Electricity For And In Our Recording Studios

May 7, 2013 by Leave a Comment

Grid Noise

We all know that the energy we receive from our local utility is full of noise. There is a whole industry out there of power conditioning companies who will for a fee provide you with a filter to take this noise or that noise out of the grid system for you. Gear companies will even provide you with gear that has its own power supply, so that their equipment does not have to use that noisy grid energy. Even power fluctuations can occur at different time periods during the day depending on the specific demand on the grid itself. Our studio usually runs at 121 volts during the day but in the evening it can go to 123 volts and even 125 volts after midnight.

Gear Stacks

Gear Stacks

Equipment Energy

Once we have the issue of producing clean energy for our studio resolved, we can deal with the noise produced by the electronic equipment that will reside within our studio. Each unit  in the signal chain has some type of electronic signature. Noise energy can be transmitted through the power wires of our studio to other units or even be distributed through the air. Remember, amplifiers do what they were designed to do, they amplify both pure signal and don’t forget about the pure noise.

Equipment Is Amplifier

The electric guitar is a good receiver/amplifier because of the way the electronics are made inside the guitar. The pick up of the guitar is a coil of copper wire which receives the signal and then sends it to an amplifier which is another device that has coils encasing a piece of iron to guess what, create an electromagnet. Thus, both the pick up and the amplifier share the same electrical DNA by acting like transformers which radiate and receive electrical fields. There are also pick ups that have two or more coils.

Humbuckers

Humbucker pick ups are known for their unique sound quailty. The famous Humbucking pickups have two coils that are wired out of phase with each other. Thus, the noise that is shared with the coils is in phase and eliminated from the system. This is a common electrical technique for dealing with noise within the lines of our electrical systems. Computers also share this same genetic code.

Noisy Computers

Laptop and desk computers also have coils within them. Look at any circuit board and one will find tiny cylinders of copper wound wire. Electrons are flowing through these coils to assist in the production of video images. Even the popular flat panel, LED and plasma, have coils inside of them. There is always a light source behind the panel screen that produces the color images. This process of providing the energy for the screen light and then the panel itself also produces noise. Watch how you run your cables together. Keep all power cables well away from video and audio signals. If they do have to cross, make sure they cross perpendicular to the audio and video cables.

Residential Dimmers

Residential Dimmers

Dimmers

Dimmers are a device that must be used with caution. Watch the quality level you use in your studio and do not use any dimmers that were made for your home. They produce too much noise because of the electrical process they use to “dim” your lights. These residential dimmers to not vary voltage to dim your lights. Instead they take a knife to our 60 cycle electrical wave and divide it into pieces. They use small pieces of the wave for dim light and all the wave not chopped up for the brighter light. Always use what is called a Variac dimmer. They do not generate the high frequency noise that will travel  through the air, but keep the transformers away from your gear just to be safe.

Cable Connector Mount

The way your cable connector is mounted to the gear chassis will also play a factor in how much resistance to noise the unit has. Our electrical goal is to create an electrical bypass so that the noise will exit the cable and flow into something else other than be transferred to our unit.  If  the noise gets into the unit, it is much harder to find and eliminate within the circuitry.  This is called the PIN-1 nomenclature used within the electronic literature.

XLR, RCA, Firewire, USB

XLR, RCA, Firewire, and USB are all connectors that can have issues with this dilemma.  The shield / pin-1 connector must be routed directly to the metal chassis. Some connectors are isolated from the gear chassis because it is easier to make in the manufacturing process. Manufactures run the signal path from pin-1 through a printed circuit to save space and money, but this process amplifies all the noise before sending it to ground. Keep the ground out of the circuitry.

Noise In / Noise Out

We must be conscious of the noise within the power that comes into our studio and then once inside, we must be careful with the noise that power can create within our gear. Computers, cable connectors, and even dimmer control devices must all be examined for noise producing capabilities. Watch for the transformer concept with pick ups and the ground connection on all our gear’s metal housing.

Filed Under: Electronics, Uncategorized Tagged With: , , ,

Mixing Issues And Solutions

February 8, 2013 by Leave a Comment

Mixing Issues

I have spoken with many engineers lately about issues they confront during the mixing process. I asked them to talk about issues that they commonly face and what they do to resolve the issues. The discussions focused mainly on equalization, compression, and time based effects.

Equalization

All the engineers had issues with equalization. Balancing the frequencies using equalization a was a common concern. One of the main concerns was using automation to compensate for an improper equalization. With an improper frequency balance, you have some frequencies that are masking others. Using automation by turning up the volume of the track that has been smothered will be a temporary fix. When the content of smothered track comes down, you now realize that the track that was turned up is now too loud.

