When you are faced with the task of choosing the equipment for a new milonga, or upgrading the existing one, the lack of information is not the biggest problem that you are going to face. There are numerous reviews of sound equipment in the online forums, there are technical characteristics on manufacturers sites, and specific recommendation as well. The problem is, however, that most of this information is relevant to either club sound systems or live stage sound systems. The club sound systems are mostly intended and built for very loud reproduction of rock, techno, etc. music, which is quite different by its characteristics from the Golden Age tango music. The high-quality stage sound systems, or cinema sound systems would have been ideal for our purposes, but the price of such a system is way beyond the reach of most of the milonga organizers.
Nevertheless, the sound of many milongas venues can be significantly improved without breaking the banks of the organizers. This article is an attempt to show, how it can be done. It is based on my personal experience of studying various milonga venues across the globe, and assembling or helping to assemble several successful installations by myself.
The article is necessarily partial, in every possible meaning of this world, ranging from “incomplete” to “narrow-minded”. It is incomplete, because, not being a professional, traveling sound engineer, I have rather limited access to various kinds of sound systems, thus, I can vouch only for the equipment that I either have used personally, or have heard on multiple occasions. It is narrow-minded, because, most of the assertions in the article will be left without proofs. It is up to you to try it out and see for yourself if it works for you or not, or to find the proof in the professional literature. The best that I can do is to illustrate my assertions and the use of the recommended equipment with three detailed case studies of a small, medium, and large milonga, each with its own set of challenges.
Please note that if you found this article by a search engine and you are building a different kind of a sound system (e.g. not primarily intended for a milonga venue), some of my advises may not be applicable to you, while certain pieces of equipment, such as limiters, vital to the health of a club house systems, or compressors and and other voice processors required for voice systems are simply omitted as irrelevant to the purpose of this article.
And the last note. All equipment, mentioned in this article that has links to its manufacturer sites has been either owned, or installed, or rented, or heard on multiple occasions by the author and is highly recommended, but only if it suits your particular settings. The equipment that is mentioned but does not have links also have been heard or used, yet it is not recommended, it is there only for comparison sake. The mentioned price ranges are in US dollars, and taken from B&H Photo/Video website, without tax (VAT) or shipment. The European or even Canadian prices may differ quite significantly, especially on the equipment with US origin and manufacturer export restrictions.
2. Sound System Components
In sound engineering slang, the sound system is often called PA (stands for Public Address, and is better suited for voice reinforcement systems, but used for any kind of professional sound systems anyway), SR (stands for Sound Reinforcement and is self-explanatory), or sometimes, simply “house”. The last name contains a strong hint that everything that comes past the computer and/or the sound card of the DJ is the responsibility of the milonga organizers, the “house owners”. While some DJs come equipped with their own mini-mixers, microphones, equalizers, power bars, etc. we do it mostly because we have to deal with barely adequate (or, sometimes, completely inadequate) house systems, not because we are so much in love with our toys and cannot live without them.
A milonga PA consists, at the bare minimum, of the following components:
- Audio Mixer (such as Mackie ProFX8 v2)
- Power amplifier (such as QSC GX5)
- Speakers (such as ElectroVoice ZLX12)
- Speaker mounts and/or stands
- Speaker cables and audio signal cables
Some of those components can be combined in one unit, such as powered mixer (highly not recommended), or active speakers (such as QSC K12), or a general purpose traveling musician monitor (such as wall-powered Roland CM-30 Cube or battery-powered LD Systems Road Jack 10), but, nevertheless, all of them must be present, and all of them affect the quality of the sound in your venue. The audio profile of the venue itself is of paramount importance to the quality of your sound, however, unless you own the venue, often there is little that you can do about it, and so, only some suggestions how to deal with a venue at hand can be given.
There is a large variety of sound reinforcement speakers on the market, ranging in price from few hundred to a few thousand dollars apiece. From the practical point of view, we will only consider the full-range, portable PA speakers with price tags well below $1000, with one notable exception of speaker arrays, explained below. You should clearly understand the limitations of these speakers – even in a modest club settings they would be used only for monitoring, e.g. they would lie flat on the stage, turned toward the musicians, and produce just enough sound so that the local talents could hear themselves playing. The FOH (front of house) speakers that send the sound waves toward the audience would be larger, louder, produce better quality sound and cost well above $1000. Even better quality speakers would be used in the classical music halls, large stadiums or movie theaters.
At the same time, some rare gems, well suitable for reproduction of Golden Age tango music can be found among the least expensive portable PA speakers.
3.1. Passive vs. Active
The passive speakers are intended to reproduce amplified, relatively high-voltage signal that comes from the power amplifier. You can easy identify a passive speaker by its rather plain back panel. There you would see only a couple of Speak On or 1/4″ phone jacks. One jack is used to send the signal to the speaker. The second jack is used to connect two to four speakers in parallel. The industry standard resistance of a two-way speaker is 8 Ω. All power amplifiers allow 4 Ω load, that is, you can connect either one or two 8 Ω speakers into each channel, while some amplifiers allow 2 Ω load, that is, you can connect up to four speakers into each channel. In total, there could be up to eight passive speakers, connected to a single stereo power amplifier. The passive speakers do not require an additional power source, as all the needed power comes through the thick speaker wire.
The active speakers are fed by the low-voltage signal with negligible power straight from the mixer. The signal is amplified inside of the speaker. In order to work, active speakers must be connected to a power outlet. The back panel of an active speakers has a whole array of various input connectors ranging from 1/8″ stereo jack for connecting phones, computers, etc. to professional balanced TRS and XLR jacks, as well as rudimentary mixers with input gains, and, sometimes, DSP chains to fine-tune the speaker. Besides the inputs, there is usually a line level output, so that you can connect as many active speakers as you want to each other.
The passive speakers are notably lighter than their similar active cousins, they cost less, they are much less prone to EM noise, they do not require additional power outlets, they do not need to be separately switched on and off, and, in general, pairing a good quality passive speaker with a good quality amplifier will produce a better result than using active speakers in the same price range. The biggest disadvantage of passive speaker system is that such system has a single point of failure – if your amplifier suddenly dies on you, there goes the milonga or the festival. With active speaker systems each speaker is independent of the others, and, even if the mixer dies, in most of the cases DJ laptop and the organizers microphone can be connected directly to the closest speaker, while all the other speakers can be reconnected to get the audio signal from the first one. Also, the latest trend of introducing high-end DSPs into the affordably priced active speakers line-ups slowly changes the landscape.
Some manufacturers, notably Electro-Voice, have series of both passive and active speakers in the same housing, such as EV ZLX series.
3.2. Size Matters
The portable speakers, active or passive, usually contain two drivers. The bass driver, also called the woofer is either 8″, 10″, 12″ or 15″ in diameter, while the combined mid and high-range driver, called the twitter, usually has a size between 0.75″ and 1.5″. The speaker itself is characterized by the woofer size in its model name. The larger is the size of the woofer, the lower notes it is capable to produce with sufficient power and without distortion. At the same time, the size of the woofer defines so called crossover frequency of the speaker, e.g. the specific tone that lies on the boundary between the woofer and the twitter reproduction ranges. All the tones that lie below are sent to the woofer, and all the tones that are above are sent to the twitter by the internal crossover circuitry. The region just around the crossover tone is usually the most troublesome in terms of consistent sound reproduction for the particular speaker model, that is, larger woofers may have difficulties with reproducing the tones that lie close to its upper boundary, and also the crossover itself may not be as “flat” as desirable.
