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Gear / Technical Help => Recording Gear => Topic started by: seashore on August 16, 2019, 12:32:55 PM

Title: 3 channel recording with mix 3-pre
Post by: seashore on August 16, 2019, 12:32:55 PM
Sorry for my lack of technical knowledge, but we all have to start somewhere. I have, until now, recorded music using a pair of omnidirectional or cardioid microphones. I am considering purchase of a mix-pre-3 machine and intend to use it primarily in the same way. Unlike my current recorder this accepts, as indicated by its name, up to three microphone inputs. I understand that if three microphones are attached, the recorder will display the level of sound being from each plus the overall level of sound in the right and left channels. How does the machine know which of the XLR inputs you wish to regard as the left signal and which for the right signal and how does the input from the 3rd microphone combine to make the overall left and right signal. As you will tell, I have never used a mixer! Thank you!
Title: Re: 3 channel recording with mix 3-pre
Post by: old and in the way on August 16, 2019, 01:40:00 PM
the mix pre 3 will due a stereo mix of all three channels or you can do a mid side recording using a figure 8 mic and left right channels . You can do a left right card and mixed in an omni on the third channel . works pretty good . the mix pre 3 will due 5 channnels total using the 3.5 mm input .ive never used all configurations since i have a sd788t ssd that can handle more inputs. but i use the mix pre 3 quite a bit and get excellent pulls . just experiment1
Title: Re: 3 channel recording with mix 3-pre
Post by: DavidPuddy on August 16, 2019, 02:36:21 PM
You can program which channels go to the L/R mix. I do not use this function (on my Mixpre6) and just do mixdown in post for both simplicity and to save battery and card space.
Title: Re: 3 channel recording with mix 3-pre
Post by: jb63 on August 16, 2019, 02:38:41 PM
Wait... you can get 5 channels out of the mixpre 3?
Title: Re: 3 channel recording with mix 3-pre
Post by: DavidPuddy on August 16, 2019, 02:41:05 PM
Wait... you can get 5 channels out of the mixpre 3?

That's when counting the L/R mixdown as 2 channels
Title: Re: 3 channel recording with mix 3-pre
Post by: aaronji on August 16, 2019, 03:43:22 PM
Use each channel’s “pan” control to set left and right. That is, pan the left pointing mic left and the right pointing mic right. The third mic will likely be panned center (that is in both channels). If I understood the OP...
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 16, 2019, 04:04:51 PM
I don't use a Mixpre myself, but I'll try to help-
One can record the 3 XLR inputs as 3 separate ISO channels (ISO=isolated, each input to its own monophonic channel), as well as recording a stereo mix made up of any combination of all 5 inputs (3 XLR inputs + the stereo minijack input for an additional 2 channels.  To record the minijack stereo input separately from the mic inputs, one would route only the minijack stereo input to the stereo mix track, and NOT route the 3 microphone inputs to the stereo mix.  The result will be 3 monophonic ISO files + one stereo mix file which contains just the minijack input signal.
^
MixPre users, please correct me if this is not accurate. [edit- It's not as explained later in the thread - but SD easily could have / should have made this possible]

You can do a left right card and mixed in an omni on the third channel ... just experiment

Or flip that- try left right omnis (spaced 3' or more) + a center cardioid into ch3)
If you have SBD, that can take the place of the center cardioid.
Title: Re: 3 channel recording with mix 3-pre
Post by: GDfan on August 16, 2019, 05:07:51 PM
I ran 2 Neumann 184s that were Din(a) and a AKG c314 set to Hyper cardoid facing directly at the stage with the MixPre3, left and right still have good separation and middle is clearer.
YMMV
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 16, 2019, 05:30:41 PM
^ Good center clarity is the primary idea behind the use of a directional microphone in the center, rather than a single omni.  Combine that with L/R directional mics indoors or wide-spaced L/R omnis outdoors.
Title: Re: 3 channel recording with mix 3-pre
Post by: morst on August 17, 2019, 02:29:17 AM
I have a MixPre6. It can record "8 channels" but only 6 "ISO" channels aka Isolated channels. The other two are the Mix.


If I was a podcaster, or doing a live feed for a professional job, I would use the Mix.
But, I am not, so I don't. I turn off recording to the mix tracks in software. I only need the raw channels for my live show archiving.


