New Feature: Playlist Center! Pick a topic and let our playlists guide the way.

Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

Explaining the microphone preamplifier

From: Audio Recording Techniques

Video: Explaining the microphone preamplifier

Almost as important as the microphone is the microphone preamplifier or Mic Pre, Mic Amp, or just Pre Amp. The circuit boosts the tiny output voltage from the microphone up to a level, which is called Line Level, that's easily sent around the studio to consoles, outboard gear, and DAWs. Let's see how it works. Most DAW interfaces and almost all consoles have mic preamps built into them, but in most cases the quality of the circuitry isn't nearly as high as what's available in a dedicated outboard piece.

Explaining the microphone preamplifier

Almost as important as the microphone is the microphone preamplifier or Mic Pre, Mic Amp, or just Pre Amp. The circuit boosts the tiny output voltage from the microphone up to a level, which is called Line Level, that's easily sent around the studio to consoles, outboard gear, and DAWs. Let's see how it works. Most DAW interfaces and almost all consoles have mic preamps built into them, but in most cases the quality of the circuitry isn't nearly as high as what's available in a dedicated outboard piece.

That said, each Mic Pre has its own sound and most engineers will select the Mic Pre and microphone combination because of the sonic color that the combination provides, which makes the captured audio fit the music better. Usually a dedicated mic amp sounds a lot better than the once included in the DAW interface or console. An outboard pre generally provides a signal that has higher highs and lower lows, meaning it has a better frequency response, and is clearer and cleaner. This increased quality comes at a price. As an outboard mic pre can cost anywhere from a fairly inexpensive hundred dollars to several thousand dollars per channel.

As a comparison a mic amp on a cheap interface frequently costs less than two dollars. In many cases you get what you pay for. Mic preamps do only one job, and that's amplify. As a result, they usually don't have that many controls although the more expensive exotic models might have some extra features. Here are some of the parameter controls that you might find on a typical preamp. The Gain control, which is sometimes called Level or Trim is one that every preamp has. It's essential because it controls how much the microphone signal is amplified.

Most mic preamps have about 60 dB of gain, which means that the mic signal is amplified by a factor of a million. There are some that have as much as 80 dB of gain to accommodate low output ribbon mics or feel the audio recording where the signals captured by the mic are extremely quiet. Some sort of metering is also found in every preamp. This can be something as simple as a single LED indicator, the signals and overload to a full on ladder style LED peak meters found on consoles and DAWs. The input pad is a switch that attenuates a signal coming from the microphone anywhere from 10 to 20 dB.

This keeps a hot signal from the mic from overloading the input circuitry of the mic preamp. It's used when the mic is trying to capture a very loud sound source like a snare drum or loud electric guitar. The phase switch changes the polarity of the microphone signal due to either a misplaced or mis-wired microphone. Set the switch to the position that has the most low-end. The high pass filter allows only the high frequencies to pass, which means that the low frequencies are attenuated, which is why it's sometimes called a low cut filter. The frequencies that are attenuated are usually anywhere from 40 hertz to 160 hertz.

They are cut off in order to eliminate unwanted low-frequency noise like they rumble from heavy truck traffic. On most preamps this frequency is fixed but on many models it's variable. It was pointed out in the previous movie that condenser microphones need some sort of power in order to operate. Mic preamps and recording consoles frequently supply that power. This is a standard 48 volts which is why it's sometimes labeled as 48V, it's called Phantom Power, and is a pretty standard feature on most dedicated mic pres.

Almost all mic preamps that are made these days have an input where you can plug-in an electric instrument like a guitar or bass to turn the unit into an active direct box. It sometimes marked as Hi-Z because the input is a high impedance input which is matched specifically for these kinds of instruments. To sum it up, the microphone preamp boosts a tiny output voltage from the microphone up to a level that can be used by the other devices in the studio. All mic pres have a gain control and some type of overload indicator but you might also see an output gain, impedance, input pad, phase, phantom powering, hi-pass filter, and more extensive metering.

