Where To Control Volume And Gain On Pa System With Powered Speakers

The performance of any loudspeaker volition be influenced by the acoustics of the space in which they operate. Difficult room acoustics, combined with improper loudspeaker placement, can interfere with achieving the allegiance of which your loudspeakers are capable. Understanding how a room interacts with audio volition help you to get the most out of your system.

Recognizing Problem Rooms

In most live environments, the room is rarely designed to maximize the listening experience. For large-scale tour productions, venues are often sports arenas that have been designed to maximize oversupply dissonance. Smaller music venues are often called for location or architectural aesthetics, rather than music reproduction. It'south necessary to recognize and correct what that infinite does to the sound system in social club to optimize the P.A.'s performance in the venue.

In general, the post-obit physical features of a room tin can impact a audio system'due south performance:

Size. The size of the room directly impacts how well certain frequencies will be reproduced. This may seem odd until y'all recall about the concrete length of sound waves at diverse frequencies. When a room's width or length correlates directly to the length of a waveform at a specific frequency, a standing wave can occur where the initial sound and the reflected sound begin to reinforce each other.

Let'due south say nosotros have a long, narrow room where the distance from one side to the other is 22.6 feet. A 50 Hz wave is also about 22.6 feet long. (To summate how long an sound wave is, split up the speed of audio—one,130 ft./second—past the frequency. For a 50 Hz wave, 1,130/fifty = 22.vi ft.) When a 50 Hz moving ridge bounces off the wall, the reflective wave travels right back forth the aforementioned path and bounces off the other wall, and the bicycle repeats. In a room such as this, fifty Hz reproduces very well—peradventure as well well. And so whatever sound in that room will take a heavy depression end because the low frequencies are being exaggerated past the room acoustics and you're likely to have for recoup for them, either in your mix or by using a organisation EQ.

Construction. Low-frequency waves can be powerful enough to cause the walls, ceiling, and even the floor, to flex and move. This is called "diaphragmatic activeness," and it dissipates free energy and strips away the depression-finish definition. So if your room's walls and floor are made of solid brick and concrete that don't vibrate much, the bass response is going to be much more powerful than if you're in a room where the walls are normal sheet rock structure and the floors are hardwood.

Reflectivity. Another way a room interacts with sound waves is through reflectivity. Similar about room anomalies, reflections tin be good and bad. Consider the effect of a cathedral'due south reflections on a choir or a piano. This type of reverberation (reverb) is quite desirable for recording and audio-visual listening merely non for loudspeakers reproducing audio at normal stage volumes. If a speaker is placed most a reflective surface (such equally a brick wall or window), the direct sound coming from the speaker and the reflected sound coming from the wall can make it at the listener's ears out of phase with each other, causing cancellation and/or reinforcement.

If you are setting upwards your loudspeakers in a reverberant infinite, position your speakers so that as much sound as possible is focused on middle of the room and steered away from reflective surfaces. Installing acoustic handling on the walls will also lessen the impact of reflections at your listening position.

Wall and Cor ner Loading

Very low frequencies are not directional, and then they radiate from the sides and dorsum of the loudspeaker, as well as from the front end. If you place a loudspeaker against a wall, the rear sound propagates back into the room. This tin increase the bass frequency output as much as vi dB if the speaker is placed near one wall (half-space loading), 12 dB if placed near 2 walls (quarter-space loading), and as much as eighteen dB if you put the loudspeaker next to the ceiling or on the floor in a corner (eighth-space loading).

To have the most control over your sound, it's best to start with the flattest response, so you normally should avoid wall and corner placement. On the other paw, if y'all need some extra bass heave, this technique may exist worth a try. Information technology is important to be aware of what's happening and exist prepared to take advantage of it or compensate for it.

Considering a floor monitor placed on the stage is unavoidably subject to half-space loading, PreSonus loudspeakers feature a "Monitor" preset. This preset is specifically designed to recoup for bass buildup while maintaining a tight mid-bass response and a clear midrange.

