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Field recording: external preamp to reduce noise? (1 Viewer)

Vollmeise

Well-known member
Hi there,

some years ago I started field recording for evidence or ID purposes by using my smartphone and different audio apps.

In most cases the recordings were usable, in some cases quiet bird songs or calls suffered from clearness due to way too much noise.

So, lately I decided to invest in field recording gear last year and my current setup now is:

- Tascam DR70 field recorder
- Sennheiser MKE600 shotgun microphone
- wind screen (dead cat) to reduce wind noises

Though signal/noise ratio is much better now, it's still not easy at all to get clear recordings of faint bird calls especially in noisy or/and windy environment.

Does someone out there have an advice how to adjust the field recorder's microphone gain presets (low/mid/high..) and the additional fine adjustments to get the best signal/noise as possible?

Does an external preamp like "TritonAudio FetHead" or "Cloudlifter CL-1" produce less noise when used with my Tascam DR70 (due to lower gain preset) and Sennheiser MKE600?

Will another field recorder with better preamps produce noticeable less noise?

Having its price in mind, which part of the recording workflow has the most bearing on sound quality - microphone or pre amplifier?

Thanks a lot!
 

Borjam

Registered User
Supporter
All the elements in the signal chain have a part :)

But the external preamps are mostly useful for long cable throws unless you can really bypass the build-in preamplifier. That said, the TritonAudio seems not to be designed for portable operation. These preamplifiers are meant mostly for dynamic microphones.

I would try updating two elements:

First, the microphone. Still within a reasonable budget Sennheiser offers the ME66 or ME67 shotguns with a much higher sensitivity and a lower noise floor.

Second, the recorder. Sound Devices and Zoom have released recorders with much better noise floors at reasonable prices. Look at the Sound Devices MixPres (3/6/10) and Zoom F4/F8.

A good portable preamplifier (like the MP-1 from Sound Devices) will surely help but it's 550€ and it's only one channel. A MixPre 3 will give you three microphone preamplifiers better performance.

And still if you want to record distant birds with good quality you will need a parabolic reflector.
 
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Vollmeise

Well-known member
Hi Borjam, thanks for your detailed reply. I'm sure your suggestions will help getting better sound quality with less noise.. but I have no idea how much better in comparison to my setup, which is about half the price.

This afternoon I'll go to Treppendorf/Germany (largest audio store in europe) for an equipment demonstration and hope to be able to try out my stuff and the gear you recommended in side-by-side comparison. My idea is to place my smartphone / a speaker somewhere in the store playing some bird calls.
 

Hauksen

Forum member
Hi,

This afternoon I'll go to Treppendorf/Germany (largest audio store in europe) for an equipment demonstration and hope to be able to try out my stuff and the gear you recommended in side-by-side comparison. My idea is to place my smartphone / a speaker somewhere in the store playing some bird calls.

Sounds promising! :)

A couple of years ago, I bought a digital recorder with built-in pre-amplifiers from that store years ago, but found that in my urban spotting locations, there was just too much background noise to sustain my enthusiasm. (I shied back from buying shotgun microphones as I thought it was a bad bet to expect them to eliminate the background noise.)

However, I was given a Cornell Raven Lite license for christmas, which I suppose must be a pretty good spectrum analysis tool, so maybe I need some fodder for that now ...

Regards,

Henning
 

Vollmeise

Well-known member
Hi Henning and a warm thank you for your hint to the Cornell Raven Lite. It seems to work with Mac OSX also.. have to try it this evening. Do you know the iOS app Sonocord?

Cheers
 

Borjam

Registered User
Supporter
Hi Borjam, thanks for your detailed reply. I'm sure your suggestions will help getting better sound quality with less noise.. but I have no idea how much better in comparison to my setup, which is about half the price.

Difficult to say...

These recordings are made with an AKG C300B+CK98 shotgun and a Sound Devices MixPre 3.

The wren was about 10 m away (I overstated the 15 m I think)
https://www.xeno-canto.org/425718

And the blackcap, which seemed to be arguing with the wren (it's the same individual in the same situation) about 2 - 3 m away from my position.

https://www.xeno-canto.org/425726

The ME66 or ME67 is much more sensitive and it has a lower noise figure. This is not a perfectly quiet place anyway, it's the coast, close to urban areas, inside the approach area of the airport...