There exists a common misconception that as long as the speakers are good in the reproduction of the mid-range, they are good for tango. Most probably, this misconception has arisen from the fact that most of the cheap club type speakers are terrible in the reproduction of the mid-range, and anything, which is better than terrible is perceived as good. But there exists another misconception that tango music of the Golden Age does not have much of bass or treble content, and so it can be completely ignored. The truth, however, is that in order to correctly reproduce the sound of acoustic instruments you just have to have an almost-perfect, flat reproduction curve, even if not for 40s, but for 50s music, but also, as any club DJ knows, in order to move your crowd in the venue you need to have a sufficient supply of deep bass in your speakers.
This statement creates a certain contradiction. In order to have solid bass you need larger woofers. But in order to have clean mid-range you don’t want your woofers larger than 12 inches, because most of 15″ speakers have their crossover frequencies placed in rather inconvenient spot for acoustic instruments.
In a club or concert hall this contradiction is resolved by introducing the sub-woofers – huge boxes with 18″ or larger cone, intended for the reproduction of frequencies, lower than 100 ÷ 150 Hz. The rest of the frequency range is served by the “tops”, the same full-range speakers but with woofers no greater than 10″, which are now emitting only the mid-range and the highs. However, the sub-woofers are quite pricey and, in general, require a separate hardware crossover, and two separate amplifiers, one with lots of power to drive the sub-woofers, and another one, much less powerful, but very high quality one, to drive the tops. You have, most probably, heard the amazing sound, produced by such systems on large festivals with high-end rented equipment. In the real world with real budgets, however, you should use the speakers with the largest woofer size, but below 15″, e.g. 12″ speakers, for the best possible bass reproduction within your budget, even though there is at least one exception from this rule, explained in the Recommendations section. The above suggestion applies to both passive and active speaker systems.
3.3. Speakers Arrays
The term “speaker array” has two meaning. The first one refers to the multi-thousand dollars speakers chains hanging from both sides of the stages on big rock concerts. The second one refers to, indeed, a vertical array of four to, maybe, eight tweeters on a top of a single woofer, which is the last resort of a sound engineer in a high-ceiling, acoustically bright and boomy hall.
The main problem with such halls is the reverberation, or, simply put, echo. When conventional speakers are positioned at the walls, the sound wave from the speakers first hits the ears of the dancers directly, but then, with a significant delay, the reflected from the ceiling wave hits the ears again… and again. This effect is often negligible in the low-ceiling room, because the delay is very small, or in a properly acoustically treated room, because the second wave is trapped inside the sound-dampening layer on the ceiling. When the ceilings are high, and acoustic treatment cannot be performed, there are only two options to solve the problem with the echo. The first option is to position the speakers above the dance floor either directly hanging from the ceiling, like in Salon Canning, Buenos Aires, or mounted on the suspension frame, like in Centro Region Leonesa, Buenos Aires. The other option is to use speakers arrays.
Unlike a conventional speaker, which has both vertical and horizontal coverage angles just about 70° ÷ 90°, the array’s vertical angle is considerably smaller, namely it is 40° or less. Because of that, the sound wave simply does not have enough power to reach the high ceiling and then reflect back into the ears. At the same time, array’s horizontal angle is usually noticeably wider than 90°, allowing for more uniform distribution of the sound in the horizontal plane. Also, arrays are capable of projecting the sound further than conventional speakers with less decay. Note, however, that the arrays can only solve the problem with the high ceilings. The bare concrete walls or mirror walls will still present the problem, although of a lesser magnitude.
A speaker array is usually active, e.g. the sub-woofer enclosure will also host the amplifiers and, often, a DSP module to fine-tune the array for the particular venue. That is to say that in most cases you will not need to purchase a separate amplifier should you decide on a speaker array. However, there are modular arrays, passive arrays, and mid-range/twitters-only arrays as well, giving an organizer a variety of options to optimize the sound in the venue.
3.4. Speakers Power Handling vs. Milonga Power Requirements
The passive speaker is characterized by the maximum power, in Watts, that it can handle before it breaks or burns. Usually, there are three distinct values: peak power handling for extremely short bursts, program or RMS power handling for prolonged periods of times, and continuous or musical power handling for indefinite periods of times. RMS power value is the most useful for all practical applications. If it is not specified, the following formulas can be used:
(program or RMS power) = 2 • (musical or continuous power)
(program or RMS power) = 0.5 • (peak power)
The only correct way for a manufacturer to determine those numbers is to actually destroy a bunch of speakers in a lab, and to average the results. Thus, even for a reputable speaker manufacturer those numbers are “ballpack figures”, while for some other manufacturers they are “guesstimates” at best or marketing wishful thinking at worst.
While the speaker power handling is indeed related to its maximum volume, in order to calculate the precise sound pressure level that the particular speaker can produce, another characteristic should be used, namely, speaker sensitivity, which is measured in decibels of sound pressure level at one Watt at one meter (dB SPL/W/m). Having this number you can calculate precise SPL value at any distance from the speaker at any power level. However, quite luckily for the milonga organizers, you do not need to concern yourself either with peak power handling or speakers sensitivity altogether.
The old rule of thumb for a rock concert says that you need somewhere around 5 ÷ 10 W of power per person in a venue, and at least double that number in an open air event (in my personal experience, much more than double the power is required outdoor). Rock concerts are routinely run pretty close to the pain threshold, that is, at about 110 ÷ 115 dB SPL peak values. On the other hand, an orquesta tipica without electric amplification can hardly, if ever, exceed 90 dB SPL, and the usual milonga levels are kept around 100 dB SPL, while some DJs, notably of European origin suggest much lower levels, such as 90 dB. That is, the music in a tango venue is, subjectively, two to four times less loud than in a rock club, or, objectively, the sound pressure level drop is between -10 dB and -20 dB. Each 10 dB drop in sound pressure level (SPL) requires ten times less power, and so, for 100 dB SPL levels, using the same rule of thumb we would only need 0.5 ÷ 1.0 W per person in a venue, even that could be considered too loud in some European milongas.
Also, unlike rock concerts, where the dynamic range at the microphone approaches 90 dB and lots of headroom is required, the dynamic range of a shellac recording is mere 30 dB, and the dynamic range of the vinyl recording is about 50 ÷ 60 dB. Therefore, we do not need any additional power to maintain large headroom, either.
Then, does it really mean that a rather common, single 500 W RMS speaker can provide enough volume for 500 people festival? No, it does not. In order to maintain a fairly consistent sound across large dance floor we always need to use two, four, or more well positioned speakers, but, as the experience shows, we never use those speakers at their full capacity, and this is why we should not be concerned about their power handling. We will continue this discussion in the Amplifiers section, and in the Case Studies section I will provide several real-life examples that confirm 0.5-1.0 W per person rule.
For active speakers usually a single “power rating” number is specified, which is often the peak power handling value for the speaker itself. For instance, passive Electro Voice ZLX speakers are rated as 1000 W peak, 500 W RMS, 250 W continuous. Active Electro Voice ZLX speakers, using exactly the same housing are rated at 1000 W, which simply cannot be accepted as their RMS rating.
In any case, 400 ÷ 500 W RMS is a very typical power rating for the 2-way, portable speakers with 10″ ÷ 15″ woofers, both passive and active, and that’s the number that we should keep in mind, together with 0.5 ÷ 1 W/person milonga venue rule of thumb. For higher quality FOH speakers, such as QSC K and E series, the numbers are doubled, e.g. 800 ÷ 1ooo W RMS.