Area Coverage

The size and shape of your room and the awarding for which it volition be used determine, to a large extent, how many speakers you lot will need and where they should be placed. In every situation, keep in mind your loudspeaker'southward coverage pattern.

Horizontal Coverage. It is of import to place loudspeakers so that in that location is a smooth transition from one loudspeaker'south coverage surface area to the next loudspeaker'south coverage area. This creates an even response throughout the listening space.

Vertical Coverage. If you are using a ground stack with a pole mount, make sure your vertical coverage matches the listening plane. Suspending speakers volition provide even further control. PreSonus loudspeakers feature dual-position pole mounts. Using the downward tilt mount volition focus the loudspeaker'due south free energy onto the audience and avoid destructive reflections. This is ideal for situations where the loudspeaker is mounted atop a tripod stand and placed on a stage, or where the pole-mounted loudspeaker is on the flooring and the coverage surface area is relatively shallow (briefing, java business firm, etc.).

A Quick Annotation on Stage Monitoring: When used as a flooring monitor, a loudspeaker'due south coverage pattern will contrary (that is, horizontal coverage becomes vertical coverage and vice versa). In most cases, this new pattern offers benefits. For instance, when laid downward as a flooring monitor, a PreSonus ULT12 has a l˚ (H) x 110˚ (V) coverage pattern. Equally the dispersion narrows to 50˚ in the horizontal, the floor monitor'due south free energy is focused to a relatively limited expanse that won't drain over into either side, creating listening zones and better clarity. The 110˚ dispersion in the vertical allows the performer the liberty to move forward and back inside their zone. For instance, a singer tin can stand up directly on top of their floor monitor to attain out to the audience and hear their mix equally well as they can when they dorsum up to the front of the drum kit to jump off the bass pulsate. Some loudspeakers, such as the PreSonus ULT-serial, allow you lot to rotate the horn so that the dispersion pattern is the same in both vertical and horizontal orientations. In full general, this feature should be reserved for horizontal mains use, non for floor monitoring.

Distributed Filibuster Systems

In most situations, a PA system relies on a master speaker system, positioned at the front of the room, to reproduce audio for the unabridged performance space. As a event, the level of the organisation is considerably louder at the forepart of the room than it is at the mix position.

In situations where sound must be reproduced exterior of the main organization's optimum range, well-placed delay systems can extend the intelligibility of the front-of-house system. By creating listening zones throughout the room, your front-of-firm system merely needs to be loud enough to comprehend the front of the room. As a issue, you tin can lower the mains level, give the front end-row listeners' ears a break, and become better fidelity from your speakers.

The goal of distributed audio is for the people in the back row accept the same listening feel as the people in the front end, but it isn't as easy as just putting up an extra pair of speakers. Since electricity travels much faster than sound, listeners in the rear of the room volition hear the sound coming from the nearest set of speakers before they hear the sound from stage. This dampens the attack and intelligibility of the sound, creating an unpleasant phasing effect. In large venues, this can actually sound like a short echo.

To create a delay sound system, yous need to delay the point going to the additional speakers. For example, since sound travels at about 1,130 feet per second (with some variation due to temperature, humidity, and elevation), information technology takes about 45 ms for audio to travel 50 anxiety. So if you put your delay speakers 50 feet abroad from the Front-of-Business firm system, you need to filibuster the indicate going to the satellite system past 45 ms.

To calculate the delay, divide the distance measured in anxiety past one.13.

Once y'all have positioned and delayed your satellite system, utilize an SPL meter to match the output of the main and delay systems at the measurement bespeak. For example, if y'all are standing 30 feet from the left side of the principal organization and 10 feet from the left side of the delay system, and the output of the main organisation is 85 dB, then the output of the delay organisation should likewise be 85 dB.

It should be noted that frequencies in the sub-bass range of a delay system do non require distribution. In fact, a delay system's highpass filter should be rolled up as high equally 300 to 400 Hz to avert sound going dorsum toward the stage as low frequencies become omnidirectional.

