Topic: Sound Devices MixPre-3 and 6, Part 8

[morst]

Interesting no 12V spec listed

I’ve used some of those to run 12V taper gear. 15V is enough to run and charge my Toshiba laptop albeit slightly below spec

USB does not support 12v directly

[breakonthru]

USB PD standard has been around for over a decade, and has become ubiquitous in battery banks in the last few years

the newest 3.2 standard introduced a few years back supports up to 48V though 12,15 and 20 are far more common voltages in the many PD devices on the market. Generally the max voltage is loosely tied to battery size you don’t see batteries under 10000 mA pushing out high voltages because the current draw exceeds their design spec

I have 10000 ma batteries that push 12 and 15V but the only ones I have seen that push my laptop a proper 20V are 20000 mA power bricks and above

https://www.usb.org/usb-charger-pd

Of course 5V is no more natural from a battery than higher voltages, as all are stepped up from 3.7V cell voltage

There are numerous cables available to provide negotiated fixed voltage out of a PD-compliant USB-C jack. There are more advanced cables which offer user-selectable voltage as well. The fixed voltage cables are cheap (<$10) and feature the standard 5.5mm x 2.1mm and 2.5mm barrels.

10000 ma batteries are a good match for mic pres/ADs that either want 12V (lead sled era) or is flexible on input voltage (RME gear takes 9-18V) **users must be careful to use a cable with a fixed upper voltage matched to their equipment. A 20V cable may provide 12V out of one battery then you plug it into a larger battery and watch the magic smoke exit your device as 20V is applied**

The newest PD standard with EPR and AVS can actually provide any voltage from 5V up to 48V in 100V increments

https://plugable.com/blogs/news/what-is-240w-usb-extended-power-range-epr

Thanks to checht for pointing out the anker spec page. Voltages are typically left out of the Amazon listings but as a top-tier mfr their website actually has good details. Their flagship power banks (24 and 27000 ma options) output 28V at 5A  on each of the USB-C ports and their 20000mA batteries top out at 20V

[morst]

Oh I forgot abut USB-C, yeah it can do like 100 watts so I guess it does have to be able to make higher voltages than 5V.
wow 240 watts now!

[breakonthru]

Oh I forgot abut USB-C, yeah it can do like 100 watts so I guess it does have to be able to make higher voltages than 5V.
wow 240 watts now!

as seen on southwest max8 just now

The usb-c is marked 60W and should power many laptops with the right cable

https://imgur.com/a/e2wSgVg

[voltronic]

I don't own one of these, but I'm hoping the thread doesn't mind a quick question:

When in 32 FP mode, do these recorders lock analog gain to a fixed level, with only post-ADC digital signal level remaining adjustable? Or can the actual preamp gain still be adjusted in this mode?

There's a discussion on the Zoom F3 thread where a few of us are trying to clear up confusion caused by a poorly written manual. Zoom F series locks preamp gain to a fixed level in 32FP mode; I'm wondering if the MP-II series behaves the same way.

[dallman]

I don't own one of these, but I'm hoping the thread doesn't mind a quick question:

When in 32 FP mode, do these recorders lock analog gain to a fixed level, with only post-ADC digital signal level remaining adjustable? Or can the actual preamp gain still be adjusted in this mode?

There's a discussion on the Zoom F3 thread where a few of us are trying to clear up confusion caused by a poorly written manual. Zoom F series locks preamp gain to a fixed level in 32FP mode; I'm wondering if the MP-II series behaves the same way.

My understanding has always been that on the MixPre 6II, you can adjust the gain. Here is a quote:
How can I adjust the input gain levels on the MixPre-6 II?
You can adjust the input gain levels by using the gain knobs located next to each input. Turning them clockwise will increase the gain, and counterclockwise will decrease it.

That said, It really does not matter as I have found little or no difference in the end result if I set gain high or low. The move in post to put the output volume (fader) where I want it results in a clear and non distorted sounding file, just like the F3 or F6 which I also use. I know some will disagree which is fine, but these are my impressions after using all 3 decks quite a bit.

[commongrounder]

I own a Mixpre-6II and a Zoom F3, and I agree with dallman. I have done analysis of files recorded on the Mixpre in 32-bit float mode, and I have determined that there is no *analog* gain adjustment being made when using the trim or mix knobs. The entire 142db dynamic range of the outstanding Kashmir preamp can be captured in each sample, no matter what the setting is (except for “off”, of course). The front knobs main function is to digitally mix the iso tracks into the stereo mix tracks. If “gain” is set to “basic” in the custom advanced menu, the front panel knobs digitally set both the mix level and iso track level. I think of the level controls on the Mixpre in 32-bit float in the same way as I do the “magnification” on the F3, just (essentially) continuous rather than stepped. I set the Mixpre levels to a healthy meter deflection to allow comfortable monitoring. A big difference with the Mixpre from the F3 is one can change the levels during recording. I do have to say, however, I’ve long felt (even since analog days) that level changing (“riding the gain”) during a recording is a big no-no, so I am extra averse to touching the knobs (except in an emergency) once recording has commenced. 32-bit float technology has reinforced that feeling. But that’s just me.

[breakonthru]

I try to never change levels during a recording if I can help it. Pain in the butt to level out the volume changes later. With modern gear (anything over 100 dB s/n) I’ve never had a recording that was lacking for levels to be too low. Ambient noise is way above microphone noise which is way above the noise floor of the input.

