Become a Site Supporter and Never see Ads again!

Author Topic: Sound Devices MixPre-3 and 6, Part 3  (Read 29467 times)

0 Members and 1 Guest are viewing this topic.

Offline johnw

  • Trade Count: (9)
  • Needs to get out more...
  • *****
  • Posts: 3745
  • Gender: Male
    • My cd List
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #375 on: September 13, 2017, 03:20:35 PM »

4. Don't all the other SD multitrack recorders use Polywave files?


My 744 does mono files. Still requires wave agent  for my workflow.
Schoeps MK41 & MK4V  |  Schoeps CMC6, Schoeps KCY, AKI/2C, PFA, Nbox Cable/PFA  |  Grace V2, Nbox Platinum  |  SD744T, SD MixPre 6, Sony PCM M10

Canon 16-35mm/2.8L mkii, 24-70mm/2.8L, 70-200mm/2.8L IS, 50mm/1.8 mkii, 135mm/2L, 100mm/2.8L IS, Sigma 35mm/1.4 A  |  Canon 5D mk4

Offline Todd R

  • Over/Under on next gear purchase: 2 months
  • Trade Count: (29)
  • Needs to get out more...
  • *****
  • Posts: 4857
  • Gender: Male
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #376 on: September 13, 2017, 03:26:30 PM »
Thinking more about the noise of the Mixpre-6 and not the dynamic range, I've been trying to work through what it means to record at close to 0dbFS (by actively riding gain levels presumably, and thus the need for configuring for gain knobs and not fader knobs) vs just setting and forgetting and maybe getting peaks of -12dbFS, or -24dbFS.  Trying to understand how it affects your recordings after you normalize in post to bring the -24dbFS peaks to 0dbFS.

You need to think about the overall noise in the system, which would include the internal noise of the MixPre-6 and the noise of the microphones you're using (among other sources of noise).  The specs of the MP-6 put the noise at -128dBu (or -130dBV).  Noise of a gain stages (op amps, whatever) are largely independent of gain levels.  So the noise at -128dBu spec'd by SD at 76db of gain, is probably something close to -128dBu at only 20db of gain, or whatever.

The MP-6 has noise of -128dBu and a max input level of 14dBu.  A very low noise mic like the Shure KSM-141 has a signal to noise level of 80db.  For comparison, the Schoeps cmc6/mk4 has a S/N level of 79db and the DPAs have a S/N level of 74db.  With a somewhat typical mic sensitivity of 10mA/Pa (-38dBu at 94db SPL), you'd have noise levels from the mic of about -92dBu at concert SPLs (~120db say).  This mic noise level gets amplified whether you use the mic pre of the MP-6 to amplify it or whether you amplify it in post by normalizing.

In this example, say you will need about 26db of gain to reach 0dbFS.  If you provide 26db of gain at the MP-6, the noise of the KSM-141 mic once amplified is about -66dBU, and the recorder has a noise floor of -128dBu (so the mic noise swamps the MP-6 recorder noise).  If you provide no gain, you get peaks of -26dbFS, and you need to add 26db of digital gain in post to get to 0dbFS.  Your mic noise once amplified in post is once again -66dBu, but the noise of the MP-6 (-128dBu) once normalized to get to 0dbFS is now -102dBU.  So the noise of the MP-6 is much higher by recording lower and adding gain in post, but it doesn't matter and you won't hear it, since the mic noise is at -66dBu and still swamps the noise of the MP-6.

Not the case if you do the same thing with the Tascam DR-70d.  It's specs put it at -92dBu of noise (and a max mic input of 0dBu).  With the same Shure mic with an 80db S/N ratio and the same concert SPL, if you add gain at the recorder to get to 0dbFS, the recorder noise floor will be below the mic noise floor.  But record at -12dbFS or less, once you add digital gain in post, the noise of the DR70d once amplified in post is now louder than the mic noise of the Shure mic. 

So with the MP-6 and the noise level of its preamps, you can add 25-30db of gain (or more) in post and the recorder noise floor is still below the noise floor of the mics.  Not the same for the DR70d, record at peaks of -12dbFS or less and normalize in post, and the noise of the recorder becomes worse than the noise of the mics.