A piece of advice anyway.

When listening to the recordings try not to raise the volume too much. Try to achieve a natural level. Otherwise even the very best equipment will sound quite dirty ;)

And yes, the best thing you can do is to visit a good place and test equipment. Just take yours, make a couple of recordings of store abience and compare the noise levels.

So visiting Thomann :) I purchased my MixPre 3 from them, but online. I am in Spain.

And I am adding a separate thread on an interesting offer I just saw.
 
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Vespobuteo

Well-known member
High gain, low noise floor is nice to have in nature recording as the sound levels often are pretty low.
With the SD MixPre-3 you get +76dB of gain which is more than +10dB better than the Tascam,
that would be clearly audible when you need to turn up the gain:

MixPre 3/6 review:

https://www.youtube.com/watch?v=piomdez4iSM

The DR-70D I think have the same preamps as the older DR-60D mk II and
have around +64 dB of gain:

DR-701D (6 channel version):
https://www.youtube.com/watch?v=bl0DnLRkFDE

DR-60D mk II:
https://www.youtube.com/watch?v=TRoIMPHS91U
 

Borjam

Registered User
Supporter
High gain, low noise floor is nice to have in nature recording as the sound levels often are pretty low.
With the SD MixPre-3 you get +76dB of gain which is more than +10dB better than the Tascam,
that would be clearly audible when you need to turn up the gain:
Anyway the equivalent input noise for both (although underspecified for the Tascam) is not the same.

Tascam: -120dBu or less
Sound Devices: -128 dBu with 76 dB of gain.

That's an important difference and close to the best theoretically achievable performance.

So. Comparing both recorders at max gain, the Sound Devices will have a significant advantage.
 

Vespobuteo

Well-known member
Anyway the equivalent input noise for both (although underspecified for the Tascam) is not the same.

Tascam: -120dBu or less
Sound Devices: -128 dBu with 76 dB of gain.

That's an important difference and close to the best theoretically achievable performance.

So. Comparing both recorders at max gain, the Sound Devices will have a significant advantage.

Yes, the MixPre is a bit more expensive but worth it in my opinion.
 

Hauksen

Forum member
Hi,

Hi Henning and a warm thank you for your hint to the Cornell Raven Lite. It seems to work with Mac OSX also.. have to try it this evening. Do you know the iOS app Sonocord?

Just be warned I actually didn't try out Cornell Ravenlite yet, except to see if it works at all :) I don't have any IOS devices, so I haven't heard of Sonocord, I'm afraid.

Regards,

Henning
 

Mark Lew1s

My real name is Mark Lewis
I don't know much about Raven Lite (or other versions of Raven) but I do know that you either pay for them, or access them within time limitations. A really good alternative is Audacity, which lots of bird recorders use these days.

Some instructions in the basics here:

https://www.dropbox.com/s/j9ycbi188tghs5b/Audacity_guide.pdf?dl=0

I think a lot of bird sound recorders can get carried away with trying to get the best equipment - but learning how to get the best out of your recordings in whatever software you use is probably more important than a few decibels here and there.
 

Borjam

Registered User
Supporter
Raven Lite 2.0 is actually free of charge now.

https://store.birds.cornell.edu/Raven_Lite_p/ravenlite.htm

The big advantage: Working with sonograms. Not so many editors get it right I think.

iZotope's RX Elements, for example, includes a standalone audio editor that can work in spectral mode. RX Elements is on sale for $29 right now. Alternatives with spectral edition are Reaper ($60 ?) and Acoustica (acondigital.com) for much more and a sluggish spectral edition window.
 

horukuru

Here I Come !
Just wondering, do you increased the gain of the recording in audacity or any processing apps when the sound is too low?
 

Mark Lew1s

My real name is Mark Lewis
You can amplify the recording (or just parts of it), increase the playback gain, or spectrally select and increase 'volume' of the noise you're interested in in Audacity.
 

Vollmeise

Well-known member
Hi there,

and thx a lot for your detailed and useful help. Lately I've tried these external amplifiers without the desired sucess. If the recorder's signal/noise ratio is poor, then it keeps being poor no matter how much you raise gain either by the recorder or by an external amplifier.