It's distracting to see the mix channels hit the PEAK lights on the phone app, but it's fair warning.
Title: Re: 3 channel recording with mix 3-pre
Post by: perks on August 17, 2019, 12:02:33 PM
^ Good center clarity is the primary idea behind the use of a directional microphone in the center, rather than a single omni.  Combine that with L/R directional mics indoors or wide-spaced L/R omnis outdoors.

I have a MP-3 that I have not started experimenting with yet so I’m very interested in learning more about utilizing the 3rd channel. I bought the recorder to use as a 2 channel all in one hoping I’d like the preamps and a>d enough to have another tiny footprint option and could leave the external pre at home. But the 3rd channel is intriguing. If I’m capturing an ORTF stereo image wont the 3rd channel collapse the stereo image?
Title: Re: 3 channel recording with mix 3-pre
Post by: ycoop on August 18, 2019, 01:42:21 AM
I don't use a Mixpre myself, but I'll try to help-
One can record the 3 XLR inputs as 3 separate ISO channels (ISO=isolated, each input to its own monophonic channel), as well as recording a stereo mix made up of any combination of all 5 inputs (3 XLR inputs + the stereo minijack input for an additional 2 channels.  To record the minijack stereo input separately from the mic inputs, one would route only the minijack stereo input to the stereo mix track, and NOT route the 3 microphone inputs to the stereo mix.  The result will be 3 monophonic ISO files + one stereo mix file which contains just the minijack input signal.
^
MixPre users, please correct me if this is not accurate.

You can do a left right card and mixed in an omni on the third channel ... just experiment

Or flip that- try left right omnis (spaced 3' or more) + a center cardioid into ch3. Makes for a considerable improvement IME ;)
If you have SBD, that can take the place of the center cardioid.

I’m not an MP3 user but I’m close to 100% certain that you can only record a total of 3 channels with it.
Title: Re: 3 channel recording with mix 3-pre
Post by: seashore on August 18, 2019, 11:27:28 AM
Thank you for your many replies. You have cleared things up no end!
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 19, 2019, 12:45:04 PM
If I’m capturing an ORTF stereo image won't the 3rd channel collapse the stereo image?

Yes, unless the ORTF configuration is modified the additional contribution from the center-panned center microphone can make the recording more monophonic and center-heavy (unless it happened to be lacking center image stability and weight to begin with).  To counter that you'll want to space the Left/Right cardioids more widely, or angle them more widely, or a some combination of both.  How much more?  A good rule of thumb is about twice as much spacing or twice as much angling, or half as much of both, as you'd use for the single pair.

ORTF represents an "pre-optimized" 2-channel microphone configuration with the aim of producing a balanced stereo image, ambient reverberant pickup qualities, and direct-sound clarity on its own.  Same goes for NOS, DIN, etc.  All of those are optimized 2-channel stereo microphone arrangements, and the introduction of additional microphones in close proximity messes with that pre-baked optimization.  Same goes for how far omni are space. Generally the need for figuring precise spacing is less critical with omnis, but its still best to try and get twice as much spacing between omnis when you place a third microphone (or a coincident pair) in the center between them, as long as you can arrange to do so.
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 19, 2019, 12:56:19 PM
I’m not an MP3 user but I’m close to 100% certain that you can only record a total of 3 channels with it.

It can most definitely record 3 ISO channels plus a stereo mix track at the same time.  That's more than 3 channels.  For instance, one can record the 3 XLR inputs directly to ISO channels and also record a mix of those same inputs to the stereo mix track.  That a total of 3 inputs but 5 recorded channels. 

[edit], see Morst's post above concerning the MPixpre6
I have a MixPre6. It can record "8 channels" but only 6 "ISO" channels aka Isolated channels. The other two are the Mix.
Mixpre3 features the same behavior, but with less inputs [/edit]

The question is if the stereo minijack input may be routed to the mix track exclusively, while the 3 XLR inputs are sent to the ISO channels but not routed to the stereo mix track.
Title: Re: 3 channel recording with mix 3-pre
Post by: mnm207 on August 19, 2019, 01:36:42 PM
The question is if the stereo minijack input may be routed to the mix track exclusively, while the 3 XLR inputs are sent to the ISO channels but not routed to the stereo mix track.

The answer to this is no.

Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 19, 2019, 03:06:21 PM
The question is if the stereo minijack input may be routed to the mix track exclusively, while the 3 XLR inputs are sent to the ISO channels but not routed to the stereo mix track.

