NL5
Unpossible!
So is a DI input into a preamp just an unbalanced 1/4" input?
Did you read the thread?
So is a DI input into a preamp just an unbalanced 1/4" input?
DI's convert from unbalanced instrument or line level to balanced mic level (not line level). You still need a mic preamp after the DI.
The purpose of a DI is to convert the signal to balanced mic level so that firstly, you can use a mic preamp to up the level and secondly, so you can run the balanced signal over a longer cable run (like through a snake on the stage or tracking room and into the mic preamp) and not worry about losing signal strength and/or picking up RF interference from a long unbalanced cable run.
You can input either instrument or line level (the latter is usually from a keyboard or FX box). You don't have to use a DI if the preamp has 1/4" inputs and your cable run is only a few feet (around 6 ft or less is a good rule).
If your original output is line level (keyboard or FX) and you don't have a long cable run to the recorder inputs then you don't really need a preamp at all unless you just want to use it for the sound or the output level on the keyboard/FX is extremely low.
Sorry for jumping in late. Yes, I did read the whole thread, and I'm thinking the only use for that input (the DI of a preamp) is for an unbalanced mic or line level signal. I guess I'm just asking if there is a difference between preamp unbalanced in and preamp DI? If so, is that difference that the DI converts to balanced and the unbalanced in doesn't?
A "line level input" is for inputting a line level signal. It's that simple. A DI is to connect an instrument directly to the preamp. It will be looking for a lot lower level signal, and will show the proper impedance to the pickup.
Ok thanks. So if I'm recording bass directly into a preamp unbalanced 1/4" input then into the computer, it's going to be fine since the cable runs are really short. If I'm doing the same thing on stage and the bass cable runs 30 feet to the amp, then I need DI input so the signal is balanced and won't degrade over the long cable run, correct?
Well thanks for your patience. I do appreciate it. I'm thinking I'll just get a copy of that book as well.
for me the most helpful explanation of the DI box has to do with going back to my college physics and remembering V=IR. The transformer (or circuit) in the DI box simply takes the high voltage, low current signal from a pick-up and transforms it to a higher current, lower voltage signal that can drive the mic input on the preamp (as well as isolating the input from the output signal and balancing the output).
Boingo, the horse is already dead, but it doesn't mean we can't keep beating it. NL5, thank you for making me think critically about the signal path. You have stimulated me to read as much as I can, and for me the most helpful explanation of the DI box has to do with going back to my college physics and remembering V=IR. The transformer (or circuit) in the DI box simply takes the high voltage, low current signal from a pick-up and transforms it to a higher current, lower voltage signal that can drive the mic input on the preamp (as well as isolating the input from the output signal and balancing the output). I think it's coming together. Thanks also to the original poster for pulling this old horse out of the barn.
For the purposes of audio signals, current isn't important, but if it helps you visualize, cool. The important things are that the signal on the output of the DI is balanced, and is lower impedance than the input.
At the risk of being completely wrong, here are some of my thoughts. First, I was under the impression that typical circuits were designed in kind of a two stage process. The mic input hits a mic amp, where the line input hits a second amp in the same series as the mic imput on a lot of gear. My understanding was that the two amps are used when using the balanced mic level input, where when using the line input (be it xlr or 1/4") that only the second stage of this amplifier circuit was used. Due to this you can still drive the input section to add some of the overall charachter of that specific equipment. The pad and polarity reverse, as I understand it, is often applied to the first of the circuits, which means they do not affect the line input, although where these two functions inject in the path can be different in different designs, so sometimes the pad and/or polarity can affect the line input as well. I was also under the impression that the output trim can come after the transformer so that high saturation with manageable output leaving the equipment can be acheived. If this is how a lot of stuff is built then it would allow to run something like keyboards through an external preamp and drive it hard for a tonal change but still re-record it at a manageable level.
Once again, I may be wrong about some, or even all of this, but that is a basic explanation about how I understood things worked. Basically you have a mic head amp and a line head amp and often the two can be in series where the input signal is routed through one or both depending on how you have it set or plugged in (via the mic or line input jacks and/or any button or switch selections on the equipment itself). Personally, as long as your converters aren't awful, I would see no problem in adding one extra round of conversion in order to warm up some keyboard settings through external equipment be it a preamp, EQ, compressor, or whatever. I would probably not risk this with something like a nice piano sample, but for something like an organ or moog virtual instrument, sending it out through even M-Audio converters or similar quality converters through a nice outboard preamp for character or a nice comp could certainly net in what I might consider a thicker, and as a result, better sound in the end.
Now it makes sense. But I think I alluded to something like that application in this thread.
Yes, I also stated that before I posted the Atlas link. My OPINION is that it's mostly bull. I do love the sound of a saturated output tranny - however, it is quite difficult to do that thru a preamp, and very easy to do thru a compressor. They do make output attenuators so you can do this more easily with a preamp.
try it. i do it thru my neves and apis and dakings on recording tracks. i don't saturate - you don't need to. i just run tracks through them. big difference in sound - in a good way mostly though that last point is subjective...as is degredation i guess.
a guy just came to my house a few months ago and hooked up old API transformers to the output of my soundworkshop 34. if you call bigger and better a degredation...well ok... i do concur with your opinion in general...i'm just relaying an experience.
the line in's on the avril stuff aren't dedicated line amps...they're just a way to get into the mic amp. i think it's the same way on most standalone mic pres.
No i'm not confusing anything. I've used them for both line level signals and as a DI - the function is the same so people are using them interchangeably.