What helped in the end was changeing the whole setup. I sent back my new Tascam and Sennheiser and upgraded in

- Sound Devices MixPre-3
- Sennheiser MKH70 with a dead cat
- AKG P420
- Dodotronics parabolic microphone (Hi Sound stereo, custom made with four AOM-5024L capsules) with windscreen
- Dodotronics XLR to PIP adapter (to get advantage of the MixPre-3's low noise preamps you have to connect your mics via XLR. Connecting mics with 3,5mm PIP directly creates noisier recordings)

Useing the parabolic microphone for the first time caused a big smile immediately. The sound of passerines is overwhelming, crisper, clearer and much louder than with any microphones I ever used.

When it comes to sounds lower than 1000 Hz and/or windy situations the parabolic mic reaches its limits. After searching for a high end shotgun mic with low internal noise and excellend humidity resistance I came across the Sennheiser MKH series. Well, the MKH70 is a big and pricy beast but seems to fit my needs when it comes to recording owls, amphibians or mammals. So, in the end I bought a used one at a reasonable price and didn't regret it for a single moment.

The Mixpre-3 is, besides its specs, just a pleasure to use. Borjam, Vespobuteo: A warm Thank You for your recommendations! Very helpful is btw that you can save, recall and even share presets on demand within seconds. Compared to the Tascam's chaotic control logic the MixPre shows its features and menus just as you'd expect them. There are some points which could be improved either (maybe I'll talk about it separately), but in total the MixPre is a fine, user friendly workhorse.

Thanks for your help and patience!

Vollmeise
 

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Borjam

Registered User
Supporter
Glad to be of any help! Good additions to the MixPre 3 are a bag and a large battery. Low noise electronics literally suck batteries dry!

I got a poor man's MKH70 myself: The Rode NTG8. I'll upload some recordings to Xeno Canto this week.
 

Vollmeise

Well-known member
@Borjam: you're right, a large battery is compulsory especially if phantom power is needed. I'm useing the double USB-A to USB-C Cable with a large power bank to solve that.

As seen in the picture, I don't use a bag for my mixpre, instead I mounted a strap to keep full access to all the side placed switches and knobs of the recorder.

This is IMHO one of the issues of that small recorder gem. The ON/OFF switch is tiny and poorly accessible, esp when whearing gloves or in the dark. The same point when useing the touch screen: I'd like to turn it off when not needed and swap to the knob operation in some cases (e.g. wearing gloves).

Maybe Sound Devices will fix that in a firmware release once.

Cheers!

P.S.: Curious about your recordings :)
 

Borjam

Registered User
Supporter
@Borjam: you're right, a large battery is compulsory especially if phantom power is needed. I'm useing the double USB-A to USB-C Cable with a large power bank to solve that.
I wouldn't recommend that, kludges usually bite you in the worst moment.

Sound Devices has a web page with excellent advice and the USB-C power bank they recommend is very cheap.


As seen in the picture, I don't use a bag for my mixpre, instead I mounted a strap to keep full access to all the side placed switches and knobs of the recorder.
Yes, I noticed. Although not cheap there are bags specifically designed for audio recorders with room for some accessories, batteries, and even openings to arrange the cables neatly.

In the particular case of a MixPre with a power bank and a flimsy USB-C connector a bag is really beneficial. It will keep your cables safe from strain.

For example the Orca OR-270XS

https://www.orcabags.com/product/or-270-xs-sound-bag-for-mixpre-3m-6m/

I use a Sachtler SN607 and I keep the power bank attached to the bottom using velcro.

This is IMHO one of the issues of that small recorder gem. The ON/OFF switch is tiny and poorly accessible, esp when whearing gloves or in the dark. The same point when useing the touch screen: I'd like to turn it off when not needed and swap to the knob operation in some cases (e.g. wearing gloves).

Maybe Sound Devices will fix that in a firmware release once.

I sent them a suggestion last month. Given that the super bright screen consumes a lot of power and some nature recordists work at night it would be great to have an option to turn it off. Moreover, with the Bluetooth application you can still monitor recording levels, etc, but using the phone battery for that instead. I monitored the power consumption in different situations and Bluetooth is negligible.

As far as I know they liked the suggestion, but they never confirm wether with will implement an improvement or not. Anyway when I purchased it I made a suggestion and it got implemented in the next firmware version.

They listen to customers.
 

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