Sound Devices MixPre-6 II (second generation)

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Re: Sound Devices MixPre-6 II (second generation)

PostTue Jun 30, 2020 11:29 pm

rick.lang wrote:I know I could benefit when using the MKH416 mounted on the camera. But I can see needing two if it works well as I’d still put one filter on one of the L-R mixes.


Well, the MixPre version, at US$300, is selling for half the price of the 800 series version :)

I think it's likely that this will work, the question being for what kinds of problems and to what degree. On those issues, I'll be looking for guidance on Wexler's site and at Sound Devices demos. There are also a couple of people on YouTube who know what they're talking about and are likely to make videos.

Thanks for raising this, I wasn't aware of the announcement/product.
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Re: Sound Devices MixPre-6 II (second generation)

PostWed Jul 01, 2020 12:25 am

dondidnod wrote:The waveform showed a notch filter applied not only to the low base frequency, but to every harmonic of that frequency. This had a bad effect on her voice, making it more distorted. .


This is why iZotope RX has a specific tool that lets you decide how many harmonics to affect and which ones. It's called Select Harmonics and the key command on a Mac is Shift Command H. In the photo below, it's the tool that looks like a ladder (which is what harmonics look like graphically) in the centre of the green circle.


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Re: Sound Devices MixPre-6 II (second generation)

PostWed Jul 01, 2020 1:01 am

Kim Janson wrote:Why would in device noice cancellation be better than on post production ?


The main thing that I've learned from several years of using iZotope RX is to avoid the need to use it if at all possible. RX is also too expensive for a lot of people. Courtesy of Rick, I've just learned about Sound Devices's plugin. One thing that I'd like to know is whether one can hear what it's doing on headphones before pressing "Record". If you can, and if it works, this is a complete no-brainer. Even if you can't, it's something that I'll purchase if it solves common problems and the results are predictable.
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Re: Sound Devices MixPre-6 II (second generation)

PostWed Jul 01, 2020 1:34 am

By the way, if the WAVE file in the screen capture two posts up looks a bit odd, it's because it represents a single note from a public piano at King's Cross Underground Station in London. The piano was made in the late 1800s and was sampled to create a virtual piano. The WAVE file is one of the samples. The virtual piano is available at https://www.pianobook.co.uk/library/kin ... ndergound/

Below is a video about making the King's Cross virtual piano and what it sounds like. It ain't a Steinway, but that's the point. It offers interesting sound design possibilities.



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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 02, 2020 12:34 am

robedge wrote:
rick.lang wrote:I know I could benefit when using the MKH416 mounted on the camera. But I can see needing two if it works well as I’d still put one filter on one of the L-R mixes.


Well, the MixPre version, at US$300, is selling for half the price of the 800 series version :)

I think it's likely that this will work...


The NoiseAssist for the 800 series is $600 for two instances so you could apply it to the L and R mix channels. NoiseAssist for MixPre II is on ‘sale’ for $300 for only one instance so you could use it on a specific channel or one mix channel.
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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 02, 2020 12:47 am

rick.lang wrote:
robedge wrote:
rick.lang wrote:I know I could benefit when using the MKH416 mounted on the camera. But I can see needing two if it works well as I’d still put one filter on one of the L-R mixes.


Well, the MixPre version, at US$300, is selling for half the price of the 800 series version :)

I think it's likely that this will work...


The NoiseAssist for the 800 series is $600 for two instances so you could apply it to the L and R mix channels. NoiseAssist for MixPre II is on ‘sale’ for $300 for only one instance so you could use it on a specific channel or one mix channel.


Hi Rick. Sorry, I haven't worked out the ins and outs of the cost for 800 series and MixPre recorders in various channel combinations. Based on what you're saying, the MixPre plugin appears to be half the price if you're recording with one mike, which in many cases works for a lot of people, including me.

In any event, I'm mostly interested in this video, which suggests that you can hear the effect of the plugin on headphones before pressing "Record". If that's true, I just want to know more about how effective this plugin is.

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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 02, 2020 1:27 pm

Ha! Sound Devices has invited people to submit examples of their use of NoiseAssist for a chance to win a pair of Sound Devices branded black and orange socks. Deadline July 10:



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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 02, 2020 2:29 pm

Having now watched Sound Devices's videos on NoiseAssist, and having downloaded and listened to the six demo files on its site, I'm pretty persuaded.

One of my most common scenarios is using a single condenser or lavaliere mike to record a person speaking. If I needed to suppress background noise and decided that a high-pass filter wouldn't do the trick, I would send the signal to two channels, one channel with NoiseAssist active and the other without. This gives the most latitude in post.* Cost is US$300. Adding an additional channel would cost another $300.

For me, one of the big attractions of NoiseAssist is that one can hear its impact via headphones, and dial in the amount of noise suppression desired, before pressing record.

