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Spring has sprung in Georgia!  Here at the Danley HQ we are enjoying warm weather, some nice spring showers and, of course, lots of pollen.  We hope spring will bring the reminder of new life to you in the coming weeks.  Join us this month as we announce the winner from last month's Tech Corner contest; introduce another team member of the month; and keep you up to date on Danley Sound Labs.
Featured Product of the Month:  SM80F

Danley is proud to premier another great, solution-driven product this month.  This cabinet is based on customer needs and recent feedback.

So, what do you do if you need a high power, full-range Danley speaker system, but have no room for subwoofers in your venue? Enter the new SM80F! The SM80F combines the high output high/mid frequency capability of the ever-popular SM80, with two extremely high output 15” woofers, which utilize tapped horn technology, to create one full-range high output cabinet!!! Using a similar concept that was utilized in creating the current SM100F, which houses the SM100 and one high output 15” tapped horn woofer section, the SM80F now gives our customers a much higher output option. For more details about specs and pricing, contact your local Danley sales representative.
Danley Sales Rep Retreat

For three days, February 27 – March 1, almost 20 of Danley's sales reps descended on Gainesville for the 2017 Rep Retreat.  Events included an overnight stay at a beautiful lodge, Skeeter Branch, near Lavonia, Georgia. A fantastic steak dinner was served along with lots of tales told 'round the campfire afterward. Those who wanted took part in a successful duck hunt the following morning. Then, we loaded up for a drive to North Carolina to tour our cabinet making facility. Wednesday was spent in training sessions in the Gainesville facilities and a lunch of pizza and duck poppers.  It was good to get to spend a few days with an important part of the Danley Sound Labs team. Thanks for coming Guys!

Team Member of the Month

This month’s Danley team member spotlight shines on Jay Andrews of Lienau AV (Mid Atlantic/NYC/Upstate NY/New England).  Jay covers Virginia, and often times beyond into Maryland, or wherever the Lienau AV team needs him.  Jay’s enthusiasm and knowledge has quickly made him an invaluable partner to many of our dealers. Recently, Jay rolled up his sleeves and assisted one of our dealers in an evening installation and system tuning session where his experience with our new line of amplifiers and DSP was put to good use. Like all Danley manufacturer’s reps, demoing the product line is an everyday occurrence.  Jay says, "It's really easy to promote something you believe in and it's easy to believe in something that demos so well." Jay is also adding a Danley rig to his personal inventory.  He will use it for weekend festivals where he enjoys mixing and providing quality reinforcement to the local Bluegrass community.
Amp Limiters
Amplifier DSP functions – Limiters 
By Josh Millward
As was discussed last month, the DNA series products are ideal for use with the Danley Sound Labs loudspeakers. However, the savvy operator can use the extensive palette of tools available in the DNA series products for far more than just the Danley Sound Labs loudspeakers. The DSP processing in the DNA series products can be used with any loudspeakers to provide processing and network control.  Last month the linear phase LIR crossover filter was discussed, this month the topic is limiters. 
The DNA series products all offer a very extensive suite of limiters. There is an RMS and peak limiter (VX Limiter), a thermal limiter (tmax Limiter), and an excursion limiter (xmax Limiter). 

VX Limiter
The VX Limiter is an RMS and peak limiter setup that allows the operator to set the RMS limit threshold and then specify how many dB beyond that threshold the peak limiter is engaged. There is another feature in the limiter whereby it is possible to set different thresholds for different parts of the passband. Considering the case of a basic two-way loudspeaker, the woofer is typically capable of considerably more power handling than the compression driver. It is possible to set a crossover frequency and adjust the limiter for the compression driver separately from the woofer. Also, the peak limiter may be adjusted separately. Clearly, this makes for an extremely powerful limiter configuration on its own, but there is more!
tmax Limiter
The thermal limiter is set as a continuous voltage that the loudspeaker or driver is capable of sustaining. The attack and release times can be adjusted to suit the application. This allows an additional layer of thermal protection beyond the already extensive limiters discussed above. 
xmax Limiter
The excursion limiter offers a method of limiting the excursion of the loudspeaker drivers. A frequency is selected and a voltage level is selected. Then, any signal that exceeds the prescribed voltage below the prescribed frequency is limited. This is an amazing feature that is capable of limiting excessive excursion in subwoofers when the DJ’s hit the system with their low frequency oscillators and attempt to turn the subwoofer drivers inside out. With these limiters in place, the subwoofers will live to play another day. 
When used together, all of these limiting methods provide a very comprehensive suite of management and control. There has been a significant effort put into setting up the limiters in the factory presets for the Danley Sound Labs loudspeakers. This is an effort to ensure that they will always operate with the highest degree of reliability. However, these tools are all available to anyone who would like to use them with loudspeakers of their own design or loudspeakers from other manufacturers. When used with the other DSP tools available in the DNA line up, fantastic reliability and unparalleled sound quality can result. 
The current version of PodWare is 6.24.04. This version is available for download from our website:
The current version of firmware for the DNA 10K4 Pro and DNA 20K4 Pro amplifiers is 1.238.
The current version of firmware for the DNA SC48 is 1.364.
Loudspeaker Master Preset Stack version is 20161020
The firmware and loudspeaker presets are included in the PodWare download zip file for PodWare 6.24.04.
Tech Topic Winner

Remember last month's Tech Corner?  Professor Doug Jones asked a question and promised a prize to a random correct answer.  We are happy to announce that reader Brent Schmelzle of Florida was drawn from the correct answers and will be receiving some cool Danley swag.  Congratulations Brent and thanks to everyone who took the time to answer the question. 