Get It Right From The Beginning

Get It Right From The Beginning

Automation

Most engineers agreed on the solution. The solution was to use equalization to balance the frequencies between the tracks that are in question. most agreed that this was not an easy solution or process but that the trade off in time and effort was worth the results. This process was viewed as a check against doing the wrong thing. One engineer said that if you think you need to automate every word in a vocal track, you should be looking at equalization to solve the issues instead of automation.

Old Mix Review

One engineer suggested pulling up your old mixes and get rid of all the automation. Spend time with equalization and you will quickly see that a well balanced mix can be achieved without using volume automation. All commented that automation has its place because you can not always use a compressor to level out vocals that are extreme in nature. Sometimes you want a vocal part a little louder than other parts and that automation should be used mostly to create certain sonic effects by changing levels, using panning, and with some plug ins.

Use Less To Create More

Use Less To Create More

Reverberation Levels

Adding too much reverb or delay was another issue that seemed to be common among the engineers. Most made the comments that too much reverb was the indication of an unprofessional mix. Usually too much reverb is used to try and solve pitch issues or as some stated to make the vocalist sound better. Vocalist wanted more reverb, especially if they were the engineer.

Reverb Necessary Evil

All agreed that the best way to use reverb and everyone agreed it was necessary, was to find the correct amount of reverb that sounded good at loud volumes and then lower the volume until it sounded good all through the mix. Some suggested bringing the reverb down to the level of barely audible. Spend time listening at this low level with the send bypassed. Most believed that this method added thickness and a richness to the mix without adding any undesirable effects. Most said that this approach also worked with the delay.

Big Picture First

If you solo a track and use EQ on it it will sound one way. If you then put it into the mix, it can sound thick or muddled. All agreed that one needs to do the majority of your processing with the entire mix playing. Examining a solo track or a couple tracks is acceptable but keep the entire mix in your mind and focus on the total mix.

Middle Frequencies

When you ask someone to listen to your mix and they tell you to turn it up because it will sound better. Obviously, these comments lack the experience of a professional mix. Professional mixes sound good at soft and loud levels. This is the result of the engineer understanding that our ears can hear more of the middle frequencies than it can the low er and higher frequencies. This is probably due to our need to hear vocals for communication purposes as a species. It takes more energy to produce low and high frequencies than it does to equal the apparent loudness of our middle frequencies.

Focus On Vocals

As you turn down your mix, you will notice that the vocals jump out in the mix since they are focused in the middle frequencies. Pay attention to the lead vocal as you turn up the mix. The drums and bass energy will start to take over the vocals. If you mix loud, you can not balance the mid range correctly. If you listen at higher volume levels, everything seems to smooth out but more difficult to hear the mid range. When you turn the volume down and listen at lower levels, the issues in the mid range stand out.

Mix At lower Levels

Mixing at lower levels is the solution. If you need to check the low and high end, one can turn it up for this purpose but once checked and verified, lower the volume levels. Less is more and this philosophy should also be applied to the use of effects and processors. Use small amounts of EQ and small amounts of compression. Train your ear to hear the subtle differences in music and add or subtract small amounts of processing just enough to compliment and not dominate.

Filed Under: Electronics, Uncategorized Tagged With: , , ,

Trouble Shooting Signal Chain Distortions

February 4, 2013 by Leave a Comment

Signal Chain

Our signal chain is composed of many different components. We have instruments, vocals, microphones, cables, mixers and so on. All of these devices carry electrical energy that must be able to travel freely from the beginning of the signal chain to the speaker. Sometimes all of this equipment with each component speaking its own language causes something to occur that we do not want. Signal chain distortions take many forms.

Hum

Hum is an issue that will appear regardless of how many components are in the signal chain. What is hum? Hum is a continue signal. In the United States we are operating at 60 Hz. In Europe, we are operating at 50 cycles. Our power supplies are the first place we want to look at. Once that is ruled out, we next need to look at our transformers. If our transformers are too close to an amplifier, the amplifier will do what it does best and amplify sound energy even if it is a hum. Amplifiers are equal sound employers.

Cables Everywhere

Microphone lines next to power lines are something to be avoided. Video signals must also be isolated from power and audio cables whether signal or power in function. Keep all three of these lines separated and if they have to cross which should be avoided, make sure they cross at a right angle. The most common cause of hum in almost all situations is the dreaded ground loop. To begin our quest, we must decide if the hum is continuous or affected by gain controls.

Continuous Or Intermittent

If our hum is continuous or unaffected by gain controls, then the ground loop is probably in one of the components that connects to the device in question. If the hum increases in amplitude when increased gain is applied to the signal, we need to look at the components that are ahead of the mixer or gain producing device. With our mixing consoles, we can suspect our microphone pre-amps and the slider. Op amps will affect the hum level also.