The six demo files show that NoiseAssist will address common noise problems in an urban environment. Paul Isaacs made the first demo in his backyard. If you know Sound Devices co-founder Jon Tatooles's voice, it's clear that he made the other five in indoor and outdoor environments.

In the video below, Paul Isaacs and his colleague talk throughout with NoiseAsist on. They are both in rooms with air conditioners running in the background. Listen to what happens when Isaacs turns off NoiseAssist at 10:10. I didn't even realise that background noise was being suppressed until Isaacs showed it.

For me, the big caveat is that NoiseAssist suppresses the sound of the recording space generally rather than selectively. Whether this matters depends on the purpose of the recording. In the case of Isaacs and his colleague, I don't think it matters. As mentioned, I didn't even notice. However, if one wants the sound of the space, this has an impact on how much NoiseAssist to dial in and on whether it may be necessary to add room tone (sound of the space) later. As Paul Isaacs says in the video, NoiseAssist will suppress reverb, but that is a mixed blessing. If one has to add room tone, there's a question about whether it's a good idea to use NoiseAssist in the first place. Note the comment earlier about recording to two tracks, one with NoiseAsist and one "clean".

I want to hear more demos, but my first impression is favourable. A few months ago, while helping a friend make a Kickstarter video, we had to change locations and shoot a different day because his Manhattan theatre district apartment is two floors above the roof air exchange vents of an adjoining building. There was no point in trying to record sound. NoiseAssist may well have have solved the problem, and importantly we could have tested its impact before making our decision on whether to reschedule and change our recording location.

* My understanding is that this NoiseAssist/Clean split can be done with the 800 series recorders. I'm still unclear about how NoiseAssist works in the signal chain and I need to confirm this for the MixPre. I'd also like to know whether one can use a stereo microphone with the MixPre and apply a single instance of NoiseAssist.


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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 02, 2020 6:57 pm

On Wexler's Sound Group forum there are two threads about NoiseAssist but no posts yet from anyone who has actually tried using it.

As suggested in the above post, I think that the way to use NoiseAssist is to record to both a NoiseAssist track and a raw track.

In relation to that general approach, I came across this interesting exchange on Wexler's forum:

Question: "I wonder if MixAssist and NoiseAssist can both be ran simultaneously on the mixpre ii series?"

Response from a Sound Devices employee: "They can! And you can record raw on location and then use NoiseAssist and MixAssist in Remix mode to deliver to post with the raw files!"

I also think that NoiseAssist may be useful for live broadcast, such as with Blackmagic's ATEM mini, or where there's just no interest in reducing noise in post. The Paul Isaacs video above is a very good example of a situation where there's a real question about whether correction in post is worth the time and effort.

Note that the Wexler forum thread on NoiseAssist and 800 series mixer/recorders is about workflow where the location recordist and the sound editor are different people. Decision-making about NoiseAssist may be different in some cases where the recordist and the editor are the same person.

There are a number of references in the Wexler forum discussion to Cedar. Cedar hardware is what I had in mind when I referred ten posts up to a much more expensive, much less convenient solution. This Gotham Sound video shows how Cedar works:


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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 02, 2020 7:23 pm

Turns out that Curtis Judd has already made a video on using NoiseAssist with an 800 series recorder/mixer. I would also like to see Alex Knickerbocker make one. I would think that Judd will revisit this now that NoiseAssist is available for the MixPre v.2.

00:55: Judd's basement
05:05: his kitchen
09:20: outdoors with a highway in the background


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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 03, 2020 3:27 pm

This new video appears to be the first on YouTube in which an ordinary MixPre user demonstrates the use of NoiseAssist. The video makes it obvious that NoiseAssist works well enough that in some cases its use can avoid a trip to iZotope RX, assuming that one even owns RX. Outside sales, RX 7 Standard is US$400, and Advanced, which I've used since about RX 3, is $1200.

In the video, NoiseAssist is used to suppress the sound of an air conditioner. Because I'm wary of blocking all sound of a recording space (aka room tone/atmo), I would like to have heard the effect with -3dB and -5dB dialled in. This is nevertheless a highly persuasive demonstration. It confirms what Paul Isaacs's video (three posts up) also shows.

I think that there is a big market for this. Note that Sound Devices's current price is described as "introductory". Given the recent MixPre price hikes, I take that proviso seriously.


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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 03, 2020 6:45 pm

Kim Janson wrote:On the Judd's video above, the kitchen -5 db sounded pretty ok, -6 db sounded bad, but surprisingly -9db sounded better? The highway - 10 db was pretty much unusable for me, better without.

On these examples it would be really useful to have both, the one with noice assist and without, of the exactly same recording.


The problem with Judd's highway example is that he went for complete suppression of the highway's sound. This is a very good example of the concern that I expressed above about blocking the sound of the recording space (aka room tone/atmo) entirely. The result is completely unnatural, and unusable, to borrow your word, for that reason alone. Since when does someone stand 100yds/90m from a busy highway and the highway is practically silent? I would like to have heard this example with less suppression.

