Some Questions About DI And My Gear

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bdam123

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I am currently running a BAE 312a into an Avid MBox 3 Pro. The only type of recording I've done so far are vocals. I've spent the past few months learning about guitar emulation and messed around with it a little but still don't have my head around how I am suppose to go about this with my gear.

Basically I want to get my guitar signal into PT properly so I can use the various emulation programs while having a solid direct signal just in case I need to get it reamped.

I'm plugging into the 1/4' input thats in front of the BAE (which I believe is the direct input) but when I turn the Gain knob it still effects my signal. Is this right? I though that a DI is suppose to be just that; direct.

From there its going into "Mic/DI 01" on the front panel of the MBox. There is also an input labeled "Line Input" on the rear panel. How does this differ from the one in the front? I also understand that there are mic preamps built into the Mbox that can't be bypassed unless you run a different AD/DA into the SPDIF input in the back. Is turning the gain knob all the way down the best I can do? I currently have the gain of my BAE all the way down also.

Would this be considered a true "direct signal" that a real studio would use for reamping?
 
Why are you running a guitar through the BAE unit at all? I don't know them, but aren't they primarily a vocal pre-amp? Isn't adding some gain precisely what it's there for? If you want to be more direct wouldn't it be better to just plug straight into the MBox, or does the particular guitar require a special pre-amp?
 
I'm plugging into the BAE because from what I've read its a great DI.

Its an electric guitar. I'm using it in conjunction with emulation software and possibly re-amping.
 
Plug your guitar into your d/i box then plug that into your interface and that should give you a VERY raw guitar track to work with.
 
Thats exactly what I'm doing.

But what I'm trying to say is that my DI is also a preamp. If you look at any description for the BAE 312a it will say, "High impedance direct input for guitar and synthesizer". So is this unit essentially acting as a DI once I turn the gain knob all the way down?

I am wondering the same thing about the MBox. Is there a benefit to plugging into the BAE first or should I plug directly into the MBox?
 
Mbox 3 has two DI inputs on the front.

Plug the guitar into one of them.

Reamping is a different thing.
You put a mic in front of an amp, and play a recorded dry track out of a line output, through a reamp box and through the guitar amp.
 
Can I assume that the DI on my BAE is of higher quality than the ones on the Mbox?
 
I doubt it, but unless it's got a digital output, it doesn't matter either way.
 
bdam123 said:
I'm plugging into the BAE because from what I've read its a great DI.

Its an electric guitar. I'm using it in conjunction with emulation software and possibly re-amping.
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Hi,

I'm no expert, and I hope that somebody will correct me if I'm wrong, but it seems that you're possibly confused about what "DI" is.

As far as I know, DI just means Direct Injection (some will say Direct Input) it's a method, not some special box for processing a signal. [EDIT: OOPs. :o Apparently it can mean both a method and a box....sorry about that... but I'm still unsure if that's what you need here] It usually refers to the difference between taking a signal from your pickups by the most direct route into the computer - rather than (for instance) playing through a guitar amp and sending the signal to the DAW via a microphone in front of the amp.

What you seem to want is a signal that's as 'dry' as possible - i.e. without any effects added. As you doubtless know, it's much easier to add any of the huge number of possible effects later than it is to try and subtract something if it was added before you recorded, and you change your mind. Some setups will even allow you to record both at the same time - a processed one and a 'dry' version as a fall back.

Units like that BAE are predominantly designed to boost weak signals - such as vocals from certain mics - and you certainly don't 'need' one for your guitar.

But what I'm trying to say is that my DI is also a preamp.
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I think you have this the wrong way round. The BAE isn't "also a pre-amp", surely it IS a pre-amp. More specifically it's designed as a mic pre-amp. If you need a signal boost then you can stick it in a Direct Input chain. Mic your drums, your voice, or whatever. If you're dealing with vocals or acoustic drums then going through a mic is about as direct as you can get. Electric guitars, synths etc can go straight into the board. Calling it the unit a DI is a bit like calling your car a "Drive".

Can you please explain why you think you need it in the chain? Your MBox can easily handle the input of your guitar, and (unless I've got it wrong too :rolleyes: ) I don't think that the BAE is going to add 'greatness' or 'DI' in any useful way. It's a tool for a specific job. A job that you don't seem to need to have done. So why is it there at all?

Chris
 
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Hakea, hate to be that guy, but I think you've got some of this mixed up too.


Yes, DI is direct input designed specifically for instrument level. Ie an electric guitar or bass,

but it can be a 'special box for processing a signal'

AFAIK (and I could be wrong here), a DI box is an impedance matching pad, designed to take a high impedance unbalanced signal, and output a low impedance balanced signal that's acceptable to a mic pre.


The 312a is billed as a mic preamp with High impedance direct inputs.
If the OP used it before his mbox, he'd be effectively using it as a DI box.


I agree with your last point though.
OP is probably right in saying that the 312a would be better quality than the DI in the mbox, but he'd still have to put the 312a through the mbox line in or whatever, so i doubt there'd be any point.
 
Steenamaroo said:
Hakea, hate to be that guy, but I think you've got some of this mixed up too.
Click to expand...

