Topic: Sound Devices MixPre-3 and 6, Part 3

[johnw]

Great explanation MIQ, thanks!

[willndmb]

Great explanation MIQ, thanks!

yes thanks

And John here is a chart that helped me http://www.sengpielaudio.com/calculator-transferfactor.htm
That's how I saw I would need to be at or below 130 to be safe, just so happens it is in blue to stand out.
Because that would give me 4dBu and if my tinybox adds 4db gain I'll actually be at 8dBu of the 10 allowed

[hi and lo]

... As an example, a Schoeps MK41 (14 mV/Pa) puts out +10 dBu at 139 dBSPL, which is insanely loud (Schoeps specs the max at 132 dB).  Even a few feet from the drums, it is unlikely to reach that level.

Maximum Sound Pressure Level specifications are provided as Peak Sound Pressure (Lpeak or Lpk), which can easily supersede the RMS Maximum SPL value by 20dB. If you're at a concert and the A-weighted SPL meter reads 100db+, Peak SPLs are actually very close to to the maximum and can hit 130-140dB, but you would need a Peak SPL meter to measure them. When close-miking drums Peak SPLs can exceed 145db!

Considering that the source of this issue was an on-stage Soulive recording, I have no doubt that the peak SPLs were in the danger zone for a +10dB rated input.

[noahbickart]

mk41v:  http://bt.etree.org/details.php?id=593900

Dead & Company
BB&T Pavilion; Camden, NJ
June 25, 2017

Location: DFC behind the board at ~5 feet
Source: Schoeps mk41v (20cm PAS)> NBob KCY> Darktrain KCY Snake> Naiant PFA> Sound Devices Mixpre6 @ 24/48
Transfer: Mixpre> usb-c> Macbook> Reaper (DSP)> Sound Studio (Tracking and Fades)> xAct (Tagging and Flaccing)

mk22:  http://bt.etree.org/details.php?id=593904

Dead & Company
BB&T Pavilion; Camden, NJ
June 25, 2017

Location: DFC behind the board at ~5 feet
Source: Schoeps mk22 (NOS)> NBob KCY> Darktrain KCY Snake> Naiant PFA> Sound Devices Mixpre6 @ 24/48
Transfer: Mixpre> usb-c> Macbook> Reaper (DSP)> Sound Studio (Tracking and Fades)> xAct (Tagging and Flaccing)

[hi and lo]

2007?

[noahbickart]

2007?

oops. Edited. Thanks.

[aaronji]

... As an example, a Schoeps MK41 (14 mV/Pa) puts out +10 dBu at 139 dBSPL, which is insanely loud (Schoeps specs the max at 132 dB).  Even a few feet from the drums, it is unlikely to reach that level.

Maximum Sound Pressure Level specifications are provided as Peak Sound Pressure (Lpeak or Lpk), which can easily supersede the RMS Maximum SPL value by 20dB. If you're at a concert and the A-weighted SPL meter reads 100db+, Peak SPLs are actually very close to to the maximum and can hit 130-140dB, but you would need a Peak SPL meter to measure them. When close-miking drums Peak SPLs can exceed 145db!

Considering that the source of this issue was an on-stage Soulive recording, I have no doubt that the peak SPLs were in the danger zone for a +10dB rated input.

It would be nice if it could take a hotter signal (especially since that’s at line level).  In most taping situations, however, with most microphones, +10 dBu should be OK.  If it’s not, you might as well forget about those nice Kashmir pre-amps on the MixPre-6, as you will be right in the danger zone with them also (+14 dBu).  Actually, you are probably in trouble with many Sound Devices products, such as a 702 or 744 (+10 dBu minimum, low gain mode, gain control fully down) or a 633 (0 dBu minimum, trim control fully down). 

As for the drums, "close-miking" versus "taper’s distance" (even on-stage) is a pretty huge difference.  Even a full-on rimshot on a metal shelled snare is in the 120 dB range at 1.5 or 2 meters.

Maybe it will prove to be the case that the consumer level input on a prosumer level box will be generally inadequate.  For now, we have only SD’s spec and one anecdote to work on, so, personally, I am not going to write it off quite yet…

[sos]

MixPre Series Firmware v. 1.11 is out, with major fixes. Also, an ASIO driver for Windows OS (v2.9.87.5) is now available for download:

https://www.sounddevices.com/support/downloads/mixpres-firmware
https://www.sounddevices.com/support/downloads/mixpres-asio-driver-download


Changes introduced in 1.11 include:

New

    When playing back a file, the file's remaining time is now shown in the Status Bar.

Changes

    The File List Number is now editable from 1 to 9999.
    The Current Project name is now displayed in the Menu>Project header.
    The Headphone output is briefly muted when Aux In Mode is changed to prevent loud audible pops.
    Various system improvements and enhancements.

