Category Archives: field recording

Sound Devices MixPre 10-II tip

 

 

Late 2021 I took the leap and ordered a Sound Devices MixPre 10-II I was motivated by a number of factors, first was a desire to record 32bit 192kHz with multiple microphones. My old SD 788T is still a rock solid performer, but its hardware limits it to only capturing 4 channels of 192kHz audio. So I mainly use it for AMB recording where 96kHz is fine, and for that it is brilliant. I had upgraded the HD to an 500GB SSD and with NP1 battery I can do long runtime recordings eg yesterday I used it to record 5 channels of 24/96 capturing over 10 hours of real-time recording, swapping batteries every few hours.

I still have my other SD recorders – two 722 and a 744. So I can combine them with C.LINK to do six channel 192kHz recording, but it is not ideal to be powering and monitoring three seperate recorders.

The other feature of the MixPre10 is the Musician plugin. This directly suits a few music projects I am working on. But I will document that once I am further down the track and have some experience with it.

So the new Mix Pre 10 arrived, I ordered a NP1 battery cap for it and have it all up & running, and it is fantastic. But there was one aspect of the MixPre that I could not understand. I read the manual before it arrived and again after I’d used it for a bit and still I could not understand it.

This is so basic, every one of my other SD recorders provides it by default, but the one thing I wanted:

Direct access to the input gain of every channel!

As an example, if I plug a mic into my 722, power it up and hit record. The gain knob on the front of the 722 gives me direct access to instantly control the input gain of the mic. This is essential. Every time I record something the first thing I do is gauge the extremes of volume and set the gain, to cleanly record without clipping.

But for some bizarre reason, this is not how the MixPre is set up, by default. The MixPre has three modes.

1. Basic
This is fixed at 48kHz, I will never use Basic mode.

2. Advanced Mode
I set up a project as 32 bit 192kHz recording. I enabled phantom power for each mic and armed the record tracks. BUT The gain knob on the front of the MixPre does not control input gain! It controls post-record level, for creating a LR guide mix! Now I do appreciate why this is useful: it is essential for every production sound recordist. Delivering a guide mix to the director and to camera is as important as recording the iso tracks. But for me: I never record a guide mix. The LR bus is only of use for monitoring. I work at a fixed monitor level & solo to check mics etc…
With the MixPre in Advanced mode, the only way to access the input gain of each channel takes 3 steps: first select mic input 1 with a click, then click select input gain, and then use the fiddly little knob beside the headphone jack to set the gain. Then do the same for mic 2. Then do the same for mic 3. Then do the same for 4. Then do the same for 5. Then do the same for 6. Then do the same for 7. Then do the same for 8. Even reading that was a pain!

3. Custom Mode
I was getting frustrated by this point. There must be a way!? I read the manual and found Custom Mode, which mentioned one feature that still did not make sense:

Gain
Allows advanced operation of channel gain, including dual gain stage (gain and fader) and Remix.

Huh? What fader?
In frustration, I asked on the MixPre FB Users Group and some lovely helpful people replied!

First thanks to Robert Keilbar, who replied with a handy photo:
“Hey Tim, try custom mode and in the submenu set Gain Basic, that should solve the problem”

Bingo! Problem solved.
But as I said I have used SD recorders for many years. I had read the manual and I was stumped. I don’t consider myself an idiot, but why was this so difficult to discover? Why is there not a default MixPre set up for this, its always been a default?

It seems like Sound Devices decided that production sound takes priority, and everyone else should have to manually set up a custom mode to get it to work, the way their recorders have always worked.

Now someone else commented (thanks Bernard Ulrich!) saying the old MixPre 10 manual was better. They provided a link and I checked. And he is right, the old manual clearly explains it on page 24.

“CUSTOM MODE
By setting the Channel Custom Setup to Advanced and the Gain Custom Setup to Basic, you can use all the Advanced Channel Input features while retaining single gain stage control using the physical channel knobs. This allows you to use the channel knobs to adjust the level going to the ISO tracks.”

Why was this removed from the new MixPre manual?
I would have found that instantly and had zero confusion.

Now someone else joined the discussion at this point, and his comments were very helpful in understanding how the MixPre differs from previous recorders (but it still does not explain that omission from the manual)

Thanks to Dmitry Chernov:
“Even in the advanced mode the knobs do not control Input gain. They are after ADC and control at what level the digital signal is recorded into ISO tracks of a poly WAV file either in 32 bit or 24 bit mode. There is no analog input gain control at all neither in MixPre II series nor in Zoom F6. The only option to choose different levels prior to ADC is switch between Mic and Line level sensitivity.

The preamp has a fixed gain and then the signal goes to the ADC that consists of three 24 bit converters receiving the analog signal at 3 different levels to cover the wider dynamic range. The processor then combines the outputs of the 3 ADC converters to get the best signal-to-noise ratio and prevent digital clipping.”

That is very useful insight. It explains how the MixPre achieves its great results, but it still doesn’t explain the default allocation of knob useage.

I have contacted Sound Devices and provided my feedback. I hope they improve the manual, because I should have solved this myself instantly when reading the manual. Had I read the old manual, I would have solved it!

And it’s not just me. Someone else commented: “Thank you all for this enlightment! I thought there was no way to use the front knobs to adjust gain.”

Please improve your MixPre manual, Sound Devices!

Listening from 2317km away!

This is utterly incredible!