No, it's all good. Thanks very much for chiming in. :)


Yes, DI is direct input designed specifically for instrument level. Ie an electric guitar or bass,

but it can be a 'special box for processing a signal'

AFAIK (and I could be wrong here), a DI box is an impedance matching pad, designed to take a high impedance unbalanced signal, and output a signal low impedance balanced signal that's acceptable to a mic pre.


The 312a is billed as a mic preamp with High impedance direct inputs.
If the OP used it before his mbox, he'd be effectively using it as a DI box.
Click to expand...

OK. I'm more or less with you, and I've now read this Wiki on DI :) but for what purpose here? What advantage could a mic pre-amp provide to a raw electric guitar signal, in this instance?


I agree with your last point though.
OP is probably right in saying that the 312a would be better quality than the DI in the mbox, but he'd still have to put the 312a through the mbox line in or whatever, so i doubt there'd be any point.
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That's my reading of it too. Whatever the potential terminology confusion, he still seems to be running a guitar signal through two pre-amps without actually needing both.

Thanks for the extra info. I'm hoping to learn more here, as well as see if the OP can get his answer. :)

Chris
 
This is the Wiki description that seemed most relevant:

Why a DI Is Necessary

The Direct Injection box takes a high impedance, unbalanced signal and converts it to a low impedance, balanced signal.
This allows the signal to be sent over long cable runs with significantly less signal loss (especially in high frequencies) due to the lowering of the impedance, and greater rejection of interference due to the benefit of common mode rejection in a balanced signal. Furthermore, the lower impedance (around 600 ohms is normal) allows an insignificant load to the input of a mixing console or preamp which is also designed to accept input from low impedance microphones.
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That sounds to me like a fairly special case. It's what I was getting at when I said " It's a tool for a specific job. A job that you don't seem to need to have done."

But maybe I'm still missing the point...

Of course, there could be a silver lining here too - I might discover that I 'need' another bit of gear that I haven't got yet.... :cool:

Cheers,

Chris
 
Hakea said:
What advantage could a mic pre-amp provide to a raw electric guitar signal, in this instance?
Chris
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IDK, i guess it's not really about that. It's not that you want to put a mic pre in the chain,
It's usually more like you have a mic pre already, and want a way to plug a guitar into it.

I suppose it depends what his 312a is outputting. If it outputs line level, then i guess there's an argument for using it with the mbox, but still not a strong one.

The reason i say that is, mbox line inputs (historically, at least) don't bypass the mic pre, So he'd be using a 'direct' box to be slightly less direct than he could be! lol.
 
Steenamaroo said:
The reason i say that is, mbox line inputs (historically, at least) don't bypass the mic pre, So he'd be using a 'direct' box to be slightly less direct than he could be! lol.
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Thanks. That's interesting info too. :)

I've just bought an MBox pro 3rd Gen so I'm currently at the stage that the height of my enthusiasm is only exceeded by the breadth of my ignorance. I must admit I'd been wondering about that very point. My explorations so far haven't got much further than plugging into various sockets and hopefully watching the signal lights going up and down (not perhaps the most illuminating method...)

I have a feeling that I'm going to have to keep reading that pesky on-screen manual.... sigh...oh for the 'good old days' when you got a printed booklet...

Chris
 
Ha! You're right.
Nothing quite like a printed manual.
At least then you had something to throw in the drawer and pretend you don't need :P

Hey, If i can help, just shout :)
 
Hey guys thanks for chiming in.

If you look up any descriptions of the 312a it usually says something along the lines of, "High impedance direct input for guitar and synthesizer". The most important part being, "high impedance". Also on the front panel it actually say, "312A MIC PRE/DI". Since it is powered I'm pretty sure it is considered an active DI, which is what most recommend for guitars and basses with passive circuitry.

My main concern was capturing a true direct signal so that if I was going to re-amp it would be as close to plugging in the amp as possible. After some reading I found out that the impedance on a high end pre-amp's input is likely higher than that of a guitar amp's input so in order to get it perfect you would have to do all kinds of stuff I don't feel like going through (but rolling off the tone knob could essentially have the same effect I think).

I also found out that going through the "Line In" on the Mbox does indeed bypass the the built in pre-amps.

I'm gonna play around and see what I like best. Hopefully I wont have to re-amp and I can just get away with amp emulation in the box.
 
bdam123 said:
I also found out that going through the "Line In" on the Mbox does indeed bypass the the built in pre-amps.
Click to expand...

Does it? Plug something into the line and see if the gain knob has effect to be certain.

Regarding impedance etc, I'm pretty sure a reamping box takes care of that, but having said that, I've never used one so there ya go.
 
bdam123 said:
I also found out that going through the "Line In" on the Mbox does indeed bypass the the built in pre-amps.
Click to expand...

Yes, I've just been fiddling around and came to the same conclusion (in my case that should be "provisional conclusion"... )

On mine there are two combo inputs (1 and 2) on the front. Gain knobs work as expected.

Round the back there are a number of additional inputs, including 4 line input sockets, that can be routed to the 1,2,3 and 4 controls on the front.

If I use the line inputs then the gain knobs indeed have no effect any more.

So that does look like the way to go - either go straight into the Mbox combo inputs (and possibly skip the BAE) or else use the BAE and run it into line 3 or 4, or whatever.

Thanks go to both bdam123 and Steenamaroo. I've learned some useful new things. :)

Cheers,

Chris
 
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