Here's Doug Jones' official, correct answer:  "The correct answer was that Volt meters, like everything in audio, have a frequency response.  It is easy and cheap to build a meter that will read accurately at a narrow range of frequencies. Meters that indicate true RMS at any frequency or waveform are generally quite expensive. Since  60 Hz is the frequency used in the US power grid, it is likely that a cheap VOM will be designed to be accurate at 60 Hz. We wanted to use a tool that was readily available and inexpensive yet accurate enough to do the job.”
Phrequency, Phase and Philters

Prophessor Doug Jones

This month, I’m going to try to explain some of the most fundamental aspects of audio.  This is part one of a two-part series that will culminate in a discussion of FIR filters.  It did not seem right to me to discuss FIR filters if we are a little fuzzy on “regular” filters, so here goes!

Let's start with the concept of frequency.  The term frequency is defined as Events Per Unit Time.  Years ago, a friend of mine had an antique, vacuum tube based analyzer called an EPUT meter.  It was a rudimentary frequency counter! The frequency of a full moon is one event per month.  The frequency of Christmas is one event per year. Before 1960 the official unit of frequency was the cycle per second.  We now call the unit ‘Hertz’ to honor the German physicist Heinrich Hertz.

We are all familiar with the sine wave shown here. We like to use the sine wave in these explanations because it is the result of simple harmonic motion.  We like simple!  Imagine you had a pendulum and attached a marker to the weight, and set it in motion above a sheet of paper such that the marker was drawing a line on the paper. If you pulled the paper under the marker at a steady rate it would draw for you a nice sine wave.  A sine wave is really a graph of something where the X axis is time.

If this graph represented the action of the pendulum, the vertical axis of the graph or the Y axis would be the displacement of the pendulum in some length units, like inches or centimeters.  If this graph represented an audio signal, the Y axis might be volts.  If this were a representation of an acoustic wave, the Y axis would be pressure.   So in an acoustic wave, the events that we count are oscillations of pressure, and the time unit is the second.  The graph in figure 1 shows 2.5 Hertz or 2.5 cycles in a second.  Generally speaking, we perceive frequency as pitch, and our ears, at least young undamaged ones, respond to frequencies between roughly 20 Hz and 20,000 Hz, with us older, shall we say “seasoned” folks maybe making it out to 12,000 Hz.

Ok, onward to phase! Phase is related to, but not equal to, time.  It is most often expressed in degrees. One cycle of a sine wave can be thought of as a 360-degree event. The beginning of the cycle is 0 degrees, ¼ of the way through is 90 degrees, ½ of the way through is 180 degrees etc.  Here is an imperfect analogy that might help. Imagine a racecourse, say an oval.   A blue car and a red car are driving around the oval at exactly the same speed.  You could say that they are in phase because no matter where they are on the track, they are side by side.  Now imagine that the red car hits a patch of mud on the track and slows down a bit.  Now the blue car is ahead.  We could measure the difference in degrees.  If the red car is behind by a ¼ of the track we might say that red is 90 degrees behind blue.  It gets really interesting when red is delayed by exactly 360 degrees. Now the cars are back in “phase” but the blue car is winning!

Most of the time when we talk about phase we are comparing something to something else; the red car to the blue car, the phase of a signal at the input of a circuit to the phase of the signal at the output of the circuit and so forth. 

The question of how we perceive phase is a very loaded one and deserves a better treatment than what I can do here, but phase shift can be perceived as a cancellation or even as a sort of time smear that messes up the perception of a stereo image.

Ok. Now on to filters!  One of the very cool things that smart people discovered a while back is that there are things that behave differently depending on frequency.  A wire is not one of them, right?  Wires (at audio frequencies) don't care what signal is going through them 20Hz, 90Hz, 15,762Hz… it’s all good.  Until you take that wire and make it into a coil.  It then becomes an inductor, and guess what?  Low frequencies go through it just peachy, but high frequencies do not.  The inductor belongs to a class of devices known as reactive devices.  The capacitor is the other member of this exclusive club.  It behaves as precisely the inverse of the inductor.  A capacitor will block low frequencies but allow high-frequency signals to pass through.  In the analog world, all filters are built using reactive devices.  Now I’m not going to try to explain how these reactive devices work, but like all real world devices, they take time to do what they do, and this time is manifest as a phase shift!
Of course, filters are used in all forms of audio processors from crossovers to equalizers to the humble tone control.

It has taken me 879 words to get to the point of this article… analog filters always produce a phase shift.  They have to.  It's the law!  Not a suggestion. . . not optional compliance!  Next time, the mighty FIR filter!
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