A Real World Subwoofer Application

Looking at some pictures that were sent to us over the last few days we noticed that a subwoofer array was setup as a center cluster. The array had 6 TCS subs across the front of the stage. So after looking at the image and doing a couple software models we wanted to share with you the coverage of the center cluster vs. using the same number of subs as a stereo setup with three subs per side of the stage.

On the top graphic you will notice a very even coverage throughout the listening area with attenuated bass to the sides of the stage but a bit of bass under the stage area (Green Square.)

In the bottom graphic you will notice very intense lobes throughout the listening area that results in uneven coverage and unsatisfactory results.

We are also including a picture of the actual stage so you can see what it looked like.

When dealing with subwoofers and low frequencies, compromises have to be made. In this case, the provider chose to have a little bit of extra bass under the stage to get the desired smooth coverage in the listen area. Since the TRX3210As were flown, there was no need to stack the speakers on top of the subwoofers, therefore they didn’t need to do the inferior compromise of using a stereo subwoofer array.

Take a look at how you deploy your subwoofers and think outside the box a little, you may be pleasantly surprised.

Carvin-Center-Cluster-vs-Stereo-Subs-graphical-display

Carvin-Center-Cluster-of-TCS-Subs

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How should I set up my subwoofers, three ideas to consider.

When considering where and how to deploy your subwoofers there are many factors to consider. For many of the smaller systems or for events where the logistics prevent hanging the main P.A. system, the only obvious choice is to ground stack the system. Since most people would end up stacking the main speakers on top of the subwoofers on either side of the stage, the system technician needs to understand the interference that the subwoofers will have with each other. In the image below, you will notice that there are distinct lobes in the audio coverage of the subwoofers. This will always happen when using subwoofers placed apart from each other as such.

Carvin Stereo Sub Placement

As the mix engineer or system technician walks the area to tune the system, caution needs to be taken to understand where these lobes are and to not try to tune the system based upon the lobes. Trying to add additional output in these areas could cause harm to the subwoofers.

When you have an event where you are able to get a center cluster of subwoofers, you begin to benefit greatly. The first benefit you get is smooth horizontal coverage. Since the subwoofers act as a single device with a large mouth, there is almost zero phase difference between the boxes. This prevents the lobes in coverage and it gives the additional benefit of coupling. Since the subwoofers will be in close proximity you will gain up to 6 dB of additional output plus you gain in pattern control. Notice the nice even coverage on the attached image.

Carvin Mono Subs

To get even better pattern control from you subwoofers, you can consider different subwoofer arrays such as the Cardioid Subwoofer Array. The Cardioid Array is most often used when less low frequency content is desired on the stage. This will make the monitor engineers job way easier and allows for much cleaner monitor mixes.

The easiest way to create this array is to have one subwoofer pointed backwards with two subwoofers pointing forward on each side of the reversed subwoofer. Then reverse the polarity of the reversed subwoofer and delay the forward subwoofers to align with the reverse subwoofer. This is an advanced system setup that will require experimenting with different settings using to get the pattern control required. By slightly varying the delay, you can maximize the cancellations to the back at different frequencies.

Since the reversed subwoofer is canceling out part of the output of the forward subwoofers, it actually takes more speakers to get the same output as a regular center cluster subwoofer array. To be approximately equal in output to four subwoofers you will actually need at least six subwoofers for the array as is pictured in the graph below.

Carvin Cardioid Sub

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Setting Limiters

How to calculate a limiter setting, for your speaker.

First you need to convert the power rating of your driver to Volts rather than watts.

Lets assume you have a driver rated for 600 watts at 8 ohms nominal. The formula would be….

Sqrt(watts*ohms) so sqrt(600*8) = 69.28 volts

Next you need to convert the volts to dBu using the formula 20 Log(volts/.775)

so 20 Log(69.28/.775) = 39.03 dBu

Now lets assume you have an amplifier capable of 800 watts at 8 ohms. Now let us convert that to dBu using the first formula used with the speakers wattage.

sqrt(800*8) = 80 volts. then we convert that to dBu also.
20 Log (80/.775) = 40.28 dBu

Now to find the limiter setting you subtract the amplifier output from the dBu required for the driver.

39.03-40.28 = -1.25 dBu

Now you would set your limiter for 1.25dBu below full output of your amplifier.

