• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Need help understanding "D.I out", XLR out, etc.

Skel

Skel

Jun 19, 2005
3,237
45
Boulder, Colorado
#1
I have always been confused by the term "D.I. out". If I'm not wrong, D.I. is an abbreviation for "direct input", and it seems like an oxymoron - direct input...out. I think I understand the XLR out, which is, I believe, the output signal taken after the preamp, with the option (sometimes) of having pre or post EQ. This is, I think, a 600 ohm (whatever that means) balanced output. I think "balanced" means there is some kind of noise cancelling signal, and if both ends are balanced, the noise gets cancelled by this signal that both ends understand. When an amp has both a D.I. out, and an XLR out, is the difference that one is balanced and the other is not, or is it simply the type of connector, as it seems a D.I. out is always a quarter inch connection and XLR is XLR. And why not call a D.I. out, just a D.O., or direct out? Would you use this connection to have something come "in" to the amplifier?

Last, I am never sure when I use an XLR out, whether to use the pad or not - it seems like it doesn't matter. I am primarily interested only in running direct to a live mixing desk situation, but I'd like to understand all this stuff for live and/or recording.

Sorry if my questions are confusing. I hope they are understood.
 
#3
dave_bass5 said:
i always thought DI meant direct Injection
Click to expand...
You are 100% correct, DI does indeed stand for Direct Injection.

EDIT:

Skel said:
And why not call a D.I. out, just a D.O., or direct out? Would you use this connection to have something come "in" to the amplifier?
Click to expand...

It is called a DI because you are being put directly into a mixing desk, you are correct it is coming out of the amp but the signal is going into the desk.

Skel said:
as it seems a D.I. out is always a quarter inch connection and XLR is XLR.
Click to expand...

A DI is generally an XLR connection because (as mentioned above) it is the input on most sounds desks.


Skel said:
I think I understand the XLR out, which is, I believe, the output signal taken after the preamp, with the option (sometimes) of having pre or post EQ.
Click to expand...
On the back of my amp I have a DI output that is XLR and a jack that is a 'tuner' output but this can also be used a DI but this comes pre EQ where-as the DI (XLR connection) comes post EQ. I think the pre or post can be switchable as you say.

Skel said:
I think "balanced" means there is some kind of noise cancelling signal, and if both ends are balanced, the noise gets cancelled by this signal that both ends understand.
Click to expand...

Balanced as far as I am aware means it is a stereo signal but i'm not 100% on this.

Hope that helps, I may not be explaining it very well, someone else may word it better than me.
 
  • Like
Reactions: devnulljp
#6
'Balanced' is a three-wire scheme for carrying a signal. It's used for microphones, instrument D.I. cables, and for some high end stereo interconnects. It was designed for studio use where there's a lot of electrical noise, and where long cable runs are often needed.

A standard unbalanced signal uses two wires. One of them is live, carrying the changing a.c. voltage of the input device. The other is neutral, and carries the return current. In some cases the neutral wire is also the shield; in some the shielding is electrically isolated from the signal.

In a balanced cable, both signal wires are live. Their polarity is reversed. In a situation where an unbalanced wire cable would have +4 volts on the live wire and the 0 volts on the neutral wire, the balanced cable will have +2 on one wire and -2 on the other. The third wire is the ground and is isolated from the signal.

The point of this is that it elegantly eliminates noise. Any noise that the cable picks up (which it will because a cable is basically a big antena) will be picked up equally by both live wires. Because of the inverted polarity of the two wires, any signal that's added equally to both will simply cancel out to zero.
 
  • Like
Reactions: -Boscoe-, Balog, Ronzo and 3 others
#8
Direct inject is where the signal within the mixer is brought out to a three pole jack socket where you have the option of breaking into the signal path to connect something else (like a compressor). Because you are inserting a new function in the signal path, this is known as 'direct injection'.

A DI box usually takes your bass signal, and taps off some to send to a mixer. The rest goes to your back line (if you have one). It is not quite the same thing, but close enough to be given the same name.

In summary, anything that splits off your signal to send to a mixer, may be labelled as a DI out, and is often a balanced feed through an XLR. Anything that breaks into your signal path may be labelled as a DI, and will usually be a three pole quarter inch jack (wired send, return, and ground)
 
#13
Mottlefeeder said:
Direct inject is where the signal within the mixer is brought out to a three pole jack socket where you have the option of breaking into the signal path to connect something else (like a compressor). Because you are inserting a new function in the signal path, this is known as 'direct injection'.