Fixed

    In some custom setups, ISO Tracks were recorded low level when Tracks L and R were disarmed.
    File corruption when power was depleted mid-recording.
    Some custom mode settings were not retained after a power cycle; for instance, 40 Hz Low Cut Filter setting was set to 80Hz after a power cycle.
    After a power cycle, channel gain was not set correctly until the channel knob was slightly adjusted.
    Channel 5 and 6 did not correctly show limiter activity when Input Source was set to Aux In.
    Clip indicator showed twice for one clipping event.
    Changing headphone gain while in the Solo/Mute screen caused incorrect monitoring and routing of signals to the headphone output.
    Gain and pan controls were not grayed out on channel 2 when channels 1 and 2 were linked as a stereo or MS pair. (MixPre-3 Only)
    Engaging record with a full SD card inserted created small files.
    Incorrect message was displayed when attempting to record with a locked SD Card inserted. Now, 'SD Card is Locked' is reported.
    Camera Meters (C1, C2) did not display signal activity in Custom Mode with Advanced Headphone Settings.
    Camera and USB Meters didn’t show any activity during playback.
    USB Audio Routing was incorrect while playing back.
    The Open Project Menu list was displayed incorrectly when rapidly scrolling through it.
    Audio Delay could have been incorrect after changing sample rate.
    A recording's first sample could have been incorrect after changing sample rate.
    Improved stability of HDMI Timecode.
    USB Keyboard shortcut Ctrl + Z did not perform Undo.
    USB Keyboard shortcut F2 did not enter the File List.
    The Record/L&R Gain setting incorrectly altered the L&R track playback levels. The setting should only affect the L&R record levels, not the L&R playback levels.

[jbell]

^thanks for the heads up!

[tom the taper]

MixPre Series Firmware v. 1.11 is out, with major fixes. Also, an ASIO driver for Windows OS (v2.9.87.5) is now available for download:

https://www.sounddevices.com/support/downloads/mixpres-firmware
https://www.sounddevices.com/support/downloads/mixpres-asio-driver-download


Changes introduced in 1.11 include:

New

    When playing back a file, the file's remaining time is now shown in the Status Bar.

Changes

    The File List Number is now editable from 1 to 9999.
    The Current Project name is now displayed in the Menu>Project header.
    The Headphone output is briefly muted when Aux In Mode is changed to prevent loud audible pops.
    Various system improvements and enhancements.

Fixed

    In some custom setups, ISO Tracks were recorded low level when Tracks L and R were disarmed.
    File corruption when power was depleted mid-recording.
    Some custom mode settings were not retained after a power cycle; for instance, 40 Hz Low Cut Filter setting was set to 80Hz after a power cycle.
    After a power cycle, channel gain was not set correctly until the channel knob was slightly adjusted.
    Channel 5 and 6 did not correctly show limiter activity when Input Source was set to Aux In.
    Clip indicator showed twice for one clipping event.
    Changing headphone gain while in the Solo/Mute screen caused incorrect monitoring and routing of signals to the headphone output.
    Gain and pan controls were not grayed out on channel 2 when channels 1 and 2 were linked as a stereo or MS pair. (MixPre-3 Only)
    Engaging record with a full SD card inserted created small files.
    Incorrect message was displayed when attempting to record with a locked SD Card inserted. Now, 'SD Card is Locked' is reported.
    Camera Meters (C1, C2) did not display signal activity in Custom Mode with Advanced Headphone Settings.
    Camera and USB Meters didn’t show any activity during playback.
    USB Audio Routing was incorrect while playing back.
    The Open Project Menu list was displayed incorrectly when rapidly scrolling through it.
    Audio Delay could have been incorrect after changing sample rate.
    A recording's first sample could have been incorrect after changing sample rate.
    Improved stability of HDMI Timecode.
    USB Keyboard shortcut Ctrl + Z did not perform Undo.
    USB Keyboard shortcut F2 did not enter the File List.
    The Record/L&R Gain setting incorrectly altered the L&R track playback levels. The setting should only affect the L&R record levels, not the L&R playback levels.

YES! - Thanks for the heads up!

[johnw]

Did this fix the ability to link channels in custom mode with basic gain on the Mix Pre 6? I don't see anything about that.

[dallman]

Did this fix the ability to link channels in custom mode with basic gain on the Mix Pre 6? I don't see anything about that.

Fixed

    In some custom setups, ISO Tracks were recorded low level when Tracks L and R were disarmed.

That was the issue. Linking them was not an issue, unless there was a specific situation you had. I was able to link under the situation you list above, but the levels were really low.

