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Welcome to the August edition of the Danley Newsletter. Do you love a mystery? Check out Professor Doug Jones' column! Danley's own Ivan Beaver begins a new series called "Ivan's Audio 101." Read about a new SBH install in New Jersey. Need specs on the brand new J7? Follow the link below. Other important information is included here, so take a minute and read through to the end. Enjoy!
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Danley's newest Jericho: The J7
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The J7 created a huge buzz during InfoComm '19 in Orlando. The spec sheet is now available. Follow the link to see what all the fuss is about.
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This was the second year that Danley Sound Labs sponsored an English camp in the town of Malcoci, Moldova. Over 80 children and 15 adults participated in the camp, which was designed to help them learn conversational English. The Danley part of the team included Mike and Anita Hedden, Cooper Hedden and Jeff Pulliam. The rest of the team was from First Baptist Church, Lawrenceville, Georgia. Students arrived at the local school each day and spent the morning in one of three classes, which were divided based upon English speaking ability. Lunch was then served to participants, followed by recreation time at the local football field. An adult group met in the afternoons at a local church. Overall, it was a great week and we are already looking forward to next year!
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Venue Spotlight - St. Leo The Great Church
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St. Leo the Great Church was established in Lincroft, New Jersey over sixty years ago during the area’s suburban boom of the late 1950s. Its beautiful sanctuary seats approximately 800 people but provides tough acoustics for intelligibility, a problem that had previously been dealt unsatisfactorily with several lines of delay loudspeakers. Recently, local AV integration firm Concept Professional Systems designed and installed a beautifully simple new sound reinforcement system at St. Leo the Great Church. Ditching the delays and relying on Danley Sound Labs’ famous pattern control and phase-coherent, long distance throw, the church now enjoys intelligible speech and lively music reinforcement from the front pew to the back pew.
“We originally got involved at St. Leo the Great when they called us to service their old system,” explained Don Gspann, owner of Concept Professional Systems. “After several years, the old system fell into disrepair to the point that everyone agreed that it was time to start fresh. The space it-self is quite reverberant. The walls are all block, the floor is linoleum, and the ceiling is wooden and shallow. That’s a tough situation. We had had great success with Danley SBH10 column-form loudspeakers at St. Paul’s Ocean Grove Church, another Catholic Church in the area. In fact, that system sounded so fantastic that we kept inviting industry friends just to come check it out. It was easy to imagine that the Danley SBH10s would work a similar miracle at St. Leo the Great.”
For proof of concept, Gspann arranged to bring in a pair of Danley’s SBH 10’s and the smaller SBH20 column-form loudspeakers for a demo. Like the SBH10 and all of Danley’s Synergy Horn loudspeakers, the SBH20 is a true phase-coherent, point-source design. “Everyone was thrilled with the clarity from the front to the back,” Gspann said. “The demo is really what sold the job.”
We were a little concerned about where the speakers would be located permanently, in relation to the pulpit and lectern mics, as well as all of the musical elements – piano, choir & orchestra – which are located on the floor in front of the chancel and thus in front of the Danley SBH10s! The musical elements were eventually going to be reinforced during phase two of the project, with other Danley loudspeakers. Fortunately, or unfortunately, the same Danley phase coherence that led to better-than-expected gain-before-feedback in the demo also helps out with the odd arrangement in the permanent installation. “They’re still able to reinforce those instruments without trouble,” Gspann said.
The Danley SBH10 has the perfect coverage pattern: 140 degrees horizontal but only 10 degrees vertical, perfect for hitting ear drums but avoiding ceilings and walls. In addition, a pair of SBH10s could cover the entire sanctuary, making the installation to either side of the chancel relatively easy. A BSS Blu-100 DSP system also serves as a behind-the-scenes mixer, and Crown XTi amplifiers power the system.
We went to the first service, dialed things in, and switched out the Father’s lectern mic to something that better matched his assertive mic technique noted Gspann. Everyone is thrilled with the sound, especially the clarity of the all the spoken word. It doesn’t matter where you sit in the sanctuary; it’s all clear and intelligible.”
Concluded Joe Manzi, director of finance, operations and development, “The system was a godsend. We had many years of poor communication during our worship services. People were constantly complaining of hearing no sound or the sound was too noisy. This new system allows for uniform distribution of sound throughout the church and in the entranceway. Lectors do not have to scream into the microphones and can deliver God’s word in a calm manner. We have received many compliments about the system and people comment that it is a joy to worship at Saint Leo’s.”
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This is the first in a series of articles that will cover what should be considered “basic audio.” An audio guy needs to grasp these concepts and hopefully remember them. We will not try to have a Ph.D.- level discussion, but rather just cover the basics of each topic.
We'll begin with the Inverse Square Law.
The “quick definition” of the inverse square law is: for every doubling or halving of the distance from a sound source, the level will change (decrease or increase) by 6dB.
The formula for the dB change between two distances from a source is: dB change=20 log D1/D2 where D represents distance.
This is a basic law that not only applies to audio, but to any “energy field” that is expanding. This expansion is both horizontal and vertical.