So if your amplifier has full output at +4dBu then you would set your limiter for +2.75dBu.

To add a little extra protection, consider setting your limiters based upon the type of music and the skill level of the technicians. For highly compressed music such as Electronic Dance Music, setting the limiter closer to the Continuous rating of the speaker will provide a little extra cushion. For highly dynamic music such as Jazz or vocal based music, setting the limiter closer to the Program rating of the speaker will perform really well.

Also to consider, if you have an electrical source that may not be up to the task, you may want to lower your limiter settings by a decibel or two for a little extra protection to prevent premature clipping due to voltage sags.

No amount of limiting can protect your speakers completely, so you need to be aware of how your system is performing. Be sure to make adjustments as needed to keep your speakers within safe operating conditions.

There you go, now you are a little safer.

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DIY -20dB Pad Adapter

Occasionally you need to have a pad on a mixer that doesn’t have an input mic-preamp pad switch. Here we will show you how to build your own balanced -20dB Pad adapter. These are very handy when you have a bass amp with a DI output, but no DI volume. Or you have a hot line level output going into a microphone mixer input. Now you have the ability to build your own -20dB Pad adapter.

20-dB-Pad-Circuit

This project will take about 20 minutes to make and will be very handy when those times arise.

You’ll need a couple of tools and a couple parts to build this project.

Tools needed:
Solder Iron
Solder
Tweezers
Scissors
Small wire cutter
Small wire stripper

Parts List:
1 Male XLR Connector
1 Female XLR Connector
1′ of Balanced audio cable
2 680 ohm 1% resistors (1/4 Watt if you can find them)
1 150 ohm 1% resistor (1/4 Watt if you can find them)

Carvin-Pad-Parts

This very simple circuit uses the two 680 ohm resistors in series with Pins 2 and 3 and then has the 150 ohm resistor in parallel between the Pin 2 and 3 Leads. It works work phantom power so you can still use your favorite condenser microphones.

It is highly recommended that you use very small (1/4 Watt or 1/8 Watt if you can find them) resistors for this project so that they will fit inside the XLR shell easier. For illustration purposes, 1/2 Watt resistors were used here so that you could see them better in the photos. They DO NOT fit into the XLR shells very well.

Step 1. Trim the leads and solder the 680 ohm resistors into the cups of Pins 2 and 3 of the female XLR

Step 2. Trim the leads and solder the 150 ohm resistor into the cups of Pins 2 and 3 of the male XLR

Carvin Soldered Resistors

Step 3. Solder the leaders from the 1′ piece of Audio cable into the cups with the 150 ohm resistor and the pin 1 cup of the male XLR. Make sure you put the shell on the cable prior to soldering to avoid the aggravation of undoing your work…been there, done that!

Carvin Soldered Male XLR

Step 4. Solder the leads of the other end of the cable to the trimmed leads of the 680 ohm resistors and the pin 1 cup of the female XLR. Again, remember to put the shell on the cable first.

Carvin Soldered Female XLR

Step 5. Assemble the XLR shells and you are good to go.

Carvin-Pad-Finished

For a better looking job, use tiny pieces of shrink tubing over the exposed leads inside the XLR shells. This will take some tiny tweezers to get them in place and hold them away from the solder iron as you solder.

Have fun building this project and hopefully you will find it as easy and handy as we have described it.

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Common Audio Voltages and Levels

In professional audio, we frequently see many voltages and levels referenced in dBu or dBV that we should all know. Below is a short list of the most common levels and their voltages that they represent that we highly recommend you memorize. These levels will help you to optimize the setting of your system processors and effects units by understanding what levels are going into and out of different pieces of gear.

Some of these are the Nominal Operating Levels of gear, while others are the Sensitivities of Amplifiers (Level required for full output), and others are often stated in spec sheets as the maximum output levels of common pieces of gear. These numbers have been rounded to the nearest 100th of a volt or 10th of a dBu to reflect the commonly seen numbers on specification sheets of audio gear.

dBu Volts dBV
Common Professional Levels
0 dBu .775 Volts -2.214 dBV
+4 dBu 1.23 Volts 1.786 dBV
+5.2 dBu 1.4 Volts 2.923 dBV
+18 dBu 6.16 Volts 15.786 dBV
+22 dBu 9.76 Volts 19.786 dBV
+24 dBu 12.28 Volts 21.786 dBV
     