At that place are standalone speaker processors that provide output delays to configure distributed filibuster systems. Likewise, some digital mixers, like the PreSonus StudioLive series, offering delay on some or all outputs for precisely this purpose.

Delay systems should be placed where the master arrangement's intelligibility falls apart as information technology is overcome by environmental obstacles:

Inside. Indoors, yous are trying to overcome the direct-to-reverberant reflections. Your goal is to find where the direct point-to-reverberation ratio has reached almost fifty/50. At this signal, the reflections in the room are at an equal level to the straight audio of the P.A., and vocal intelligibility is lost.
Outside. Outdoors, you are trying to maintain level as the racket floor of the oversupply begins to exist at equal level to the P.A. in the intelligibility range. At this point, the primary system needs more support in order to deliver the same perceived loudness as y'all get further from the source.

Adding a Subwoofer (or Two)

Adding a subwoofer to your audio arrangement allows it to run more efficiently considering the low-frequency content is reproduced by the subwoofer instead of the full-range organisation. This section will guide you through the steps necessary to add a subwoofer so that yous get the most out of your investment.

Near subwoofers, including those made by PreSonus, provide throughputs to connect satellite full-range systems. Notwithstanding, in a large venue, it'due south recommended that you run your subwoofers on an output split from your main forepart-of-firm total-range loudspeakers. A postal service-fader aux mix output is ideally suited for this every bit information technology provides independent level control over the subwoofer arrangement and greater flexibility over the bass content in your mix, while withal following the master mix mutes. Creating an aux mix for your subwoofer system is merely like creating an aux mix for a floor monitor simply instead of creating a mix for a musician, yous volition be creating a mix using instruments that provide sub-free energy content. Some other advantage of using an aux mix is that if, for example, y'all want the boot drum to punch louder in the subwoofer, you can raise its level in the subwoofer just. It is also recommended that you run your subwoofer system in mono, even if your total-range organization is in stereo. For information on creating an aux-fed subwoofer mix, please review this article.

Setting the Crossover

When adding a subwoofer to your full-range system, you volition also need a crossover. This external device provides a highpass filter for full-range loudspeakers to remove sound content beneath a specified frequency, besides equally a lowpass filter for subwoofers that removes sound content above a specified frequency. Depending on the organisation, leaving a frequency content overlap between 60 to 120 Hz in your full-range loudspeakers and subwoofer can introduce destructive cancellation and reinforcement. Using a crossover will eliminate this frequency overlap and assist you to create a more seamless transition with your subwoofer. Almost external crossovers are fully variable, assuasive you to create a smooth transition from your subwoofer system into your full-range system.

Many full-range loudspeakers, including PreSonus StudioLive AI-series and ULT-series loudspeakers, help to mitigate this issue by including a 100 Hz highpass filter. Some subwoofers, like the PreSonus ULT18, AIR15s, and AIR18s, are equipped with a variable lowpass filter, allowing y'all to punch in the all-time crossover point for your system. In this fashion, you can set the upper end of your subwoofer at the everyman frequency point that your total-range system tin can reliably reproduce. PreSonus AIR-series subwoofers make this fifty-fifty easier by providing lowpass filter presets optimized for each AIR-series total-range speaker. For instance, if you lot are using an AIR15s subwoofer with an AIR10 full-range speaker, enabling the AIR10 lowpass filter preset will correctly set the AIR15s lowpass filter for use with the AIR10.

To set the crossover transition between your subwoofers and your full-range system:

Set the subwoofer's lowpass filter to its highest cutoff frequency. This will create an overlap between your subwoofers and your full-range system's frequency response.
Play program music with a lot of bass through your full system.
Experiment with the polarity setting on your subwoofer to see which position provides the all-time bass response. Leave the polarity in the position that provided the loudest bass response. This means that your subwoofer is in stage with your total-range speaker.
From this signal, you tin can experiment with the lowpass and highpass filter settings until you notice the one that provides the smoothest crossover transition. Once more, your subwoofer should naturally extend the depression-frequency response of your full-range system. You lot should non hear whatsoever frequency boosts or cuts.

