Educate ME: Preamp Basics!

[adamjknight]

As the title suggest, i am just after a few suggestion on the usefulness/applications of preamps.

Now as i understand it, a preamp simply boots a signal to line level; do all signals generally require going through a preamp? Drums?

What are the particular applications of a two channel preamp as apposed to one, instrument wise?

Initally, i was looking to save for a GR MP-2NV but has since found maybe investing in a API lunch box and 2 GR 500 NV's would be cheaper.

Does anyone see any draw backs on adopting this approach?

[lrieves]

the quick answer:
when sound hits a microphone, say an sm57, the pressure changes in the air cause the diaphragm of the microphone to move back in forth in rhythm with the changes in air pressure (sound). essentially, this creates a tiny alternating current (AC voltage) at what we call mic level. this signal is so small, we have to bump it up to Line Level, which a preamp does, as well as convert the AC current into DC current, which is much more stable. it also will generally "bridge" the impedance. a good way to think of this is by picturing a water hose with water coming out on one end at a medium pressure. if you want more water pressure, you could turn the nozzle, OR you could put a faucet head/push your thumb at the end of the hose to increase the resistance, therefore making it come out with much more pressure/rate. if the impedances (which is essentially resistance) of the mic and preamp are the same, the signal will act like the water hose as mentioned above, but if the resistance (impedance) is higher (at least 10x) then you will have a much more efficient level of sound coming through. i hope that translates.

[adamjknight]

Thanks for the response lrieves ...!

Can anyone please tell me the practical applications of a 2 channel preamp ? I know the theory, that is it takes two signals? But was kind of tracking requires this?

Would you use a 2 channel on stereo keyboard signals?
Drum overheads?
Obviously would use it for stereo recording acoustic guitar right?

Fundamentally, i want to invest in a nice preamp, and i am just not sure if i should go with one channel or two...so any insight into there practical applications would be great.

Any insight most appreciated!!!

[dhiltonlittle]

two channel preamps simply give you that. two channels. if you are going to do stereo micing of any kind or want to record two different tracks at the same time you'll either need two single mic pre's or a two channel. i sometimes run my stereo mix through two 1073's. that's another plus to having more than one of the same pre.

[adamjknight]

Can anyone give me some good examples of when stereo micing is useful or called for? I know i am asking the basic here...just trying to learn the ropes that it all.

Thanks.

[Tapeworm]

Originally Posted by adamjknight

Can anyone give me some good examples of when stereo micing is useful or called for? I know i am asking the basic here...just trying to learn the ropes that it all.

Thanks.

Acousitic guitars, drums, congas....many, many things.

[jinksdingo]

If you are recording now you will be using a preamp; either a channel on a mix desk or interface. All audio signals need to go thru a preamp.

A very high quality Preamp and even mediocre ones will show up the inadequacies of your room's acoustics and noise level therein.

From the questions you are asking there is much you can do to improve your current sound before purchasing an expensive preamp. Adequate results can be achieved with a quality interface and/or mix desk.

When you know what you want in a Preamp then it is time to purchase one.
For e.g. I know I want a preamp that can give me a variety of tonal qualities as I don't have enough dough to outlay for a top of the line model of every Preamp design type.

[_Morph_]

Originally Posted by lrieves

this signal is so small, we have to bump it up to Line Level, which a preamp does, as well as convert the AC current into DC current, which is much more stable.

Mind that this AC->DC conversion happens to the power supply, not to the signal path.

[adamjknight]

Originally Posted by jinksdingo

From the questions you are asking there is much you can do to improve your current sound before purchasing an expensive preamp. Adequate results can be achieved with a quality interface and/or mix desk.

I understand the room, treatment, mic, mic placement and performance are the fundamentals of a good sound. I am currently running through MBox2 preamps and can see i can get some results...will probably go to digi 03 (more channels) at some point because i am tied to ProTools; as a result there is not much room for improving the qaulity of preamps on the interface front.

So outboard is the best answer then?