I also think that this was an obvious situation for trying a good lavaliere rather than a "short shotgun"; in other words, a DPA 4060 rather than the DPA 4017 that he used. A 4060 lav plus enough NoiseAssist to reduce, but not suffocate, the sound of the highway would have been a much more informative test. For that matter, a test with a more directional mike (the 4017 is actually a supercardiod) would have been more helpful.*

I think that NoiseAssist is going to be useful for people who record sound in urban areas and can't control drone-like sounds, especially sounds above about 80Hz, in the background.** This often includes air conditioners and building air vents, but I'd like to hear more real life examples.

For example, how effective is NoiseAssist with overhead airplanes, which in many places are a constant problem? Jon Tatooles, in one of Sound Devices's demo recordings, says that there is a plane above, but I want to hear that plane before and after NoiseAssist is applied. Can't blame Tatooles, because it was chance and right now planes aren't exactly in plentiful supply, but that will change. One reason that a plane is a good test is that it tests NoiseAssist's learning ability and speed of learning, which a constantly running air conditioner does not.

All that said, I think so far that this is a serious product, and that for many people it will be more useful, as a practical matter, than 32-bit recording. There are a fair number of comments on the internet from owners of an original MixPre who are talking about this as a reason to upgrade.

Your second paragraph reflects precisely how sound recordists working on higher-end commercial shoots, where the recordist and the sound editor are different people, are going to use NoiseAssist. See the discussion on Wexler's forum about NoiseAssist and Sound Devices's 800 series recorders/mixers.


* The Schoeps CMC641, widely used to record dialogue, is also a supercardiod. I've never heard anyone call it a shotgun mike, short or otherwise.

** Below 80Hz, sometimes below 100Hz, I think that a high pass/low cut filter would be a better choice. For reference, the lowest note on a standard 88 key piano is 27.5Hz and Middle C is 262Hz.
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Jul 04, 2020 3:38 pm

When using aSound Devices 800 series recorder with NoiseAssist, it's possible to set up the recorder so that one mike yields two tracks, one with NoiseAssist applied and one without. It is not at all clear whether one can effectively do the same thing, possibly via a mix track, with a MixPre. Sound Devices's silence on this question in its MixPre NoiseAssist documentation is not encouraging. I plan to phone Sound Devices this coming week to see what I can learn.

For MixPre recorders, it's possible that a final decision on whether to apply NoiseAssist has to be made at the time of recording. Depending on what one is recording, that would be a definite limitation. However, it's less of an issue if you normally run a backup mike on your source anyway, or are prepared to when NoiseAssist may be needed. Apply NoiseAssist to one mike and record the other clean.

Does anyone here know the answer to the question?
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Jul 05, 2020 9:30 pm

This afternoon, Curtis Judd raised the question posed in the above post during his weekly live stream. He has tested NoiseAssist with an 800 series recorder (see video five posts up), but he doesn't have the MixPre version and doesn't know the answer. Neither did the participants in the discussion. Also, no-one knew what happens if you use a stereo mike. Given how new the plugin is, not surprising, and the documentation is fairly sparse.

Time for a call to Sound Devices support.
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Re: Sound Devices MixPre-6 II (second generation)

PostMon Jul 06, 2020 3:15 pm

It seems to me it might be safer to leave the direct individual channels alone and just apply perhaps 4-5 dB NoiseAssist to the mix L and/or mix R. That way if you don’t like it, you don’t have to use it in post.
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Sound Devices MixPre-6 II (second generation)

PostMon Jul 06, 2020 3:17 pm

iZotope now has software to match the room reverb from one clip to another. So again if the Noise Assit is too strong, you can dial in room ambiance from another track.
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Sound Devices MixPre-6 II (second generation)

PostFri Jul 10, 2020 3:55 am

I hope I’m not repeating myself here (pandemic lockdown apparently can lead to brain ‘fog’), but I thought I’d report how I solved the problem of the Mac Pro late 2019 having no standard live audio (mic) input. There is a standard output (speakers inside the Mac Pro case), but no standard input. Guess the machine was getting too expensive so Apple had to save $10 somewhere.

I have my Line Audio Design CM-4 XLR mics running into the MixPre-6 II and then the mixed stereo audio out the USB-C port to Mac Pro where it was instantly recognized as the System Input. Resolve / Fairlight / ADR also then picked up the audio so I’ll be able to do ADR or Voiceover once again.
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 10, 2020 5:20 am

For anyone not needing field audio, but wanting a high quality and inexpensive input for their computers, check out the Solid State Logic SSL 2 or 2+...

It's a computer audio interface, so not suitable for the production side of things, but it's quite a bit less expensive than a MixPre.
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 10, 2020 5:30 am

Thanks, Rakesh. I went with a deluxe solution since I already had the gear. So it might be a thousand dollar audio input but it’s free now.
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 10, 2020 5:38 am

rick.lang wrote:Thanks, Rakesh. I went with a deluxe solution since I already had the gear. So it might be a thousand dollar audio input but it’s free now.