Buzz Is Hum’s Cousin

Buzz is another signal chain distortion. Buzz and hum are siblings. Buzz is the sound produced when the hum becomes distorted. Dimmer noise can be buzz. Dimmer noise is still a 60 cycle issue but sounds like a buzz because of its wave shape. Dimmer buzz can also enter our microphone lines. When we have buzz that occurs when we connect two pieces of equipment together, we can be fairly sure that there is some type of electrostatic coupling.

Electrostatic Coupling

Electrostatic coupling can occur even with transformerless inputs and outputs. Transformers that have electrostatic shields sometimes referred to as Faraday shields, will usually solve the problem. However, these devices need to be grounded like all others, so the potential for a ground loop is increased. The only fix for this scenario is to reconfigure the total electronic signal chain.

Oscillation

Oscillation is defined when the output of a device is electrically joined to the input of the same unit or another component in the signal chain. It appears in many different forms. The distortions produced by oscillations may sound blurry or fuzzy. The sound produced can begin as a steady sound. If you hear this sound, get out an oscilloscope. It will show immediately on an oscilloscope. If the sound appears at higher gain levels, one needs to look at cables and inductive couplings.

Static

We have all had static and pops to deal with in our electronic equipment chains. Static and pops are usually the result of a poorly designed ground system or no ground system at all. Sometimes a floating ground or a more correct term is floating the system above the ground is used. Not only is this process very poor engineering, it can result in a deadly shock. Never float grounds. You are only substituting one minor problem with another that can be life threatening.

RF Interference

If the static occurs with short sustained pops, one can look at radio frequency interference which has entered the system through some open portal. A poorly shielded cable or a cable connector that has worked its way loose must first be examined. With no ground or a poor ground, the cable shield can not do what they were designed to do by shielding against radio frequency interference.

Signal Chain Distortions

Distortions in our signal chain have many causes. We can have annoying hum, buzz, oscillations, and static. Hum and buzz are closely related. Buzz is simply a hum that have been distorted by a waveform created by an electronic component. Oscillations and static can be corrected by a properly grounded system. Floating the ground above the system itself maybe a quick fix but it will be dangerous to use and is not worth the cost of electrocution.

Filed Under: Electronics, Room Acoustics Tagged With: , , ,

Hi – Fi Set Up Basics

August 13, 2012 by Leave a Comment

Set Up Issues

I am continually amazed at two channel systems I see set up incorrectly. Some have speakers that are unequal distances from side walls. Others I see, have speakers too close to the front wall or will have one speaker a certain distance from the front wall and the other a different distance. I also see sub woofers in corners. Why would we want to place a high energy producing device in an area where all room modes exist? It is hard enough to get room resonances under control. Lets make our room tuning efforts more positive from the beginning by getting back to basics.

Sound Has Speed Limits

Speakers are an electromechanical device that produces sound energy when fed electrical current from an amplifier. Once that energy leaves our speakers, it travels at the speed of sound which we all know is constant. If we have two speakers producing a sound that is traveling through the air in our rooms and into our ears, we need to have that sound start at the same physical location every time and that physical location needs to be the same number for left and right channels. There are no exceptions to this first set up basic.

Equilateral Triangle

The equilateral triangle that is formed using our two stereo speakers and listening position must remain a triangle. The distance from each speaker and listening position should be the same number. However, that “triangle” can be positioned at different positions within our rooms. We do not necessarily have to fit it into our rectangular room so that it is centered and symmetrical with the room. Different room dimensions and the resonances produced by those dimensions will be our driving force for placing our speakers/listening position in order to achieve a smoother frequency response.

Side Wall Reflections

Side wall reflections must be managed correctly and the distance from our speakers to the room side walls must be the same. This is another no compromise variable. Our goal is to reduce side wall reflections time signature, so that it reaches our ears after the direct sound from our speakers. If we are going to manage this energy with acoustical technologies, we must have equal distance from both speakers and side wall, so that the reflected energies time signature from both side walls is constant.

Direct Vs. Reflected

How much slower the side wall reflections need to be when compared with the direct energy from our speakers is a subjective question. The direct energy is the energy that travels in a straight line from our speakers to our ears. The exact number is open for discussion, but we are talking about a time window that is denoted in milliseconds, not seconds. Current thinking is in the 15ms. to 20ms. range. The human ear can detect time differences as low as 1ms. We can choose absorption or diffusion to tackle this reflection issue.

Room Treatment

If we use absorption, we must use the same amount and type on each side wall as our starting point. I recently saw an installation that had a glass window for the right channel side wall and a book case filled from floor to ceiling with books as the left channel side wall. One can not treat the patient when we now have two different surfaces to deal with with that have vastly different acoustical signatures. Over absorbing on one side wall and under absorbing on the other side wall produces an unbalanced coloration to our presentation at the listening position.