Of course, there's also the noise at the venue (HVAC, people shuffling feet, whatever), which is probably easily at a SPL of 55-60db.  This noise will swamp both the mic noise and the recorder noise, regardless of which recorder you use and regardless of whether you record at -18dbFS or 0dbFS.

At any rate, there really is no need with the MP-6 to try to record at say -2dbFS is you're planning on boosting in post anyway.  Add 2db in post, add 20db in post, really doesn't make a difference.
Mics: Microtech Gefell m20/m21 (nbob/pfa actives), Line Audio CM3, Church CA-11 cards
Preamp:  none <sniff>
Recorders:  Sound Devices MixPre-6, Sony PCM-M10, Zoom H4nPro

Offline noahbickart

  • Site Supporter
  • Trade Count: (28)
  • Taperssection All-Star
  • *
  • Posts: 1576
  • Gender: Male
  • So now I wander over grounds of light...
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #377 on: September 13, 2017, 04:06:55 PM »
Don't forget that the only way to realize 130db dynamic range in a PCM recording is to run 24 bit at almost full digital scale. If your recording peaks are just reaching -8, then you are only recording at 16 bit depth. You'll still get 96 db of dynamic range which is more than most recording situations have anyway. Just don't put too much weight on 130 db analog dynamic range when running full digital scale is the only way to actually get it.

Yes, and actually playing back music at 130db would render you unable to ever hear anything ever again. The point remains that the mixpre is never going to be the limiting factor in terms of noise. So running levels conservatively will allow for capture of full signal.

I understand and respect that tapers wish to use the knobs on the mixpre to set gain. I'm just reminding everyone that you might consider using "advanced mode" and leave the gain at +10db, never peak over at -20 and normalize in post.

That's true. I'm certainly not opposed to having those feature added and might even use them.

Also, people have different sonic and ergonomic preferences. The zoom machine might work better for some users. I bet recent Purchases of mixpre6 and mixpre3 recorders won't lose much value.

AGREED.  But.
I would think being able to link the GAIN channels, having a Record Pre-roll and record Pause would benefit many and hurt none.

TS community support for feature requests is appreciated https://www.sounddevices.com/support/inquiry ;)
Recording:
Capsules: Schoeps mk41v, mk4v, mk22, mk3 & mk8
Cables: 2x nbob KCY, 1 pair nbob actives, Darktrain 2 and 4 channel KCY extensions:
Preamps:    Naiant Littlebox, Naiant IPA, Naiant PFA, Sound Devices Mixpre6
Recorders: Sound Devices Mixpre6, Sony PCM m10
Home Playback: Mytek DSD 192> Adcom SLC 505> Marantz Ma500 (x2)> Eminent Tech LFT-16; Musical Fidelity xCan v2> Hifiman HE-400
Office Playback: Grace m903> AKG k701

Offline dallman

  • Trade Count: (27)
  • Taperssection All-Star
  • ****
  • Posts: 1509
  • Gender: Male
    • Clifford Morse
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #378 on: September 13, 2017, 06:43:08 PM »
We can send our feature requests to Sound Devices here https://www.sounddevices.com/support/inquiry

I would think being able to link the GAIN channels, having a Record Pre-roll and record Pause would benefit many and hurt none.

TS community support for feature requests is appreciated https://www.sounddevices.com/support/inquiry ;)
Based on the above link and note, I reached out to Sound Devices and I explained how I use the deck and that it'd be nice to link channels when the front knobs are being used for gain. I also asked for pause with pre-record and record lock. I received a very nice personal note in a fairly short amount of time that stated many others are requesting the same things and while they make no promises my request is being added to the list for future firmware updates.

So anyone else who might want software changes, I suggest letting Sound Devices know. I couldn't hurt and at least they are listening.
Support Live Music: Tape A Show Today!
Deck>possibly something here> Mics

Offline tom the taper

  • Site Supporter
  • Trade Count: (6)
  • Taperssection Regular
  • *
  • Posts: 99
  • Gender: Male
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #379 on: September 13, 2017, 07:31:15 PM »
We can send our feature requests to Sound Devices here https://www.sounddevices.com/support/inquiry

I would think being able to link the GAIN channels, having a Record Pre-roll and record Pause would benefit many and hurt none.