The other evening (Saturday, Jan 15th) I was out in the garden messing around with the bath I have installed for sound FX recording, and I heard some distant booms. They sounded like large-scale fireworks or munitions, distant enough to have that “pahrump” attack to them, but carrying enough sub-bass that you could feel the scale. My first thought, why would anyone have a fireworks display during daylight? This was about 7pm and sunset isn’t until 9pm at the moment. When they have a large fireworks display in Wellington harbour, we can barely hear it here….

Soon after I went inside and a friend on Twitter messaged me:
Did I hear it?
Yes, but what was it?
The eruption in Tonga, 2500km away!
Whaaaaaat?

At first I thought he was joking.
But checking official NZ MetService Twitter account:

 

 

 

 

wow!!
There were comments on that tweet from people all over NZ who heard it.
I would not call what I heard “a rumble” – it was definitely discrete booms!

But even more amazing: people heard it in Alaska 6000 miles away!!

 

 

 

 

 

 

WOW!!
Check the shockwave timelapse captured by the Himawari Satellite

“Japanese Geostationary Satellite ‘Himawari-8’ captured an eruption of a volcano near Tonga. Not only the eruption but also the shock wave can be seen. On the other hand, the terminator between daylight and night caught up with the shock wave. This means the terminator runs faster than the speed of sound, that is, the surface speed of the Earth’s rotation exceeds the speed of sound, and we are rotating at supersonic speeds!”

 

 

And there is great info here with regards to scale of eruption.

This is a recording of the eruption captured in Fiji, 800km away!

Sonic boom from Hunga Tonga Hunga Ha'apai Volcano

I posted some comments on a local FB group to see if anyone else heard it, and a dozen or more commented they did. But one was skeptical: “Are you sure? On the 6pm news it had already erupted and they had an initial video of the early tsunami waves”

Me: The speed of sound in dry air at 20 deg C = 343 m/s.
Plimmerton is 2,317km (or 2317000metres) from Tonga…
By my maths that = 6,755 seconds or 112 minutes of travel time.
(Speed of sound would vary with humidity and temperature)

I can understand their doubt, and as one of the reports mentioned,
Scientists will be studying this event for many years to come.
Meanwhile Tonga has a massive recovery ahead.

Temperature Inversion

My field recording work is often exterior, so I am often dependent on the weather…
Wind & rain ruin recordings (unless that’s what I’m recording) but checking the hourly weather forecast I keep noticing how the wind always dies down at night… Why is that?

Answer: temperature inversion
Longer answer is here

“The wind speed tends to decrease after sunset because at night the surface of the Earth cools much more rapidly than does the air above the surface. As a result of this difference in cooling ability, it doesn’t take long for the ground to become colder than the air above it. The air in close contact with the ground — say in the lowest 300 feet of the atmosphere — then becomes colder than the air above it.

This circumstance leads to the development of what is known as a temperature inversion. Inversions dramatically reduce the amount of mixing that occurs between different vertical layers of the atmosphere. As a consequence, once the inversion sets up (after sunset), it is much harder for fast-moving air above the ground to mix down to the surface, where it could appear as a gust of wind. During the day it is very easy for the air to mix and cause surface gusts.”

First Field Recordings

By 1998 I was in the slow motion process of dropping out of University – I’d started a degree in Electrical Engineering, and the further I got into it the less I liked it! One of the few interesting elements was the anechoic chamber which I spent time in when I could…

Around the same time a couple of friends were at Ilam Fine Arts School. The drummer in my band was studying film, and via him I managed to start using their field recording equipment: a beautiful Nagra 4.2 and a Sennheiser MKH416 shotgun mic in a Rycote.

Prior to going to Film School in 1990, I spent a gap year living in an abandoned church in central Christchurch, playing in bands and starting to experiment making my own music and sound. And borrowing that Nagra and 416 whenever I could!

Sometimes the greatest motivator can be a lack of access, so whenever I had that Nagra I spent quality time with it – learning to record, and also learning to manipulate sound with it. Making tape loops, playing sounds backwards and splicing tape.

At one stage I had a part time job, working a nightshift at a gas station in the suburbs. I think their motive was that my meagre pay was cheaper than insurance, while mine was being paid to do very little. Except I didn’t – I did all sorts of things while I was at work, and remember a couple of people coming into the station about 2am, only to find the counter covered in bits of 1/4″ tape!

Another part time job I had was at a company who built sound systems – I mainly helped with assembly but I made friends with a hippy guy who worked in their machine shop. He built all the speaker enclosures so had a full workshop of saws, routers, drills etc… and I soon realised this was an opportunity not to be missed!

I managed to talk him into coming in to work during the weekend, and borrowed that trusty Nagra and 416 again and recorded a great little library of machine tools. One of my favourite sounds from that session was an air powered staple gun, I was recording at 15ips as much so i could slow sounds down as for the quality. And that staple gun sounded great at half speed.

I think those recordings would be the earliest recordings that are still in my library. At some point in the 90s I transferred them to DAT, at real speed and at half speed. And then a few years later digitised the DAT and added it to my growing CDROM sound library… and then as hard drives became affordable, copied the CDROMs to hard drive, and now to a NAS.

So here is a few of my earliest recordings, time travelling from 1988 to your ears now!

Kia Ora

This blog is primarily about field recording, sound editing and sound design but will also grow to include tutorials, workflow tips, reviews of tools used and also to host sound design challenges, and share free sounds.
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