In very general terms, the permanent or semi-permanent installations with more than two speakers will be less expensive, easier to use, and overall better if passive speakers are used, the single-speaker portable PA is obviously better be active, while two-speakers portable or permanent PA is right on the boundary.
The ultimate winner in under $500 active speakers category is EV ZLX-15P from Electro-Voice ZLX. This is not a typo. I indeed recommend 15″ Electro-Voice speaker over its smaller 12″ cousin. Try it. Listen carefully to the quality of the mid-range reproduction and then pay attention to its full and meaty bass line. Let me know what you think. Or, if you are on a really tight budget, or have a very small venue, get the 12″ instead, for $400. Most other speakers in this range, such as JBL, Yamaha, Yorkville, Mackie, etc. are much less suitable for tango venues. On the other hand, el cheapo active Behringer and the likes should be avoided at all cost. You will waste your money on those extremely harsh sounding speakers, and they will fail you in the least expected moment.
If you are willing to spend a bit more more, the clear winner in under $100o active speakers category is QSC K12 from QSC K series for $800. This is no longer “a stage monitor speaker”. QSC K12 has an amazing sound and all possible mounting options as well, for a surprisingly reasonable price. For the European organizers, a highly recommended, great-sounding system in a somewhat similar price range, is a full-range 12″ speaker HK Systems Linear 5 112, and sub woofer HK Systems Linear SUB 1200.
In the passive speakers category the choice is quite similar. You can look at Electro-Voice ZLX for $300 ÷ $400 or QSC E Series for $450 ÷ $550, or spend the equivalent if not larger amount of money and get in return much less satisfying sound from others otherwise decent manufacturers such as Yamaha. Again, Behringer and other cheap alternatives should not be even considered.
If you do have bigger budget, and large venue you may explore the option of adding the sub-woofers. Both QSC and Electro Voice offer matching sub-woofers for their lineups, however, you should ask for professional help in planning the installation and tuning up such a system.
The speakers arrays, as it was explained before, are the only “non-intrusive” solutions for high-ceiling, boomy halls. The highly recommended array lineup is RCF EVOX, either EVOX-8 (12″ sub-woofer) or EVOX-12 (15″ sub-woofer). However its $1,600 ÷ $2,600 price tag might be rather hard to swallow. The only substitute that I have used is Bose L1 array with $900 list price. In my personal view, Bose and tango music lie so far apart from each other that there cannot be any happy marriage, ever, because of heavy “electronic” coloration that Bose usually adds to the sound. But together with carefully adjusted house EQ it might still be your best bet for under $1000 apiece. Bose is always shy to publish any power ratings of their speakers, but, as the experience shows, two Bose L1 speakers, if well positioned, are sufficient for 250+ people festival venue. Luckily, this system is readily available both on the aftermarket with well-reduced price, and in the rental facilities as well. Do try before you buy this one!
The arrays is a rapidly developed field. For a list of various options, with street prices, you can check out this Column PA Systems review, and also look at the Case Studies section.
Finally, for an ultimate portable, all-in-one solution for up to 30 people indoor milonga you should check out Roland CM-30 Cube for $200. For up to 50 people outdoor event you might want to look at LD Systems Road Jack 10 for $300. Both speakers have an array of various inputs, from balanced mike-level XLR to mini-stereo, 2 band EQs and some additional options for quick and easy setup. However, do not expect sound fidelity, comparable to any of the above recommended speakers from either of these two. Also, when planning an outdoor milonga you should not forget about the life-time of your computer battery. From this perspective, using a high-capacity (e.g. 200 watt-hours or more) power bank with 110/220V outlet, equipped with pure sine wave inverter (important for any audio gear), paired with an active speaker of your choice, might give you a better alternative to a battery powered speaker.
In a milonga venue the quality of the speakers is as important as the quality of the tango tracks that your DJ is using and his sound card. Everything else is of a second order of magnitude. However, any PA is a chain, and the strength of any chain is defined by its weakest link, which might be found anywhere, including your power amplifier.
4.1. Amplifier Classes
In an ideal world, power amplifier should simply produce clean, uncolored signal with the power, sufficient to drive the speakers.
In reality, however, the sound of a PA amplifier can range from smooth, detailed and warm to extremely harsh and unpleasant, and it has nothing to do with the “warm tube sound” of audiophile realm. The quality of the sound of a PA amplifier is mainly defined by the topology of its output stages, denoted by an amplifier class. The classes that are of interest to us are A, AB, G, H, and D.
The pure A class, or so called open-ended amplifiers have amazing sound qualities, but they convert more than 70% of the energy into heat, and, as such, exist only in the home audiophile realm. The pure B class, or so called push-pull amplifiers are much more efficient, but cannot be used for audio reproduction because of an inherent design problem with crossover distortion. The hybrid, AB class amplifiers waste only about 30% of the energy, and, at the same time, their sound quality are almost as good as of A class amplifiers. This is the chosen design of high class power amplifiers up to about 300 ÷ 500 W per channel, restricted to 4 Ω load. With even higher power ratings heat dissipation once again becomes a serious problem, and so enters G class and its ancestor, H class. The G class adds on the top of AB class amplifier a switching power supply, while H class amplifier uses a continuously-regulated power supply, achieving even higher efficiency, possibly, wasting just about 10% of the energy, and yet, producing as good sound as a classic AB class amplifier.
But now enters the D class. D class amplifiers are amazingly energy-efficient, they waste even less than 10% of the energy, they are much lighter than their AB or H class cousins with comparable power ratings, and they are considerably less expensive… So, is there a catch? Indeed, there is. Those amplifiers have their legitimate use either outside of audio domain, or in driving the sub-woofers or, in some cases, inside the active speakers housing. But when they are used stand alone, for driving the full range speakers, their sound ranges from plain bad to horrible. Pretty much like a sound of an “ION Party Speaker”, no matter how good is the speaker that they drive. There are several reasons why it is so:
- By its design, D class amplifier is an emitter of powerful high-frequency electromagnetic noise. With insufficient shielding both the pre-amplification circuitry of the amplifier itself and all other equipment around it are affected by this noise. However, since the selling point of those amplifiers is reduced cost and reduced weight, the shielding is not necessarily sufficient.
- By its design, D class amplifier requires a low-pass filter between its output stage and the speaker. This filter should consist of high quality elements, capable of passing through all the power that the amplifier produces. If the filter is not steep enough, or not of the highest quality, or mismatched, the high-frequency metallic tingling will escape into the speakers. However, since the cost of this filter is about 30% of the total amplifier cost and it also has a considerable weight, while the selling point is the reduced cost… well you have got the idea about the “high quality”…
- The problem with the filter is further aggravated by the varied load of the amplifier. In theory, there could have been multiple, or at least, configurable by a switch filters to match the 2 Ω, 4 Ω, and 8 Ω load, but since the selling point… well, you have got it.
- And, finally, because of the filter, any class D amplifier has rather low damping factor, meaning that the amplifier cannot efficiently fight back EMF from the speaker, which in turn means that D class amplifier simply cannot deliver as punchy and and crispy clear sound as AB class amplifier.
When D class amplifier is used for driving the sub-woofers most of the above problems simply disappear, because of the nature of the sub-woofer. When a well designed D class amplifier is carefully paired with a cone of a high-end, modern active speaker with DSP, all of the above problems can be dealt with more or less successfully. But when you buy a D class amplifier to drive your main speakers you simply destroy your sound, and the ears of your DJ and your patrons.