The answer to this is no.

In that case I'm disappointed Sound Devices dropped the ball.  Especially if the MP6 and MP10 similarly lack this functionality.  If I were an SD user I'd request a firmware update which allows routing of the AUX/minjack input directly to the stereo mix bus.  This would improve flexibility dramatically for soundboard feeds and external preamps.

Quoted from the user manual- "In Advanced Mode, the MixPre-3 is configured as a five-channel recorder." to which I'll add.. yet is apparently unable to record more than 3 seperate input sources, with the possible exception of the USB input. 

Note that such functionality has been around in similar recorders from less prestigious manufacturers for a long time now. For example DR-680 is a 6-channel recorder that can record a total of 8 inputs separately if the mix track is leveraged that way.
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 19, 2019, 03:10:56 PM
Wait... you can get 5 channels out of the mixpre 3?

Out yes, In no.
Title: Re: 3 channel recording with mix 3-pre
Post by: morst on August 19, 2019, 04:27:56 PM
In that case I'm disappointed Sound Devices dropped the ball.  Especially if the MP6 and MP10 similarly lack this functionality.  If I were an SD user I'd request a firmware update which allows routing of the AUX/minjack input directly to the stereo mix bus.  This would improve flexibility dramatically for soundboard feeds and external preamps.

MP6 can record all 6 of its inputs (4 combos & a stereo mini jack), plus the (useless to me) mix track. They call it an 8 channel recorder, but it's only got 6 that do anything unique!
Similarly, MP10 can handle 8 XLR and two mini inputs for a total of ten.
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 19, 2019, 04:38:50 PM
MP6 can record all 6 of its inputs (4 combos & a stereo mini jack), plus the (useless to me) mix track.

It's really unfortunate the mix track was not made more useful this way.  This should be firmware correctable if SD wished to do so.
Title: Re: 3 channel recording with mix 3-pre
Post by: kuba e on August 19, 2019, 05:11:01 PM
I am very surprised too. A big pity that it is not possible to use the mix track for jack in. SD should remedy this.

Here is my little experience for those who starts to record near spaced pair and center mics. I am using a near spaced pair with a center mic only when recording stealth. My difficulties arise during mixing. I don't have good listening skills, it isn’t easy for me to assess all positives and negatives when adding the middle microphone. Mostly I overhear the negatives at the first listening. Also, recording of third channel costs some effort, so I tend to use it. I don't want to throw it in the trash. But in the few cases I was recording in this configuration, I used only a single pair in the end. I didn't mix in the third microphone. Single near spaced pair sounded more natural itself and the third microphone was causing a little bit of comb filtering too. Sometimes, I did small adjustments of the stereo by Mid / Side manipulation. These are small changes as opposed to adding the middle microphone, but it can help a little bit too.

Gutbucket's advice is golden. I've never had a problem with center microphone when using bigger spacing and angling.

Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 19, 2019, 06:16:39 PM
Single near spaced pair sounded more natural itself and the third microphone was causing a little bit of comb filtering too.

This gets back to what Perks was asking about.  Ideally one needs to modify any standard 2-channel stereo microphone configuration to compensate for the addition of the center microphone.

The content from the center microphone must differ sufficiently from the content of the other two channels so that there isn't too much monophonic build up nor audible comb filtering problems when the center is routed Left and Right and mixed with those channels. 

The comb filtering thing is essentially the stereo>mono downmix compatibility thing, but 3>2 channels rather than 2>1 channel.  It's also what the 3:1 rule in intended to address when placing multiple microphones which will be summoned together in front of a group of singers or horns.
Title: Re: 3 channel recording with mix 3-pre
Post by: aaronji on August 22, 2019, 10:32:10 AM
This should be firmware correctable if SD wished to do so.