[commongrounder]

I try to never change levels during a recording if I can help it. Pain in the butt to level out the volume changes later. With modern gear (anything over 100 dB s/n) I’ve never had a recording that was lacking for levels to be too low. Ambient noise is way above microphone noise which is way above the noise floor of the input.

Indeed! We live in glorious times for sound recording.

[morst]

I do have to say, however, I’ve long felt (even since analog days) that level changing (“riding the gain”) during a recording is a big no-no, so I am extra averse to touching the knobs (except in an emergency) once recording has commenced. 32-bit float technology has reinforced that feeling. But that’s just me.

Not just you.
 
It's a post-processing perspective, but we live in a time where DAW software is a free download, and hard drive space is relatively cheap compared to audio recording file size!!!

[mccordo]

Ran a test for Greensky Bluegrass with my MixPre 3 with the added channels upgrade. I own a MixPre 6 too and know that it can be used to run 4 XLR mics, but I wanted to test out the 2 extra channels on the MixPre 3. A pair of AKG ck63 went direct into channels 1 and 2 via XLR. Then AKG ck61 > MixPre > 3.5mm tape out > MixPre 3 channels 4 and 5 via 3.5mm aux in. I set the levels on the MP3 at 0db for channels 4 and 5 and used the MixPre to adjust the levels.

The metering was just like running 4 channels on the MP6, although it was 5 channels with channel 3 unused. Everything worked flawlessly, although it was funny to see the ck61s as channel 4 and 5 in post instead of the usual 3 and 4. Overall, I was quite pleased with the process, although I HATE being forced to set up under the balcony at HOB Orlando.

https://archive.org/details/gsbg2024-01-14.AKGMatrix

[fanofjam]

I set the levels on the MP3 at 0db for channels 4 and 5 and used the MixPre to adjust the levels.

Thanks alot for the report in.  Nice to know that everything works well.  I'll need to pick up an XLRF x 2 > stereo mini and then buy the plug-in.  You never know when a SBD feed might be available to grab on the fly.

A couple of questions, if you don't mind:
 
Obviously, on channels 1, 2, and 3 we set levels with the gain knobs, but IIRC you can also pre-set levels in a menu (or maybe that's another recorder...hmmm it's been awhile since I've been out).  So when you said you used the mix-pre to adjust levels on Ch 4 and 5, do you mean there's a menu option that allows you to move levels up and down? 

Are they individually adjustable for each channel? 

Can you gang all of the channels for gang level changing?

Is level setting on Channels 1 and 2 menu selectable in the same menu's as those for Channel 4 and 5?

(Sorry for being lazy and not checking SD's website to answer these questions myself, but they don't give a whole lot of details about the details of the plug-in.)

[mccordo]

I'll need to pick up an XLRF x 2 > stereo mini and then buy the plug-in.  You never know when a SBD feed might be available to grab on the fly.

That's my next purchase now that I got the extra channels. I was using the 3.5mm out on the MixPre 3, but having an XLR > 3.5mm would be perfect for this setup to take a SBD feed or run an extra pair of mics with an external preamp in a pinch.

Obviously, on channels 1, 2, and 3 we set levels with the gain knobs, but IIRC you can also pre-set levels in a menu (or maybe that's another recorder...hmmm it's been awhile since I've been out).  So when you said you used the mix-pre to adjust levels on Ch 4 and 5, do you mean there's a menu option that allows you to move levels up and down?

Correct. The front knobs still control channels 1-3, including arming/disarming and raising/lowering the gain. To control Channels 4-5, you have to open the menu and go to the submenu for each channel. The headphone knob changes the gain and the arm/disarm is on the screen (iirc). I set channels 4-5 on the MixPre 3 at 0db and used the MixPre to adjust the gain of the signal coming into the MixPre 3.

Are they individually adjustable for each channel?

Yes; each channel is individually adjustable. I'd like to find a way to adjust channels 4-5 without having to go thru the menu, but I haven't figured out if that is possible yet.

Can you gang all of the channels for gang level changing?

I'm not sure if you can gang channels 4-5. It sounds worthwhile, so I'll see if that's a possibility.

Is level setting on Channels 1 and 2 menu selectable in the same menu's as those for Channel 4 and 5?

No; channels 1-3 still use the front knobs. Channels 4-5 use the menu to make adjustments.

[commongrounder]

Some clarifications to mccordo’s post.
The Mixpre-3ii can only gang inputs one and two. The 6 and 10 allow other channel ganging combinations. There is a shortcut to get straight into the channel 4 and 5 adjustment menus. Press the headphone/select knob and then press either the front panel channel 1 or channel 2 knob. 
A feature that is new in firmware 9.02 is the ability to adjust the gain on the aux inputs separately from the mix level to the mix tracks. Previously, the mix level was fixed, so gain adjustments necessarily affected mix levels. I don’t record my mix tracks (only the iso tracks), so it was never a big issue for me.

[Gutbucket]

I've a question on ganging channels-
Can that be done in such a way that the various channels of the ganged group retain their relative levels, even as the levels of all channels in the group are further adjusted in unison (like Tascam DR680), or are identical levels forced across all channels in the ganged group? (Like Zoom F8)