Please, always look for the “topology” specification of your chosen amplifier. If it says “Class AB”, “Class H”, “2-tier Class H”, “Class G” or, even, “EEengine”, which is Yamaha name for their proprietary Class H schematics, your are OK. If the output topology is not specified at all, and the amplifier is suspiciously cheap and powerful – this is class D. Do not buy it!
4.2. Amplifier Power Ratings
Amplifier power rating defines how much clean power the amplifier can deliver to a specific speaker load per channel. The theoretical peak power can be correctly calculated based on the full rail voltage, but the ridiculous figures that we will get as the result, can hardly be achieved, and much less sustained for even a few milliseconds. More realistic ratings, unlike speaker power handling can be precisely measured and stated in the manual, however the results are usually a bit confusing.
The most useful and practical specification is “rated output power, THD < 0.1%, 20 Hz ÷ 20 kHz”. This specification is also referred to as “RMS rating”, even though it has nothing to do with RMS. In plain language, the above definition says, “this is how much power I can deliver, with any type of music, and with negligible distortions”. Often, instead of 20 Hz ÷ 20 kHz rating, a “midband power, at 1 kHz” rating is specified. Midband power is easier to measure, and is good from the marketing perspective, because somewhat 10 ÷ 30% higher than RMS power. To calculate RMS power you can use an approximate formula:
(RMS power) = (0.7 ÷ 0.9) • (midband power)
Sometimes “rated power” is stated without any explanation, and so we could only assume that it is either midband or RMS power, depending on how optimistic we are, and how much we trust the particular manufacturer.
However, this is not it yet. The power rating will depend on the specific load, e.g. on the number of speakers, connected to each amplifier channel. While the Ohm law suggest that the power value should be doubled each time the number of speakers is doubled, it is not so. Most of the amplifiers will produce considerably less than a doubled value, because of their internal protection circuitry. Also, we should not forget that rated power is specified per single channel.
Further on, the recommendations on matching the amplifiers to the speakers in various literature range from “rated power must not exceed half of the speaker RMS rating” to “rated power must be no less than twice speaker RMS rating” While both of those recommendations makes sense under certain circumstances, there is 4 (four) times difference in the result, yet, neither of them is directly applicable to milonga venues.
As have been shown above, we rarely, if ever, use all the power of our speakers in the milonga venues. In order to have reasonably even coverage of a large venue with 300 people capacity, we would use at least four speakers. The standard 12″ speaker will deliver about 500 W RMS. With four of them we can get 2000 W RMS. Yet, for 300 people, according to 1 W/person rule we would not require any more than 300 W of clean power from the amplifier, which translates to 150 W RMS per channel into 4 Ω load, or about 75 ÷ 100 W into 8 Ω load. And this would be a very modest power requirement indeed, pretty much any professional amplifier can pump much more power than that.
At the same time, if your budget allows, and there is even a slight chance that your system will be used by others, or that you might use it outside, or that you might want to throw in more speakers in the future, you should chose the amplifier with higher power rating. In such case value up to the full speaker RMS rating would do.
Let us continue with the four 500 W RMS speakers example. Since I am going to use two speakers per channel, the total power per channel is 500 + 500 = 1000 W. Now I need to look at the amplifier RMS power rating into 4 Ω load. If this rating is anywhere close to 1000 W this amplifier is in the ball pack. A very high quality QSC RMX 2450a for $750 delivers clean 800 W RMS into 4 Ω load, so it is indeed in the ball pack, and I could safely get this one. However, my minimal requirements are 150 W per channel, and so if I am on a tight budget I may as well chose the lowest model in this line, namely QSC RMX 850a for $400, which still delivers 300 W per channel into 4 Ω load, but for almost half the price. Or, I can go instead with a lower class, and yet, very decent QSC GX3 model for $300, which delivers 425 W of “midband power”, or about 350 W RMS into 4 Ω load. Both alternatives to 2450a have more than enough power even for a 500 people tango festival, e.g. they both can deliver more than 500 W RMS from two channels combined, but not necessarily enough power for a dark rave party, or large outdoor event. The choice is yours.
One word of caution. Having too much power is not good, either. Any AB class amplifier, or derived from it G or H class amplifier has a small amount of crossover distortion. However, it is small only in relation to the full voltage that the amplifier can produce. If the amplifier is constantly run at very low power setting (e.g. your volume knobs are turned almost all the way to the left), this type of distortion might become quite audible.
On the other hand, if you have decided on a less powerful amplifier make sure that you never overdrive it into clipping. As a matter of fact, a relatively weak, yet clipped signal from the amplifier will burn your speakers much faster than overly strong, yet clean signal from an overpowered amplifier. Luckily, with a typical sound pressure levels that we use, for a typical milonga venue, it is next to impossible to overdrive even the weakest professional amplifier in the market.
There are plenty of good quality amplifiers on the market. Unlike speakers, any AB or H class amplifier that suits your budget would do just well. Among those that I have used I would suggest either less expensive QSC GX series, capable of handling up to four speakers (two per channel) starting from $300, or QSC RMXa series, capable of handling up to eight speakers (four per channel), starting from $400, or Electro-Voice Q series, starting from $650. Some of those amplifiers are AB class in the lower end, others are all single- or multi-tier H class. The lowest priced model in each line-up would be well sufficient for most of the practical purposes, e.g. for an indoor milonga with several hundreds people.
At the bare minimum, a mixer suitable for a milonga or festival should have:
- One or two XLR microphone jacks with gain knobs and HPF buttons for the organizers microphones
- One or two stereo line inputs with volume control for DJs
- Main fader
The smallest, 2-mikes, 4-channels model in the new Mackie ProFXv2 lineup gives you all of the above, plus 5-band graphic EQ, plus a few other goodies. In terms of the features is the best mixer that I can recommend in the $100 price range.
If once a year you have a festival with live music it is better to ask your festival PA engineer to rent the mixer for the event, together with all the rest of the stage equipment, e.g. mikes, monitors, compressors, cable snakes, etc. A sexteto tipico with a singer will require nine to ten mikes only for themselves, plus another one or two for the organizers, and so you are looking at 12 microphones mixer, with lots of additional nice-to-have, e.g. channel inserts, one-knob compressors, FX unit, sub-groups, busses, etc. for a good $800 ÷ $1,200. “Wow factor” aside, there is no other reason to invest into such a mixer if most of the time only a single DJ channel will be used.
However, in between these two extremes you might want to get a decent, 4 ÷ 6 microphones mixer that you could use for your regular milongas as well as for the smaller live music events, such as Mackie ProFX12v2, or a similar model within $200 range. This mixer, and some other modern mixers come equipped with 24 bit / 96 kHz two channel DAC/ADC, which you can use either as a very decent USB soundcard for DJing, or for recording the band performance straight into your computer. This, by itself justifies an additional $100 in the price.
There is a hybrid between the mixer and the amplifier called a powered (or active) mixer. Those mixers are not recommended. Pretty much all of them use D class amplifiers, with rather harsh and unpleasant sound. Unfortunately, they are more than often seen and heard both in the regular milongas and in the festivals, even though their intended purpose was only to serve a small band of street musicians. The better models, such as Yamaha EMX5016 do exist, but you could find a better use for a $1000.
There are two types of the cables that you might need – speaker cables, only if you have decided on passive speakers and audio signal cables for any kind of PA.
