You are here

Sound Devices MixPre II range

All about the tools and techniques involved in capturing sound, in the studio or on location.

Re: Sound Devices MixPre II range

Postby Bob Bickerton » Tue Sep 03, 2019 8:25 am

This thread has taken an unfortunate turn gentlemen.

A cursory glance (at Sweetwater) would suggest the M10 II version is selling for US$400 less than the previous iteration. I’m OK putting up with improved specs with a price saving like that, despite what the sceptics say.......... and I’m OK operating a piece of gear knowing that idiots will have a better chance of grabbing a decent take, even though I know a little about gain structures myself.

I can imagine the improved headroom would be useful for natural history recording, for example where I might be recording distant birdsong but then have something start up close by.

Oh, and I really like the look of the enlarged main encoder....... and I see the MixPre 3 now ships with a power supply :thumbup:

Bob
User avatar
Bob Bickerton
Frequent Poster (Level2)
Posts: 3872
Joined: Fri Dec 20, 2002 1:00 am
Location: Nelson, New Zealand
http://www.bickerton.co.nz

Re: Sound Devices MixPre II range

Postby Hugh Robjohns » Tue Sep 03, 2019 9:52 am

Paul Isaacs wrote:But there are some real world cases where this can be of real benefit

Yes, I get that completely. Good points, well made... and I agree with you about the constructed music thing too.... :lol:

H
User avatar
Hugh Robjohns
Moderator
Posts: 24343
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Sound Devices MixPre II range

Postby John Willett » Tue Sep 03, 2019 10:13 am

Hugh Robjohns wrote:
Paul Isaacs wrote:To eliminate chance of clipping in 1), make an input stage that can handle a huge dynamic range...

...or just set the recorder's gain structure up properly with plenty of headroom so that clipping can't happen... :-)

To eliminate chance of clipping in 2), use 32-bit float format such that you can now record 100's of dB above 0dBFS.

...or set the recorder's gain structure up with plenty of headroom so that converter overload can't happen... :-)

Without wanting to bash Sound Devices' technological mastery in these matters, it seems to me this is really about marketing numbers to match the competition, and to make the unit's operation almost totally idiot-proof -- rather than meeting any genuine engineering or operational requirements.

Obviously this kind of technology primarily reduces the need to configure and operate the equipment knowledgeably and skilfully at source, allowing what would otherwise be incompetent, overloaded and unusable, recordings to be salvaged in post-production. It's the audio equivalent of RAW files for digital cameras, allowing over- or under-exposed images to be fully recovered...

It's the modern way, I guess. Why bother to teach/learn and apply a complicated technical skill, when the technology can do it for you? After all, it's been a hugely successful and popular approach in the world of in digital cameras.

All we really need now is a self-positioning microphone, or some kind of new mic technology that can analyse the soundfield it captures and work out what the ideal sound should be if one or more virtual microphones were placed somewhere other than where the real microphone actually is located... And I'm quite certain it will happen within a decade or so... :D The SoundField technology goes some of the way already...

I guess a lot of this is also to do with the fact that many MixPres will be used by cameramen who know very little about sound and the excellent headroom is to enable a novice user to get good audio. ;)
User avatar
John Willett
Jedi Poster
Posts: 6254
Joined: Tue Mar 07, 2000 1:00 am
Location: Oxfordshire UK
John
Sound-Link ProAudio
Circle Sound Services
President - Federation Internationale des Chasseurs de Sons

Re: Sound Devices MixPre II range

Postby Wonks » Tue Sep 03, 2019 10:14 am

But does it then get normally passed over to someone who does know what they are doing? Just curious as I don't know. If so, why aren't they there for the recording - cost I suppose?
User avatar
Wonks
Jedi Poster
Posts: 9220
Joined: Thu May 29, 2003 12:00 am
Location: Reading, UK
Correcting mistakes on the internet since 1853

Re: Sound Devices MixPre II range

Postby ef37a » Tue Sep 03, 2019 11:36 am

"This thread has taken an unfortunate turn gentlemen."

