NL5
Unpossible!
Did you read the thread?
Line level input vs. DI
- Thread starter JTC111
- Start date
Did you read the thread?
guitar zero
c = b#
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?
NL5
Unpossible!
There you go...A DI has the impedance set for pickups, and passes through the preamp stage. Unbalanced line level would not want to go through the preamp, and I've never seen an unbalanced mic, although I'm sure radio shack makes 'em.....
guitar zero
c = b#
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?
NL5
Unpossible!
NO.
Seriously. Re-read what I posted. This entire thread really needs to be in the newbie section. This is some of the most basic aspects of recording.
guitar zero
c = b#
Well thanks for your patience. I do appreciate it. I'm thinking I'll just get a copy of that book as well.
NL5
Unpossible!
I don't know if that info is in that book or not. It is an excellent book though. Hubers book is also excellent. There has to be some resources online explaining what a 1/4 unbalanced line level is, 1/4 balanced line level, and what a 1/4 hi-Z DI input is. I'm sick as a dog today, so I don't really feel like to a search, but most of the info is in this thread already........
guitar zero
c = b#
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.
JTC111
Active member
I'm about a third of the way through that book NL5 recommended to me. It's pretty good and is definitely giving me some new ideas, however, it's also nice to know that much of what I was doing intuitively was correct. But there are also solutions to problems that I wouldn't have come up with. It's definitely a worthwhile read although it doesn't say jack-sh*t about line level inputs.
I reread this thread tonight because I wanted to see if it made any more sense and I found something NL5 put here from the Atlas site that I'd missed before: Q: Why would I want line input instead of an instrument level DI?
A: Many engineers like to run signals through iron core transfomers to add harmonics to the signal (alternately known as 'warmth'). You can run individual tracks through the line level input, or run full stereo mixes or subgroups through them to take advantage of the OSA iron core output transfomer.
Now it makes sense. But I think I alluded to something like that application in this thread.
NL5
Unpossible!
There are two separate discussions here that are confusing everyone. We are talking about a DI input on a preamp, not a DI box.
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.
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.
NL5
Unpossible!
Excellent post.
Yes, in my delirious state, I forgot that often times there can be two separate amp stages, so you could pick up a little "color" from the line amp stage as well. I still personally believe that a crappy sample is not gonna benefit much from a little "preamp" color - I think a preamps effects are way overblown for the most part. Also, you can get much more saturation on a compressors output tranny, as you have complete control over the output. Maybe there are preamps with more output control, but mine only have a 10db reduction.
NL5
Unpossible!
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.
Mike
NL5
Unpossible!
Can you post some samples? I've done it before and that is the reason for my opinion.
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'm not sure how changing output transformers in a console relates to the topic? As I stated I do love the sound of output transformers - especially when pushed. The fact that they do degrade the signal is a fact, and is not subjective. However, the benefits can definitely outweigh the cost. My argument is adding an extra pass thru conversion, and a re-balancing may not be worth it - that is just MY opinion.
Again, I think you are confusing a DI input with a line in input. Two totally different things. It really is amazing to me how many people don't understand the difference. The Averill Neve and Api units do NOT have a "line input". Almost all high end stand alone preamps do not have a "line input". In fact, the OSA ones listed are the only ones I am aware of. To me, it's a marketing gimmick feeding off all the preamp hype on GS and elsewhere.
"Can you post some samples? I've done it before and that is the reason for my opinion."
No time for that, sorry. Take it or leave it. I only log in at work.
"I'm not sure how changing output transformers in a console relates to the topic?"
I used it as an example of putting a device in the chain where it did good. i'm not changing your opinion i'm pointing out that in a lot of cases...it actually does good...if you can point a bad side of sounding better...be my guest.
"Again, I think you are confusing a DI input with a line in input. Two totally different things. It really is amazing to me how many people don't understand the difference. The Averill Neve and Api units do NOT have a "line input". Almost all high end stand alone preamps do not have a "line input". In fact, the OSA ones listed are the only ones I am aware of. To me, it's a marketing gimmick feeding off all the preamp hype on GS and elsewhere."
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.
if you think it's a marketing gimmick, that's fine with me. all i'm saying is it changes the tone in a good way in a lot of cases. the difference between a line in and a DI is nil if the input functions as both, which the pres i listed do.
Later,
Mike
No time for that, sorry. Take it or leave it. I only log in at work.
"I'm not sure how changing output transformers in a console relates to the topic?"
I used it as an example of putting a device in the chain where it did good. i'm not changing your opinion i'm pointing out that in a lot of cases...it actually does good...if you can point a bad side of sounding better...be my guest.
"Again, I think you are confusing a DI input with a line in input. Two totally different things. It really is amazing to me how many people don't understand the difference. The Averill Neve and Api units do NOT have a "line input". Almost all high end stand alone preamps do not have a "line input". In fact, the OSA ones listed are the only ones I am aware of. To me, it's a marketing gimmick feeding off all the preamp hype on GS and elsewhere."
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.
if you think it's a marketing gimmick, that's fine with me. all i'm saying is it changes the tone in a good way in a lot of cases. the difference between a line in and a DI is nil if the input functions as both, which the pres i listed do.
Later,
Mike
NL5
Unpossible!
So the OP's original question is invalid. They are the same thing. OSA is just ripping people off to convert the line in to a DI. Sorry, I must have everything confused.
I give up. In fact, I'm gonna fire off a letter to Mr Fearn! I paid damn good money for a line to mic level converter, when here all along they are the same! Dammit. 
DigitMus
Member
There are a number of high end preamps with dedicated line inputs (NOT DIs) - Crane Song and Buzz are 2 off the top of my head. Most preamps have at least 2, and sometimes more, gain stages, and the line inputs usually feed the circuit right after the 1st stage, so the signal can benefit (or suffer detriment) from the rest of the circuitry. A DI input should have the equivalent of a passive DI box built in and feeding the 1st gain stage, taking advantage of all the subsequent circuitry. The primary purpose of a DI (input or box) is to provide proper impedance matching for pickups, which have a significantly higher impedance than a microphone or line level signal.
A secondary function of DI boxes (though not necessarily inputs) is to balance the signal to avoid losses in long cable runs - e.g. from stage to FOH mixer. Most preamps (even high end) are unbalanced internally, and provide balancing at the output, often using a transformer. Many people like the 'sound' or 'color' of particular preamps, and so might use them to inject line level signals to the next piece of gear in the recording chain.
Some preamps do have a dual purpose line/DI input - the better ones are usually switchable between functions. In ones that aren't, the input impedance is usually a compromise between the best for line and the best for instrument - the sound may suffer a little on one and/or the other application, but only your own ears will tell you if this is a 'deal breaker' for your purposes.
A secondary function of DI boxes (though not necessarily inputs) is to balance the signal to avoid losses in long cable runs - e.g. from stage to FOH mixer. Most preamps (even high end) are unbalanced internally, and provide balancing at the output, often using a transformer. Many people like the 'sound' or 'color' of particular preamps, and so might use them to inject line level signals to the next piece of gear in the recording chain.
Some preamps do have a dual purpose line/DI input - the better ones are usually switchable between functions. In ones that aren't, the input impedance is usually a compromise between the best for line and the best for instrument - the sound may suffer a little on one and/or the other application, but only your own ears will tell you if this is a 'deal breaker' for your purposes.