6.1. Speakers Cables
Speaker cables deliver the audio signal from the amplifier to the speakers. The older speakers and amplifiers would use 1/4″ TS connectors, also known as phone plugs. The newer ones use Speak On connectors. On the back of the modern amplifiers you will usually see a combo jack, that allows to connect either TS or Speak On cable. Unless you have bought an older pair of speakers, which do not have Speak On connectors at all, always buy Speak On cables. This connector is more reliable than TS, and also it has a lock that prevents the cable from falling out of the jack in the most unexpected moment.
Also, it is important to buy as thick cables as you budget allows. Even though, as we discussed earlier, the power that needs to be delivered to the speakers is minimal, and the current, flowing through the cables will be negligent, the cable thickness severely affects the damping factor of the amplifier. The resistance of the cable must be as close to zero, as possible, and the thicker is the cable, the lower is its resistance, the higher is the damping factor and the punchier the bass. Those cables are quite pricey. A single, 14 gauge, 50 feet (∅ 1.63 mm / 15,24 m) Speak On cable will have the resistance 0.13 Ω (that’s unacceptably high!) and will cost you around $35. A thicker 12 gauge (∅ 2.06 mm) cable will have resistance 0.08 Ω (much better!) and will cost around $55. However, much better cable deals can be found on Amazon. If the cable is considerably more expensive than that, check if it is a “four-poles” cable, and, if so, look for another one. Four-poles cables have four wires, while you only need two. The cables for the left and right channels should be kept of the same length, even though often only one long cable is often needed. At the same time, try to keep your cables as short as possible. Having very short cables is especially important if you use sub-woofers, as it is the low and ultra-low frequencies that are most affected.
Do not ever use unbalanced audio patch cables, e.g. a cable with a single wire and a shielding, such as guitar cable to connect passive speakers. In the worst case scenario such cable might heat up to the point of melting and cause a short circuit and/or fire. In more realistic scenario your sound will be audibly affected by such cable, e.g. you will lose both the punch and the high frequency content.
On the other hand, there is nothing magical about the speakers cables, despite all the claims in audiophile magazines. If you feel comfortable with soldering iron, get a bulk length of 12 gauge speaker wire, a pack of Speak On connectors, and make your own cables, especially if you are making a permanent installation.
6.2. Audio Cables
Audio cables are used for all other connections, that is, they connect active speakers to the mixer, mixer to the power amplifier, wired mikes or receiver of wireless mikes to the mixer and so on. Always use balanced cables, e.g. either with either TRS or XLR connectors. In some cases a TRS jack on a mixer may be labeled balanced or unbalanced, but the only case when we actually require such jack, is when connecting the DJ laptop or sound card to the mixer. In all other cases only balanced cables must be used. This is especially important when connecting to low-impedance XLR output jacks of a mixer. If you use an unbalanced TS cable with TRS/XLR adapter in some cases you may burn out your mixer. Don’t do that.
There is no need to buy any golden-plated, cryogenic-treated and/or snake-oil-rubbed audio cables. For unbalanced cables, such as your DJ cable it makes sense to look for better mechanical and audio cable quality, because you plug/unplug it a lot, and also because it is only the shielding that protects the cable from EM noise. For balanced audio cable, most of the protection is happening in the differential amplifier on the receiving end of the connection, and so, any reasonable cable would do well. Better quality is required for long cables carrying weak signals, such as microphone cables. However, no matter how good your cables are, do not lay out a long run of a power cable close to an audio cable, otherwise you will pick up a considerable amount of EM noise on the way. Also, to minimize the noise in the long running cables from the mixer to the active speakers, make sure that the mixer sends full strength signal to the speakers, and only cut the power to the needed for your venue volume at the speakers end. Better yet, make sure to setup correct gain structure throughout the whole audio chain.
7. Speakers Placement and Mounting Options
Proper speaker placement is an art, which requires both knowledge and experience. Here I will provide only some general advises on various options of mounting the speakers, in the best to worst order.
7.1. “Flying” Speakers
Suspending the speakers above the dance floor, if the ceiling is sufficiently high is by far the best possible option, but also is the most expensive of all. A speaker can be suspended if, and only if it has clear manufacturer specification of being “flyable”, and has special threaded sockets for the rigging hardware, such as QSC K series speakers. Alternatively, a speaker may be mounted on a suspended from the ceiling metal frame, but only if there is an accessory mounting frame, produced by the original speaker manufacturer, such as this universal bracket for Electro-Voice ZLX series speakers. A rigging kit for a single speaker with bolts, rings and wires will cost anywhere around $100. A single ZLX mounting bracket is also about $100. Add here the professional installation cost, additional cables cost, and you may be easily looking for an additional thousand dollars for four speakers installation.
However, this is indeed the best mounting option. First off, with an oblong floor two well positioned flying speakers may have better coverage than four speakers in the corners, for which you still will need to buy speaker stands. For instance, two QSC K12 with generic rigging kits will cost about $1800, while four EV ZLX 15P with stands will cost about $2300. So, you will get better quality speakers and spare $500 to pay for the installation itself.
With flying speakers you have the sound exactly where it supposed to be, so that people at the tables can talk without raising their voice, while people on the dance floor can enjoy the music at lower volumes, because people at the tables do not need to scream in order to hear each other. You have also solved the reverberation problem – with properly positioned speakers there is no need for any additional sound proofing. You can put several additional tables in the space that would’ve been otherwise occupied by the speaker stands legs, and there is no cables running to those stands through the whole room.
7.2. Wall Mounted Speakers
If the ceiling is too low, or the speakers of your choice do not allow flying, the next best option is to mount the speakers on the walls. Any speaker that have a standard pole mounting hole may also be mounted in a vertical position on a generic wall-mounting bracket such as On Stage SS7322B. When choosing the bracket for mounting, make sure that its load capacity well exceeds the weight of your speaker and that the tilting joint has a solid safety pin. This particular bracket sells for $50 per pair, but you can find both more and less expensive options.
A speaker can be mounted either vertically or horizontally with the help of a dedicated mounting bracket. Such brackets are available for both EV ZLX and QSC K lineups. Do not forget, however, that your speakers are not just heavy, they are also vibrating all the time, therefore I would strongly suggest to hire a contractor for the installation.
Try to position the bracket as high as the ceiling allows, and then direct the speakers axes toward the dance floor.
7.3. Speakers on the Stands
The last good option is to place speakers on the speaker stands. Do buy sturdy, heavy stands with load capacity well exceeding the speakers weight. A good speaker stand would cost about $80 or more. Extend the legs fully and raise the stands so that at least the twitters are positioned well above the peoples heads. Now rotate the speakers so that they would not point straight to the opposite walls or to each other. If you have to use stands, you might want to experiment with speaker’s tilt adapters, especially when using only one or two speakers in smaller places.
In general, when choosing the positions for the speaker stands, always remember that the main goal is to deliver the sound waves to the dance floor, as evenly as possible, and spare the people sitting at the tables. Place the stands right at the edges of the dance floor, between the tables, not at the walls behind the tables. Also, in oblong halls place the speakers between the tables that are close to the corners, rather than behind corner entrances to the dance floor. Also, with multiple speakers placing them in checker pattern generally may give better results than opposite to each other.
Make sure that all the cables are firmly taped to the floors, or, better yet, use cable covers. For active speakers do not run signal and power cables close to each other.