That was more intended for people on the fence and not certain that they needed to spring for a MixPre. I have a MixPres 6 Mark II for field use + an SSL 2+ attached to my computer... :)
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Sound Devices MixPre-6 II (second generation)

PostFri Jul 10, 2020 2:00 pm

Understand. I like my faux studio setup though, now I can control the ambient noise in the room better than when I had the iMac. For sound work I can turn off the noisy RAID and just use the internal SSD in the Mac Pro. At least that’s the plan. Those inexpensive Line Aufio Design CM-4 mics are nice for voice.
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 10, 2020 4:06 pm

I do still use my MixPre 6II quite a bit, but having it reserved for field use does simplify my home setup a bit. As far as sound quality, with the default setting it would be hard to tell them apart, but I'm actually quite pleased with the SSL 4K setting on the SSL 2+. The distortion it adds is surprisingly pleasing.

And I'm still using my inexpensive Rode NT-1 for dialog and voice over. Its sound is very neutral, almost clinically so, probably what makes the 4K emulation on the SSL2+ sound so nice. Otherwise it's sometimes TOO clean, as is the MixPre. Of course, too clean is far easier to deal with than not clean enough, so... :)
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Jul 11, 2020 3:23 pm

OK, I have read all 14 pages of this thread, with maybe skipping a few pages deep in the middle. Also, in the earlier stages of the thread I admit I cheated and went to Resolve's update page to see if it would ever handle 32 bit audio.

I am about to get the MixPre-6 II and pair them with Diety BP-TRX, Deity You-RX, and Rode VideoMic NTG. And of course the Tentacle Sync E is a part of this as well. Like Rick (thank you for all the initial work you have done with this!), I will also be a typical one man show and being able to set the sound bag aside and know I have backup recordings happening is essential and still get great sound.

The question I have pertains to everyone's comfort level with not only my choice of sound equipment, but the ability to work successfully with the MixPre-6 II and Resolve with as close to zero issues as you can have.

Thanks all.
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Jul 11, 2020 4:48 pm

I'll admit that I haven't used the 32-bit option that much yet because it hasn't been necessary (I usually have a sound person), but I think that Resolve has support for it now.

Having 32-bit audio is a nice option though. I wouldn't go so far as to call it essential, because it's definitely better to get the levels right than to fix them in post, but I did a shoot at an event where I was running solo and didn't have an opportunity to set the levels based on the performances (musicians). For that I used the 32-bit option and it allowed me to extract surprisingly clean audio from that -- seems that my mic placement worked out better than expected with regards to background noise, but more importantly the music was surprisingly clean.

I just don't like relying on that by default, because doing so leads to sloppy field recordings and more post work.

That's not to imply that it's a bad feature, by any means. Just don't let it make you complacent.

If you set the recorder to 32-bit, set your levels initially with some care, then you get the best of both worlds. Even if the actual performance levels turn out to be higher or lower than expected, you're in the ballpark so you aren't creating much extra work for yourself, but your recording is so forgiving that you can generally recover the parts that went beyond anything you could have planned for and didn't have enough hands or enough time to adapt to on set.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Jul 12, 2020 3:32 am

Rakesh’s last paragraph is the key advice I think for a one-man band. When you have time before you are capturing video and audio, you still should check the levels you can. 32bit is another kind of insurance that you’ll get audio in as much as your microphones can manage the highs and lows.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Jul 12, 2020 11:31 am

Thanks Rakesh and Rick. Ordering in a few weeks so trying to get everything nailed down.
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Sound Devices MixPre-6 II (second generation)

PostSun Jul 12, 2020 3:27 pm

One item I don’t think I mentioned is the model. I wanted something small enough to have the option to mount the mixer/recorder as part of my rig. Ergo MixPre-6 II.

The reality is I mount the device on its own stand away from my shooting rig. I only use XLR mics and I can fill all four XLR inputs on the MixPre-6 II. I thought it would be enough but perhaps I should have bought the MixPre-10.

I’ll try to live with my limitations though as I’m not buying more gear until it’s necessary for a project.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Jul 12, 2020 3:52 pm

True statement on the size. I am building both a wireless and wire system so that's one reason why I like the Mix-Pre 6 / Deity combo, all of which will fit into an Orca-28 bag.
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Re: Sound Devices MixPre-6 II (second generation)

PostThu Jul 16, 2020 1:25 pm

Kim Janson wrote:Testing and learning.

After some recearch I got Rode NT1 pair for nature sound and ambience sound recording.
...


Have you seen this video?