Common Consumer Levels
-7.8 dBu .32 Volts -10 dBV
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NEW! Carvin SCB7 Bevel Top Seven String Guitar

Carvin SCB7 Bevel-Top Seven String Guitar
Carvin is excited to offer our latest Custom Shop instrument, the SCB7 bevel-top seven string guitar. Since the introduction of the six string SCB6 at NAMM, seven string players have been asking for their own version, and the Custom Shop is happy to oblige. The SCB7 is a radical departure in aesthetics from other Carvin seven string models, with sleek and stylish looks combined with superior materials and craftsmanship in a USA-made instrument that is suitable for all playing styles at any level.

Neck-through design, an alder body with Eastern hard rock maple neck and tune-o-matic “M” bridge provides unsurpassed playability and amazing tone with sustain for days. A Hipshot™ hardtail bridge or Floyd Rose tremolo is also available. Like all Carvin Custom Shop instruments, you can choose from a
massive assortment of finishes; premium neck, body, fingerboard and top woods; inlays; fretwire and much, much more. The SCB7 comes equipped with Carvin’s popular direct-mount D26 humbuckers, with master volume and tone controls and a 3-way lever-style pickup selector.

The Custom Shop can build your new SCB7 exactly the way you want it, creating a masterpiece that will impress you, your bandmates and your audience. Whether you’re an experienced seven string player, or looking to make the leap up from six strings, Carvin’s SCB7 and our other seven string models will help you take your playing to the next level.

Read More:  Carvin Custom Shop SCB7 Bevel-Top Seven String Guitar

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5 Easy Tips To Make Your Systems Sound Better In Small Venues

Use Proper Cables: By using the correct type and quality cables for your applications you will often notice a significant difference in sound quality. Use as short of cables as is practical to avoid voltage drops. Short unbalanced 1/4″ TS cables should be used for instruments only, while using high quality, balance TRS or XLR cables for all sound system interconnects. Use Extra Hard Service power cables for your power runs and avoid laying them parallel to your audio cables whenever possible.

Place Speakers to the Proper Height: Point your speakers will they will be heard. Placing your speakers on the ground won’t help when the audience is standing and their ears are 5′ off the ground. By getting the High Frequency Drivers above head height, the music will be much clearer from the front to the back of the room. Use tri-pod stands as needed to get the speakers above the heads of the audience.

Less Speakers Sound Better Than More: Whenever you try to array speakers horizontally you will end up with some degradation of sound due to “Comb Filtering.” Use the correct number of speakers to cover the area, paying particular attention to keep the sound off of the walls and ceiling. In most small venues a single 80 or 90 degree horizontal speaker will almost always sound better than a pair of boxes. Giving up a little SPL by only using one box per side of the stage will actually make the audio more intelligible without having to be so loud.

Don’t Mix Too Loud For The Room: Notice all the people sitting at the back of the room? They really want to be up close to the musicians but it’s too loud right in front of the stage. Walk the room to verify that the volume is appropriate in all areas. If you are playing to two hundred people in a small room there is no reason to turn it up to the same volume as an arena show.

Play at the Proper Stage Volume: All too often the singer’s girlfriend comes to the sound guy and says she can’t hear her boyfriend because the Guitar is too loud. Of course the sound guy doesn’t even have the Guitar in the mix because his amp is turned up to 11, because it’s one more. As the mixer, do your best to communicate to the musicians to play at a reasonable volume for the venue. Playing too loud doesn’t help anyone. By having the musicians turn down, not only will your front of house mix sound better but they’ll hear the monitors better too.

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Aux Fed Subwoofers

Aux fed subwoofers have become a very useful tool for the audio engineer in the last several years. There are two main reasons for using aux fed subwoofers. Each of them is beneficial to the other.

1. Using Aux Fed Subwoofers gives the engineer more control over the relative Low Frequency SPL.
2. Using Aux Fed Subwoofers allows the engineer to keep inputs with little or no LF content out of the subwoofers for a cleaner, more intelligible mix.
 