I doubt you will see this anytime soon. The way I interpret it, SD was putting some distance between the MixPre-3 and the MixPre-6 with this, uh, "feature". If you could use all 3 XLRs plus the 1/8" on the Mixpre-3, as you can with the MixPre-6 and -10, you would end up with a MixPre-5, with only one XLR input separating the 3 from the 6. A lot of people would probably opt to save the $250 difference and sacrifice one input...
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 22, 2019, 10:55:45 AM
Yes I agree.  Apologies for this OT aside, but one of the philosophical problems I have with SD is that this type of thing carries through most of their lines.  For instance, they never provide preamps on all the primary input channels.  To record 6 phantom powered mics into a Mixpre 6 requires an outboard preamp for 2 of those channels, etc.  The 744 four channel analog input recorder included only 2 preamp input channels, the 788 eight channel analog input recorder only 4[edit- I was mistaken on this one, see below..] They make quality gear, but it always seems somewhat hobbled in this way by design.
Title: Re: 3 channel recording with mix 3-pre
Post by: aaronji on August 22, 2019, 11:10:24 AM
^ Yes, it's a little strange. With the MixPre series, I tend to think of them as a 2-, 4-, or 8-track recorders with 1 or 2 "bonus tracks"...
Title: Re: 3 channel recording with mix 3-pre
Post by: jb63 on August 22, 2019, 11:42:05 AM
(Snip) one of the philosophical problems I have with SD is that this type of thing carries through most of their lines.

Exactly!
This is why I never ended up with a mixpre or a 744, I just read and read and the more I read the more confused I was at what they were making. So far the mixpre 6 looks like the best product for multiple channels. If you only ever want 2 channels then their products make perfect sense.
Title: Re: 3 channel recording with mix 3-pre
Post by: dactylus on August 24, 2019, 09:59:04 AM
Yes I agree.  Apologies for this OT aside, but one of the philosophical problems I have with SD is that this type of thing carries through most of their lines.  For instance, they never provide preamps on all the primary input channels.  To record 6 phantom powered mics into a Mixpre 6 requires an outboard preamp for 2 of those channels, etc.  The 744 four channel analog input recorder included only 2 preamp input channels, the 788 eight channel analog input recorder only 4.  They make quality gear, but it always seems somewhat hobbled in this way by design.

The 788t does provide preamps on all 8 primary input channels.  The 788t and the 788t-SSD are now both discontinued.   The 788t-SSD was just recently discontinued by Sound Devices...


Analog inputs 1-4 on XLR connectors and analog inputs 5-8 on TA3 connectors, are the primary connections into the recorder. These inputs accept balanced or unbalanced mic- or line-level inputs. Gain is controlled by the front panel Input Gain Pots.

The 788T has eight inputs and twelve record tracks. Inputs can be analog or digital sources. Analog inputs 1 through 4 are on 3-pin XLR connectors; inputs 5 through 8 are on 3-pin TA3 connectors.  Digital AES3 inputs 1-8 use the DE-15 (D-Sub) connector.

Phantom power (48 volts) can be activated individually, for each analog input on. Phantom power can be used for both mic- and line-level inputs. Enable or disable Phantom Power in the Input Settings Window using the Tone key to select 48V (phantom power for mic level only), 48VL (phantom power for mic- and line-level), or Off.



Title: Re: 3 channel recording with mix 3-pre
Post by: jb63 on August 25, 2019, 08:27:02 PM
THAT is why I wanted a 788t instead of a 744! But that's mighty expensive! I'd do it, though, for the right price. How long before a 788t goes under $2000?
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 26, 2019, 11:01:15 AM
The 744 four channel analog input recorder included only 2 preamp input channels, the 788 eight channel analog input recorder only 4.

The 788t does provide preamps on all 8 primary input channels.

Thanks for correcting me on this! (I've edited my post above)

Knowing that, I'd love to pickup a 788.
Title: Re: 3 channel recording with mix 3-pre
Post by: dactylus on August 26, 2019, 12:23:18 PM
The 744 four channel analog input recorder included only 2 preamp input channels, the 788 eight channel analog input recorder only 4.

The 788t does provide preamps on all 8 primary input channels.

Thanks for correcting me on this! (I've edited my post above)

Knowing that, I'd love to pickup a 788.

^
Agreed!  There are a few 788's available now on eBay, JW Sound, Reverb. 
Title: Re: 3 channel recording with mix 3-pre
Post by: dogmusic on August 26, 2019, 07:45:41 PM
The 744 four channel analog input recorder included only 2 preamp input channels, the 788 eight channel analog input recorder only 4.

The 788t does provide preamps on all 8 primary input channels.

Thanks for correcting me on this! (I've edited my post above)

Knowing that, I'd love to pickup a 788.

^
Agreed!  There are a few 788's available now on eBay, JW Sound, Reverb.