I looking at making my own blimp for recording. According to the research I've read, an ellipsoid shape is the most effective. The larger the better, to the extent that people trying to measure environmental noise levels record from within a tent like structure. There are commercial blimps for ambient recording, but they cost thousands. Its easy to create a basic geodesic frame in Blender for 3D printing but I've got a bit of learning to do to make something practical for mounting a microphone. I also want it to be easily broken down to make the blimp easily transportable.
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 17, 2020 10:08 am

Kim Janson wrote:First tests with the setup. This is with iPad using MixPre as audio source



turn the volume up, I heard those birds parely with plain ear

That is insane sensitivity, must have been extremely still air.
Unfortunately I am more likely to be to try record in high wind during a ski tour :-)
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Jul 31, 2020 10:41 pm

robedge wrote:The main thing that I've learned from several years of using iZotope RX is to avoid the need to use it if at all possible. RX is also too expensive for a lot of people.

How about iZotope RX for free?
https://www.pluginboutique.com/articles ... A26,8K2I,1
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robedge

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Re: Sound Devices MixPre-6 II (second generation)

PostWed Aug 05, 2020 12:54 am

dondidnod wrote:
robedge wrote:The main thing that I've learned from several years of using iZotope RX is to avoid the need to use it if at all possible. RX is also too expensive for a lot of people.

How about iZotope RX for free?
https://www.pluginboutique.com/articles ... A26,8K2I,1



The version of RX7 that is currently being sold for US$29 is a perfectly good introduction to the app. It's important to look at what features are included to determine whether it meets your needs.

I believe that it is highly likely that RX8 will be released this fall.
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Re: Sound Devices MixPre-6 II (second generation)

PostWed Aug 05, 2020 1:09 am

I had a discussion with Sound Devices about Noise Assist and the MixPre ii recorders. It's now clear that Noise Assist can be used on those recorders in a way that results in both a Noise Assist track and a "clean" track".

I believe that there will be a video coming out in the near future that demonstrates what Noise Assist can and can't do with both 800 series and MixPre ii recorders.
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Re: Sound Devices MixPre-6 II (second generation)

PostWed Aug 05, 2020 1:34 am

Re 32 bit recording...

Two weeks ago, I used a MixPre ii to make a stereo recording of the most dramatic thunderstorm that I have experienced in three years. The weather forecast made it clear that were in for a show. I decided to make the recording using one set of mikes and 32 bit rather than two sets of mikes at different gain levels.

I processed the files using Reaper, having used Adobe Audition in previous tests. This is not the kind of recording that I want to process in DaVinci Resolve or Final Cut. Currently, Logic insists on converting 32 bit files, on import, to 24 bit. Sound Devices's own WaveAgent will not process 32 bit files. Importantly, iZotope RX7 Advanced, which I don't own (I have RX6 Advanced and I'm awaiting RX8), is the only version of RX that will process 32 bit files.

I think that using 32 bit was the right decision in this case, but doing so has real implications for workflow and for dealing with levels when editing sound. On the latter, the issue isn't just what you do with the otherwise clipped audio, but what you do with the non-clipped audio relatively speaking. From a sound design perspective, this is the kind of recording that iZotope RX is made for, but unless one has RX7 Advanced, the whole file has to be exported, with a 32 bit-friendly application, in 24 bit before bringing the recording into RX.

I remain of the view that 32 bit should be avoided unless there is a hell of a good reason to use it. Some months ago, a person posted here that he's using 32 bit because he records political demonstrations with a single camera-mounted mike. I totally get that. What I don't get are the theoretical discussions that aren't based on practical experience with using 32 bit.

By the way, this was my first experience with Reaper and I think that it's pretty capable software. If you're coming from another DAW, it's a bit idiosyncratic, but Kenny Gioia's videos on YouTube (the channel is called Reaper Mania) are very good if you're trying to figure it out.
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Re: Sound Devices MixPre-6 II (second generation)

PostFri Aug 07, 2020 6:49 pm

This is my first post here, so apologies if I'm rehashing something from the past, but I've been paying attention to the 24-bit vs. 32-bit float capture discussion on this thread, and thought this might be useful.

In my search for an acceptable field recorder a few months back, I ended up with a Zoom F6. I kind of wish I had gone with the MixPre-6 II instead, but alas. There are a couple of things I prefer about the F6, though, and the ability to capture in 32-bit float and 24-bit simultaneously is one of them. (The integrated Sony NP battery slot is another.) I generally like using 24-bit files, but it's really nice to have the insurance with 32-bit float. It's super great to get both at the same time. I always plan on using the 24-bit capture, but if something crazy happens, it's no big deal to use 32-bit float instead. (Well, except that Logic still can't read 32-bit float natively.)

I hope the MixPre series can add this kind of functionality in the future with a firmware update. Don't know if the hardware makes that possible or not. I'm still considering jumping over from the F6.
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Aug 08, 2020 1:47 am

The Other Mark Williams wrote:This is my first post here, so apologies if I'm rehashing something from the past, but I've been paying attention to the 24-bit vs. 32-bit float capture discussion on this thread, and thought this might be useful.

