Sunday, 22 June 2014
Thursday, 5 June 2014
Unit 2: Audio Engineering Principles - Task 4
Part 1: Specification
Channel List:
1 KICK - AKG D112 - BEHRINGER PRE
2 SNARE - SM57 - BEHRINGER PRE
3 FLOOR TOM - SM57 - BEHRINGER PRE
4 R. TOM 1 - SM57 - BEHRINGER PRE
5 R. TOM 2 - SM57 - BEHRINGER PRE
6 OH LEFT - KM184 - FOCUSRITE PRE
7 OH RIGHT - KM184 - FOCUSRITE PRE
8 BASS AMP - AKG D112 - BEHRINGER PRE
9 GUITAR 1 - SM57 - BEHRINGER PRE
10 GUITAR 2 - SM57 - BEHRINGER PRE
11 VOCALS - SE GEMINI - AVALON PRE
For recording the full band I've decided to use the two AKG D112 microphones on the kick drum and bass amplifier, and this is because this microphone can pick up frequencies as low as 20Hz, and can withstand high sound pressure levels, which you would find with signals coming from a kick drum and bass amp as they're low frequency and contain lots of energy which equates to a high sound pressure. It's important to use a mic that picks up frequencies as low as 20Hz as between 20-100Hz is the part of the frequency spectrum where these sounds are found, and therefore picking them up accurately is crucial to getting a detailed recreation of the sound. The shape of the D112 is such as it has a gap where bass frequencies multiply called a bass resonance volume chamber, and this makes for a bigger bass sound as the signals resonate inside it and harmonically increase. These mic's are an industry standard for recording these bass instruments, and are the most suitable from the list for this job, due to their characteristics. The frequency response diagram below shows how it picks up sounds from 20Hz upwards, and has a resonance or peak in dB of sensitivity at 100Hz where the main detail of a bass instrument is found.
I then chose to use the SM57 microphone for the Snare, all Toms and Guitar Amplifier as these all operate between 40Hz and 15KHz, which is the range of this microphone, and they all can be picked up with this microphone as a result. It's a cardiod pattern, meaning it picks up sound in a domed shape and the cradle, so anything you close mic with it will be picked up accurately, and the frequency response curve shown below shows how in the mid range it's right at 0dB so won't accentuate any sound between 1Khz - 5Khz, and will give a clear sound as a result. This makes it appropriate for use on all these instruments, and given that I have overheads on drums, these too will pick up tom and snare in spill also.
For all the above microphones I'm using the eight Behringer channel pre-amps to record the signals. My reason for this is that these require less detail and attention that my overheads and vocals, as they just need to present and well recorded, rather than having the highest quality pre-amp to nurture the sound. I've deciphered that the Behringer pre-amps are the lowest quality of the choices from the specifications of the three and the price also. Firstly, the gain range of the Behringer pre for microphone inputs is +10dB to +60dB, which means that any signal requiring less would be less clear and maybe slightly distorted sounding, as this gain range isn't as subtle as say the Avalon which is 0dB to +58dB. Also from the price which is aimed at a low budget market, you can infur that the components and build quality is where they've been able to save money to drive down price, so could assume that the gain range and distortion results would reflect this, meaning for the greater detail required in the reproduction of vocals for example, that these mic-pre's wouldn't be sufficient for the job. Also as the specification of the product is vague and doesn't mention noise varyable to the amount of gain applied to a signal, then we can assume that as the gain is applied, the pre-amp is noisy and not as clean and clear as you'd would want for vocals for example.
Behringer Specs
For my drum overheads I chose to use the Neumann KM184 microphones, as I know from experience they're excellent at this, and give a very clear and detailed reproduction of cymbals and toms. They have a frequency range of 20-20Khz which means cymbals which create sounds up around 15,000Hz are picked up well, and it has a low impedence of 50 ohms, which means little detail from the electrical signal travelling to the desk is lost sound the sound isn't compromised in any way. They require phantom power which they will be given from the Focusrite mic pre's one and two which I've chosen to use for this job, simply as there needed to be two, and the Avalon only has one, but I know the mic-pre's of the Focusrite are good quality, and will be good for this job. They had a total harmonic distortion rate of 0.001% at 1Khz, which means when the signal is multiplied, only this percentage of distortion relative to it is effected, which would be inaudible meaning the signal would be very clear even as the gain increased. It's frequency response matched that of the KM184's, meaning no frequencies could be lost at this stage, and the sound we stay as accurate and detailed as it was from the microphone. The chart below shows the frequency response of the KM184, showing how in the mid range it's completely flat for pin point accuracy, and the accentuation at 8Khz onwards makes for a nice bright tone to cymbals.
