Makes sense, except the necessary equipment part. That's what I was asking about when I asked how to accomplish getting each source into the computer.

Record each source to a separate track for sure. Isolating (or blending) the acoustic interplay is a whole other skill set. Studios have gobos (partition baffles), and iso booths. If the set up allows it, configure the players in a circle so the mics are off axis from the other sound sources and use directional mics. If you need to purchase mics, Shure SM57 and 58 are low cost and sound decent on just about anything. They're also pretty much indestructible.

There's only one mic, the RODE that is pointed at the speaker's face, just above the picture frame. Ideally, that mic should only pick up the voice, but due to the volume of the speakers which are producing the sound of the guitar and piano, the mic picks them up, regardless of the mic's directionality.

So going back to recording each source to a separate track. The question is - I have all these sources going into my mixer. How do I get each source into Vegas on its own track? That's the part that escapes me. The mixer has a USB out, but I think that just outputs the mix, i.e. left and right.

The whole point of a mixer is to mix tracks together, so you end up with fewer (e.g., two) channels. That is why I was talking about using separate devices to record each source. If the devices can produce a .WAV file, you can import each of those files to your computer at edit time and then place each of them on a separate track. Other than that, once the tracks are mixed, it would be very hard to separate them (I don’t want to say impossible, but close to that).

If you somehow wanted to get it all to Vegas at once, your computer would have to have a sound device with enough separate audio inputs and you would have to be able to hook each source up to a separate input, and the computer would have to be powerful enough to record them all to different Vegas tracks without skipping. That would require specialized equipment which would cost you a lot more than having a separate recording device (I mean, not attached to the computer, something like these) recording each input to a card or such, and then importing each audio file into Vegas at edit time.

Run a second camera with a separate audio input or purchase an audio recorder and record to it separately. Otherwise, like Red Prince said, you need a computer with multiple inputs capable of handling multi-track recording.

Well the computer definitely doesn't have multiple inputs. I assume you mean on its sound card? If so, what sound card would be required? And how powerful of a computer is needed to record each to a different track without skipping? Mine is Intel Core i7-2600k, 3.4GHz with 8GB of memory

Alternatively, what would be a good audio recorder to use? This isn't a Hollywood epic I should remind you. If I use an audio recorder, I would no longer use the mixer since all sources would be going to the audio recorder, correct?

The link I gave you above (marked by the blue text) shows several audio recorders, including some that can record to 6 or even 8 tracks at the same time. The Zoom F8 Multitrack Field Recorder is probably more than you need (and it costs $800), but here is a video about it:

Another option would be to get the Zoom H6 Handy Recorder (you can record six tracks on it). It is very popular, costs $350, and should be more than enough for your current need. The F8 is better if you expect to record more than six tracks in the near future. Though probably an overkill. This video is about the F6:

There's only one mic, the RODE that is pointed at the speaker's face, just above the picture frame. Ideally, that mic should only pick up the voice, but due to the volume of the speakers which are producing the sound of the guitar and piano, the mic picks them up, regardless of the mic's directionality.

Then you definitely need to record each input separately. I am not sure whether Vegas can do this (I use Audacity for all my audio editing), but it is possible to subtract those extra sounds the mic picks up, as long as you have them on separate tracks.

The basic way of doing that is to match the volume of an extra sound picked up by the mic and the corresponding separate track (that is, you would lower the volume of the separate track until it is the same as the extra sound picked up by the mic). You then reverse the polarity of the separate track and add it to the mic track (this is mathematically the same idea as adding -5 to +5 to get 0, because reversing the polarity is like reversing the sign of a number). You would do this with copies of the separate tracks, as you still want to keep the originals for your final mix.

If your PC only has a two channel audio interface (left and right) and an external multi-track recorder is not available, I would record the instruments (premixed) to one track and vocals to the other. This would give you at least some mixing options in post. If you mix everything together together on-set, it's very difficult and usually impossible to adequately change (aka, unbaking the cake),.. even with Spectral Layers or IZ's RX.

By multi-track recorder, you mean one of the Zoom units? I looked, and see that that H4 could probably do the job that I need as I only have 4 sources (voice, guitar, piano, MP3) I saw some videos on youtube when I searched for how to record guitar and mic at the same time, but then again, I don't know if they're using speakers, they seem to all be acoustic guitars that are mic'd.

Here is a rather detailed comparison of the four most likely recorders to do what you need there:

This guy knows what he is talking about, so I suggest you watch it in its entirety (some 44 minutes) to avoid buying a device that seems right on the surface of it, but may perhaps not be right because of some details. For example, if you need to record a passive signal (e.g., a guitar with no pre-amp) and the device does not have the necessary pre-amp, it may not be the right device (or may require an external pre-amp).

I watched the first 12 minutes late last night, and am going to watch the rest now because this discussion has whetted my appetite for one of these. 😎 I just need to decide which one.

The POS Zoom H4n has two XLRs (or 1/4" line) and two 3.5mm mic inputs. As Red stated, there are different impedances and such. For instance, many acoustic guitars w/ internal pickups, have a high impedance (100k ohms) instrument level output that would require an D.I. (direct inject) interface if plugged into a mixer (same with an electric guitar if not micing the amp.. which BTW is usually an integral part of an elec guitarist's sound.. put that's another story.

If your getting an external recorder, I would recommend something with at least 4 XLR mic inputs and a stereo internal mic to pick up ambient room live sound which is usually nice added to the mix. I would prefer a Tascam for low cost portable recorders.