Do you folks consider the 788 to have superior preamps to the MixPre-10 (which also has 8 preamps)?
Title: Re: 3 channel recording with mix 3-pre
Post by: morst on August 26, 2019, 11:12:12 PM
MixPre6 has six preamps, but only 4 are the higher quality and power hungry Kashmirs, which supply 48v phantom power.
Likewise, the 10s have 8 Kashmirs and two more non-phantom-powered preamps channels.
Title: Re: 3 channel recording with mix 3-pre
Post by: dogmusic on August 27, 2019, 08:04:09 AM
MixPre6 has six preamps, but only 4 are the higher quality and power hungry Kashmirs, which supply 48v phantom power.
Likewise, the 10s have 8 Kashmirs and two more non-phantom-powered preamps channels.

Right. We’re not in disagreement. My question is why would those who are looking to buy a used 788 for $2000 not get a MixPre-10 for $1800 brand new when they both have the same number of 8 preamps. Do you consider the 788 preamps superior?
Title: Re: 3 channel recording with mix 3-pre
Post by: aaronji on August 27, 2019, 10:29:24 AM
^ I don't know how the pre-amps compare with each other, but the 788 has a bunch of extra features, a more solid build, and a longer track record. Lots of reasons someone might prefer one or the other, depending on their specific needs...
Title: Re: 3 channel recording with mix 3-pre
Post by: ButchAlmberg on August 30, 2019, 12:15:12 PM
What program do you all prefer for 3 channel post-processing. I ask because I just did my first 3 channel recording and sound forge pro wouldn't cooperate. I ended up using logic pro x but I'm at the bottom of the learning curve using it.
Title: Re: 3 channel recording with mix 3-pre
Post by: Gutbucket on August 30, 2019, 01:04:37 PM
Sound Forge is limited to 2-ch stereo editing as far as I'm aware.  You need a multitrack editor.  Lots of options there, both free or paid, and choice of which is mostly a personal choice pivoting on familiarity and work flow more than program capability.  Any of them will be able to mix 3 channels to 2.  Audacity is free and works for many folks here.
Title: Re: 3 channel recording with mix 3-pre
Post by: jb63 on September 03, 2019, 04:02:33 PM
MixPre6 has six preamps, but only 4 are the higher quality and power hungry Kashmirs, which supply 48v phantom power.

Probably covered somewhere else, but since we're here:
So the 5 & 6 channels provide phantom power but only through a 3.5mm stereo jack?
But with noisier preamps? And no digital in...

Man, I was hoping for a LITTLE bit better.
The noise floor on the Oade-modded R44 is mighty low, and I can't believe the bargain prices those fetch now. But they are heavier and bulkier than the Mixpre6.
Title: Re: 3 channel recording with mix 3-pre
Post by: DavidPuddy on September 03, 2019, 04:23:37 PM
MixPre6 has six preamps, but only 4 are the higher quality and power hungry Kashmirs, which supply 48v phantom power.

Probably covered somewhere else, but since we're here:
So the 5 & 6 channels provide phantom power but only through a 3.5mm stereo jack?
But with noisier preamps? And no digital in...

Man, I was hoping for a LITTLE bit better.
The noise floor on the Oade-modded R44 is mighty low, and I can't believe the bargain prices those fetch now. But they are heavier and bulkier than the Mixpre6.

No phantom on 5&6, just gain from non-Kashmir preamps.
Title: Re: 3 channel recording with mix 3-pre
Post by: noahbickart on September 11, 2019, 10:30:33 PM
No phantom on 5&6, just gain from non-Kashmir preamps,

I think the confusion here is the definition of "preamp." I think there is a ~60db gain range on these inputs, and it wouldn't surprise me at all if you could run a phantom box into these inputs for loud rock concerts without a "preamp."

Kashmir is simply a marketing term for these particular kind of combo jacks which take 1/4 inch or xlr, "line" or "mic" and provide 12v or 48v phantom power.

Channels 5 & 6, on the mini jack are designed for "line" and not "microphone" level inputs. Hence no phantom. Makes running 2 pairs of microphones and a SBD feed (might need attenuator cables coming from XLR "pro" outputs on the SBD to prevent "brickwalling"), or an outboard stereo preamp easy. (Though input volume control is via the [tiny] headphone knob).

I'm happy that SD didn't add two more preamps to the mixpre6- it would have raised the cost to over a grand- an $899 box is going to have compromises. But with the (relatively inexpensive) addition of a 1/8 inch input, they gave me two more channels. It's also fun to use a single stereo preamp for fun and "flavor" in those "extra" channels.