Ambient Noise Levels

Another often overlooked but incredibly important variable is the ambient noise level in the hi-fi room. Air conditioning ducts with air moving through them and then striking a vent with horizontal and vertical vent slats can contribute immensely to room noise levels. To test this, go sit in your car in the garage and listen to a few songs on your car system. Pick certain parts of those songs that you really know and like and focus on those parts. Pick parts that represent low, middle and high frequencies. Start the car and drive. Don’t forget to open the garage door.

Song Parts

Listen to those same song parts as you are driving. Pay particular attention to the tire road surface contact. Listen to how all that frictional energy is transmitted through the car frame and then into the car body. Notice how just that one noise source contributes to the background noise madness. Now, listen to the engine noise added in. You get the idea.

Low Frequency Energy Management

Low frequency energy must be managed just like the ambient noise levels in our listening rooms. We must reduce the pressure exerted within the room by absorbing certain amounts of low frequency energy and doing it at the proper rate of absorption to have a sonic impact. Pressure sensitive, low frequency, absorbers must be positioned in the highest pressure areas of the hi-fi room to lower the pressure in those areas at the proper rate to impact the overall room low frequency decay rate.

No Wiggle Room

Speaker to speaker, speaker to listener, and speaker to all room boundary surfaces distances must be chosen to produce the smoothest, room frequency response within our hi-fi room. Our “equilateral triangle of two speakers and listening position, can be moved within our room, but only as a unit. Absorption and diffusion must be used in the correct places. When using diffusion, we must be at the correct distance, so that the diffused waveform has enough distance to fully form before it gets to the listening position. Don’t forget about bass boom. If you do, it won’t be long before you are reminded that it still lives within your room. All of this headache and it refuses to pay rent.

Filed Under: Electronics, Room Acoustics

How To Make Your Sub Woofer Sound Better

August 9, 2012 by Leave a Comment

Sub Woofer Cabinets

Our sub woofers are cabinets that contain a lot of energy for their respective size. They also produce a lot of energy for their size. It is like putting a large horsepower engine in a small car. The power to weight ratio is a large number. I used to have a cobra kit car with a 427 cu.in engine that produced 500 horse power in a 2,300 pound car. Lets see, that’s about 5 horse power per pound of car. That is about the same power to weight ratio as a sub woofer.

Same Old Drivers

Sub woofer cabinets have gotten smaller but driver size has not. We still see 12″, 15″, and 18″ diameter drivers in our sub woofer cabinets. Back 10 years ago, if we had a sealed box for a sub woofer and an 18″ driver inside, we had a box that was huge. I remember the Hi-Fi, Velodyne, 18″, sub woofer cabinets that were 40″ long and at least 30″ tall. They had that electronic servo monitor system that provided vibrational energy data to the amplifier when the driver was at its performance limits to avoid driver meltdown. Cabinet construction was a single layer of material.

Today, Smaller Cabinets

Today, we see large drivers in much smaller cabinets. Technology has allowed sub woofer designers to shrink the cabinet size and still realize low frequency output in the 20 to 30 cycle range. That smaller cabinet, however, does come with more vibrational issues. If we make the cabinet smaller, we have more pressure inside our cabinet. More pressure means more cabinet vibrational energy that the enclosure must deal with. Smaller is OK, if it is stronger.

Past Cabinet Materials

Today’s cabinet materials are different from cabinet construction materials of the past. In the past,to reduce cabinet vibrations, we had to use mass and a process known as constrained layer, mass damping. Multiple layers of materials with different densities were sandwiched together. Mass was the key ingredient in the formula. There was no substitute for cubic inches.

Layers, layers, Layers

Each layer of material was separated from the other by a substance known as a viseo-elastic damping compound. These multiple layers of materials with the damping compound reduced the amplitude of cabinet born vibrations. The ultimate goal was to reduce cabinet resonances, so they were below the audible sound of the driver in the cabinet.

New Composites

Today, we have new materials to choose from. We have composites that are made of new polymers that have more strength per square inch than our multiple layer approach of the past. These compounds can be formed into different shapes that are more conducive to speaker internal pressure reduction by having the ability to be splayed or canted to minimize parallel surface resonances inside the cabinet. With the same size drivers as we had in the past, mated with smaller cabinets, something must give and cabinet construction materials have been selected.

Driver/Cabinet Movement

With a sub woofer, we have cabinet movement even with the new cabinet compounds. A cabinet if moving enough and that movement gets laced with the driver sound, we have now to contend with room sound. The driver moves back and forth to produce a wave of energy. This process produces vibrations that are transmitted through the cabinet. Together, the driver wave output and the cabinet “sound” produce the sound energy that will be sent into our rooms. Sub woofer, sound energy is radiated from all sides, top, and bottom of our cabinet in a 360 degree array.

