Preamp and DI, what are they?

[brianli408]

So I got confused between preamp and DI when thinking to have either one of it. And anyone can suggest some good product of both of these
P.S. I am a acoustic guy so whether electric preamp or di makes a difference from acoustic one
P.S.S and suggest acoustic one if both of the gadgets above are different from electric ones.

[AndyC]

Read this:

https://www.acousticguitarforum.com/...ight=preamp+di

[pieterh]

There is a recent thread about this but to recap:

A preamp is designed to amplify the signal from an instrument (or mic) and to offer a degree of tone shaping (eq). Low and/or hi cut may also be features as well as button-activated boost and mute functions, ground lift and polarity reverse options.

A DI is a gadget that takes unbalanced signals and turns them into the kind of signal that is optimised for a mixer (for example). In a sense a DI takes an instrument signal and turns it into the equivalent of a professional microphone signal, though with a higher level. By doing this self-generated cable noise is eliminated and the cable can be much longer post-DI. A DI should also have a ground lift function.

Where many people get confused is when manufacturers include both functions in one unit (Venue, Pz-Pre etc). It is dinky confusing when it is included in name! These are still essentially preamps that happen to have a direct output, that is, a DI direct to the mixer or stage amp.

These days most guitar floor preamps have a balanced, direct out and some - like the Pz-pre amongst others - offer a pre-eq direct output where the controls don’t affect the signal sent to the mixer as well as a post-eq output ideal for a stage monitor or for where there is no one manning the front of house sound.

So to summarise: a preamp boosts and processes the signal according to the musician’s needs, a DI optimises the signal for connection to a mixer or (active) stage monitor.

[Rudy4]

Originally Posted by pieterh

There is a recent thread about this but to recap:

A preamp is designed to amplify the signal from an instrument (or mic) and to offer a degree of tone shaping (eq). Low and/or hi cut may also be features as well as button-activated boost and mute functions, ground lift and polarity reverse options.

A DI is a gadget that takes unbalanced signals and turns them into the kind of signal that is optimised for a mixer (for example). In a sense a DI takes an instrument signal and turns it into the equivalent of a professional microphone signal, though with a higher level. By doing this self-generated cable noise is eliminated and the cable can be much longer post-DI. A DI should also have a ground lift function.

Where many people get confused is when manufacturers include both functions in one unit (Venue, Pz-Pre etc). It is dinky confusing when it is included in name! These are still essentially preamps that happen to have a direct output, that is, a DI direct to the mixer or stage amp.

These days most guitar floor preamps have a balanced, direct out and some - like the Pz-pre amongst others - offer a pre-eq direct output where the controls don’t affect the signal sent to the mixer as well as a post-eq output ideal for a stage monitor or for where there is no one manning the front of house sound.

So to summarise: a preamp boosts and processes the signal according to the musician’s needs, a DI optimises the signal for connection to a mixer or (active) stage monitor.

D.I. (direct injection) boxes can be passive or active. Passive DIs do not boost the level of the signal.

The DIs purpose is to convert unbalanced signals to a balanced XLR configuration that by it's nature rejects RF and A.C. line noise from being introduced. The balanced line can run long distances without picking up stray noise, and that is it's purpose.

All the other stuff that may or may not be included is tangential to a DI's main purpose.

[pieterh]

Originally Posted by Rudy4

D.I. (direct injection) boxes can be passive or active. Passive DIs do not boost the level of the signal.



The DIs purpose is to convert unbalanced signals to a balanced XLR configuration that by it's nature rejects RF and A.C. line noise from being introduced. The balanced line can run long distances without picking up stray noise, and that is it's purpose.



All the other stuff that may or may not be included is tangential to a DI's main purpose.

You are of course quite right, I was not clear enough. A passive DI does not change signal level though in the context of what I was saying I was correct: a DI (passive or active) takes a signal and makes it similar to a microphone signal though at a higher level than a microphone signal. That is, the signal going into the DI is at a higher level than a microphone’s to begin with.

Hopefully this won’t confuse matters../

[brianli408]

Thanks all, it seems I do not need a preamp or di at the end of the day.

[Jeff Scott]

Originally Posted by brianli408

Thanks all, it seems I do not need a preamp or di at the end of the day.

What about earlier in the day?

[Mr. Jelly]

Originally Posted by brianli408

Thanks all, it seems I do not need a preamp or di at the end of the day.

Did you forget about last night!?!?!!