Once your crossover network is properly calibrated, heed to a wide diversity of your favorite music and make any final adjustments. At the end of the day, your ears are the best tools you take.

Sub Alignment

When your subwoofer and your full-range loudspeaker are placed some altitude apart, depression-frequency counterfoil or reinforcement can occur when the same frequencies are reproduced by both systems. Using an alignment delay on your subwoofer system will recoup for this. To gear up the correct delay for a custom installation, you will demand to do some calculating:

Find the spot in the room where coverage from the main speakers and the subwoofers overlap.

Measure the distance in feet from the overlap area to each speaker location.
Subtract the smaller altitude (the distance to the subwoofer) from the larger distance (the distance to the full-range loudspeaker).
Carve up that number by 1.13 and apply that delay value to the subwoofer. Go along in heed that the overlap area may be behind front-of-house.

Fifty-fifty for mobile applications, where the subwoofer is relatively close to the full-range loudspeakers, aligning the subwoofer to its full-range companion volition yield tighter bass response. Both PreSonus AIR-serial and CDL18s subwoofers feature a variable alignment delay to guarantee that your three- and four-style systems stay in alignment.

Sub-pole Mounted. When your full-range speaker is mounted straight atop your subwoofer, no delay is necessary.

Tripod Mounted. When the subwoofer is about three feet from the full-range loudspeaker—a typical distance when the loudspeaker is on an adjacent tripod stand— delay your subwoofer by 2.7 ms.

Total-range Onstage. When the full-range loudspeaker is on stage and the subwoofer is on the flooring, the typical altitude is around six feet. Filibuster your subwoofer by 5.iii ms.

Subwoofer Arrays

Nearly subwoofers are substantially omnidirectional. This means that they radiate sound around the entire cabinet, including on the stage. In addition to causing feedback onstage, subwoofer energy can brand monitoring more hard because information technology overwhelms the frequency content performers demand to hear. When two subwoofers are arranged on each side of the stage, in that location tin can be a build-up of energy, resulting in a "power alley," as energy from each subwoofer arrives at the same time and in stage with one another, summing together. Unfortunately, moving left or right of this center summation, one will find cancellation alleys.

Creating a cardioid subwoofer assortment forms a more than directional radiations pattern that keeps energy off of the stage and in the audition, where it is needed.

Ground-stacked Cardioid Array. For smaller spaces, creating a ground-stacked cardioid assortment is an easy way to focus the subwoofer onto the audience. This blazon of array is created past stacking two subwoofers, 1 on top of the other, with the pinnacle subwoofer facing abroad from the audience and toward the phase.

You lot will demand to polarity-invert the cabinet that faces abroad from the audition and delay information technology by the depth of the subwoofer. The AIR15s, and AIR18s subwoofers make this like shooting fish in a barrel by providing presets to create a ground-stacked cardioid assortment.

Once configured, your two subwoofers will radiate in a directional cardioid blueprint, assuasive yous greater steering command over depression-frequency energy.

Endfire Cardioid Array. An end-burn down array is created when subwoofers are placed in a row so that they are driving sound along the same axis. This focuses the audio in the management the front speaker is facing. Cease-fire cardioid subwoofer arrays provide approximately 20 dB more counterfoil behind the array than a basis-stacked array, so they will straight the virtually subwoofer energy away from stage.

Finish-burn arrays can be very tricky to create, because each subwoofer requires its own delay only must use the aforementioned polarity every bit the other subwoofers in the assortment. Both the AIR15s and AIR18s make this quick and like shooting fish in a barrel by providing a preset. The CDL18s provides all the tools necessary to create an cease-fire array with 2 or more subwoofers.

If yous delay your subwoofer array relative to your full-range systems, be sure to ready the same relative filibuster time on every subwoofer in the assortment.