Show transcript

This video is part of

Image for Audio Recording Techniques
Audio Recording Techniques

130 video lessons · 16652 viewers

Bobby Owsinski
Author

 
Expand all | Collapse all
  1. 5m 28s
    1. Welcome
      2m 11s
    2. What you should know before watching this course
      1m 22s
    3. Using the exercise files
      1m 29s
    4. Listening to this course
      26s
  2. 6m 39s
    1. Setting up your monitors
      4m 17s
    2. Using a basic listening technique
      2m 22s
  3. 25m 29s
    1. Exploring different microphone types
      5m 16s
    2. Microphone directional response basics
      2m 43s
    3. Hearing different directional patterns
      4m 58s
    4. Exploring how the proximity effect works
      3m 55s
    5. Explaining microphone controls
      1m 49s
    6. Reviewing microphone accessories
      3m 3s
    7. Exploring direct boxes
      1m 9s
    8. Exploring amplifier emulators
      2m 36s
  4. 24m 32s
    1. Explaining the microphone preamplifier
      3m 59s
    2. Choosing a preamp
      1m 35s
    3. Setting up the mic preamp
      1m 39s
    4. Setting the record level
      2m 29s
    5. Using proper gain staging
      1m 46s
    6. Knowing what to do if distortion occurs
      2m 0s
    7. Using the compressor during recording
      2m 58s
    8. Using the equalizer (EQ) during recording
      2m 24s
    9. Using the high-pass filter during recording
      1m 4s
    10. Exploring the principles of EQ
      47s
    11. Avoiding latency
      3m 51s
  5. 15m 40s
    1. Finding the best place in the room to record
      2m 44s
    2. Choosing the right mic
      2m 24s
    3. The secret to mic placement
      2m 12s
    4. Understanding phase cancellation, the sound destroyer
      2m 29s
    5. Checking polarity
      3m 9s
    6. Checking the phase by listening
      2m 42s
  6. 54m 29s
    1. Finding the right placement in the room for the drums
      1m 48s
    2. The keys to a great drum sound
      2m 2s
    3. Tuning the drums
      2m 19s
    4. Tuning tips and tricks
      2m 26s
    5. Miking the bass drum without a front head
      2m 15s
    6. Miking the bass drum with front head port
      1m 5s
    7. Miking the bass drum with a front head
      1m 12s
    8. Using a subkick microphone
      1m 31s
    9. Miking the snare drum: Technique one
      3m 2s
    10. Miking the snare drum: Technique two
      57s
    11. Adding a bottom snare mic
      1m 45s
    12. Miking the hi-hat
      2m 14s
    13. Miking the toms
      2m 24s
    14. Miking the cymbals
      3m 14s
    15. Miking the overall kit
      1m 25s
    16. Using room mics
      2m 2s
    17. Getting the drum sound
      2m 47s
    18. Getting the correct drum mix balance
      2m 50s
    19. Checking the drum phase
      2m 18s
    20. Panning the drums
      2m 25s
    21. Tweaking the drum sound with EQ
      3m 10s
    22. Using the one-mic drum recording technique
      2m 37s
    23. Using the two-mic drum recording technique
      1m 5s
    24. Using the three-mic drum recording technique
      1m 45s
    25. Using the four-mic drum recording technique
      1m 26s
    26. Tips for drummers to use before recording
      1m 15s
    27. Tracking a solo drum part
      1m 10s
  7. 27m 31s
    1. Finding the right placement in the room for the guitar
      1m 24s
    2. Miking the amplifier: Technique one
      1m 58s
    3. Miking the amplifier: Technique two
      1m 30s
    4. Miking the amplifier: Technique three
      1m 54s
    5. Using the Marshall cabinet miking trick
      1m 30s
    6. Recording the electric guitar direct
      6m 51s
    7. Prepping for recording acoustic guitar
      58s
    8. Recording the acoustic guitar with one mic
      2m 46s