In my search for an acceptable field recorder a few months back, I ended up with a Zoom F6. I kind of wish I had gone with the MixPre-6 II instead, but alas. There are a couple of things I prefer about the F6, though, and the ability to capture in 32-bit float and 24-bit simultaneously is one of them. (The integrated Sony NP battery slot is another.) I generally like using 24-bit files, but it's really nice to have the insurance with 32-bit float. It's super great to get both at the same time. I always plan on using the 24-bit capture, but if something crazy happens, it's no big deal to use 32-bit float instead. (Well, except that Logic still can't read 32-bit float natively.)

I hope the MixPre series can add this kind of functionality in the future with a firmware update. Don't know if the hardware makes that possible or not. I'm still considering jumping over from the F6.


Hi Mark,

A question about the Zoom F6...

My understanding is that if one uses 32 bit you can't set gain levels. Is that correct? If so, presumably it's possible to set levels for 24 bit if one is recording both. How does that work?

Thanks
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Aug 08, 2020 3:28 am

robedge wrote:
The Other Mark Williams wrote:This is my first post here, so apologies if I'm rehashing something from the past, but I've been paying attention to the 24-bit vs. 32-bit float capture discussion on this thread, and thought this might be useful.

In my search for an acceptable field recorder a few months back, I ended up with a Zoom F6. I kind of wish I had gone with the MixPre-6 II instead, but alas. There are a couple of things I prefer about the F6, though, and the ability to capture in 32-bit float and 24-bit simultaneously is one of them. (The integrated Sony NP battery slot is another.) I generally like using 24-bit files, but it's really nice to have the insurance with 32-bit float. It's super great to get both at the same time. I always plan on using the 24-bit capture, but if something crazy happens, it's no big deal to use 32-bit float instead. (Well, except that Logic still can't read 32-bit float natively.)

I hope the MixPre series can add this kind of functionality in the future with a firmware update. Don't know if the hardware makes that possible or not. I'm still considering jumping over from the F6.


Hi Mark,

A question about the Zoom F6...

My understanding is that if one uses 32 bit you can't set gain levels. Is that correct? If so, presumably it's possible to set levels for 24 bit if one is recording both. How does that work?

Thanks

Great question, Rob.

Indeed, if you select the recording mode to be "Float (32bit)", you cannot adjust gain levels (Zoom calls it "trim"). If you select "Dual (24+32bit)", you can adjust the trim level on any channel. The linear (24bit) files get written taking your trim levels into account, and the float (32bit) files get written with no regard to the trim level.

There are several annoyances for me with the F6, but the way it handles this feature is pretty great. If you can sacrifice the storage space (I almost always can), there's little reason in my mind to not record in Dual (24+32bit) mode.
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Aug 08, 2020 4:03 pm

Kim Janson wrote:What puzzles me is that 24 bit can provide 144.49 dB dynamic range. is there any microphone that can provide more?

So why they did not just simply make good 24 bits.


If you read the thread you'll see the arguments for 32-bit float for a field recorder. Bottom line is that it's ease of use / avoiding clipping.

Kim Janson wrote:Further more if 150 dB would be stored in 16 bit as decibels, not linear as it is now, that would provide 0.005 decibel separation. That should be more than enough.


Can you explain that, because I think I'm missing something.
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Aug 08, 2020 4:52 pm

Mattias Murhagen wrote:
If you read the thread you'll see the arguments for 32-bit float for a field recorder.
.


I noticed from your comment to Kim that that you're in New York. The storm referred to in the post 5 above was the one we had on July 22. Here's a screen capture from iZotope RX. The recording is 76 minutes long at 96kHz.

The Waveform Statistics True Peak (+25.7dB), Minimum RMS (-34.2dB) and "Possibly Clipped Samples" (>100,000) tell the story. The MixPre and Reaper handled this well, but it's not something that I'm eager to deal with on a regular basis :)
:


Screenshot 2020-08-08 at 12.46.30.jpg
Screenshot 2020-08-08 at 12.46.30.jpg (800.3 KiB) Viewed 8684 times
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Aug 08, 2020 6:09 pm

I remember the storm. It sounded great!
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Re: Sound Devices MixPre-6 II (second generation)

PostSat Aug 08, 2020 8:38 pm

Mattias Murhagen wrote:I remember the storm. It sounded great!



Yup. I think that it was the most dramatic storm we've had here in three years.

For those who are interested, this is what the 32-bit recording looks like in Reaper before the peaks are brought down below 0dB. The next step is to decide how one wants to bring the peaks down, which in turn depends on what one wants as a 24-bit export.

I plan to use this recording to make background ambience/sound effects. That means that just reducing the gain for the whole recording, by an amount sufficient to bring all the peaks below 0dB, isn't going to cut it. Why? Because that would dramatically reduce the levels of everything that is already below 0dB.