System Configuration Suggestions

This department describes some mutual system configurations. The size and shape of your room as well as your application will determine how many speakers you will need and where they should be placed. In whatever front-of-house situation, it's important to ensure that the horn of your full-range loudspeaker is placed then that it is in a higher place the heads of your audience. In large venues, this will require suspending your loudspeakers from the ceiling or trussing.

Please notation: Suspending loudspeakers should only be done by a licensed and insured professional person who can ensure that all rubber precautions and edifice codes are followed.

Stereo System. A stereo system allows panning and adds depth to the audio-visual paradigm. Considering of this, information technology greatly enhances live or pre-recorded music. Locate speakers to requite the best horizontal coverage. This will ensure that the listeners are well covered past the design.

Mono Cluster with Down Fill. Center or mono systems can provide a uncomplicated, economical solution for venues where speech intelligibility is the priority, rather than music. Every bit with a stereo system, brand sure the coverage pattern of the speaker focuses the energy on the audience.

The graphic beneath, shows ii speakers. The upper speaker is throwing to the dorsum of the room, and the lower speaker covers the space in the front of the room, closest to the stage.

LCR Systems. An LCR organization is a stereo system with a center speaker added. This configuration allows panning and adds depth to the audio-visual image. This blazon of system volition provide more control than a basic stereo organization and is platonic in situations where music and speech intelligibility are as important.

Distributed Delay System. The goal in a complicated system with loudspeakers distributed throughout the venue is to delay each satellite system relative to its counterpart in the primary arrangement (eastward.thou., the left front make full to the left FOH loudspeaker).

Delay the chief system relative to the source on stage. On small-scale stages where the guitar amp and drum kit tin be clearly heard above the FOH loudspeaker system, delaying the chief organization tin can "movement upwardly" the backline so that it aligns with these instruments and decreases blurring in the mix. This will tighten the overall mix and give it more than punch.
Delay the front fills relative to the primary system past delaying each side of the organisation independently (e.g., delay the left front fill relative to the left FOH loudspeaker).
Filibuster subwoofers relative to the main organisation. How you do this volition depend on how your subwoofer system is positioned and configured. In general, yous volition want to delay each subwoofer relative to the full-range loudspeaker closest to information technology.
Delay down-fill speakers (upper and under balustrade) relative to the main system, again delaying each side of the organization independently.

Stage Monitor Systems

Below are two examples of typical stage-monitor layouts. For musicians (such as a vocalizer) who don't crave a lot of low-frequency free energy in their flooring wedge, nosotros suggest using a 10" or 12" loudspeaker. On larger stages, stereo monitors will provide better clarity at a lower volume. For musicians that need a picayune more than bass, a fifteen" loudspeaker may be preferable. For the drum monitor on a large stage, it is useful to apply a full-range, three-manner organization (fifteen" loudspeaker atop a subwoofer). For smaller stages, a 15" loudspeaker atop a depression tripod or in the horizontal floor-wedge position will be more than adequate.

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Calibrating Full-Range Systems

After yous have positioned your loudspeakers, it is helpful to set up all the levels in the P.A. system so that every component is optimized. While not essential, taking the time to properly calibrate your speakers will give yous a great starting point to both troubleshoot and fine-melody your listening environs.

Speaker calibration ensures that a specific metered signal level on your mixer equals a predetermined SPL at front-of-house. Depending upon the method and reference levels used during calibration, proper calibration can assist reduce unwanted racket, minimize the chance of harm to loudspeakers and to your ears, and ensure you hear the audio as accurately as possible.

There are many methods for calibrating a loudspeaker organisation. The important thing is non the fashion you lot calibrate your environment but that your surround has been calibrated—even if you lot simply use your ears, common sense, and your favorite recording.

You should calibrate the correct and left loudspeakers independently to ensure that both are set to the same acoustic level. This will ensure that your speakers are counterbalanced and that the audition will have the same listening feel wherever they are in the venue.

