Low frequency audio reproduction is a necessity for any type of audio playback. If you were to attend a concert and there was no subwoofer, what would you make a comment about? Most people would say that the music was lacking in a certain area. In professional live sound for a large event, like Battle of the Bands that takes place in a typical gymmnasium, you would need loudspeakers that are dedicated to only low frequency audio reproduction for a more full sound. David Susilo, a certified THX1 instructor and designer, said that “deep bass adds the emotion, the physical feeling of presence and excitement, to a good music or movie performance.” In order to achieve this effect in professional live sound, you need a powerful subwoofer2.
Subwoofers for professional live sound come in many shapes and sizes depending on who is making them and what size woofers are being used. There are many companies that build, market, and sell subwoofers for professional live sound. The typical contenders people know of are JBL and Bose. They both put out phenomenal subwoofers for decent prices. However, there is a third candidate that gets overlooked: Danley. They are a company based out of Gainesville, Georgia and they likewise make phenomenal subwoofers.
In regards to sound reproduction for large events, like the aforementioned Battle of the Bands, Bose uses smaller woofers while Danley and JBL typically use 18” woofers. Bose has their F1 Subwoofer that uses 10” woofers (“F1 Subwoofer) while JBL has their SRX828SP model (“SRX828SP”) and Danley has their DBH218 (“The DBH218”). Both the SRX828SP and DBH218 use 18” drivers and because of this, they are gargantuan in comparison to the F1 Subwoofer.
The F1 Subwoofer is 0.4 meters wide, 0.44 meters deep, 0.68 meters tall, and weighs 25kg. The SRX828SP is 1.2 meters wide, 0.68 meters deep, 0.57 meters tall, and weighs 65.9kg. The DBH218 is 1.1 meters wide, 1.1 meters deep, 0.57 meters tall, and weighs 125.6kg. The DBH218 is a pumice boulder compared to the rest but is surprisingly easy to move given the caster dolly. However, the Bose is definitely the lightest and easiest to move.
Each of them provide products that compete with each other and each of them advertise their products as capable of adding deep bass for professional live sound events. Bose’s F1 Subwoofer is advertised as a subwoofer with “1,000 watts of power packing all the performance of a larger bass box into a more compact design that’s lighter and easier to carry.” (“F1 Subwoofer”). Despite its vitriolic comparison with larger bass boxes, it performs quite admirably.
In general, for a subwoofer to have prolific sound reproduction, it must have a wide spectrum of low frequency reproduction. According to Jeff Berryman of ProSoundWeb, an
appropriate performance specification for a first-class concert woofer would be from 43-120hz ± 3dB. The Bose F1 subwoofer performance specification is 40-100hz ± 3dB, so it does meet that requirement. However, even with its 2 10” drivers, its peak sound pressure level is 130dB at 1 meter. This is unfortunately abysmal for professional live sound, but even still, peaks don’t show us the entire picture. “In reality, peak power ratings are not a realistic measure of a products true power capability.” (Peak Power vs. RMS). Fortunately, by using the peak, we can find out roughly what the continuous output of the F1 Subwoofer is.
Double, or twice the power, means 6dB more sound pressure level (“Sound Pressure”). Program power is half of the power of peak power and the root mean square power is half of the program power3. So if the peak of the F1 is 1000 watts per individual 10” woofer then, when both woofers are operating, it should be an average of 124dB at their program power of 500 watts and 118dB at their root mean square power of 250 watts. This means it will be 118dB at 1 meter during normal, continuous, operation. Unfortunately for Bose, this is paltry performance for a professional live sound event.
In regards to professional live sound, you will want a significantly high continuous sound pressure level. This is because sound pressure levels decrease by approximately 6dB as you double the distance (“Sound Pressure”). This means that at 2 meters the maximum continuous sound pressure level from the Bose F1 will be 112dB and at 4 meters it will 106dB, provided nothing is blocking the sound from navigating through the crowd. Referencing our Battle of the Bands example again, the average gymnasium is generally 33.5 meters at its longest length. This means if you were using the F1 in a gym, length wise, it would be around 88dB at the farthest distance. If no one was in the gym, this would be acceptable but have you ever been in a gymnasium filled with people? Their constant noise further diminishes the sound.
Tao Jiang, a mathematician who researched noise levels in gymnasiums, placed dosimeters on teachers to record actual amounts of noise during class. He found that the ranged between 90.8dB and 106.41dB. Now that was just gym class, at the gym’s maximum capacity we are looking for at least 106dB at the longest length of 33.5 meters. The F1 subwoofer would not properly provide sound reproduction for the entire gym but there are still more options.