Room Is Speaker Cabinet

Our room is another cabinet with the same issues that a sub woofer cabinet has. Our room must deal with sound pressure injected into it from our sub woofer. The room then acts its size not its age. Room dimensions determine the room resonances we will have inside our room “cabinet”. The room resonances and the sub woofer produced energy, all work together to produce the final sound we hear in the room. To improve our sub woofer cabinet and driver sound, we need to reduce both vibrational energy from the cabinet and also absorb the low frequency energy produced by the driver.

Diaphragmatic Absorption

To accomplish both of these tasks, we turn to an old technology and blend it with a new twist. Diaphragmatic absorption is a time tested and proven method for low frequency absorption. If is combined with vibration draining cabinet fill, one can achieve both cabinet vibrational level reductions along with sound pressure absorption.

Build Diaphragmatic Absorber

If we calculate the proper cabinet depth and make sure we have the required cabinet material densities in place, we can calculate the approximate cabinet resonant frequency. Frequencies above that frequency will be absorbed and frequencies below the resonant frequency will not. If we add activated carbon or charcoal to our diaphragmatic absorber cabinet, we lower the cabinet’s Q value and achieve both a sound pressure absorber and as a platform for our sub woofer to sit upon.

Activated Carbon Diaphragmatic Absorber Placed Close To Sub Woofers .

Close To The Source

Since our sub woofer cabinet produces energy through all its walls, top, and bottom, we can place our diaphragmatic absorber under the sub woofer and gather a lot of this energy. This procedure works very well if the sub woofer is down firing. Since our diaphragmatic absorber works on sound pressure, we now have it positioned as close to the sound pressure producing source.

Activated Carbon Diaphragmatic Absorber Platform For Sub Woofers
Diaphragmatic Absorber Platform Placed Under Sub Woofers

Charcoal / Activated Carbon

The activated carbon cabinet fill is also a vibrational reducing material. Activated carbon is a fancy name for charcoal and each piece of carbon or charcoal has numerous pores that assist us in a process to minimize and absorb vibrations. The activated carbon now reduces vibrations and each carbon granule has numerous holes or pores that create a high pore to material ratio thus increasing overall absorption levels and rates with the diaphragmatic absorber.

Diaphragmatic Absorption

If we build a diaphragmatic absorber that has the correct material cabinet density, the proper cabinet depth (about 12″) to achieve our targeted overall cabinet resonant frequency and then place the appropriate amount of charcoal within our diaphragmatic absorber cabinet, we have the correct formula for both sound energy absorption and vibrational control. In order to achieve the best results, we must place our sub woofer cabinet on our 12″ high diaphragmatic absorber. Elevating the sub woofer off the floor will also improve our overall room response.

Clean And Tight Bass

With all of this in place, we will have a tight, clean, and more dynamic sounding sub woofer. Attack and decay of each bass note is more clearly defined. With an activated carbon absorber close to the speaker, we have an absorber that is pressure reactive right next to the highest pressure source. Our just built absorber is functioning at its maximum ability.

Less Vibrations / More Sound

With the vibrational controlling properties of the activated carbon inside our diaphragmatic absorber, we have less cabinet vibrations to compete with the wanted sound from the sub woofer driver. Less cabinet vibrations produces less energy that the drive unit has to compete with. Less sonic competition amongst the components produces a tighter, cleaner bass response.

Filed Under: Electronics, Uncategorized

Studio Monitors: Honestly ?

June 29, 2012 by Leave a Comment

Studio Monitors

Studio monitors are a playback device in the signal chain. They are the final link in the chain that takes all of the digital data and makes it analog, so our ears can here hear it. Studio monitors must be revealing of every sound in the recording. Each sound from a vocal or instrument must be heard over and over again time after time. They are designed to be painfully honest. They achieve this honesty with a flat frequency response.

Flat Frequency Response

A flat frequency response will not add any coloration to the sound or signal. It is not their job to sound real musical. It is their job to reveal the actual signal as it exists in the recording. Contrast this approach with that of a hi-fi speaker. A playback hi-fi speaker will have a frequency response curve that represents what the designer intended for a certain sound quality. This sound designed into the speaker can take into consideration the room’s response. A studio monitor does not figure any room response into their sound. In fact, most are designed to be listened to in a near field environment which minimizes room sound.

Working Speaker

Studio monitors are designed with the full knowledge that they are a tool. A tool that will be listened to over and over. They must be able to pass this time test period without causing listener fatigue. Clarity of signal is critical. It is the distortion that is created when the signal is amplified and poorly processed. It is distortion that causes listening fatigue, not the time spent listening. Higher sound pressure levels will produce higher levels of distortion. If the engineer’s ears are tired, he will make decisions for the mix that he would not have made if he wasn’t fatigued.