The real question i am driving is what are some practical applications of a two channel preamp; basically to justify or negate the need for a 2 channel preamp in my setup. Ultimately i have future flexibility in mind, trying to open my eyes to various tracking methods that i don't currently use, so as to not limit myself in the future by my choice of a single channel pre now.

I know for most of my applications, vocals, electric guitar and bass a single channel is fine.

Keyboards: Do you normally record mono or stereo?

Drums: Is each peice of kit normally going through its own channel and preamp?

How often do you stereo mic acoustic guitars or pianos in a full mix?

What do i hope to gain in a preamp upgrade?

A clean, crisp sound with some warmth and character to it also. Is the MBox preamps up to this, cause i can't say i have found that yet?

[Unclenny]

Originally Posted by adamjknight

Is the MBox preamps up to this

Use the MBox to get into your DAW but get yourself a couple of decent pre's and bypass MBox.

Stereo tracking gives me so many options in the mix.

[vernier]

Possibly the most important use for preamp is vocals. One way to get educated is listen to records. There are two types, tube and transistor.

All 40's, 50's, and almost all 60's records were made with tube preamps.

Frank Sinatra
Nat King Cole
Little Richard
Elvis Presely
Patsy Cline
Peter Paul & Mary
Bob Dylan
Simon & Garfunkel
Beach Boys
Beatles
Byrds
Rolling Stones
Hendrix
Who
Cream
Doors ..etc etc ..and the tons of great jazz and R&B. Those are the sound of tube preamps.

Much of the recordings made after the 60's use transistor pre's, except for the recent resurgence of outboard tube pre's you hear on big hits today.
'

[adamjknight]

Originally Posted by adamjknight

i was looking to go for a GR MP-2NV but has since found maybe investing in a API lunch box and 2 GR 500 NV's would be cheaper.

Can anyone chime in on the pro/cons of each approach (MP-2NV vs Lunch Box with 2 * 500 NV's)?

[max barker]

Alright Adam,

I was in the same boat as you, recording with just the M-Box's pre's and conversion. I'm no expert in pre's and conversion but I can tell you that the M-Box is not good for both of these.

If I were you I would get a Lunchbox, without a doubt! This way you can get your GR's one at a time AND when u can afford em. Down the line your gonna want compressor's and e.q.'s and you'll be glad you've got a Lunchbox cos you can buy the modules (which are cheaper cos your not paying for power supply, build etc...). Plus you've got portability, ruggedness, high-end sound, versatility etc....

Otherwise you could get all these things as separate units, this would look great but you'd pay for it. I can't see any pro's of getting the GR MP-2NV (in your situation) cos you've got nowhere to go from there, apart from shelling out another £1000+++ for a decent dual compressor. A Lunchbox will let you build as you go at a cheaper cost (with no detriment to sound), for me it's definately a no-brainer!

Don't worry about stereo micing and all that, just get the lunchbox and pre and take it from there, you'll start building up knowledge and get to these things in due course.

Also, forget the M-Box, use it as a dongle for pro-tools only. I've just bought a RME ADI-2 and this will give you decent conversion AD/DA. You can spdif into and out of the M-Box.

Get involved in the world of 500!

[Blast9]

Am I correct in thinking you can't actually bypass the preamps on an MBOX? i.e. your line-in still goes through the preamp circuit.

Adam - what bass preamp/DI did you get in the end?

[max barker]

Yeh, I've heard different answers to this.

It would be good to hear the definitive answer from someone who knows.

Ta.

[Blast9]

Originally Posted by adamjknight

Can anyone give me some good examples of when stereo micing is useful or called for? I know i am asking the basic here...just trying to learn the ropes that it all.

Thanks.

Hey Adam - stereo micing is great for drum overheads, or 2 room mics (or even 3 feet from the kit - picking up the whole kit. NB the room has to sound nice though.

You can also mic a guitar or bass amp with 1 mic pickin gup the room sound and 1 mic right on teh speaker or just a bit back.

Classical recording - It has been known to pick up the whole ensemble off 2 mics in a great-sounding room/auditorium