EQ: Understanding Sound

I will be doing a series of post on the general use of equalizers for live music, but for this post I wanted to just go over the very basics of sound. Knowing this information will later aid you in fully understanding the concept of equalization.

How is sound made? Simply put, vibrations in the air. The rate at which the vibrations happen is called frequency. High-frequency vibrations produce high pitches and low-frequency vibrations produce low pitches. Frequency is measured in vibrations, or known as cycles per second. These cycles per second are called Hertz (Hz). You will notice knobs on mixers, EQs, and other equipment with a number followed by ‘Hz’ – Hz stands for hertz. (Ex. 80 Hz = 80 Hertz, 1kHz = 1,000 Hz)

Now that you know about frequency, it is important to realize that sounds you hear are not just one frequency. When someone plays a note on a guitar or a piano, you will get a fundamental frequency, but you will also get some higher frequencies, known as overtones or harmonics. The fundamental frequency is the note that you recognize. The overtones make up the tone color of the notes source, or timbre. The timbre is what makes a piano sound like a piano, a trumpet sound like a trumpet, and a violin sound like a violin. When they all play the same note together, their timbre allows you to pick out the different instruments.

All frequencies make up what is called the frequency spectrum and the part of the spectrum that we can hear is called the audio spectrum. The audio spectrum is from about 20Hz to 20kHz and any portion of the frequency spectrum is known as a band. It may be a wide like the range of synthesizers or it may be narrow like the human voice. Bandwidth is how narrow or wide (measured in Hz) the band is.

This is just a basic overview of how sound is made and a couple of terms that are very useful to know. Keep checking back for more information on equalizing live sound. I will quickly go over some of the new words you learned today. 😉

Frequency is the sound vibrations related to what we hear as pitch. Higher-frequency vibrations produce high pitches and low-frequency vibrations produces low pitches.

Hertz (Hz) is a unit of frequency. Simply, the number of vibrations per second.

Fundamental Frequency is the actual pitch that you recognize.

Overtones make up the tone color, or timbre, of an instrument.

Timbre (pronounced TAM-bur) is the term for an instruments tonal characteristics. It is what makes the piano sound like a piano and a trumpet sound like a trumpet.

Frequency Spectrum is a spectrum of frequencies.

Audio Spectrum is the spectrum of frequencies that are audible by the human ear. (About 20Hz – 20kHz)

A Band is a portion of frequencies. Ex. The human voice has a band of approx 80 to 1200Hz.

Bandwidth is how wide or narrow (measured in Hz) a particular band is.


How To Color Swirl A Guitar

Here is an awesome how to video on how to do a swirl-like paint job on your guitar. It is done by Tony Gayter (@theswirling) and he recommends a lot of practice before doing this paint job. (It took him over two months of practice to get it down.) He has a website in the works that will offer tutorials on these guitar paint jobs. It sure is neat how he makes them. Maybe we will have to make one! 😉

The finished product is awesome. What do you think of it?

Selling Music Gear To Help Haiti

Seismic Audio Will Donate 10% of Sales to Haiti

If you have watched the news at all in the last few days, I am sure you have seen the coverage of the earthquake in Haiti. Thousands have died. Kids no longer have parents and parents no longer have kids. Watching the kids in need on TV has pulled at my heart. Being a father myself, I can’t imagine watching my child be in this type of situation and not being able to do anything to help him. Starting today, January 21st through the rest of the month, I will donate $10 for every $100 ordered through our website, www.seismicaudiospeakers.com. Due to fees associated with selling Seismic Audio products on eBay, Amazon, and other marketplaces, I am only able to afford donating 10% based on sales generated through our actual website. These marketplaces charge 10%-15% for each sell that occurs on their site. However, if you find us on one of these sites and decide to purchase on our website instead, I will donate the money.

I will be donating money through the Red Cross website at www.redcross.org. If you would like to help, you can text “HAITI” to 90999 $10 will go towards the Haiti earthquake relief via the Red Cross. I have personally sent five texts to them and hope you guys can send a text or two yourself.