7.4. Common Mistakes in Speakers Placement
If a speaker has a mounting hole at the bottom, and it is not used as a stage monitor, it must not be left on the floor, ever. It should be raised on a stand, mounted on the wall, or suspended in the air. Do not substitute speaker stands with any kind of furniture. The furniture is going to vibrate. Badly. Do not substitute wall mounting brackets with cute console shelves. They are going to resonate. Badly. When the speakers are placed on the stage, no matter how high the stage is, they still must be placed on the stands. The stage is a huge hollow box. It vibrates. Badly. Don’t do it. Use the stands.
Also, try not to mix speakers of different types. The strangest setup I have ever seen was a Bose L1 in the middle of a high-ceiling, oblong hall, with two smallish Electro Voice active speakers, mounted in the corners on the same wall. I am still at loss what particular problem the owners of the hall were trying to solve with such weird combination, but the results were far from perfect.
8. Puttin’ on the Ritz
This section is about some goodies that are not strictly necessary, but nevertheless quite useful.
First of all, you need to decide between wireless and wired microphone. My personal preference would be wired only. Less parts to break, nothing to setup, no outlets and no batteries required, and significantly less expensive.
Next, there are many different kinds of microphones, but the only one that you should be looking for the milonga venue is a handheld, dynamic microphone with cardioid pattern. Accidentally, this is also the least expensive kind.
And the last decision to make is either you want a speech microphone, or a vocal microphone. “Speech” microphone is an euphemism for lower quality microphones, with audible distortions. Only vocal microphones are used for professional broadcasting, and high-quality public address systems. Better dynamic stage mikes, unlike recording studio mikes, are not really “flat”, but rather “flattering” to the voice of the performer. However speech microphones obviously cost less. After dancing in many milongas in Buenos Aires to magic voice of Tito Rocco, seamlessly taking over Fiorentino, and having an honor to hand him the mike when I was djing in Club Fulgór by myself, I would certainly recommend to get a vocal mike. Because who knows, maybe tomorrow someone would approach your DJ table, ask for the mike… and an ordinary night will turn into a pure magic.
Anyway, the choice is yours, and here are some of your options. First of all, highly recommended, industry standard, virtually indestructible wired vocal mike: Shure SM58-LC ($90), which, at the time of writing was just released in the 50th anniversary limited edition. Next comes it’s much more expensive wireless cousin: Shure BLX24/SM58 (list price is $350, but I remember getting one for as little as $250). And the last one from Shure – solidly built speech mike, which might be also used for not too demanding vocals: Shure SM48-LC ($40). For comparable build quality, yet, lower prices you can also look at Audio Technica handheld dynamic microphones, I used to have one of their mikes in my DJ bag before changing it to SM58. And, finally, here is a cheap, yet, surprisingly decently performing speech-only wireless mike: PilePro PDWM1902 ($90). Even though its build quality is quite suspicious, for this price you can get a pair of them.
8.2. External Equalizers and Compressors
Unfortunately, as I have observed on more than one tango event, giving a guest DJ an option to fool around with a graphic EQ more often than not leads to rather detrimental sonic results. As a rule, a DJ who has mastered the equalizer skills would either bring his own software or hardware EQ, or would be able to dial just the most important corrections on the mixer channel EQ. And for anyone else it is better not to have too many options. Therefore, even despite all of my suggestions in the Tango Equalizer article, I cannot, in general, recommend to the event organizer to provide guest DJs with an option of an external graphic EQ.
On the other hand, if you can hire a professional with all the needed knowledge and tools to equalize your new sound system for your venue, by all means, get yourself a 31-band stereo EQ, such as DBX 231s, but make sure that its front panel is permanently covered and locked after the job is done.
The above applies even more to the compressors. While a well-tuned compressor can do wonders to the sound of your venue, in many cases you would have to either set it for each DJ using your equipment, or bypass it altogether.
8.3. DI Boxes
Sometimes, when you plug in a DJ computer into an otherwise perfectly working PA you suddenly hear the buzz. Swapping the DJ audio cable, or the adapters on the cable might or might not help the situation. A magical solution for such rather unfortunate scenario is a direct injection box (DI box) with ground lift. A good quality passive stereo DI box, with variety of input options and ground lift switch, such as Radial ProAV 2, is about $170, stereo-to-mono version is $120. However, with passive DI it all hangs on the quality of the hand-wound transformer, and there you get only as much as you pay for… Also I really wanted to recommend to you at least some good quality stuff that is made in Canada, eh? Much less expensive options (starting from $30) can be found in the Gearank review.
Think of it as an insurance policy. Try the box out, make sure you understand how it works, and that you can get the sound through in both positions of the ground lift switch, but then unplug it and keep it in your cables bag. Only when the problem actually happens, plug it in, lift off the ground, and enjoy the clean sound.
8.4. Power Bars, Conditioners and Sequencers
If you have decided on passive speakers, get yourself a decent quality power bar, plug it into the closest to DJ table outlet, and use this power bar to plug in your mixer, power amplifier, any other audio hardware such as graphic equalizer or radio microphone receiver, and always leave a spare outlet for the DJ laptop. Do not plug into this power bar any lighting equipment, or anything, which is not directly related to the sound chain. The single power bar will be the first line of defense against mains hum, but it will also help you to easily switch all of the equipment on and off. Instead of working your way up from the audio sources to the power amplifier when turning the system on, and going in strict opposite order when turning the system off, you may simply turn ON or OFF the power bar itself. This rather cavalier advice comes from the fact that all modern amplifiers have power-on delay, which will protect your speakers from a loud “thump”. Of course, you still have to close off or mute the channel on your mixer whenever you plug in or plug out a DJ computer, microphone, or any other audio source.
With active speakers the situation is a bit more complicated. If possible, run extension power cables to the speakers from the same outlet where your mixer and DJ computer are plugged in, however, make sure that those cables are not bundled together with the audio signal cables. If this is not possible, plug the speakers into any closest outlet, but if you suddenly started hearing the mains hum, try to re-plug the speakers elsewhere and see if the hum disappears. If the powered speakers are plugged into separate outlets they, of course, must be turned on after you have powered up the rest of your sound chain and turned off first.
Personally, I could never find any use for “power conditioners”, yet, depending on the quality of your electric grid, and also the additional equipment plugged in nearby, your mileage may vary considerably.
Power sequencers, on the other hand, are quite handy, when you have lots of equipment in a rack and want a full-proof way of turning it on or off. I have only used solid, reliable, but rather expensive Middle-Atlantic power products, and even that was outside of the milonga PA context.
5. An Afterthought
Most probably, if you are reading this article, you already have a running milonga, and, quite possible that you use there some of the equipment that I listed as not recommended, or plain bad. Personally, I see it as an opportunity, not as a reason for any dismay. I sincerely believe that it is better to run a milonga from a single boombox or bookshelf audio than not to run it at all, and, as a guest DJ, I do it myself, quite regularly.
But you can always try to rent some better equipment for a single event, set it up and see for yourself how much the quality of your sound would improve, and how your audience would react to it. After all, you already have your milonga, and your audience, no matter what equipment you are currently using.
A. Case Studies
A.1. Small Venue (30+ people capacity): Milonga Tula, Toronto
Milonga Tula is run monthly in a small, about 30 people capacity cafe in an old store-front building. When I was invited to DJ and co-host this milonga, I used to bring there my Roland CM-30 Cube. This is a 30 W, 6.5″, two-way coaxial active monitor, with a capable mixer and well-articulated club sound, which I use for various private parties or small milongas. As long as the room has reasonably square proportions, and I can position the speaker high enough on a sturdy shelf, and cut the bass with HPF at about 70 Hz, this speaker is good enough for up to 15-25 people milonga, like the afternoon milonga in Cafe Almacen on the photo below.