Well perhaps Bob but consider, had these dynamic range claims been made by a "lesser" audio company than Sound Devices I am sure the questioning would been less "gentle" shall we say?

I am no expert in audio of course but the figures quoted caused me pause from all I thought I had learned in the last half century and more and in the last ten years regarding digital sound (mainly gathered from SOS of course!)

I await a review with barely controlled passion!

Dave.
ef37a
Jedi Poster
Posts: 10597
Joined: Mon May 29, 2006 12:00 am
Location: northampton uk

Re: Sound Devices MixPre II range

Postby Bob Bickerton » Tue Sep 03, 2019 12:13 pm

It’s just that everyone wet their pants around here when Zoom announced the F6 with 32 bit float - but as you say, the review will be very interesting........

Bob
User avatar
Bob Bickerton
Frequent Poster (Level2)
Posts: 3872
Joined: Fri Dec 20, 2002 1:00 am
Location: Nelson, New Zealand
http://www.bickerton.co.nz

Re: Sound Devices MixPre II range

Postby MOF » Tue Sep 03, 2019 2:05 pm

But does it then get normally passed over to someone who does know what they are doing? Just curious as I don't know. If so, why aren't they there for the recording - cost I suppose?

Good question, I saw an item on the One Show that had clearly been recorded RAW and not graded, the Beeb fobbed me off again when I complained instead of ‘thank you we’ll make sure that doesn’t happen again’.
MOF
Regular
Posts: 358
Joined: Thu Mar 06, 2003 1:00 am
Location: United Kingdom

Re: Sound Devices MixPre II range

Postby Ariosto » Tue Sep 03, 2019 2:43 pm

I think the people who are ignorant about gain structure and all else will benefit from the 32bit. However, they mostly won't have trained ears and so will mess up in so many other ways, that in the end only the well trained, experienced and competent engineers/producers/musicians will really deliver good sound on their recordings.
Ariosto
Frequent Poster
Posts: 805
Joined: Sun May 04, 2008 12:00 am
Location: LONDON, UK

Re: Sound Devices MixPre II range

Postby Paul Isaacs » Tue Sep 03, 2019 3:27 pm

ef37a wrote:Hi Paul,
thank you for that explanation but this other cynical person would still like further clarification!

The input clipping level of +12dBV (+14dBu) is more remarkable but cannot, it seems to me, exist at the same time as the EIN figure?

Dave.

Yes it can because we are running more than one ADC (and more than one preamp in front of each ADC), so both -128 dBu and +14 dBu are simultaneously available, for a total of 142 dB. Gain is then applied in the digital domain. Multi-stage ADC setups are nothing new - they date back to the '70s, but ours is a new spin (with a patent) which we feel outperforms anything else. You're free to read the patent if you so choose ... https://patents.google.com/patent/US9654134B2/en, but trying a unit will reveal so much more to you. Check these samples: https://www.sounddevices.com/noise-in-32-bit-float/
Paul Isaacs
Poster
Posts: 24
Joined: Fri May 05, 2017 4:30 pm
Paul Isaacs
Sound Devices LLC

Re: Sound Devices MixPre II range

Postby MOF » Tue Sep 03, 2019 3:38 pm

If so, why aren't they there for the recording - cost I suppose?
It still stands a good chance of coming back poor quality because the camera operator rarely 'actively' listens on closed back headphones.
MOF
Regular
Posts: 358
Joined: Thu Mar 06, 2003 1:00 am
Location: United Kingdom

Re: Sound Devices MixPre II range

Postby Hugh Robjohns » Tue Sep 03, 2019 4:19 pm

Paul Isaacs wrote:Yes it can because we are running more than one ADC (and more than one preamp in front of each ADC), so both -128 dBu and +14 dBu are simultaneously available, for a total of 142 dB. Gain is then applied in the digital domain. ... ours is a new spin (with a patent) which we feel outperforms anything else. You're free to read the patent if you so choose