Screenshot 2020-08-08 at 16.29.21.jpg
Screenshot 2020-08-08 at 16.29.21.jpg (303.45 KiB) Viewed 8646 times
Last edited by robedge on Sat Aug 08, 2020 10:36 pm, edited 5 times in total.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 12:14 am

Quick question for the MIxPre 6 II. Is everyone using the branded Sound Device SAM-64SD SD card, or are you using another one?
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 12:22 am

jallen0 wrote:Quick question for the MIxPre 6 II. Is everyone using the branded Sound Device SAM-64SD SD card, or are you using another one?


I'll be surprised if a lot of people are using Sound Devices branded cards. I'm sure they're fine, but they aren't readily available, and for me, at least, don't come to mind. Personally, I use SanDisk.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 1:41 am

Kim Janson wrote:"Can you explain that, because I think I'm missing something"

16 bit is about +-32 000 levels. If the AD converter would be true 24 bit or false 32 bit as we have now, it could store the data with 16 bit in logarithmic scale, really without loosing anything. On playback it would need to be converted back to linear.

This is especially true when looking the time domain also. These pictures are already plenty of samples considering any available sample rate and 20 kHz audio signal.



You'll get the noise floor of 16bit and the floor will be raised when you decompress the audio
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 5:15 am

I'm too tired to re-read what you wrote in detail, but something tells me that you're missing something fundamental. Or I am.

Briefly: I don't think it's correct to imply that there are "the first 8 bits" that somehow represent a signal more poorly than the "top" 8 bits. A signal that is close to peak doesn't occupy multiple places during a sample, only one place, and thus only needs one value to be represented. The same is true at any point in time. Those "first" 8 bits are a part of an entire number, but they don't represent any lower "resolution" of the signal than the "top" 8 bits do. It would be like saying that the number "7842" has higher "resolution" than the number "0042". It doesn't.

Bit depth is about SNR.

And I read the previous post too and though I understand all of the words and phrases I just don't see how it all comes together to something that has meaning. What do you mean by "linear" versus "logarithmic" in these contexts? Can you link to some white papers or something on this? I really want to understand what you mean but (apart from being too tired right now) I'm struggling to see your reasoning.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 12:21 pm

Kim Janson wrote:Sound levels are given on decibels because that is how we humans experience it. If we agree on that, my question is why do we not store the audio on logarithmic scale (decibels).


I’m not following this discussion, and I don’t know how much your argument depends on the accuracy of the above statement, but it’s an oversimplification.

We developed a new way to measure loudness, now captured in broadcast standards, precisely because decibels don’t capture how humans experience sound.

For one thing, frequency plays a significant role in how sound is experienced. That experience can have an interesting impact when one records sound, setting gain in dB Full Scale. You can see this by making two sound recordings of a passing train, one without a high pass/low cut filter engaged and one with. You’ll discover that using a filter to reduce the amount of low frequency energy you’re recording, even though that low frequency energy doesn’t sound as loud to your ears as higher frequency energy (e.g. a police car siren), will significantly reduce your risk of clipping.
Last edited by robedge on Sun Aug 09, 2020 9:01 pm, edited 1 time in total.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 1:40 pm

jallen0 wrote:Quick question for the MIxPre 6 II. Is everyone using the branded Sound Device SAM-64SD SD card, or are you using another one?


I have been using these(32Gb and 128Gb), with no problems:

https://www.lexar.com/portfolio_page/pr ... -ii-cards/

A word of caution... from reading a lot of posts on this subject there seems to be a number of different cards that work, and a number that don't, all from reputable brand names and from a variety of dealer sources. Some have reported that the same model numbers have been used on different versions, making the search a mine field.

My advice (if you can't or don't want to buy from Sound Devices)...

1) Buy only premium brands from trusted retailers.
2) Buy a couple of cards of the same brand, series and capacity.
3) Format cards as recommended by Sound Devices.
4) Test both cards "extensively" before you commit them to critical tasks.
5) If you need more cards repeat all of the above tests.

The weak point of the MixPreII series is that they do not have redundant recording to a second card, but can do a backup to a USB device AFTER the take has been recorded to the original card. That doesn't represent a safety take (more a convenience than safety), imo.

I love this little machine, it has never let me down, but I would not use it for a once in a lifetime recording or commercial shoot without a true backup in place.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 2:03 pm

Thank Ron. I am planning to use the Angelbird AV PRO SD MK2 V60 128GB SD card. It meets the specs listed on the Sound design card and I would be surprised if it doesn't;t work.

You post is very informative and I am wondering if there is something else going on besides the brand of the card. If the card meets the spec it should work. I will certainly test out this card before committing to it.

As to backup's...yep I plan on having a backup. Currently that it a Deity BP-TRX, as well as a Deity S-Mic 2S on the camera. Other than buying a second audio mixer I am not sure what else I can do.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 6:21 pm

Mattias Murhagen wrote:Briefly: I don't think it's correct to imply that there are "the first 8 bits" that somehow represent a signal more poorly than the "top" 8 bits.