With modern pop music and EDM music, the engineer must be able to control the relative level of the Subwoofers in relation to the full range speakers. Since much of this music is highly compressed with almost no dynamic range the excessive LF content can easily distort or even cause damage to the subwoofers. By using Aux Fed Subwoofers, the engineer can make adjustments as needed to maximize the output without detriment to the system. Since much of the audio requires the subwoofers to be as much as 20 dB louder than the full range speakers it is often necessary to lower the LPF on these applications to maintain an accurate Acoustic Crossover. We’ll address this in future tech tips. For these applications the Aux Fed Subwoofers can derive their signal from either a Post Fader Aux output or from a Group output.
 
For many engineers running sound for bands keeping the microphones out of the subwoofers makes the mix sound much better with more accurate sounding vocals. In these applications the engineer uses a Post Fader Aux to send only the inputs that need Low Frequency reproduction to the subwoofers such as Bass, Keyboards, Kick Drum and Floor Tom. By doing so, the engineer does not have to use as high of a HPF on the vocal mics which leads to a nice, warmer sounding vocal. By keeping the inputs out of the subwoofers that don’t belong there the system runs more efficiently, as the subwoofers and amplifiers are not wasting power reproducing unwanted signals.
 
With three inputs and six outputs, the X-Drive makes for a very versatile Loudspeaker Processor which is perfect for operating Aux Fed Subwoofers. Each of the three inputs can be routed to the six outputs individually. Each output has four band Parametric EQ plus HPF and LPF to optimize your settings.
This picture shows an example of how easy it is to route the inputs to the correct outputs for Aux Fed Subs using the XD360.

xd360

KEY BENEFITS OF AUX FED SUBS
* Better Vocal Quality
* More control over LF output
* Less wasted energy
* Clean mixes
* Easy processing with Carvin XD360 Loudspeaker Processor and Carvin X-Drive Amplifiers

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Shane Gibson, 1979 – 2014

Shane Gibson

It is with deepest sadness that we announce that guitarist and Carvin artist Shane Paul Gibson passed away at 5:45 AM on April 15th, 2014 in the UAB Hospital in Birmingham, Alabama as a result of complications from a blood clotting disorder. He was 35 years old. Shane was a long-time member of the Carvin family, having conducted numerous clinics, appeared multiple times at NAMM, and performed with Carvin gear on stages around the world for countless fans.  He was a very talented and gifted musician, and his virtuosity was matched only by his wit and generosity. He will be missed beyond measure, and we take solace in knowing that his spirit will live on through his music and fans. 

Shane's final recording with his band stOrk, titled "Broken Pieces", was just released this past Monday, and showcases his talent and skill, and will be a fitting memorial to Shane's legacy as one of the preeminent guitarists of the hardcore/punk genre.

Our thoughts and prayers go out to his family, friends, bandmates and all those who loved him as much as we did.

Read More:  stOrk on Facebook

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New Vanquish Series Basses From Carvin

Vanquish Series Basses
Carvin’s new Vanquish Series electric basses represent a radical departure from traditional bass guitars, and are the next step in the evolution of the instrument. The 4-string V49K, 5-string V59K and 6-string V69K Vanquish basses are loaded with exciting new features, including a beveled body designed for comfort as well as great looks and a 5-bolt neck joint for improved neck/body contact resulting in better sustain and punch. Additionally, the V69K is the Custom Shop’s first-ever bolt-neck 6- string bass.

Other features, including a Hipshot™ A-style bridge and 24-fret neck add to the superior range, tone and playability of the Vanquish Series. Electronics consist of a pair a radiused-top humbuckers with 18V active/passive module; controls include master volume, pickup blend, push/pull active and passive tone control, stacked concentric bass and treble frequency cut or boost. Optional single-coil radiused-top pickups are available for more jazzy styles of music.

Like all USA-made Carvin Custom Shop instruments, you can order your new Vanquish bass by choosing from a huge assortment of options, including body, top, neck and fingerboard woods; finishes, inlays, fretwire, hardware and more. You can design your Vanquish bass exactly the way you want it to suit your own playing style and personal tastes.

In addition, the Custom Shop has added some new finish options.  Deep Nightburst (shown on the V69K above) is Carvin's Deep Aquaburst with the addition of purple burst edges.  Translucent Moss Green is similar to the Deep Moss Green that's been available on flamed and quilt top woods, but can but used on plain woods like alder and swamp ash. Check out the Vanquish Series basses along with these new finishes at Carvin.com, and design your own Custom Shop masterpiece!

Read More:  Carvin Vanquish Series Basses

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