In the Tula Milonga the floor is visibly oblong, and the only place for the speaker is near the DJ table, at the further end of the room, right behind two tables. With the attendance between around 15 – 20 people this monitor was still Ok. However, when in the summer time attendance increased to about 40 people, the upgrade became inevitable.
I was not at all worried about the power. 30 W per 20 to now 40 people confirmed 1 W/person rule, thus any kind of sound system would do, as long as it would provide sufficiently even sound distribution and solid bass line. After a cursory look through bookshelf systems and restaurant background music systems I quickly realized that, unless I use a separate sub-woofer, I won’t be able to get decent sound with any of those. However, there was no place for sub-woofer in the cafe, ans so, I looked back into portable PA speakers.
My natural choice was a single Electro-Voice ZLX 12P, which I wanted to permanently mount in horizontal position above the bar entrance (not visible in the photo), tilted directly toward the dance floor. However, because of budget constrains, I had to use a speaker stand instead. The cafe has rather high ceilings, and so, raising the stand to the maximum height, even without tilt adapter, allowed to spare the two tables right in front of the speaker from excessive sound levels and also to “push” the sound across the floor, toward the tables at the other end.
NOMINAL POWER CALCULATIONS: After adjusting the speaker channel gain to zero reading on VU meter, I found that the optimal position for the volume knob is at about -12 dB. The speaker is rated at 1000 W peak, or 500 W RMS, and with -12 dB attenuation it produces just about the same 30 W RMS, or, again, between 0.7 to 1.3 W/person, even though I rarely crank my sound card to full volume. So, the 0.5 ÷ 1 W/person rule holds well for small venue with a single speaker, small or large.
The sound of this speaker was so good that it sent quite a few ripples across other tango venues in the city.
A.2. Medium Venue (100+ people capacity): Milonga Ocho, Toronto
Milonga Ocho is young and very popular bi-weekly milonga in the city. It is held in an almost square low-ceiling hall with maximum capacity about 100 people, yet, the attendance often exceeds 120 people. Three walls are covered with large tapestries, the fourth wall is glass, covered by window curtains. The PA there initially consisted of a Class D Yorkville active mixer, 200 W RMS into 8 Ω and four 10″ Yorkville passive speakers at the corners.
When the organizer approached me with the request to enhance the sound in the milonga, I suggested to get just two EV ZLX 15 speakers, and do the other upgrades later. Besides a big step up in the sound quality, two instead of four speakers would allow more room for the chairs, and spare the most crowded entrance area from extreme sound levels as well.
When the speakers arrived, I positioned them in the corners of the shorter wall, opposite to the entrance area, one behind the DJ table and another one at the bar. With an empty hall, the sound distribution across the floor was quite uniform. However, at the peak of the milonga it became clear that the fall off in the farther end of the floor was too big. The other resident DJ suggested to try positioning the speakers along the longer wall, before committing to purchase another pair. Two weeks later it was his turn to play. One speaker was moved away from the DJ table, to the opposite corner, and, indeed, the sound coverage improved quite a lot, even though the hall itself has almost square proportions. The most plausible explanation comes from the fact that speaker was re-positioned into the corner between a bare concrete wall and a glass wall, while the DJ corner had both walls fully covered by tapestries.
Many people acknowledged the new sound, however, the best compliment came from the DJ himself. Somewhere in the middle of the set he looked at me and said, “Damn, those speakers are so full of details that I feel like cleaning all my tango library again. Now I can spot the problems that I have never heard before.”
NOMINAL POWER CALCULATIONS: In this rather overcrowded venue we usually aim to get the peaks just around or a bit above 100 dB SPL. The sensitivity of EV ZLX-15 is 96 dB SPL/W/m. Plugging 100 ÷ 103 dB at 1.5 meters with very modest 6 dB headroom into a calculator, provided by Crown Audio, we get 22 ÷ 45 W of required power or 44 ÷ 90 W for two speakers, or 0.4 ÷ 0.9 W/person. Once again, 0.5 ÷ 1 W/person rule is now confirmed for 100+ people capacity hall with two speakers.
If we were to use with the same speakers more appropriate for the rock club values 110 ÷ 113 dB SPL, we would get 225 ÷ 450 W per speaker, or 500 ÷ 900 W for two speakers, or 5 ÷ 9 W per person, confirming the old rock club rule of thumb, but also showing that two speakers setup would be barely adequate if we planned to have there a rock party instead.
Here is a comment on using a similar setup from Vida Mia Tango Club in Beijing, China: We use EV speakers and QSC amplifier since the opening of our venue in 2011. The equipment certainly contributed a lot to the popularity of our milonga. We often received compliments from our guests of having the best sound of all local venues.
A.3. Large Venue (200+ people capacity): Tango Loft, Toronto
Tango Loft is an established bi-weekly milonga that alternates with Milonga Ocho in the same building, but on the top floor, in a large, acoustically bright and high-ceiling hall with about 200+ people capacity. The attendance is about 100+ people on regular milongas or 250+ during TTX or Ocho festivals, which are held in both halls of the same venue.
A.3.1. CONVENTIONAL SYSTEM
There were several improvements to the sound of this milonga, gradually implemented over the last few years. Firstly, before the Toronto Tango Experience festival in 2014, four Yorkville E10 speakers were augmented with another pair, to make the sound across the floor more uniform.
About the same time, the old class D amplifier started acting up, and I suggested the owner to replace it with much more expensive Electro Voice class H amplifier. The initial impression of the owner was “there isn’t much of difference”, however, by the end of the milonga he admitted that he doesn’t experience any sound fatigue as it was the case previously, but the most intriguing comment came from a well-known in the community tanguero, organizer and DJ of another milonga. After Hugo Diaz tanda he commented “I was never compelled to dance to Diaz, but something happened tonight. The sound of his harmonica was so rich that I all of a sudden I found myself on the dance floor”. Those two points – about lack of sound fatigue and natural sound of Diaz’ harmonica are, indeed, important. No matter how good the DJ is, and how much he can try to please the audience, on a longer milonga people will get tired, and would want to leave earlier when their ears are constantly assaulted with harsh and unnatural sound of a cheap D class amplifier.
NOMINAL POWER CALCULATIONS: The rather overpowered Electro Voice Q99 amplifier sends estimated 1400 W RMS into the three-speakers load per channel, with a total of 2800 W, and usually runs attenuated between -12 dB and -15 dB. So the total power is about 100 ÷ 180 W, and we have about 0.5 to 0.9 W per person. The numbers are well in the ball pack of 0.5 ÷ 1 W/person rule, now for 200+ people capacity, with six speakers. However now we can add an observation that just above 0.5 W/person is sufficient for larger and brighter venues with more uniform sound.
However, the new amplifier still could not solve the main problem of this hall – the reverberation. The sound was still mushy and unclear, even though the organizer made a few attempts on equalizing it.
A.3.2. SPEAKERS ARRAY
A year later we decided to try speakers array instead. Bose L1 was readily available for rent, and with only two of them at the opposite walls, slightly turned away from each other, the sound changed quite dramatically. At the very first milonga quite a few people in the audience commented on the improved clarity of the music. As much as I could clearly hear the artificial coloring that Bose added to the sound, and would’ve preferred to see there EVOX arrays instead, it was obvious that for this particular hall Bose arrays win by large margin over our previous, conventional system of six Yorkville speakers and EV amplifier.