You're right; a number is a number, and there's no division. They're ALL 8, 16, 24, or 32 bits, not mixed. Whether the number is 1 or 1,000,000,000 it's represented by the same number of digits.

Bit depth is about SNR.


No, it's not. The SNR is electronic. It comes from the preamps, and has nothing to do with the bit depth of the recording; the bit depth determines how many steps you have on your ladder, the noise floor is how much of the ladder you plunked in the water. The height of the ladder depends on its height, not on how many steps it has.

And I read the previous post too and though I understand all of the words and phrases I just don't see how it all comes together to something that has meaning. What do you mean by "linear" versus "logarithmic" in these contexts?


The log vs linear thing is similar. In a "linear" ladder every step represents an incrementally higher value. In a logarithmic scale the steps of the ladder are the log of the value they're encoding. So to represent a step whose value is 1,000,000,000 you'd use (in a log base 10) 9 -- 9 zeroes, i.e. it's 1 * 10 raised to the 9th power. The log of that is 9. (It's very simple with evenly divisible numbers, chosen because they're easier to understand.)

In sound 6 dB represents twice the loudness. So the first six steps represent, say, numbers from 1-2. The next six represent 2-4. Then 4-8. Then 8-16.

Except for the specific numbers, it's exactly the same as the way that video is log encoded, in the most basic curves. The more sophisticated curves are more complex because their encoding isn't a simple and straightforward log, but reading up on log encoding for video is conceptually the same as for audio -- and for the same reason; our ears much like our eyes function logarithmically.
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Re: Sound Devices MixPre-6 II (second generation)

PostSun Aug 09, 2020 7:05 pm

Kim Janson wrote:Linear Scale 0 1 2 3 4 5 6 7 8 9 10 (+1)
Logarithmic Scale 1 2 4 8 16 32 64 128 256 512 1024 (x2)


For example 16 bit dBnoise = 20 x log (1/65536) = -96.3 dB.


Sound levels are given on decibels because that is how we humans experience it. If we agree on that, my question is why do we not store the audio on logarithmic scale (decibels).

If you look the above formula, on 16 bits we are storing values between 1 to 65536 on linear scale.

If we now calculate

20 x log (1/65536). = -96.3 dB.
20 x log (2/65536) = -90.3 dB (6 db per step)
20 x log (3/65536) = -86.7 dB
...
20 x log (1000/65536) = -36.32959 dB
20 x log (1001/65536) = -36.32091 dB (0.0086 dB per step)
...
20 x log (30000/65536) = -6.78717 dB
20 x log (30001/65536) = -6.78688 dB (0.00029 dB per step)
...
20 x log (65535/65536) = -0.000132 dB
20 x log (65536/65536) = 0.000000 dB

So you can see how on one end the change of one unit on the linear value has a huge affect on decibels.

So the way I would like to see is, lets think we have a true 32 bit AD converter, it provides 192.66 dB dynamic range. Lets store that as 16 bit but instead linear scale in decibels, so one step on the 16 bit value is always

192.66 dB / 65 636 = 0.00293527 decibels.

When playing back or editing the same conversion is do ne reversed to get the original 32 bit and 192.66 dB dynamic range presentation, without loosing anything anyone could hear.

Ps. at linear 32 bit the first step still is 6 dB

20 x log (1/4294967296)=-192.65 dB
20 x log (2/4294967296)=-186.63dB

but

20 x log (65536/4294967296)= -96.329598 dB
20 x log (65536/4294967296)= -96.329731 dB ( 0.00013 dB per step)

So with 32 bit linear presentation we get good level of details where the 16 bit noise floor is.

Note though, SD and other are not using pure 32 bit presentation, but floating point presentation and I have not seen any understandable presentation why.

from SD "The dynamic range that can be represented by a 32-bit (floating point) file is 1528 dB." this is a total overkill, best microphones can maybe handle 150 dB and from MixPre 6II specs

ADC

32 bit precision; 142 dB dynamic range min (A-weighted, gain=10dB, fader=0dB)
Equivalent Input Noise

-130dBV (-128dBu) max (A-weighting, gain=76dB, 150 ohm source impedance)

And loudest possible sound on air is 194 dB and so they are just wasting dynamic resolution with the 1528 db theoretical dynamic range.

I think your terminology is confused. PCM quantizes in a non linear fashion. It gives less bits to louder signals and more bits to lower signals. You want a linear allocation of bits per decibel, similar to what LPCM does. That sounds good, but it introduces much greater quantization error in low level signals. Higher level signals require less bit allocation while low level signals require more bits to maintain the signal to noise ratio. If you try to spread out the bits(16 bit depth) over 194db, matters just get worse as even less bits go to low level signals.
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