K10 vs. K12 -- "Throw"

Technical assistance and general Q&A about QSC's loudspeaker products. These include AcousticDesign and ISIS non-powered loudspeaker systems, as well as the HPR, K, and KW Series powered loudspeakers.

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Thu Apr 08, 2010 11:14 pm

  • I currently own a pair of K10's for a couple weeks and done several shows with them. I have them each above a Yorkville dual 10 ls700 sub. Fantastic sound!

    The only issue I seem to be finding is the lack of throw with these speakers. They sound great within the first 40 or so feet from the stage but the sound really doesn't travel. Is this simply a give and take with spread? a 90 degree spread hampers the distance the vocals travel.

    If I am looking to do larger events would it be within my best interest to move up to the 12s? These are listed to only have a 75 degree spread.

    Thanks for any input,
    Paul
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Fri Apr 09, 2010 9:44 am

  • MetroPAULitan

    Thanks for your post.

    Usually when I am asked about "throw", the questioner wants to know how to make the sound louder at the rear of the room. This is about the best definition of the term I know since there is no standard way to measure "throw". You never see it on specification sheets.

    Sound travels from loudspeakers in a very predictable way. Outdoors, the sound will decrease by six decibels (6 dB) for each doubling of distance from the loudspeaker. If I measure the sound level at 5 ft at 106 dB, at 10 ft it will be 6 dB less or 100 dB. This is caused by the inverse square law and ALL loudspeakers behave this way no matter what the dispersion angle of the high frequency horn. The chart below shows this effect. The example does not represent any specific loudspeaker, just the relationship of level vs. distance.

    OUTDOORS
    Distance___Level example
    5 ft_______106 dB
    10 ft______100 dB
    20 ft_______94 dB
    40 ft_______88 dB
    80 ft_______82 dB
    160 ft______76 dB
    320 ft______70dB and so on

    In an enclosed room, the reflections off the walls of the room will add to the direct sound of the loudspeaker for less loss with doubling of distance.

    So what does this decibel thing have to do with how we perceive loudness?

    To the human ear listening to music or speech, the smallest change in volume we can perceive is about 3 dB. The chart below shows our subjective perception of level in dB.

    Perceived level change using program material (music)

    Level Change___ Power change ________________Perceived change
    3 dB___________ 2 times or 1/2 power __________smallest change we can perceive
    6 dB __________ 4 times or 1/4 power__________ very noticeable change in volume
    10dB _________ 10 times or 1/10 power ________Twice or half as loud

    The difference in maximum rated SPL between our K-10 and our K-12 is 2 dB which according to the chart above may not even be perceptible to the human ear. So how do we increase the volume level at 40 feet?

    One way increase volume would be to add more power to the loudspeaker to double its' perceived output (10 dB). We will need to change the total power available from 1000 watts to ten times that or 10,000 watts to make the sound seem twice as loud. We could also increase the number of loudspeakers by a factor of 10.

    A better way would be to reduce the distance from a loudspeaker to the listener by placing delayed loudspeakers at 30 ft to support the sound from the stage speakers.

    I expect some questions on this relationship so lets post.
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Fri Apr 09, 2010 11:12 am

  • Afterthought on the above post.

    To understand this dB thing, take a look at your mixer's meters. They are calibrated in decibels. The sliders are sometimes calibrated in dB as well. Listen to what happens when you make a 1dB, 3dB, 10 dB change on the meters or sliders when listening to music. This can really help you get your head around what the dB represents to our perception.
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Fri Apr 09, 2010 7:32 pm

  • I appreciate all the information that you have listed above. I have just found that some speakers are labeled as long throw and some speakers are labeled as short throw. Trying to find if those labels had any merit.
    I tried the K12's at the show yesterday and found that at the same location the vocals were more discernible than they were with the K10's. I actually found myself turning the vocals down from where I had them the night before in the same location.
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Sat Apr 10, 2010 4:12 pm

  • The throw of a speaker is the distance the voice coil travels in the magnet.
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Sun Apr 11, 2010 3:24 pm

  • Historically, a "long throw" speaker was one with very narrow dispersion (40 degrees by 40 degrees perhaps ) that was aimed at the balcony from a procenium array, and was never meant to provide sound to the audience in the front of the venue. This type of speaker is seldom seen in today's systems.