Power Requirements

Power requirements differ for each speaker type and studio monitors are no exception. If we look at hi-fi speakers, we know that that they are similar to monitors in that they are detailed and accurate. However, in exchange for all this sonic detail, they can not be played at the high pressure levels “demanded” by today’s professional engineering community. A hi-fi speaker can be easily damaged with too much gain from the amplifier. Sound reinforcement speakers must play loud. They must reinforce the existing sound with more sound. Quality of the sound produced is important but their main design goals are to play loud over extended time periods.

Active And Passive

Studio monitors come in two different classes depending on how they choose to process the energy the amplifier sends them. The technical terms used are directed at the crossover which is the gate keeper for sound energy from the amplifier. With studio monitors we can have active and passive crossovers. All multiple driver speakers have a crossover to decide how the sound from the amplifier will be distributed. With a passive crossover, it is usually positioned inside the speaker and the speaker designer presets the crossover frequencies to achieve the sound he wants for the speaker design.

Active Crossover

In an active crossover, the speakers also become active speakers. Active speakers have a line level input similar to a power amplifier. Our source signal is sent to the crossover and then to the power amplifier before going to the speakers. When our source signal hits the active crossover, high frequencies can be directed to one power amplifier to cover the middle and high frequencies. The low frequencies can then be sent to another amplifier. This ability to process if you will our signal in this manner allows us to match the amplifiers to the speakers.

Studio Hybrids

Studio monitors are a type of hybrid speaker with features and benefits borrowed from both hi-fi and sound reinforcement speakers. Accuracy and detail is incredibly important because we want everything in the recording revealed to the engineer’s ears. Hi-fi speakers do a good job with this. High sound pressure output over extended periods of time is also a requirement. Clients want to hear how their music sounds with regular, medium, and high volumes. In some current musical genres, it is mostly how does it sound loud. Loud is not viewed as a negative.

Transient Coverage

It also allows for better transient coverage. When a bass note is played at the same time a guitar note is played, the amplifier will have to send more energy to reproduce the bass note. The guitar note will be short changed because the bass note took more energy from the amplifier. With the ability to have bass notes reproduced with their own amplifier behind them and the mids and highs having their own amplifier, there will be plenty of energy for the mids and highs to be heard.

Studio monitors are a blend of other speaker types. They take the detail and accuracy from their hi-fi brothers and their ability to play loud from their sound reinforcement cousins. Studio monitors speak only one language and that is honesty and faith to the recording. They achieve this sonic goal showing a flat frequency response. They are designed to reveal and revel in the music at any pressure level, especially loud. They like to be heard over and over again.

Filed Under: Electronics, Room Acoustics, Uncategorized

Music Recording vs Music Playback Environments

April 28, 2012 by Leave a Comment

Record vs. Playback

I am always amazed at the difference between the recording process used for music and the playback process environments that individuals use to enjoy this recorded music in. In the recording process, the engineer has to make sure that all instruments and vocals are heard in the mix and that nothing is smothered or buried under another vocal or instrument. Different microphones are used to record vocals and instruments and separate microphones are used to even record the sound of the room. The professional recording engineer has separate rooms that are used to record certain instruments and vocals. Unfortunately, when this recorded music is played back, it is played back and heard in less than ideal environments that do not meet the same standards that it was created in.

Car Audio

Many sonic advancements have been made in the realm of car audio. There are car audio amplifiers that today resemble the equipment we have in many professional recording studios. One can use different amplifiers to power the middle and high frequencies. There are separate amplifiers one can even use to power the bass speakers in our cars, so that no energy is lost in the transient response coverage when a bass note is played simultaneously with a guitar note and the energy from the amplifier needed to produce the bass note does not rob energy from the middle and high frequency vocals and instruments. Bi-amplification and even tri-amplification are popular amplification scenarios today in car audio.

Car Audio Components

There are also many improvements in other components in the car audio signal chain. Digital to analog convertors have also come a long way in their ability to convert detailed, digital signals from our compact discs into analog waves that our ears can hear through our speakers. One can even purchase separate digital to analog convertors that are not integrated into the receiver in the dash. These processors can even send the signal to multiple speaker arrays which are spread out and located in different positions inside our vehicles with the sonic goal of bringing a more lifelike presentation to our mobile music environments. Special care and attention has been given to the number of speakers and the speaker positions inside our vehicles by car manufacturers to try and portray the music in a realistic manner. Electronics “steer” the audio signal to try and produce a multitude of “room sounds”.

Glass Bowl Effects

Unfortunately, all of this technology can not hide the impact of the music inside of our “glass bowl”. Listening to music inside of our vehicles is like listening to music inside of a glass room. Reflections from our windshield and our windows produce a harsh glare that can destroy any musical presentation our mobile equipment is capable of producing. Sound takes on the characteristics of the surfaces that it strikes. If it strikes wood, it takes on the welcomed smooth and warm “sound” of the wood. If it strikes glass, it takes on the harsh and glaring characteristics of the glass. This phenomenon is especially apparent with high frequencies which can produce an ear piercing glare. All of this reflected glare conceals parts of the music. The engineer who created the recording never wanted this to be part of what one heard in his recordings.