The JBL SRX828SP is one such subwoofer that would be a better choice over the Bose F1 for both sound pressure level and performance specification. It is 35-120hz ± 3dB with a peak of 135dB at 1 meter (“SRX 828SP”). This means that it goes 5hz lower than the Bose F1 while similarly getting 5dB louder at its peak sound pressure level. Trickling back down using the math presented earlier, at 1 meter the SRX828SP puts out, on average, 123dB at its root mean square and 129dB at its program. These numbers tell us that it will be 5dB louder than the Bose F1 in every situation.
If you placed an SRX828SP in a gymnasium, using its longest length wise, it would be around 93dB at the farthest distance. As you can see, these numbers are slowly getting larger and more usable. It is a 5dB increase and, according to Acoustics By Design, this is a noticeable change in volume to the human ear. A 3dB increase is the first, barely noticeable, change in sound to the human ear. While a 5dB will be a significantly noticeable increase and a 10dB increase will sound twice as loud (“Perception Vs. Reality”).
The SRX828SP will be noticeable louder than the Bose F1 in a gym setting. This proves that Bose’s claim of matching a larger bass box in a smaller platform is false in this scenario. However, 93dB is still not loud enough. The ideal decibel would still be somewhere around 106dB to at least match the maximum noise of a gym class. The only option left on our list, to meet the 106dB requirement for our Battle of the Bands example, is the Danley DBH218.
Now, there is a difference between the DBH218 and the SRX828SP. The SRX828SP is a bass reflex cabinet (“SRX828SP”) and the DBH218 is a bass horn cabinet (“The DBH218”). This basically means that the SRX828SP is a front firing subwoofer while the DBH218 follows a path that artificially amplifies the sound. They can both reproduce adequate frequency ranges though. If you read the performance specifications of the DBH218, you will find that the DBH218 is 34-300hz ± 3dB with a peak of 147dB (“The DBH218”).
Right from the start you can tell that the DBH218 will be significantly louder than the SRX828SP, but how much louder? Well, if you apply the same math to the DBH218 as I did to the F1 and SRX828SP, then you will find that the DBH218 will put out, at 1 meter, roughly 141dB at its program power and roughly 135dB at its root mean square. By looking over the numbers, you can tell that the DBH218 puts out, continuously, the same sound pressure level as the SRX828SP’s peak.
In a gym, this subwoofer would put out roughly 108dB from 33.5 meters away. This is enough to properly provide professional live sound for a typical Battle of the Bands that takes place in a gymnasium. It would be louder than the maximum noise level of a gym class and, therefore, be able to be heard throughout the gym without a problem even with excessive background noise being put out by the guests in attendance.
If you were given an option or opportunity to provide sound for a gymnasium, only the DBH218 could adequately provide for your needs by itself. You would need multiples of the other subwoofers in order to equal the power of a single DBH218. So it is fair to say that the DBH218 would be the best choice for a professional live sound dependent event. However, with the information provided regarding subwoofer’s and their performance, one can properly dissect any subwoofer and properly make a claim on how it will perform inside a gymnasium.
THX is a quality assurance company that provides certifications to competent audio setups that are capable of reproducing the audio as the original creator intended it to be heard.
Powerful subwoofer implies higher sensitivity. The sensitivity of a loudspeaker matters significantly more than how much wattage it can handle. However, by using the wattage and peak sound pressure level one can work backwards to derive the sensitivity of a loudspeaker, which is typically measured with 1 watt at 1 meter. It can likewise derive the root mean square and program output.
Program power has come to be known, by people within audio, as a doubling of the root mean square power. In truth peak is 4x the root mean square. However, to make it easier to understand, it has been separated into doubling, because a speaker can, typically, take double the root mean square and be fine, but it’s not recommended for extended use, due to potential voice coil overheating.
In order to understand certain aspects of professional sound, one must understand why these aspects are important. For my situation I needed a reason why a subwoofer is required. David Susilo is a certified THX instructor and designer. This means that he has a great deal of knowledge regarding the necessity for the entire spectrum of sound to be reproduced, including the deep bass that subwoofers provide.
“F1 Subwoofer.” Bose Corporation, Bose Corporation, www.bose.com/en_us/products/speakers/speaker_accessories/F1-subwoofer.html. Accessed 6 Mar. 2017.
It is always welcome when using a familiar brand that almost everyone knows. Bose is a world renowned company for their home theater setups. While their professional live sound speakers are lacking, they provide a nice starting point for the discussion. It must be made clear that when using this source, I am not referring to their home audio capabilities. I am only referring to their professional live sound capabilities. They do provide great products in both areas though, they just don’t get loud enough for large events.