I plan to send my donations every day for the previous days sells. For example, if today we do $2000 worth of sales, I will send $200 tomorrow. For weekends, I will send the money for Friday, Saturday and Sunday sales on Monday. I will attempt to post receipts given to me from Red Cross. I will do everything I can to show legitimacy in this campaign, but it may require you taking my word for it when it comes to sales. View our feedback on eBay and Amazon, check us out on Facebook, or just Google us, and you will see I run an honest company and treat people the right way. $2000 worth of sales from the website would be a good day for website sales, based on past history.

If this campaign increases sales for Seismic Audio, then great. If not, that is fine. Increasing sales is not my goal with this campaign. I have been blessed to be in a business I love. I figure I can afford to give away 10% of my gross sales for a good cause for 10 days. Also, since I named my company Seismic, I feel like I should donate to this cause.

If you don’t need any pro audio gear, then I would hope you would still donate. Simply text “HAITI” to 90999 and $10 will be donated to the people of Haiti who have been devastated by the earthquake.

Keep Rockin,
Steve Acree
Seismic Audio Speakers owner

Rock Band Network Is Transforming The Music Industry

Recently, game developer Harmonix opened up the beta for musicians and bands to upload their own song into the Rock Band Network. Each completed song that is submitted will go on sale in the Rock Band Network store along with hundreds of other Rock Band tracks already available. Now, this is just the beta testing, but once all the bugs are worked out and the library is big enough, the created content will go live and will be downloadable by any player’s XBox 360 or PS3 Rock Band Network store.

This has great potential for both music creators and Harmonix. Not only can unknown, indie bands get noticed through the internet, but now they have a new way they can be heard and played by thousands of people. Game developer Harmonix also gets a great deal because they can sell songs they don’t have to spend time creating. Usually, it takes a day to do 2-3 songs for Harmonix and they sell constantly. So, the only logical move was to find a way to produce more songs and make more money. And that’s exactly what they are doing by allowing creators and bands the chance to share their songs. Oh, and of course creators get a 30% cut for each of their songs that sell on the network.

Rock Band Network - Create Your Own Rock Band Song

Unfortunately, this is not something that everyone will be able to sit down and do in a few minutes. To create a song you have to use full blown professional editing software and it will take first-time users 20 to 40 hours to complete a song. So, if you are up for the challenge you can get started at the “Rock Band Network” Creators Club official site. If all the computer recording and editing is not for you, I am sure soon there will be plenty of people willing to create the song for you for a small price.

Everybody Is Trying To Run With Pants On The Ground

Do you Remember General Larry Platt? I sure hope that you remember his catchy song, “Pants On The Ground.” Over the past several days since the air of his American Idol audition everybody wants to be like Larry. Here is just a small sample of the ‘remixes’ that people have done of “Pants On The Ground.” Everything from rap remixes to Jimmy Fallon as Neil Young to Brett Favre and the Vikings!

That is just a few – there are several hundred and you could spend all day watching them. All video and audio belong to their respective owners.

Connecting An Amp To Speakers

So, you got yourself a great pair of Seismic Audio Dual 15″ Pro Audio PA / DJ Speakers.  You also have great amplifier to power those speakers.  You are ready to get out there and start rockin’ the house!  There is just one problem – you don’t know how to hook the speakers to the power amp.

The most important place to start is at the amplifier itself.  It is extremely important to make sure that amp is capable of handling the impedance (ohm) load from your speakers.  For this blog, we are going to assume that you are using 1 channel of your amp and have a single pair of identical speakers and want to run in mono mode. Other configurations will be addressed in future blog entries. Most of the time, when running a PA in this mode, your speakers are going to be daisy chained (or run parallel).  You daisy chain speakers by hooking one speaker up to an amplifier and then out of that speaker you hook up another speaker.  Keeping in mind that for this example we have only 2 speakers with the same impedance rating, when you daisy chain speakers you divide the impedance. (For example, two 4-ohm speakers connected in parallel result in a 2-ohm overall impedance.) This is why it is important to be sure your amplifier is capable of handling the ohm load.  If the ohm load of your speakers is lower than what your amplifier can handle, you will most likely cause severe damage to you amplifier!  (And most of the time – void your warranty!)