I'm not entirely sure about the impedance stuff. It's an archtop guitar with a humbucking pickup.

I've been doing some more research on the mic itself. I learned that this RODE mic has the super cardioid polar pattern which means it does pick up sound to the rear, which is where the speakers are. I've discovered that I also have a Shure SM58 available, which is cardiod. Perhaps if I use that microphone, and reduce the volume of the speakers to only what they need to hear what they're playing, I might be able to continue using the mixer, instead of having to go the audio recorder route.

The guitar almost certainly will need a DI to feed your mixer. I use active DIs for guitars and such, but a low-cost passive DI would work. The Rolls DB25 (and 25B) is about $25usd and useful all around. It also has a ground-lift, a pad (three position switch or rotary) to tame hot sources.

The SM57/58 is best used for close micing and rejection of other sound is good.

I actually have one of those DB25 boxes in my stash, never knew what it was for! But recently, someone on another recording forum said I should use it, but I can't figure out how to even use it. When I plug the guitar into it, I get all kinds of noise and it just sounds terrible. What is it even for? To make the guitar sound awful because that's what it seems to do? Every time someone tells me to use it, I try plugging it in, but it either doesn't do anything, or if I switch the ground lift, it just makes ton of noise.

What kind of input are you plugging the DB25's XLR into? it should be a balanced mic level XLR. Have you tried different cables? (both the cable from the guitar and the XLR). Phantom power should be disabled on your preamp or mixer channel... though it should not matter on a balanced XLR. For guitars, attenuation is normally not needed, so the pad should be set to 0dB.

Otherwise, most folks use the DB25 for taking a feed from an event's house mixing console or DJ, plugging the DB25's XLR output into a camera or field production recorder 's XLR mic input. If there's a 'ground loop' (typically a 50/60Hz low frequency hum), enable the ground lift switch,

Most folks carry adapter cables as well to feed the D.I. from difference types of outputs: 1/4" to 1/4"; RCA to 1/4" and 3.5mm plug to 1/4" (BTW, the tip and ring terminals on the 3.5mm TRS plug should be tied together to pick up both left and right channels.

I'm going from the guitar direct into the DB25, and from the DB25 with a (good) XLR cable into the first XLR mic channel of my ZED10FX mixer. Attenuator off, and set to GND. Notice I have to turn the gain on the mixer channel all the way up to get any kind of signal whatsoever, and not even a good one. Produces a loud hum (even worse on the lift setting) So with the DB25, I get little to no signal, and a loud hum. What am I doing wrong if these direct boxes are so important?

EDIT: I just discovered what was causing the noise. It was the placement of the direct box. I had it on top of the audio rack and it was sitting next to an Acoustic Image Clarus. When I moved the box away from the Clarus, the noise went away. So that's progress... Next question. When using the DB25, shouldn't I still be using a pre-amp for the guitar instead of going straight into the mixer? I have a Presonus Bluetube that I can use.

You can save money and time by buying a multichannel PC interface. I use the Behringer XR18, gives me 18 inputs (and outputs, each is bi-directional) and 6 aux outupts. The USB connection to a PC records each of the 18 inputs directly into Vegas. The musicians can use the aux outputs to dial up their own custom monitor mix live, while they are playing, with their phones.

There are interfaces with fewer inputs if you don't want to spend $600 and don't need 18 inputs... but I would go the route of using an interface vs. buying a dedicated external recorder, recording everything, transferring it to a PC, then editing it (this approach takes longer and costs more). The Behringer also has built in FX for each channel, so you can EQ each mic, add compression, noise gates, etc. and you can also use it to mix live sound, it isn't just an interface.

I'm going from the guitar direct into the DB25, and from the DB25 with a (good) XLR cable into the first XLR mic channel of my ZED10FX mixer. Attenuator off, and set to GND. Notice I have to turn the gain on the mixer channel all the way up to get any kind of signal whatsoever, and not even a good one. Produces a loud hum (even worse on the lift setting) So with the DB25, I get little to no signal, and a loud hum. What am I doing wrong if these direct boxes are so important?

EDIT: I just discovered what was causing the noise. It was the placement of the direct box. I had it on top of the audio rack and it was sitting next to an Acoustic Image Clarus. When I moved the box away from the Clarus, the noise went away. So that's progress... Next question. When using the DB25, shouldn't I still be using a pre-amp for the guitar instead of going straight into the mixer? I have a Presonus Bluetube that I can use.

ANOTHER EDIT: Instead of the Bluetube, I plugged in the Clarus. And it seems to be working ok.

When using the DB25, shouldn't I still be using a pre-amp for the guitar instead of going straight into the mixer?

Confirm the attenuation switch is set to 0dB (no attenuation). 99.999% of the time it is not necessary to use a pre-amp between the guitar and DI.. unless it has a specific sound the player desires, and the mic input in the mixer or computer interface already has a preamp. Try another guitar or other input source, if the output is still unusable, the DI may be broken. This would be odd though, since DIs are pretty robust and there's very little that can go wrong with a passive DI, aside from a broken internal connection. Maybe a factory defect.

The DI I have is definitely broken, physically, one of the input jacks outer ring has broken off. After doing some research, It seems that I need an active DI because the pickup in the guitar is passive (rule of thumb). I've located this one on Amazon that got pretty good reviews and doesn't break the bank so I think I will give it a try:

https://www.amazon.com/Samson-MDA1-Mono-Active-Direct/dp/B015OGAID8 unless you see some problem with it?