monitor the left-right recording mix, being recorder to you SD card.

F6 Block Diagram.png


I understand the situation is slightly different in the F6 32bit float recording mode. In this mode, I don't think you set trim in the same way. Instead by default you set the recording levels and faders with the same knobs, with the knobs setting recording levels prior to pressing record, and setting the faders during recording (see text box in extract of diagram below, which points to the recording levels and faders).
F6 Block Diagram Float.png
I think the basic logic of not having the faders on the individual tracks, is that you set the levels for a track with trim or recording levels, and control the mix with the faders.

As the F6 is one of a select few 32-bit float recorders, if you use this mode the recording levels are more forgiving, so if you set the recording levesl too high you can get away with it. I have read somewhere that in theory 32 bit float provides headroom to record up to 1500dB (Krakatoa was the loudest noise every recorded at 310dB, so a noise this loud, would probably be enough to not only to destroy you and your recording gear, but also all life on earth!). The F6 apparently warns if the signal is greater than +2dB. As 3dB is circa a doubling of sound level, you have quite a lot of wiggle room if you set the recording level too high and go above 0dB. In this case you would load the 32bit file into your post production software and reduce the level to -3dB without loosing any information or having any distortion. The only problems with 32 bit float and high sampling rates is that the file size is large and that battery life is reduced.

With regard to your question on software, lots of people use Audacity for simple recordings, which is free. For multi-track work, Reaper is modestly priced, and seems to work well, although it takes a bit of study to understand. If you are doing lots of video work and have a subscription with Adobe to use Premier Pro, then I understand Audition interfaces well, but this is a more expensive option.

Apologies for making things so complex, but your recorder is not a simple 'twiddle the gain and press record' option.

Regards

Jon Bryant
 

Joe94

Well-known member
United Kingdom
Hi Joe,

I don't think things are that different if you are using a single mic. If this is routed to the LR recording and the balance is set to centre, then you will record two equal tracks (in effect dual mono). The trim and gain will them work as Mono described very well above.

The same is also true if you add additional mics and create a LR mix in the field. In this case you can set the balance for each mic (to adjust the ratio of signal split between the left and right tracks). The trim and fades would then control the mic levels. In this case you probably will want the main subject to be as close as possible to -3dB, but other parts of the mix to be substantially lower (so not as to drown out the main subject).

Setting the trim based on the maximum sound levels and fading down is easier when you are recording instruments or voice and can do sound checks. In the dynamic and transient world of wildlife recording, I tend to 'guess' a trim level than use the faders in the field. If you try to set trim and then adjust fade when you find a subject, it may well have stopped vocalising of moved by the time you finish adjusting settings!

The slight complexity with my recorder (not an F6) comes if I want to record multiple tracks but do not want to combine them in a LR mix in the field. As I understand you are only using the one mic for the moment, it is probably best to ignore all the blurb below for the moment. With my recorder, if I am recording to separate tracks, then I can set the trim of the mics, but the faders don't work. Looking at the block diagram for the F6, I think this may also be true for your recorder. The diagram below is from the F6 user manual and shows that the trim (yellow) is on all lines, but the TR1-6 Faders and LR Fader (both green) only affect the LR tracks and the Line Out and Headphones. Tracks 1,2 and 5 and 6 do not have fader control. As Mono described, the headphone monitoring can either be pre or post faders, as highlighted in blue. Pre-fader would allow you to check the source and post fader to monitor the left-right recording mix, being recorder to you SD card.

View attachment 1390398


I understand the situation is slightly different in the F6 32bit float recording mode. In this mode, I don't think you set trim in the same way. Instead by default you set the recording levels and faders with the same knobs, with the knobs setting recording levels prior to pressing record, and setting the faders during recording (see text box in extract of diagram below, which points to the recording levels and faders).
View attachment 1390405
I think the basic logic of not having the faders on the individual tracks, is that you set the levels for a track with trim or recording levels, and control the mix with the faders.

As the F6 is one of a select few 32-bit float recorders, if you use this mode the recording levels are more forgiving, so if you set the recording levesl too high you can get away with it. I have read somewhere that in theory 32 bit float provides headroom to record up to 1500dB (Krakatoa was the loudest noise every recorded at 310dB, so a noise this loud, would probably be enough to not only to destroy you and your recording gear, but also all life on earth!). The F6 apparently warns if the signal is greater than +2dB. As 3dB is circa a doubling of sound level, you have quite a lot of wiggle room if you set the recording level too high and go above 0dB. In this case you would load the 32bit file into your post production software and reduce the level to -3dB without loosing any information or having any distortion. The only problems with 32 bit float and high sampling rates is that the file size is large and that battery life is reduced.

With regard to your question on software, lots of people use Audacity for simple recordings, which is free. For multi-track work, Reaper is modestly priced, and seems to work well, although it takes a bit of study to understand. If you are doing lots of video work and have a subscription with Adobe to use Premier Pro, then I understand Audition interfaces well, but this is a more expensive option.

Apologies for making things so complex, but your recorder is not a simple 'twiddle the gain and press record' option.

Regards

Jon Bryant
Hello Jon,

THANK YOU so much for this! Yes it is complex haha but the way you have so kindly explained it and linked it to the diagrams too has really really helped my understanding.

Not only do I now feel more confident in my understanding of the difference between trim & fader / pre fade & post fade, but I also feel a lot more confident in my understanding of how sound recorders work in general - When I first say these diagrams a few days ago I was mind boggled haha but you have turned that around for me for sure!

It may seem strange to many, but yeah although for now I am going to start with basic mono track (single mic) recording of bird noise and with that in mind the F6 probably does seem OTT; however for my getting the F6 and extra mics was not just about recording birds sound, but to also give me something to learn. I wanted to get equipment now that I can learn about and then use with my expanded new learned knowledge.

I have always loved technology and the digital world and have a particular interest in photography & videography, but the one thing I have never really learned about properly was the digital world of audio (apart from commercial music/tv speakers & headphone), but proper raw audio recording was one thing I have not got great knowledge with and so is something I want to learn all about : )

So yeah again thank you very much for this post and your previous posts because it really has and is helping me understand and learn my new skills : )
 

Users who are viewing this thread

Top