Anything that breaks into your signal path may be labelled as a DI, and will usually be a three pole quarter inch jack (wired send, return, and ground)
Click to expand...

No, I've always called this the Insert Point.

The circuit the OP asked about is called Direct Inject because there is no mic. The signal goes direct from the instrument to the board.
 
#16
To answer your question about ohms and the DI level control:
A DI box often has a transformer that converts the low-level, high-impedance (~100K Ohms) signal of a bass guitar up to the +4dB standard low-impedance (600 ohms) recording level. A transformer is usually found in amps having an XLR out. Whenever there's a 1/4" out on an amp (like the tuner out) it's commonly line-level. (RCA connections for consumer-grade stereos are also line-level)
The use of a balanced wiring scheme, high voltage level and low impedance makes the microphone cable a natural for carrying signals long distances without degradation. That is why it's so often used for DI outs on amps and why it's also important to understand how it all works.

The different gain structures of various mixers, amplifiers and recorders have necessitated the need for a level control on the XLR out. I like to keep my bass' volume consistent so rather than turning my bass up or down to accomodate the engineer, I can use the DI level to control my send level independently of everything else. And even with the same equipment, engineers do things differently than others. One night, the engineer will say you're coming in too hot and ask you to turn the send down and on another night a different engineer says, "give me some more". You never know. That's why I have since changed my definition of DI to "Direct Interpretation". :D
 
#17
VintageBT6Lover said:
To answer your question about ohms and the DI level control:
A DI box often has a transformer that converts the low-level, high-impedance (~100K Ohms) signal of a bass guitar up to the +4dB standard low-impedance (600 ohms) recording level. A transformer is usually found in amps having an XLR out. Whenever there's a 1/4" out on an amp (like the tuner out) it's commonly line-level. (RCA connections for consumer-grade stereos are also line-level)
The use of a balanced wiring scheme, high voltage level and low impedance makes the microphone cable a natural for carrying signals long distances without degradation. That is why it's so often used for DI outs on amps and why it's also important to understand how it all works.

The different gain structures of various mixers, amplifiers and recorders have necessitated the need for a level control on the XLR out. I like to keep my bass' volume consistent so rather than turning my bass up or down to accomodate the engineer, I can use the DI level to control my send level independently of everything else. And even with the same equipment, engineers do things differently than others. One night, the engineer will say you're coming in too hot and ask you to turn the send down and on another night a different engineer says, "give me some more". You never know. That's why I have since changed my definition of DI to "Direct Interpretation". :D
Click to expand...

Yes, I too experience inconsistencies with engineers - some want more, some less and I just give them what they ask for. The thing that really boggles me is how a signal can have a known impedance, like ~100 K ohms. Impedance as I understand it, is simply resistance to alternating current (the signal). So, impedance relative to what? I understand how a signal can have frequency(s) and amplitude, but the impedance part is confusing. Beyond the scope of this thread for sure.

Thanks - Skel
 
#18
Im still a bit confused about this level control on my SA450
I have only seen a variable level control on a DI once, and thats on my SA450. i always thought that the DI goes in to the mixer at mic or instrument level and that the channel gain controlled the input level to the rest of the channel. also all the amps ive owned (even my ABM) have had no control over the DI level and that the DI is always pre master so you cant change the level apart from using the input level (and that would effect the amp sound as well)
 
#19
dave_bass5 said:
Im still a bit confused...I always thought that the DI goes in to the mixer at mic or instrument level and that the channel gain controlled the input level to the rest of the channel.
Click to expand...
A primary reason for the "idea" of having a level control at the DI can be found in your post.

The part where you say "I thought the DI goes into the mixer at mic or instrument level...."

Well because there are so many variables (in addition to "line level") on any given mixer plus the myriad of ways cabling, patch bays, etc. can influence the issue you additionally must realize that it varies from brand to brand among mixers, consoles, PAs.

So someone thought that having a level control on your DI is a convenience to you because its "normal" level may be too hot for any number of inputs on any number of mixers, recorders, PAs, foldback, etc.

However, in practice you may discover that you need it wide open all the time with anything you connect it to. You may discover that you can't turn it up enough. Case-by-case basis.

While I'm not familiar with the DI in your specific amp I will add that I usually prefer a separate, dedicated DI box like a Radial JDI. I say that because I've never met an itegrated DI that I liked mainly due to level weakness or hum. But I haven't tried all that many either.
 

Latest posts

Top Bottom
Back