Now, let’s go back to your pair of Seismic Audio Dual 15″ Pro Audio PA / DJ Speakers (SA-155T) for an example. Individually these speakers run at 4-ohms a piece.  When you hook them up parallel (daisy chained), the ohm load of the speakers is 2-ohms.  Remember, running your speakers parallel divides the impedance.  A large majority of amplifiers can handle 2-ohms per channel (running non-bridged mode) – but it is important that you check your amplifier and find out!  So, if your amp can handle 2-ohms per channel, you are ready to hook up the SA-115T because daisy chained together they carry a 2-ohm load.

Let’s say you got the same 2-ohm per channel amp, but you have a pair of speakers with a higher ohm load.  So, you have two 8-ohm speakers and when you hook them up is parallel they would be a load of 4-ohms.  Can you do this?  Yes, as long as the ohm load is not lower than the amp is capable of handling then you are okay.

But what if you have an amp that is 4-ohms per channel and the SA-155Ts which run at 2-ohms parallel?  Well, you guessed it – DO NOT DO IT!  If you run this configuration, you will more than likely severally damage your amplifier!

This is just a general example and there are many ways to configure running your speakers to an amplifier.  What I am trying to point out is the fact that you should NEVER run an ohm load lower than your amp is capable of handling.  This can permanently destroy your amplifier!

Now that you have figured out that your amplifier can handle the ohm load of your speakers, you are ready to get them hooked up!  The last step is actually connecting the speakers to the amplifier.  You need to find out what kind of connectors your amplifier and your speakers use.  Some might only offer binding post connectors in which you would use banana plugs.  Others might have inputs for 1/4″ connectors or speakon connectors.  What is the difference in these connectors?  In the context of this blog entry, it is just the connector itself.  When applicable, I prefer to use speakon connectors because they lock in place and you know that you have a great, secure connection.  Also, when the stage is crowded, speakon connectors insure that no one is going to accidentally step on a cable and pull it out of the speaker.  Another thing to keep in mind when buying a speaker cable, the heavier gauge wire you use, the better.  Heavier gauge wire insure that you are getting less resistance from the wire and therefore, less signal loss. Keep in mind that the lower the gauge number of the wire, the heavier the wire, i.e. 14 gauge is heavier or thicker than 16 gauge. The size of the wire is really dependent upon the amount of power you are pushing through it and the distance of the run. The details of that are beyond the scope of this blog entry though. Just be sure to use speaker cables and not instrument cables!

Well, you got the correct amplifier, a great set of speakers, and all the proper cables.  All that is left is to hook up the speakers and to power up the amplifier.  To daisy chain the speakers just plug in a speaker cable into the output of the proper channel of the amp and run it one of your speakers.  Once you have put that cable into the input of the speaker, grab another cable and go from that speaker to your other speaker.  Now you are ready to start the gig and to bring down the house!

What Size Amplifier Do I Need?

These are very common question we get:  What size amplifier do I need?  What amp will work with these speakers?  How many amplifiers do I need?

A good rule of thumb to start with is to pick a power amplifier that can deliver twice the power of the speaker’s continuous power rating.  For example, let’s look at Seismic Audio’s SA-155T (Dual 15″ Pro Audio PA/DJ Speaker Cabinets) which have a power rating of 700 watts RMS.  So, according to the rule of thumb, to power these speakers we would need an amplifier that can produce 1400 watts. Another important thing to take in consideration is impedance of the speaker. (The Ohms at which the speaker runs.)  Now, let’s go back to our SA-155T example.  The SA-155T have an impedance of 4 Ohms and, therefore, we would need an amplifier that can produce 1400 watts into a 4 Ohm load.  Using twice as much power as the speaker’s continuous power rating insures that you are getting a clear and undistorted sound to your speakers.

You don’t have to run 500 watts through a speaker just because it can handle that much.  If, for whatever reason, you have to use an amplifier with less power than your speaker, be sure to use caution.  If your amp is being driven into clipping, this could really damage your speakers.  Use your ears!  If you can hear that your speakers are distorting, crackling, or popping, you need to turn it down!  Just because your amplifier can put out 200 watts doesn’t mean you should run it at 200 watts.

For more information and help, be sure to visit Seismic Audio’s Tech Help Page.

Seismic Audio

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