Glass Treatments

We can minimize reflections from our windshields by placing absorptive material on the windshield itself; just kidding. We realize that we must be able to see out of our windshield, but we can treat the primary reflection from our speakers to the windshield with small amounts of acoustic foam that do not interfere with our vision. We can also treat the dash of our vehicles with acoustical foam to minimize reflections from the windshield to the drivers and passengers listening
position. Don’t forget to treat the deck area behind the backseat and rear window. If you do not have rear seat passengers, you can also treat the rear side windows by temporarily placing acoustic foam on those windows. Make sure you are not obscuring any lateral or side vision pathways. Low frequency absorbers can be added to tighten up our bass response. They can be added inside our trunks or even placed behind the rear seats in our sports utility vehicles.

Room Treatment

In our room playback systems, we can also do many things to enhance our musical presentations. We can position our stereo systems in our room in a manner that produces a frequency response that is smooth and even with no exaggeration or loss of any frequency groups. We can control side wall reflections at our listening positions by treating them with sound absorption or sound diffusion technologies. Front and rear wall reflections can be treated with sound diffusion technologies that can spread reflections our evenly without any loss in signal. Our ceilings can even be treated to make our ceilings acoustically disappear and make our rooms appear sonically larger. Bass absorption technologies are available to minimize resonances produced by low frequency energy and clean up any muddle or smearing excess bass energy can produce.

Lets meet our recorded music and recording engineers half way and play it back in environments that allow for equal representations or all recorded material. Recording engineers go through great efforts to make sure we hear all of the music the artists use to create their music. They even design separate rooms to record vocals and drums in so that all sounds are captured and represented in the music. We do not need to have separate rooms for our musical playback environments, but we do need to have environments that allow for all the music to be heard and hopefully felt. Lets make sure we listen to the music without hearing the room or the car.

Filed Under: Electronics, Room Acoustics, Uncategorized

Why Is Hi – Fi So Expensive?

March 23, 2012 by Leave a Comment

I have been looking through the January, 2012 edition of Absolute Sound Magazine. This edition has listed what Absolute Sound considers to be the best gear that they found and I am assuming from the associated text that they reviewed the piece of gear and were able to create an informed opinion about. What a great job to have.

Amplifiers

I was impressed with the Constellation Hercules power amplifier, mono blocks at $140,000 per pair. Weighing in at 270 pounds each and producing 1,000 watts, these amplifiers are powerful and expensive. We also have a solid state preamplifier that is named the Constellation Altair. It tips the scales at $60,000.

Speakers

The Focal Stella Utopia EM comes in at $90,000 for a 4 way loudspeaker. We have a Clearaudio Goldfinger Statement phono cartridge that retails for $15,000 and a AAS Gabriel/Da Vinci MKII turntable at $76,000 to install it in. Lets see, we are at around $320,000 and we still need a phono preamplifier to round out our analog playback system to say nothing about a digital transport with converter.

What Is Our Goal?

What is our goal in spending this amount of capital on a hi-fi system? Is it to have the best technology from inventors and designers that has been created to date by those said designers and engineers. If it is so, then mission accomplished. Hi-Fi gear at this price point does represent what the designer had in mind as his best efforts applying his current knowledge to his associated technologies. Most manufacturers I know put their best efforts into their highest priced products. Not all the time and not with all the manufacturers, but as a general rule this is the case at least among the ones I know.

Is it a Music Goal?

I am hopeful that there is also a sonic goal of better sound and better music to connect emotionally to. When I hear these components at trade shows, I realize that that sound is what the designer wanted and spent the time and materials to get that sound. He arrived at this price point by achieving that sound. I hope this is true and manufacturers are not plugging in marketing hyperbole and sensationalism into that number. I hope it is their best efforts technically to date and this best effort has a cost that when plugged into their dealer or whatever marketing program, produces this retail price. Unfortunately, one will never hear what the designer intended you to hear without treating your room to acoustically deliver the equipment’s best. There is no way.

Final Frontier – The Room

The room is usually the final frontier considered when placing any type of equipment regardless of price. It should be the first frontier. One can take a $320,000 system and place it in an untreated and unprepared room and that $320,000 system will sound like a $3,000 system. Low frequency layering and definition, the speaker and amplifier designers took great pains to build into their products, will not be heard. The room will blur and smear these low frequency waves of energy and the room will be creating pressure zones that will cause elimination of some and over exaggeration of other frequencies. Middle and high frequency reflections from room boundary surfaces will impose themselves upon the listening position and mix with the wanted direct sound from our loudspeakers and confuse our brain with these signals battling for their respective time positions at our listening position.