However, sound arrays defy the conventional logic in placing the speakers. Our original placement had two problems. First, because arrays have both long “throw” and very wide horizontal angle, several “sound pockets” were heard on the dance floor, even though we slightly offset and turned away the speakers from each other. Also, when array is placed right on the edge of the dance floor, in its close vicinity the highs become too prominent. Both problems were solved by placing the arrays on the stage. The sound field became noticeably more uniform, both in the level and the spectrum. Now, however, the stage itself responded with a rather nasty resonance somewhere below 50 Hz. This problem was easily resolved by cutting 50 Hz band and slightly boosting 100 Hz band on the DJ EQ. Also, gently slopping down the high end of the spectrum, from 10 kHz and up, helped to tame the electronic coloring of the sound.
A4. Pittsburgh Tango Marathon (200 people capacity)
The main hall at Wightman School in Pittsburgh spelt nothing but trouble for any PA engineer. The high, arched ceilings would happily produce rather resonant response to any conventional speaker system in any configuration, even though the “ceiling” was obviously acoustically treated by itself. Luckily, the hall had a stage, and, if I were asked for a solution, I would certainly recommend Bose L1 or a better pair of active sound arrays, with not-so-long extensions, positioned in few meters from each other and pushed a bit back from the edge of the stage.
However, the hall already had a permanently installed PA, and what a PA it was! If you look at the photo, you would see rather a strange whitish ball, hanging straight from the ceiling, and this ball was the only sound source in the venue. The sound was crisp, clear, and even though it lacked a bit in the low end, there was not even a shadow of reverb. As it turned out later, this strange ball, called Soundsphere 2212-1, was engineered back in the 70s and was quite popular at disco clubs. At 200 W RMS the sound level was more than sufficient to cover the venue, and had quite a bit of headroom as well, as we all clearly heard, after a mishap with a microphone. However, it should be clear that either the original 2212-1, or the modern Q-12A (250 W RMS) model, should only be used in the rather high ceiling, squarish (not too oblong!) halls, with a surgically precise placement. For the perfect sound quality, I would have augmented the installation with sub-woofer, set at 80 Hz cross-over frequency, and well-balanced with the main speaker.
B. Contributed Case Studies
If you have your own case study that you would like to share with everyone, please send it to elespejero at gmail dot com. I will publish it ‘as is’, under your name and with a link to your FB or other public page. Do specify the name of the milonga, the size, the shape and other relevant characteristics and problems of the venue, the equipment that you have used and any other tricks that helped you to solve your problem.
B.1. Large Venue (150+ capacity): Lithuanian Embassy in Minsk
– Contributed by Aleksey Doro
This is a once-a-year event held by the Lithuanian Embassy, with 150-170 people attendance. The hall with high (12-15 meters) glass ceiling is divided across long walls into three sections by the pillars. The left section is occupied by a staircase to the second floor. The dance floor with chairs around it is in the middle section. The bar and the tables are in the right section.
Last year PA consisted of conventional active speakers and so, the reverberation off the glass ceiling was quite prominent. This year the embassy has acquired two new speakers arrays, MAUI 28 MIX by LD Systems. I placed one MAUI under the stairs, 2-3 meters from the dance floor, the other one – right near the staircase, one meter from the dance floor. That is, both speakers were at the long edge of the dance floor, not in the corners. There were no walls near the speakers, only the staircase with wooden facing.
With the above speaker placement the sound was great both in the empty and in the full hall. The bass was very prominent compared with the conventional 12″-15″ speakers. Very handsome and animated indeed, instead of a usual, dull boom-boom. I accidentally turned on “Another one bites the dust” by Queen and wanted to repeat it over and over. However, that was the second attempt at placing the speakers. The first one, with one speaker at the glass wall had much dirtier sound.
The sound was well heard in the bar area even though the speakers were running at 2/3 of full power.
There was only one problem with the sound. The speaker at the edge of the dance floor seemed to have too much treble content for the dancers, who were passing close to it, in the outer ronda. This particular array is 3-way, e.g. it has a sub-woofer, an array of mid-range drivers, and a separate tweeter at the top. This tweeter was the closest to the ears of the dancers, producing unbalanced sound, however, the sound field would even out around 2 meters from the speaker.
MAUI has very narrow vertical dispersion, but also quite wide horizontal dispersion, 120° instead of conventional 60°-90° angle. There is a newer, and quite different in terms of its features model of the same speaker, MAUI 28 G2.
B2. Large venue (150+ capacity): mobile center cluster
The description of this, rather unique for tango realm sound system first appeared in Tango DJ Forum. I have contacted the author, Gregor Tango Nada Mas, with a few additional questions, and then put together the answers into the following case study.
May I introduce my approach to the question? I prefer a central position of “good” speakers. In my opinion, “good” means a speaker, designed for performing acoustic music, like tango or jazz. The main advantages of a central speaker position:
- You have the shortest possible distance between the dancers ear and the speaker. This ensures the highest possible amount of direct sound (or minimal reflections).
- The loudness variations on different locations on the dance floor are minimized.
- The sound is at the right place. You have the maximum on the dance floor and it is (due to the distance) more quiet sound in the seating area.
The setup was done in February for a tango weekend in Austria. The system was constructed of six Tannoy Power V8 speakers and two Tannoy VS10BP sub woofers. And yes, it should be a task for the organizer, but I prefer to use my own equipment. I bought the equipment used and it was about 10.000€. If I would by an equivalent system new I have to calculate an amount between 20.000€ and 25.000€.
The rigging (including a check by a certified person for the insurance) was 300€ for the weekend. I asked for 500€ for equipment, mounting and evaluating the parameters for the room correction. But the price is only one side of the medal, time is the other. To be honest, I have to confess that it took me 10 hours for this construction to work in a way I was satisfied (4 hours for mounting, 6 hours for measuring, listening, redefining the filters in several loops). This makes only sense if it is a system for a tango weekend.
I usually calibrate my sound system to DOLBY-Standard – that means I try to establish a level of 82 dB (A) with pink noise on the the outer lane. But it makes sense only if the software player supports either ReplayGain or EBU R128 loudness normalization. The crossover frequency for the sub-woofers was set at 90 Hz. The room calibration software was combination of several software products (including some self-written routines). But I use RoomEQ-Wizzard, FuzzMeasure, Accourate and for the filters bruteFIR. The hardware is simple – I use Raspberry PI (Version 2) with the digital sound card by Wolfson. In February I used my “old” setup. It was basically a two channel approach. In the meantime I switched to an 8 channel version every speaker gets its own signal.
And a few notes on the sound quality. When I played in Meggengofen, Austria, I got a spontaneous applause after the first tanda, OTV instrumental from late 20s. Also, in summer I was DJing in an encuentro in Slovenia and I did a pre-milonga. All dancers kept their seats afterwards and I was playing two hours of classical music. They simply refused to go.
C. Recommended Readings
- G. Davis, R. Jones, “The Sound Reinforcement Handbook“, 2nd edition, 1989
- Column PA Systems , SOS magazine review, 2012
- Best Passive DI boxes, Gearank magazine review, 2016
- Speaker Position, Astral Sound, 2003
- Unsafe at Any Height, Sound Solutions
- Amplifier Damping Factor, EAW, 2017
Version 1.32, last updated 2017/12/14