In a nutshell, the Inverse Square Law means that as you move away from or towards the source of energy (in our case a loudspeaker that is modulating air pressure), for every doubling or halving of distance, the energy changes by a factor of 4. In the case of audio, this pressure difference is measured in dB. A factor of 4 in pressure change is 6dB. This dB change remains constant (assuming no other losses, which do, in fact, exist, such as air absorption vs frequency).
So the dB difference between 1 and 2 meters is the same dB difference as between 300 and 600 meters. Even though the actual distance (in meters) has changed, the RELATIVE distance is still 2:1. So there will be a 6dB difference in each case. Think of it this way: if you are close to a loudspeaker, a change of a couple of meters will result in a dramatic SPL change. But if you are a couple of hundred meters away, moving 10 or 20 meters is not going to change the SPL level enough to easily notice.
There are exceptions that must be taken into account, such as the size of the source vs. the distances as well as the actual origin of the source of sound. Both of these can skew the numbers quite a bit if not properly accounted for. The formula “assumes” an infinitely small source that is the origin of the sound.
As a “general rule”, you should be 10x the distance of the largest dimension of the front of the loudspeaker in order for the inverse square law to be accurate. In the case of a number of Danley Sound Labs products, both of these factors come into play. Some of the cabinets (specifically the Jerichos) are quite large, so you need to be a good distance away. Also, the apparent acoustical origin can be a couple of meters behind the cabinet. In the case of the SBH10, this origin is roughly 9 meters behind the cabinet. So, if you are using an SPL meter and these factors are not taken into account, you can end up with false readings related to the changes in distance.
The important thing to realize is where the difference in distance matters most: that is close to the source of sound.
dBspl is an absolute value, while simple dB is the amount of change, with no reference. As with other aspects of audio, it is best to think in terms of dB instead of absolute value. For example, don’t get hung up on the actual physical distance, but rather focus on the dB difference. |
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Professor Jones is messing with us a bit this month. If you can figure out the MOM, email us with your guess. Contributors of correct answers will be entered in a drawing for an RTIC 18 oz Danley bottle, autographed by Tom Danley. Be sure to read next month's newsletter for the correct answer and the winner.
MOM - AUGUST
Professor Doug Jones
This month I’m going to do something a bit different. I’m going to write about MOM. No, not my dear sainted 89-year-old Mother, but rather a Man of Mystery, MOM! Instead of introducing you to MOM the way I have in the past, by sharing stories about his life and how he got to the place where his name, in most cases became a household word, I’m going to give you a list of the things this man accomplished, and a bit of background info and ask you to figure out who I’m writing about.
MOM lived in the early 20th century, and unlike most of our other subjects, MOM was very well educated, earning 3 degrees in science, including a PhD in physics. Here is a partial list of his patents. (The titles are from the patents… “patent-speak” can be a strange language!)
1 Device for Sound Pick-up (Ellipsoid Microphone, forerunner of the parabolic mic)
2 Apparatus for Converting Sound Vibrations into Electrical Variations (First Practical Ribbon Microphone)
3 System Responsive to The Energy Flow of Sound Waves (Pressure and Velocity detecting Sound Level Meter)
4 Sound Pick-Up Device (Unidirectional or Cardioid Microphone)
5 System for the Conversion and Transfer of Energy (Condenser Microphone Step-Up Transformer with A Remote Preamplifier.)
6 Acoustic Device (Loudspeaker Horn with improved acoustic coupling)
7 Loud Speaker and Method of Propagating Sound (Passive Radiator Loud Speaker)
8 Acoustic Device (Double Voice Coil Loudspeaker)
9 Electro-acoustical Device (Ribbon Telephone Microphone/Speaker)
10 Sound Reproducing Apparatus (Multi-Cellular Horn)
11 Acoustical Device (Small Portable Closed Back Ribbon Microphone)
12 Microphone (A ribbon microphone with dual ribbons)
13 Microphone and Circuit (Microphone Mixer: instead of mixing the output voltage, this device actually adjusts the microphone sensitivity)
14 Loud-Speaker (Hybrid Bass-Horn/Bass-Reflex Design)
15 Electro-acoustical Apparatus (Line Microphone "Shotgun Microphone")
16 Acoustical Apparatus (Improved Woofer Surround)
17 Signal Translating Apparatus (Multiple Co-Axial Loudspeaker Designs)
18 Electro-acoustical Apparatus (Design of the RCA 77 Ribbon Microphone)
19 Radio Remote Control System (A remote control using different frequencies of sound)
20 Signal Translating Apparatus (Underwater Submarine Microphone)
21 Magnetostrictive Signal Translating Apparatus (Rugged Submarine Microphone)
22 Signal Translating Apparatus (Submarine Pressure Compensated Speaker)
23 Signal Transmission and Receiving Apparatus (A Wireless Earphone system. For private listening to the radio, an ultrasonic transmitter is connected to the radio. A head worn receiver converts the ultrasonic signal to an audible one, powered by the ultrasonic wave!)