TS community support for feature requests is appreciated https://www.sounddevices.com/support/inquiry ;)
Based on the above link and note, I reached out to Sound Devices and I explained how I use the deck and that it'd be nice to link channels when the front knobs are being used for gain. I also asked for pause with pre-record and record lock. I received a very nice personal note in a fairly short amount of time that stated many others are requesting the same things and while they make no promises my request is being added to the list for future firmware updates.

So anyone else who might want software changes, I suggest letting Sound Devices know. I couldn't hurt and at least they are listening.

THANK YOU Dallman!!!
That's the spirit and support I value from the TS community!!




MK4V, MK41, MK3, AKG 414XLII, CSB
V3, SD mp2, UA5
MixPre-6, 744, M10, MT II, MT2496, SV250, D5, D6
NBob Actives, GAKables

Online justink

  • Trade Count: (4)
  • Taperssection All-Star
  • ****
  • Posts: 1726
  • Gender: Male
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #380 on: September 13, 2017, 11:11:44 PM »
Don't forget that the only way to realize 130db dynamic range in a PCM recording is to run 24 bit at almost full digital scale. If your recording peaks are just reaching -8, then you are only recording at 16 bit depth. You'll still get 96 db of dynamic range which is more than most recording situations have anyway. Just don't put too much weight on 130 db analog dynamic range when running full digital scale is the only way to actually get it.

This.

And I've found that my recordings sound better when I push the levels hot while recording as opposed to running super conservative (-12db peaks) and normalizing in post.

The hotter recording always sounds more full and beefy (for lack of a better term).
Mics:
DPA 4028 (wide cards)
DPA 4023 (cards)
Earthworks TC25 (omnis) 

Pres and a/d's:
Oade ACM Grace Lunatec V3 (FOR SALE - Make Offer)
bm2p+ Edirol UA-5 (FOR SALE - Make Offer)

Recorders:
Sound Devices MixPre-10T
Oade CM Edirol R-44 (FOR SALE - Make Offer)
Sony PCM‑M10

Offline tom the taper

  • Site Supporter
  • Trade Count: (6)
  • Taperssection Regular
  • *
  • Posts: 99
  • Gender: Male
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #381 on: September 14, 2017, 12:16:58 PM »
Don't forget that the only way to realize 130db dynamic range in a PCM recording is to run 24 bit at almost full digital scale. If your recording peaks are just reaching -8, then you are only recording at 16 bit depth. You'll still get 96 db of dynamic range which is more than most recording situations have anyway. Just don't put too much weight on 130 db analog dynamic range when running full digital scale is the only way to actually get it.

This.

And I've found that my recordings sound better when I push the levels hot while recording as opposed to running super conservative (-12db peaks) and normalizing in post.

The hotter recording always sounds more full and beefy (for lack of a better term).

Agreed! :clapping:

I've thought the same but always believed it was just all in my head, which has been wrong before!

I started taping on cassettes, there was no post!  Had to get it right live :headphones:
MK4V, MK41, MK3, AKG 414XLII, CSB
V3, SD mp2, UA5
MixPre-6, 744, M10, MT II, MT2496, SV250, D5, D6
NBob Actives, GAKables

Offline larrysellers

  • Trade Count: (31)
  • Taperssection All-Star
  • ****
  • Posts: 1887
  • Gender: Male
  • Qualified
Re: Sound Devices MixPre-3 and 6, Part 3
« Reply #382 on: September 14, 2017, 12:38:37 PM »
This one has hit it's limit. New thread here ---> http://taperssection.com/index.php?topic=183580.0

 

RSS | Mobile
Page created in 0.093 seconds with 30 queries.
© 2002-2017 Taperssection.com
Powered by SMF
Website Design by Foxtrot Media, Inc., a Baltimore Website Company