    9. Recording the acoustic guitar with two mics
      1m 46s
    10. Recording the acoustic guitar with three mics
      1m 19s
    11. Exploring stereo acoustic guitar miking techniques
      1m 31s
    12. Recording the acoustic guitar direct
      1m 14s
    13. Using a limiter when recording acoustic guitar
      1m 39s
    14. Tracking the guitar part
      1m 11s
  8. 14m 0s
    1. Finding the right placement in the room for the bass
      57s
    2. Recording the bass using a direct box
      1m 44s
    3. Miking the bass amplifier
      2m 13s
    4. Using a limiter when recording the bass guitar
      3m 8s
    5. Miking an acoustic bass: Technique one
      3m 4s
    6. Miking an acoustic bass: Technique two
      1m 43s
    7. Tracking the bass part
      1m 11s
  9. 20m 47s
    1. Finding the right placement in the room for vocals
      53s
    2. Recording a scratch vocal
      1m 24s
    3. Exploring vocal mic placement
      3m 2s
    4. Using a limiter on vocals
      2m 7s
    5. Recording in the control room
      1m 35s
    6. Setting up the vocal headphone mix
      2m 26s
    7. Doubling the vocal
      2m 52s
    8. Getting the best from a singer
      1m 16s
    9. Exploring background vocal mic placement
      2m 53s
    10. Layering background vocals
      1m 5s
    11. Recording the lead vocal part
      1m 14s
  10. 10m 49s
    1. Recording a solo grand piano with one mic
      2m 14s
    2. Recording a solo grand piano in stereo
      1m 8s
    3. Close miking a grand piano with one mic
      3m 10s
    4. Close miking a grand piano with two mics: Method one
      1m 39s
    5. Close miking a grand piano with two mics: Method two
      1m 25s
    6. Recording the piano part
      1m 13s
  11. 13m 57s
    1. Finding the right placement in the room for horns
      1m 18s
    2. Recording a solo sax: Technique one
      2m 40s
    3. Recording a solo sax: Technique two
      2m 30s
    4. Recording a solo brass instrument
      3m 20s
    5. Recording a horn section: Technique one
      2m 27s
    6. Recording a horn section: Technique two
      30s
    7. Recording the horn section part
      1m 12s
  12. 7m 30s
    1. The key to miking any acoustic instrument
      1m 3s
    2. Recording an acoustic string instrument
      2m 25s
    3. Recording a dobro
      1m 36s
    4. Recording the dobro part
      1m 13s
    5. Recording the string section
      1m 13s
  13. 2m 36s
    1. Recording drum percussion
      1m 19s
    2. Recording hand percussion
      1m 17s
  14. 5m 23s
    1. Recording electric keyboards
      1m 58s
    2. Recording acoustic instruments with a pickup
      2m 11s
    3. Recording the synth part
      1m 14s
  15. 12m 4s
    1. Understanding the idea behind stereo recording
      1m 14s
    2. Using the X/Y configuration
      3m 21s
    3. Using the ORTF configuration
      2m 27s
    4. Using the spaced pair configuration
      3m 16s
    5. Using a stereo mic
      1m 46s
  16. 20m 26s
    1. Setting up for a tracking session
      4m 17s
    2. Setting up a talkback mic
      1m 27s
    3. Using sound leakage to your advantage
      1m 36s
    4. Setting up the headphone mix
      2m 31s
    5. Setting up a click track
      2m 11s
    6. Setting up for overdubs
      2m 17s
    7. Recording the rhythm section in the studio
      6m 7s
  17. 48m 47s
    1. The keys to a great rough mix
      4m 55s
    2. Setting up the effects
      3m 47s
    3. The rough mix of Simply Falling
      35m 35s
    4. The final mix of Simply Falling
      4m 30s
  18. 1m 2s
    1. Goodbye
      1m 2s

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold

Are you sure you want to delete this note?

No

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.