Finally, I chose to use the SE Gemini microphone, recorded though the Avalon mic-pre for the vocals. I believe the human is the most detailed and unique sound from the band, and therefore requires the most detail from the recording, to give a completely accurate recreation of the vocalists voice. Like the KM184's it has a 20Hz-20KHz response so will pickup the human voice (which sits right in the middle of the spectrum) very accurately and cleanly. It cannot withstand a massive SPL, but as a vocal microphone doesn't need to, as the voice doesn't create so much pressure, and the tube component which is the internal mechanism which generates the signal from the vocals is said to provide an effect of warmth and depth which would complement the sound of a voice without in any way processing it, and give the dry signal good qualities, so the fact it's a tube makes it more appropriate for the vocal than anything else in the band. Also the Avalon pre-amp is the best choice to accompany it, as it too uses vacuum tubes as it's internal circuitry which mean this will further complement the vocal tone and sound. It had the grate gain range of 0dB to +58dB which I mentioned earlier, meaning the detail can be retained when gain is added, and it has +48 phantom power as an input mode so can provide the neccessary power to the condenser mic. Across the spectrum it has low noise, and this an example of being opposite to the Behringer where components are of high quality, and the design is detailed and refined, which is reflected in the high price bracket, and proven in the results it gives.
Part 2: Definitions
Frequency Response - Frequency response is how much sound across the frequency spectrum is picked up to be reproduced, and can be in relation to the range of sounds a microphone can pick up, or a mic-pre can work with. Frequency relates to pitch, but also pitchless sounds can vary across the frequency spectrum, so a large frequency response is one that covers a large range of all frequencies, like for example 20Hz to 20KHz. Frequencies go on to well above that, but as human hearing range stops at 20Khz, it's effect though having a knock in the bracket we can hear, is otherwise inaudible.
Signal to Noise Ratio - This is the combination of low level noise and the signal you aim to record overall in a sound. The noise can be a bi-product of a piece of equipment like a transducer component or a low level sound in the room, but the ratio of the two is how loud the noise is relative to the loudness of the signal. For example, a guitar amp recorded in a room will have noise of the room combined with the amp itself, and the less noise the better, as it makes for clearer sounds and a better recording.
Operating Levels: +4dBu & -10dBu - These are signal levels at which you work with recording gear, -10dB being a domestic level, the other being professional.
RMS Level vs Peak Level -
Channel List:
1 KICK - AKG D112 - BEHRINGER PRE
2 SNARE - SM57 - BEHRINGER PRE
3 FLOOR TOM - SM57 - BEHRINGER PRE
4 R. TOM 1 - SM57 - BEHRINGER PRE
5 R. TOM 2 - SM57 - BEHRINGER PRE
6 OH LEFT - KM184 - FOCUSRITE PRE
7 OH RIGHT - KM184 - FOCUSRITE PRE
8 BASS AMP - AKG D112 - BEHRINGER PRE
9 GUITAR 1 - SM57 - BEHRINGER PRE
10 GUITAR 2 - SM57 - BEHRINGER PRE
11 VOCALS - SE GEMINI - AVALON PRE
For recording the full band I've decided to use the two AKG D112 microphones on the kick drum and bass amplifier, and this is because this microphone can pick up frequencies as low as 20Hz, and can withstand high sound pressure levels, which you would find with signals coming from a kick drum and bass amp as they're low frequency and contain lots of energy which equates to a high sound pressure. It's important to use a mic that picks up frequencies as low as 20Hz as between 20-100Hz is the part of the frequency spectrum where these sounds are found, and therefore picking them up accurately is crucial to getting a detailed recreation of the sound. The shape of the D112 is such as it has a gap where bass frequencies multiply called a bass resonance volume chamber, and this makes for a bigger bass sound as the signals resonate inside it and harmonically increase. These mic's are an industry standard for recording these bass instruments, and are the most suitable from the list for this job, due to their characteristics. The frequency response diagram below shows how it picks up sounds from 20Hz upwards, and has a resonance or peak in dB of sensitivity at 100Hz where the main detail of a bass instrument is found.
I then chose to use the SM57 microphone for the Snare, all Toms and Guitar Amplifier as these all operate between 40Hz and 15KHz, which is the range of this microphone, and they all can be picked up with this microphone as a result. It's a cardiod pattern, meaning it picks up sound in a domed shape and the cradle, so anything you close mic with it will be picked up accurately, and the frequency response curve shown below shows how in the mid range it's right at 0dB so won't accentuate any sound between 1Khz - 5Khz, and will give a clear sound as a result. This makes it appropriate for use on all these instruments, and given that I have overheads on drums, these too will pick up tom and snare in spill also.