    This achieved the same result as placing a second loudspeaker closer to the listeners in the balcony which is the solution I suggested in my first answer The 40 degree horns were not broadband devices (no lows) and were used mostly for speech intelligibility.
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Mon Apr 12, 2010 1:50 pm

  • nigelwright7557 wrote:The throw of a speaker is the distance the voice coil travels in the magnet.


    Actually, that's correctly called "excursion."
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Mon Apr 12, 2010 9:36 pm

  • [quote="Bob Lee"]The K12 has a 75° dispersion angle, so if you're used to working with loudspeakers that have significantly wider or narrower coverage, you'll have to adapt your setup. Loudspeakers with narrower coverage angles like the K12 will usually seem to "throw" or "project" further by concentrating the acoustical energy somewhat, although with some practice you can often also use wider-angle loudspeakers and primary reflections off walls and ceilings to get the sound out over a distance. Be sure to get your loudspeakers up high enough so the sound isn't buried in the audience.

    This was on another forum post but this is a direct example of my original question. The difference between 90 degree and 75 degree might not be much but it is a difference in throwing distance. A speaker throws the same amount of energy. It's just which way. Is it left and right or is it forward.
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Tue Apr 13, 2010 6:21 am

  • So, to continue this conversation. How would one use the K12's in an Outdoor situation or a large room? Is there an easy solution to spread several of the K12's around the "field" and handle any delay issues? How? Details?
    Cheers,
    Alan Vance
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Tue Apr 13, 2010 9:06 am

  • metropaulitan wrote:The difference between 90 degree and 75 degree might not be much but it is a difference in throwing distance.


    It's not so much a matter of distance as it is of relative intensity. The sound energy doesn't end at a certain distance; it continues on but spreads out, decreasing in intensity just as the Inverse Square Law describes. Joe described it very well earlier in this thread.
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Sun Apr 18, 2010 4:33 am

  • Hi

    I'm in the market for a new PA and seriously interested in the K-series. I didn't find any retailer in my area able to demo them. I'm quite confident in the people who recommended the system, and in QSC as a brand, so I might eventuallly order a set blindfolded, but need some of my questions answered, and this is indeed one of them: the "throw".

    I am familiar (being a sound professional with 30 years of experience (and a broken back, hence my interest in a smooth sounding, lightweight system)) with the basic physics of sound, so the above explanations are ok for me, except that things are quite a bit more complex than that, IHMO. On paper, everything is cool, but the original poster's real-world observation does make sense to me: some speakers "throw" further than others, it's a phenomenon I have observed many times, and it's a main concern for smaller bands with simple PA's that cannot afford to have a separate system for each type of venue.

    Still, I'm a bit puzzled: metropaulitan, when you say your K10's don't reach over 40 feet, could you please elaborate? That's amazingly short. The old HK Audio Lucas 1000 I'm planning to replace with a K sytem does exactly that and that's just what my problem is: cool, smooth , non-agressive sound, quite hi-fi really (I hate the agressive mid-highs from most amplified plastic boxes) but is totally lost beyond 30/40 feet. But the Lucas is an older conception, and has a 3/4" HF driver, 8" MF driver, 200 watts tops; a single 600W 15" LF sub, and very agressive limiting which definitely helps to protect the speakers but ruins the sound. What sort of program material are you playing? What are your expectations? I hope I can expect (much) better from this modern, state-of-the art 4000W QSC system? I don't need ear-shattering, ground-shaking volumes at 100ft in open air, I'm looking for well-defined, well-balanced sound with good percussion in the bass for a alround pop-rock pub/function band that does 50/50 open-air/indoors gigs. Typically, outdoors, people dance in the 30-40 feet front area, and sit down an have a drink while listening in an area 40 to 100 feet from the stage. I want the sound to remain clear and well-balanced in that area too. I guess it's a quite standard situation, and expected the K-Series to be just perfect for this. In addition, the system should be confortable for the audience in indoor venues like pubs and bars where we are much closer to the public.

    I initially thought that 2 K10's (and 2 KSubs) would cover this all. (I was quite sold on the K8's because of the wide dispersion angle, especially for pub/bar indoors gigs, but thought that for the typical outdoor gig I'd need to crank up the volume a bit to high and risk feedback due to the possible overlap with the stage area) But if what you say is true, and we'd need to add an additional delayed pair of K10's to go comfortably beyond 40 feet, I will need to change my mind.

    So, what system to consider now? I'd appreciate your advice!