Emotional Connection

It is not the price of the gear that produces the sound energy into our rooms that is important. It is the emotional connection to the music that we receive from the equipment. This should be our only goal. More pricy equipment usually does (not always) produce better sound quality which furthers the emotional connectivity to music. It is this emotional connection we crave and must have, especially today.

To make sure we receive that connection, we must take great care and concern by placing our playback system in a room that has had the acoustical issues dealt with that rob our gear from producing its best sound. This trilogy of the amplifier, speakers, and room must not be broken apart. In the old days it was all about the boxes; the amplifier and speaker. Now, there is a new box that must be considered. It is the room. The room must meet the amplifiers and speakers more than half way.

Filed Under: Electronics, Room Acoustics, Uncategorized

“Radio Receiver Operating In An Automobile”

March 12, 2012 by Leave a Comment

In Harry F. Olson’s book entitled, “Acoustical Engineering” which was originally published in 1947, he discusses a radio placed in an automobile. It is interesting to see the “acoustical thought” that was in use in 1947 and compare that thinking and application with current acoustical trends.

Rather than paraphrase his book section and make comparisons to modern day applications, I will just quote the entire section below and let you, the reader, make the modern day similarities and differences. Any parentheses inserted are by myself to improve understanding when text refers to a graphic:

Acoustical Engineering – Automobile Radios
The primary loudspeaker in an automobile is usually located in one of four locations, namely in front of instrument enclosure (this would be a front panel mounted speaker), in the top of the instrument enclosure (this would be a dash mount speaker firing into the windshield), in the fire wall or dash, and in the header above the windshield. The header location gives somewhat better distribution of the high frequency response in the back seat than the three other locations. However, the low frequency response of a loudspeaker mounted in the header is usually attenuated due to the small volume behind the loudspeaker.

The dash or firewall location gives fair distribution of the high frequency response in the front seat, but very poor distribution in the rear seat. The low frequency response in this position can be made very good by employing a large loudspeaker case or by venting the back of the case into the engine department. Sometimes a combination of a low frequency dash loudspeaker and a high frequency header or instrument panel loudspeaker is employed. At the present time, the favored position for the loudspeaker appears to be in the instrument panel because in this location the radio receiver, loudspeaker, and controls may be combined into a single compact unit.

The distribution of sound is excellent in the front seat and good in the back seat. The stiffness presented to the back of the cone because the entire radio receiver case volume is used to enclose the back of the loudspeaker. In this manner, the response can be maintained in the low frequency range. In order to improve the reproduction of sound in the rear seat, a secondary loudspeaker is used in the rear. (header area between rear seats and windshield)

The conditions under which an automobile radio receiver operates differs widely from those of a loudspeaker in the living room. It will be seen that the automobile is a small enclosure with short distances between the loudspeaker and the listener. This is fortunate because wind,road rumble, and engine noise mask the reproduced sound. The power output of the receiver should be powerful enough to override these noises and give intelligible reproduction of speech and pleasing reproduction of music.

In view of the fact that the sound level delivered to the loudspeaker is quite high under the noise conditions, it is important that the frequency response characteristics be smooth and free of peaks, otherwise the reproduced sound will be disagreeable due to the high level of peaks relative to the general level. It is also important that the nonlinear distortion be kept at a low value because spurious components in the reproduction of sound are more apparent at the higher sound levels.

Conclusion
Speaker locations today, differ slightly from those represented in this book chapter. Now, we do most of the speaker and sound manipulation in the digital domain and bounce the sound around between the speakers inside the vehicle to try and produce some order to our sound presentation. It is difficult in a “glass bowl” for even a computer.

Filed Under: Electronics, Uncategorized

Home Theater Receiver

August 3, 2011 by Leave a Comment

A home theater receiver is an amplifier, preamp, video processor, and possibly a tuner to receive AM and FM signals. Another way to bring all of these functions into your home theater is to use separate components for all of these functions. Separates allow the end user to control the quality level of each component more accurately.

A home theater receiver manufacturer will design a receiver that will be sold for a particular price point in a certain market segment they are targeting. They will mix and try to match a video processor, amplifier, preamplifier etc. and make their quality and costs fit into a targeted pricing framework. This will create a product that has multiple functions, but will usually lack the individual quality level found in separates.

A home theater receiver has everything under one roof sort of speak, and thus they are all sharing a common circuit board, chassis, and cabinet. Separates will usually have all these components but will not have to share functions with other parts. For example, each component in a video processor will be designed to focus and create a video image full time without sharing any other functions of their design with a preamp or tuner. A manufacturer of separates can maximize the performance of his unit because he can focus solely on one function and maximize its potential.

www.acousticfields.com

Filed Under: Electronics, Uncategorized
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