For all the above microphones I'm using the eight Behringer channel pre-amps to record the signals. My reason for this is that these require less detail and attention that my overheads and vocals, as they just need to present and well recorded, rather than having the highest quality pre-amp to nurture the sound. I've deciphered that the Behringer pre-amps are the lowest quality of the choices from the specifications of the three and the price also. Firstly, the gain range of the Behringer pre for microphone inputs is +10dB to +60dB, which means that any signal requiring less would be less clear and maybe slightly distorted sounding, as this gain range isn't as subtle as say the Avalon which is 0dB to +58dB. Also from the price which is aimed at a low budget market, you can infur that the components and build quality is where they've been able to save money to drive down price, so could assume that the gain range and distortion results would reflect this, meaning for the greater detail required in the reproduction of vocals for example, that these mic-pre's wouldn't be sufficient for the job. Also as the specification of the product is vague and doesn't mention noise varyable to the amount of gain applied to a signal, then we can assume that as the gain is applied, the pre-amp is noisy and not as clean and clear as you'd would want for vocals for example.
Behringer Specs
For my drum overheads I chose to use the Neumann KM184 microphones, as I know from experience they're excellent at this, and give a very clear and detailed reproduction of cymbals and toms. They have a frequency range of 20-20Khz which means cymbals which create sounds up around 15,000Hz are picked up well, and it has a low impedence of 50 ohms, which means little detail from the electrical signal travelling to the desk is lost sound the sound isn't compromised in any way. They require phantom power which they will be given from the Focusrite mic pre's one and two which I've chosen to use for this job, simply as there needed to be two, and the Avalon only has one, but I know the mic-pre's of the Focusrite are good quality, and will be good for this job. They had a total harmonic distortion rate of 0.001% at 1Khz, which means when the signal is multiplied, only this percentage of distortion relative to it is effected, which would be inaudible meaning the signal would be very clear even as the gain increased. It's frequency response matched that of the KM184's, meaning no frequencies could be lost at this stage, and the sound we stay as accurate and detailed as it was from the microphone. The chart below shows the frequency response of the KM184, showing how in the mid range it's completely flat for pin point accuracy, and the accentuation at 8Khz onwards makes for a nice bright tone to cymbals.
Finally, I chose to use the SE Gemini microphone, recorded though the Avalon mic-pre for the vocals. I believe the human is the most detailed and unique sound from the band, and therefore requires the most detail from the recording, to give a completely accurate recreation of the vocalists voice. Like the KM184's it has a 20Hz-20KHz response so will pickup the human voice (which sits right in the middle of the spectrum) very accurately and cleanly. It cannot withstand a massive SPL, but as a vocal microphone doesn't need to, as the voice doesn't create so much pressure, and the tube component which is the internal mechanism which generates the signal from the vocals is said to provide an effect of warmth and depth which would complement the sound of a voice without in any way processing it, and give the dry signal good qualities, so the fact it's a tube makes it more appropriate for the vocal than anything else in the band. Also the Avalon pre-amp is the best choice to accompany it, as it too uses vacuum tubes as it's internal circuitry which mean this will further complement the vocal tone and sound. It had the grate gain range of 0dB to +58dB which I mentioned earlier, meaning the detail can be retained when gain is added, and it has +48 phantom power as an input mode so can provide the neccessary power to the condenser mic. Across the spectrum it has low noise, and this an example of being opposite to the Behringer where components are of high quality, and the design is detailed and refined, which is reflected in the high price bracket, and proven in the results it gives.
Part 2: Definitions
Frequency Response - Frequency response is how much sound across the frequency spectrum is picked up to be reproduced, and can be in relation to the range of sounds a microphone can pick up, or a mic-pre can work with. Frequency relates to pitch, but also pitchless sounds can vary across the frequency spectrum, so a large frequency response is one that covers a large range of all frequencies, like for example 20Hz to 20KHz. Frequencies go on to well above that, but as human hearing range stops at 20Khz, it's effect though having a knock in the bracket we can hear, is otherwise inaudible.
Signal to Noise Ratio - This is the combination of low level noise and the signal you aim to record overall in a sound. The noise can be a bi-product of a piece of equipment like a transducer component or a low level sound in the room, but the ratio of the two is how loud the noise is relative to the loudness of the signal. For example, a guitar amp recorded in a room will have noise of the room combined with the amp itself, and the less noise the better, as it makes for clearer sounds and a better recording.
Operating Levels: +4dBu & -10dBu - These are signal levels at which you work with recording gear, -10dB being a domestic level, the other being professional.
RMS Level vs Peak Level -
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