    Thanks
    Dirk
    PS outdoors, I can eventuelly fly speakers up to 4 meters (16 ft) high
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Sun Apr 18, 2010 9:36 pm

  • Loudspeakers don't "throw" further than others except by putting out more SPL. Loudspeakers follow the same laws of physics that everything else does! IMHO, even the word "throw" ultimately leads to misunderstanding of how loudspeakers behave.

    As I mentioned before, what is commonly misunderstood as "throw" in terms of distance is actually all about relative intensity. The Inverse Square Law shows us that SPL decreases 6 dB with every doubling of distance. That's because the energy in the sound wave, at 2× the distance, is spread out over an area 4× as large. When a loudspeaker puts out an SPL of 126 dB at 1 m, the SPL at 2 m will be 120 dB; at 4 m, 114 dB; at 8 m, 108 dB; at 16 m, 102 dB; and at 32 m, 96 dB, and so on. This relationship will carry on indefinitely until the sound waves hit walls or other obstructions or until the SPL has descreased to where it's undetectable amidst all the background noise.

    If you boost the signal to the loudspeaker so that it puts out 129 dB @ 1 m, then the SPL at all those points I mentioned above will increase by 3 dB as well. Conversely, if the signal is decreased so that the loudspeaker puts out 120 dB at 1 m, then the SPL examples above will all decrease by the same amount, 6 dB.

    It's often valuable to be able to direct acoustical energy to where you need it and decrease it where you don't. That can help you get better, deeper coverage with fewer problems taming reverberation.
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Mon Apr 19, 2010 2:30 am

  • Thanks Bob, I knew that already, but I appreciate your input.

    I do think that indeed the impression (note the term) of "throw" is closely related to 1: the acoustical properties of the venue 2: the wideness of the dispersion pattern and, to a lesser degree the behaviour of the enclosure outside it's nominal dispersion area. The conical dispersion of the K-series, despite being an interesting option, might not suit all venues especially indoor venues with reflective floors and low ceilings. Compared to more classic 90°x40° HF dispersion patterns, the level of floor, walls & ceiling reflexions will disturb the direct sound closer to the enclosure, hence a diminution of the "comprehensibility zone", interpreted as "lack of throw".

    The K-series have a VERY wide vertical dispersion in all cases: even the narrowest K-12's 75°angle is almost twice as open as a conventional 40° horn. I guess that is something to be considered.
    It's all about the difficult compromise between sound quality, especially smoothness in the mid-high range and even frequency response off-axis, and versatility.

    Correct me if I'm wrong!

    Dirk
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Wed Apr 21, 2010 2:24 pm

  • I used my 4 K12s for FOH with a room capacity of 300. I put two K12 with 18 subs at the front sides and 2 K12 at the middle sides. The K12 were mounted on stands that literally lifted them above the people around. I had a favorable result and with regards to covering the area but I lack the impact of having a frontal throw. I had no choice because a projector screen and a band set up which had another PA system with them cover the front area.

    I tried having two K12 speakers per side and they have accomplished what I wanted the audio to be.. The output of the speaker will greatly depend on how you will use them... Having a height advantage will help in giving a longer and even sound to the crowd. The more speakers the better sound. You don't have to crank it up in order to be heard at the back.
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Thu Apr 22, 2010 4:20 am

  • ishowcebu wrote:. I had a favorable result and with regards to covering the area but I lack the impact of having a frontal throw.


    Maybe because you didn't time-align them?

    Dirk
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Tue May 04, 2010 10:16 am

  • If I turn the speakers more to the center front, it will hit the screen on one side and the band set up on the other. I had no choice for that matter. The whole area was cover with white cloth for lighting reasons and the decor on stage did not give me any space to put my speakers there as well. That would have been the perfect location, side of the stage or I could have flown the speakers to have a better "head room" hehehe.. but they love the sound of my system a lot better than the band's audio system which kinda had problems along the way.

    That room might need 4 units KW153 with 4 subs for corporate launch or band set up. I normally use 3 per side using Mackie 1530 speakers(6) with subs(4). I like the sound of the Mackie 1530 more than the HPR 153. I hope the KW 153 are better sounding when it is used at high decibels. The HPR 153 tend to make a strong harsh sound that wants you to move away from the speaker. I have no problem driving the K12s at high decibels :D .
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    set ups like this no speakers or any equipment visible.
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