[hi and lo]

...
If it’s not, you might as well forget about those nice Kashmir pre-amps on the MixPre-6, as you will be right in the danger zone with them also (+14 dBu).  Actually, you are probably in trouble with many Sound Devices products, such as a 702 or 744 (+10 dBu minimum, low gain mode, gain control fully down) or a 633 (0 dBu minimum, trim control fully down). 

Correct, which is why professional recorders have Line Inputs. Assuming phantom power is available, as it is on all the 7xx recorders and the Mix-Pre 3/6, bypassing the Mic Inputs and recording via the Line Inputs is the best practice. It will provide the proper headroom and sound better with less noise than a Kashmir microphone input stage that is overloading or running at minimum gain.

We shouldn't think twice or worry in the slightest about not using "Kashmir" preamps (or any preamp for that matter). When a condenser microphone provides an appropriately "hot" signal, using a microphone input stage will only risk overload and, usually, add noise as almost all microphone amplifier have the highest THD + Noise specifications at minimum gain. Running directly to the Line Inputs is one less gain stage with far less overall THD + Noise.

Pardon me for calling it a common misconception, but the idea running the signal through a preamp because it will somehow 'flavor' the sound beneficially is not a best practice. The theoretical best sound between the microphone capsule and recorder should be a "straight wire" and every device placed in between are additional source of noise and distortion. It's fine to 'enjoy the sound' of a preamp when it makes sense to use one for needed gain, but not if you are inserting it into the signal path and operating it at the setting that produces the least optimal THD + Noise.

As for the drums, "close-miking" versus "taper’s distance" (even on-stage) is a pretty huge difference.  Even a full-on rimshot on a metal shelled snare is in the 120 dB range at 1.5 or 2 meters.

When discussing SPLs, it's important to always differentiate between RMS and Peak. They are different measurements.

https://www.youtube.com/watch?v=6WzAM_y2iWw

Here's a excellent video of snare-drum SPL measurements. Notice the SPL meter is an RMS meter and that 110 dB SPL is easily achieved by normal play style. Peak SPLs aren't indicated, but they are much higher than the RMS rating; probably 125-130 dB, easily.

Now imagine a heavy metal drummer using heavy sticks and really laying into it. The RMS SPLs will go up, let's say 120 dB, and the peak SPLs are going to exceed that of our favorite condenser mics. 140+ Peak SPL is no problem. It's loud enough to clip at the capsule and will easily produce a signal that can clip the mic input of any recorder. No preamp required... to say the least.

[noahbickart]

Did this fix the ability to link channels in custom mode with basic gain on the Mix Pre 6? I don't see anything about that.

Fixed

    In some custom setups, ISO Tracks were recorded low level when Tracks L and R were disarmed.

That was the issue. Linking them was not an issue, unless there was a specific situation you had. I was able to link under the situation you list above, but the levels were really low.

I just updated the firmware, but I still can't link channels 1+2, 3+4, and 5+6 in "Custom" Mode with Gain at "Basic."

It would be so nice to create a preset for just that. A 6 channel, three pair recorder, no LR, each pair linked so that the odd channel is gain and the even channel balance.

[aaronji]

MixPre Series Firmware v. 1.11 is out, with major fixes. Also, an ASIO driver for Windows OS (v2.9.87.5) is now available for download:

There's a new version of the manual as well.

As for the drums, "close-miking" versus "taper’s distance" (even on-stage) is a pretty huge difference.  Even a full-on rimshot on a metal shelled snare is in the 120 dB range at 1.5 or 2 meters.

When discussing SPLs, it's important to always differentiate between RMS and Peak. They are different measurements.

https://www.youtube.com/watch?v=6WzAM_y2iWw

Here's a excellent video of snare-drum SPL measurements. Notice the SPL meter is an RMS meter and that 110 dB SPL is easily achieved by normal play style. Peak SPLs aren't indicated, but they are much higher than the RMS rating; probably 125-130 dB, easily.

Now imagine a heavy metal drummer using heavy sticks and really laying into it. The RMS SPLs will go up, let's say 120 dB, and the peak SPLs are going to exceed that of our favorite condenser mics. 140+ Peak SPL is no problem. It's loud enough to clip at the capsule and will easily produce a signal that can clip the mic input of any recorder. No preamp required... to say the least.

Yes, I was indeed referring to maximum, not RMS.  If you look at that video, they are measuring from a distance of ~ 5 cm, give or take.  Even if your beefy metal drummer was whaling away, hitting 150 dB SPL maximum at that distance, it would be down to 120 dB at 1.6 meters.

Point well taken about the pre-amps, though.  Actually, despite a fairly close reading of the manual, I missed that phantom power is available on the MixPre-6's line inputs.  I thought it was like one of it's close competitors, in which phantom is only available through the mic pres.  Very useful.  Although I suspect I will still need to use the pres sometimes, it is nice that I won't be forced to in order to get all-in-one functionality.  Thanks!