“SRX828SP.” JBLPRO, Harman International Industries, http://www.jblpro.com/www/products/portable-market/srx800-series/srx828sp. Accessed 6 Mar. 2017.
There are many choices of middle ground subwoofers before you hit line array subwoofers, I have chosen to go with somewhat familiar products. JBL is commonly known brand since their parent company, Harman, owns many different audio brands e.g Infinity, Crown, and AKG. Generally, most people know about JBL and they are heavily used within all levels of audio reproduction. Their SRX828SP subwoofer is a newer model that has not yet attracted as much attention. By using the SRX828SP as an example, it can expand upon the previous models that use similar drivers, like the previous SRX728. Owners of the SRX728 can take my research and contrast the SRX728 with the SRX828SP.
“The DBH218.” Danley Sound Labs, Danley Sound Labs, www.danleysoundlabs.com/products/subwoofers/dbh/dbh218/. Accessed 6 Mar. 2017.
Generally, Danley is an unknown company. I have chosen to use their product as a source because it is one that not many are aware that it even exists. The familiar contenders for professional live sound would be JBL, Bose, Electro Voice, RCF, Yamaha, Peavey, L’Acoustics, Cerwin Vega, and Mackie. By introducing an unknown company, I can shed light on products that most people might not be aware of but provide exceptional sound pressure levels. Other options I thought of before choosing Danley were Funktion One, Meyer, and Bassboss. However, from my limited research, I found that the DBH218 was the loudest of the bunch.
Berryman, Jeff. “Build A (Great Sounding) Subwoofer Enclosure.” ProSoundWeb, 4 Apr. 2013, www.prosoundweb.com/topics/sound_reinforcement/building_a_big_woofer_enclosure/.
Prosoundweb.com is a website devoted to live audio reinforcement. The majority of their users are sound engineers with many years of experience. Jeff Berryman is no exception. His knowledge on sound reinforcement is unparalleled by lower tier sound providers. The average DJ will not know much about live sound reinforcement, so one must start looking in areas that audio engineers congregate. If someone spouts off a wrong opinion, they will be denied. It’s sort of similar to the scientific method and assures all readers that their information is spot on.
“Peak Power vs. RMS Power.” Sonic Electronix, 14 Oct. 2010, knowledge.sonicelectronix.com/car-audio-and-video/car-subwoofers/peak-power-vs-rms-power/.
Most people in audio are aware of peak, program, and root mean square power, however, the average reader is not. I have selected an average website to support this information in case any readers are curious as to why peak does not matter as much. The average DJ or sound engineer knows that the peak can only be sustained for a matter of seconds, if not less. Therefore, the peak is not a good representation of the real world performance you will get.
“Sound Pressure p and the Distance r.” Sengpiel Audio, www.sengpielaudio.com/calculator- SoundAndDistance.htm. Accessed 6 Mar. 2017.
Similar to the last citation, this citation provides the mathematics used within this report. They support and prove my statements as true. The reader can likewise use this source to find out the exact formula to calculate sound pressure level in regards to voltage or wattage. They also have built in calculators to double check the math, which I used. This source has significant usage in professional live audio and is quite helpful.
Jiang, Tao. “Can Noise Levels at School Gymnasia Cause Hearing Loss: A Case Study of a Physical Education Teacher.” Acoustical Society of America 133rd Meeting, 17 June 1997, State College, Pennsylvania, Penn State Conference Center, Acoustics, acoustics.org/pressroom/httpdocs/133rd/2paaa7.html. Accessed 6 Mar. 2017.
Some might claim that this sources validity is lessened by the research done regarding hearing loss, however, the data within the research is the only thing that is relevant in a comparison of subwoofers for professional live sound usage. Tao is a brilliant researcher who provides excellent data regarding the sound pressure levels in a gymnasium. If you want your subwoofer to be heard, it will have to louder than his data.
“Perception Vs. Reality: What Our Ears Hear.” Acoustics By Design, 12 Dec. 2008, http://www.acousticsbydesign.com/acoustics-blog/perception-vs-reality.htm
Perception Vs. Reality is yet another source that is only used as reference and support for my statement. Their research shows that dB increases are not as audible to the ear as one might think. Acoustics by Design provides sound reinforcement support for architectural design. Knowing the dB increase that are noticeable to the ear is significantly important for achieving a high sound pressure level. They also provide a good contrast between the subwoofers I have chosen.