Thanks for the link Paul. I've only skim read it so far (I hate reading patents...), but that looks a very elegant and clever solution. :thumbup: :D

H
User avatar
Hugh Robjohns
Moderator
Posts: 24343
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Sound Devices MixPre II range

Postby cyrano.mac » Thu Sep 05, 2019 6:04 pm

ef37a wrote:The 32 bit float bit I get. What boggles me is an analogue stage with a dynamic range of 142dB? .

Yep. Seems remarkable that the same mic pre has a DR of 142 db. That would be quite a feat. Don't get me wrong, these mic pres are quite good. But 142 dB is in the realm of next-to-impossible for a mic pre.

That's not the only thing that's dodgy. They list Logic Pro X as "not supporting 32 bit float". I'm pretty certain it does. Most DAW's work internally in 32 bit float. Reaper and some others even work in 64 bit float. Hec, even Audacity works in 32 bit float internally.

Maybe Logic Pro X doesn't import their version of 32 bit float files?

And then there's this, very dubious answer:

Q: Will you continue to support the original MixPre series?

A; The MixPre Series will continue to receive updates that the hardware will support

I'm pretty sensitive to this kind of foolery because, while I loved my USB pre, I had to junk it because Sound Devices flat out refused to update the firmware loader. How hard can it be to update a tiny tfpt app? And this answer might lead some to think that their older recorders will be updated.

And then there's this bit about 770 dB headroom. Yeah, right. try again please!

Unless they're using AD's that are 32 bit float internally. Only I've never heard of such beasts. 32 bit, yes. 32 bit float @ 196 kHz?

I'm guessing they use the exact same trick as Zoom is using. Two 20 bitters, level shifted. That results in 32 bit alright, but not in 32 bit float...
cyrano.mac
Regular
Posts: 61
Joined: Sun Jun 02, 2019 5:00 pm

Re: Sound Devices MixPre II range

Postby ef37a » Thu Sep 05, 2019 6:19 pm

cyrano.mac wrote:
ef37a wrote:The 32 bit float bit I get. What boggles me is an analogue stage with a dynamic range of 142dB? .

Yep. Seems remarkable that the same mic pre has a DR of 142 db. That would be quite a feat. Don't get me wrong, these mic pres are quite good. But 142 dB is in the realm of next-to-impossible for a mic pre.

That's not the only thing that's dodgy. They list Logic Pro X as "not supporting 32 bit float". I'm pretty certain it does. Most DAW's work internally in 32 bit float. Reaper and some others even work in 64 bit float. Hec, even Audacity works in 32 bit float internally.

Maybe Logic Pro X doesn't import their version of 32 bit float files?

And then there's this, very dubious answer:

Q: Will you continue to support the original MixPre series?

A; The MixPre Series will continue to receive updates that the hardware will support

I'm pretty sensitive to this kind of foolery because, while I loved my USB pre, I had to junk it because Sound Devices flat out refused to update the firmware loader. How hard can it be to update a tiny tfpt app? And this answer might lead some to think that their older recorders will be updated.

And then there's this bit about 770 dB headroom. Yeah, right. try again please!

Unless they're using AD's that are 32 bit float internally. Only I've never heard of such beasts. 32 bit, yes. 32 bit float @ 196 kHz?

I'm guessing they use the exact same trick as Zoom is using. Two 20 bitters, level shifted. That results in 32 bit alright, but not in 32 bit float...

Have you looked at the patent Cyrano? I only get the barest inkling of how it works but it seems to switch seamlessly (?) between pre amps which are of the optimum gain and headroom
as the signal changes level and "best fit" pre is routed to a converter.

Seems to this old analogue dino' that is is roughly akin to class G power amplifiers?