Calibrating Using a "Standard" Reference

Standard reference scale is one of the most common calibration methods because information technology is the least subjective. The goal of this method is to ensure that when the output meters on the mixer register 0 dB, the SPL in the audience is a specified decibel level.

This level will vary depending on your application:

Acoustic (folk, spoken give-and-take, etc.): 75 to xc dB
Jazz: lxxx to 95 dB
Classical: 100 dB
Modern house of worship: xc to 95 dB
Electrical (stone, land, R&B): 95 to 110 dB

This department will take you through the basics of standard-reference calibration. Calibrating speakers requires both an SPL meter and pinkish noise. Both signal noise generator and SPL meter apps are available for iOS® and Android™, many for free.

Connect the main outputs of your mixer to your loudspeakers.
Set the level on your loudspeakers to their everyman setting.
Ready the principal mix level on your mixer to the everyman setting.

Annotation: If you have whatsoever outboard processors (EQs, limiter, etc.) connected between the mixer and your loudspeakers, disconnect or bypass them. If your mixer has onboard processing, brand sure that it is zeroed out or bypassed.

Play 20 Hz to 20 kHz full-bandwidth pinkish noise at 0 dB through the master outputs of your mixer.
Turn up the main mix to unity gain. Unity gain is the setting at which the signal level is neither additional nor attenuated. It is normally marked by a "0" or a "U" on the mixer. You should not hear the pinkish dissonance. If yous exercise, repeat step 2.
Begin slowly increasing the volume of your left speaker until the sound pressure level of the pink noise reaches 3 dB below your desired SPL in the center of the room. When both speakers play simultaneously, the overall SPL will increment by almost
+3 dB.
Power down your left speaker.
Slowly increase the book of your right speaker until the acoustic level of the test tone playing reaches the same SPL as the level attack your left speaker.
End the pink noise and turn your left speaker back on. Play some plan music you are familiar with through your speakers and motility throughout the room, making sure that your speakers audio counterbalanced.

If you are using a subwoofer, follow the same steps as above, but set up the level on the subwoofer 6 dB less than the level you lot set on your full-range loudspeakers (that is, if you set up the level on each loudspeaker to 95 dB, ready the subwoofer level to 89 dB).

Ringing Out Monitors

Feedback is brusk term for a feedback loop, where a portion of the signal from the speaker returns to the microphone, resulting in a constant tone at the offending frequency. "Ringing out" is a process of attenuating the frequencies that are feeding back to maximize proceeds before feedback in your flooring monitors.

Note: Ringing out stage monitors will produce feedback. If you are not careful, you lot can produce a lot of feedback. Do not make sudden proceeds boosts; go slowly and advisedly to avoid causing damage to speakers and ears.

With the mic input gain at an appropriate level, bring the aux transport level up on the mic aqueduct y'all wish to ring. Do not "proceeds upward" the mic indicate on the monitor mixer for the sake of getting more volume out of a stage monitor. Gain staging is very of import in order to have a feedback-gratuitous show.
Slowly bring the aux output level up until you hear feedback.
Using a real-time analyzer (RTA) or spectrograph volition permit y'all to see which frequency is causing the problem and use an blaster to remove the offender from your stage monitor. If you don't take an RTA or spectrograph, you lot can create a narrow notch in a parametric EQ and sweep it across the band until the feedback is removed. Stage-monitor feedback typically occurs in the college frequencies, which too is where intelligibility comes from, so but reduce the offending frequency to just below the point of feedback.

If you do not have these tools at your disposal, bring back the level on the channel transport to simply before the indicate of feedback and then you don't take out too much signal content. Maximizing your intelligibility and gain structure results in clearer-sounding monitors.

When yous are ringing out a system, and more than than two or three feedback loops are happening simultaneously, you have reached the level where stability can no longer be achieved. Attempt bringing downwardly the overall output level or find a physical solution, such as moving the speaker or microphone.