24 Air Suspension Loudspeaker (yet another improvement on the surround)
25 Synthetic Reverberation System (a primitive reverb system using tubes of various lengths with transducers at each end to create delays)
26 Diffraction Type Sound Absorber (a novel form of broadband absorber using perf board and “fibrous material”)
27 Diffraction Type Sound Absorber Covered by A Membrane (an improved version of 25)
28 Diffraction Type Sound Absorber with Complementary Fitting Portions (again an improvement to #25)
29 Diffraction Type Sound Absorber with Fiberglass Walls (Cylindrical version of #25)
30 Single Element, Unidirectional, Dynamic Microphone (A cardioid ribbon microphone with very good LF behavior)
31 Feedback Controller System for Recording Cutters and the Like (important element of a Phonograph Recording Lathe)
32 Directional Microphone (Coincident Pair of Ribbon Microphones with Horizontal Pattern Control)
33 Coaxial Dual-Unit Electrodynamic Loud-Speaker (Improved Version)
34 Transformerless Audio Output System (Tube Amplifier output section without a transformer)
35 Means for Improving the Sensitivity and The Response Characteristics of Velocity Microphones
36 Line Type Pressure Responsive Microphone (a small microphone which can be used on camera and not be obvious)
37 Velocity Type Microphone (a ribbon mic with an acoustic High Frequency Equalizer)
38 Suspension System for Dynamic Microphones
39 Distortion Analyzing Apparatus (Improvement over existing tools)
40 Second Order Gradient Directional Microphone (directional mic with 2 or more elements)
41 Portable Radio with A Bass-Reflex Cabinet
42 Noise Discrimination System
43 Cabinet for Sound Translating Apparatus (an improved loudspeaker enclosure with resonance damping)
44 Multi-section Acoustic Filter (Filtering Out Frequencies above 5,000 Hz)
45 Uniaxial Microphone (directional mic using a pressure gradient)
46 Noise Reduction System (a method of reducing noise in a tube amplifier by multiband processing)
47 Sound Translating Apparatus (adding a Second Speaker Inside the Cabinet)
48 Coaxial, Dual Unit, Electrodynamic Loud-Speaker (Improved Magnetic Structure)
49 Velocity Microphone (Improved Magnetic Structure)
50 Dynamic Microphone (Compact Design)
51 Unidirectional Microphone (Low Cost Ribbon Design)
52 Acoustical Resistance for Pressure Type Microphones (tuning cardioid microphones for optimum directional performance)
53 Methods of Restoring Phonograph Records (Re-synthesizing The Recording)
54 Transducer with Fluid Filled Diaphragm Suspension (another novel suspension system)
55 Loudspeaker Structure (Shaped Cone for High Frequency Pattern Control)
56 Combination Chassis and Loudspeaker
57 Directional Microphone (Using Two Microphone Elements to Increase Directivity)
58 Noise Discriminating System (a system for reducing high frequency noise in phonograph recording and playback systems)
59 Music Synthesizer (the first Electronic Synthesizer – utilizing 12 tone generators and numerous filters and envelope generators. Programed using punched paper tape)
60 Wide Range Dynamic Phonograph Pickup (a dramatic improvement on the phonograph cartridge)
61 Acoustic Apparatus (Improved acoustic labyrinth for use in cardioid microphones)
62 Signal Frequency Change Detector (a system for analyzing speech as a first step towards speech synthesis)
63 Vibration Control Apparatus (active vibration control)
64 Apparatus for Speech Analysis and Printer Control Mechanisms (a system to convert speech into typed output. An early version of speech to text.)
65 Electronic Sound Absorber (improved active noise cancellation)
66 Directional Electrostatic Microphone (an improved condenser mic)
67 Music Composing Machine (random number generator and method for “constraining the randomness” to produce music in a certain style)
68 Stereophonic Loudspeaker (an early attempt to create immersive stereo)
69 Voiced Sound Fundamental Frequency Detector (a device to determine the fundamental frequency of a spoken word)
70 Multi-groove Stereophonic Sound Recording and Reproducing System (a 4-channel system, LCR plus surround)
MOM is someone you may not know, but given his accomplishments, you really should!
One of his experiments, now considered a classic, determined the preferred bandwidth for the reproduction of music. Previous experimenters had found that listeners seemed to prefer a high-frequency cutoff of 5000 Hz for reproduced music. MOM carried out an experiment in which a small orchestra sat behind a visually opaque but acoustically transparent screen. The screen incorporated a concealed low-pass acoustical filter having an upper-frequency cutoff of 5000 Hz. This filter could be opened or closed, allowing either the full range of frequencies to pass or the range only below 5000 Hz. The listeners were asked to select their preference between two conditions: full bandwidth or restricted bandwidth. There was an overwhelming preference in favor of the full bandwidth. Next, the orchestra was replaced with a sound-reproduction system where the loudspeakers were located in the position of the orchestra, behind the screen. When the sound system was free of distortion, the listeners preferred the full bandwidth. But when he introduced small amounts of nonlinear distortion, the restricted bandwidth was preferred, thus demonstrating clearly the importance of high quality in audio systems.
Ok well, this may not be my most scintillating contribution (or maybe it is…?) but see if you can figure out who MOM is. If you do figure it out, remember his name! He made a huge contribution to the world of audio.
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