I am concerned by YOUR concern that there will be a trail of broken SD devices left in a few years time? I don't quite know why but I get a whiff of the "whizz kid/yuppy/let's make money and sod the legacy stuff" attitude?

Said it before, there orta be a law.

Dave.
ef37a
Jedi Poster
Posts: 10597
Joined: Mon May 29, 2006 12:00 am
Location: northampton uk

Re: Sound Devices MixPre II range

Postby cyrano.mac » Thu Sep 05, 2019 6:32 pm

Paul Isaacs wrote:Yes it can because we are running more than one ADC (and more than one preamp in front of each ADC), so both -128 dBu and +14 dBu are simultaneously available, for a total of 142 dB.

That explains a lot. Not a "classic" number from measurement, but it's not exactly a "classic" thing to explain either. :headbang:

I've since downloaded the pdf of the patent. It's more readable than Google's text, that leaves out the pics...

Can you explain to a simple soul, like myself, what's different between your dual ADC approach and the one that's been used for let's say, several decades?

AFAICT from the patent, it's mostly the same. But then patents aren't written to be readable...
cyrano.mac
Regular
Posts: 61
Joined: Sun Jun 02, 2019 5:00 pm

Re: Sound Devices MixPre II range

Postby cyrano.mac » Thu Sep 05, 2019 6:45 pm

ef37a wrote:Have you looked at the patent Cyrano?

Like Hugh, I've only skimmed it. Enough to realise it's a patent. It tells us as little as possible, in a very complicated way. That's just how patents are.

I am concerned by YOUR concern that there will be a trail of broken SD devices left in a few years time? I don't quite know why but I get a whiff of the "whizz kid/yuppy/let's make money and sod the legacy stuff" attitude?

Said it before, there orta be a law.

Dave.

Well, surely not broken Dave. Recorders are standalone devices, fortunately. Interfaces, OTOH...

I still have the old computer I kept to keep the USB Pre running. I first started up with an old OS, ran the firmware loader and rebooted into a somewhat less ancient OS...

But that's hardly practical, so I changed to an RME. At least they provide drivers for their old hardware. And my RME is old now. But it still runs fine. Costs less too and the preamps are better. Digitally controlled. Still, I liked that little black box with it's colorful metering.
cyrano.mac
Regular
Posts: 61
Joined: Sun Jun 02, 2019 5:00 pm

Re: Sound Devices MixPre II range

Postby Paul Isaacs » Tue Sep 10, 2019 3:08 am

Thought this might be of interest to some of you ...

https://www.sounddevices.com/low-signal-32-bit-float/

Paul
Paul Isaacs
Poster
Posts: 24
Joined: Fri May 05, 2017 4:30 pm
Paul Isaacs
Sound Devices LLC

Re: Sound Devices MixPre II range

Postby Hugh Robjohns » Tue Sep 10, 2019 9:50 am

I don't understand the presence of apparent quantising steps in the 24 bit version. The noise I get, obviously, but not the steps. Something amiss there surely?

H
User avatar
Hugh Robjohns
Moderator
Posts: 24343
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Sound Devices MixPre II range

Postby ef37a » Tue Sep 10, 2019 9:54 am

Hugh Robjohns wrote:I don't understand the presence of apparent quantising steps in the 24 bit version. The noise I get, obviously, but not the steps. Something amiss there surely?

H

I am struggling with all this! Just a wild guess Hugh but are you saying dithering should have removed the steps?

Dave.
ef37a
Jedi Poster
Posts: 10597
Joined: Mon May 29, 2006 12:00 am
Location: northampton uk

Re: Sound Devices MixPre II range

Postby Hugh Robjohns » Tue Sep 10, 2019 10:09 am

Yes... it looks under-dithered to me...
User avatar
Hugh Robjohns
Moderator
Posts: 24343
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Previous

Who is online

Users browsing this forum: fruitcake, jimh76