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jngggggggg View Drop Down
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    Posted: 02 April 2018 at 6:04am
this is a very general question - is it a correct statement to say that:

if a BR speaker system is placed in a specific room and as a result, encounters room effects (generalizations here), a horn loaded speaker system in the exact same room and position will result in more severe rooms effects?

Im thinking things like phase cancellation, reverb/echo-ey sound etc. - due to the large throw and directivity of the horn system

i ask this because i am considering a horn deisgn for my subs in a 4 way system that may be deployed in small venues from time-to-time (~150 person)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 10:10am
Yes, a horn loaded system will experience more severe effects.

The issue isn't one of 'throw' or 'directivity', it's rather that the walls of the room contribute to the efficiency of the horn in the same way as stacking horns together does, so a boost or null of 6dB in a reflex system might be 12dB in a horn system (numbers for illustrative purposes). -10dB being half as loud, the variance in a system that goes +10dB in some places and -10dB in another would be 1/4 volume, which as you can imagine is impossible to ignore and difficult to compensate for, especially if you have well distributed HF.

'Throw' is a very unfortunate word to describe the behaviour of a sound system, because it implies the system is somehow picking up the wave and redistributing it to the back of the room, and the waters get muddied from the heaps of anecdotal reports of horn loaded system operators describing their rig doing exactly that (bass in the car park but not much in front of the rig, that sort of thing), but that's a description of the effects I mentioned (plus obviously in the car park you only hear bass so that exaggerates the effect even further).

What system were you considering exactly and for what applications?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 2:19pm
Originally posted by jngggggggg jngggggggg wrote:

this is a very general question - is it a correct statement to say that:

if a BR speaker system is placed in a specific room and as a result, encounters room effects (generalizations here), a horn loaded speaker system in the exact same room and position will result in more severe rooms effects?

Im thinking things like phase cancellation, reverb/echo-ey sound etc. - due to the large throw and directivity of the horn system

i ask this because i am considering a horn deisgn for my subs in a 4 way system that may be deployed in small venues from time-to-time (~150 person)

Insert Universal Audio Answer #1 Here.

AKA, It Depends (© I. Beaver 1908)

At frequencies where the horn has better directivity than the BR system (ie mids) there may be LESS interaction with the room as the sound from the horn might not spread out as widely.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jngggggggg Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2018 at 3:07am
Hemisphere, thanks for the detail. Much appreciated.
in your explanation, can you elaborate on what you mean by 1/4 volume? all else seems to make sense.

I am considering hogs on bass, MA215mk3 on kicks and midtop design to be confirmed (likely add tweeters in future).  i guess this discussion could also be extended to include the midtops but one thing at a time Wink

i often second guess myself on whether a 2 way BR system would be better than the above. seems less complicated and smaller design, but my #1 concern is fidelity.

rooms generally will be 150-200 persons with the off 200-300 persons
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2018 at 7:44am
I mean it would be perceived by the listener as 25% as loud in one place than the other place. 10dB is generally considered a doubling or halving of perceived volume.

Personally I'd say that even if your number one concern is fidelity, reflex should be considered very seriously. A well implemented reflex system can be about as hifi as it gets.

What's changed in particular since Speakerplans and the bulk of online DIY speaker culture was developed (along with much of the collective knowledge that culture has created and archived), is the availability of frankly monstrous reflex drivers and seriously cheap capable Class D Watts (Behringer iNuke NU6000 ie).

That's changed the old dichotomy between 'loud/efficient horn loaded system' vs 'huge inefficient/relatively quiet reflex system'. It's now possible on a practical budget to build a reflex system approaching the SPL capacity of a horn loaded system, but more practically scalable for small gigs and more reliable performance in small and odd shaped venues. 

If you play outdoors much or you have an audience/genre that demands extreme bass levels then horns are still worth looking at, but for 150 capacity average indoor gigs, especially if you're playing at different indoor venues all the time, reflex will probably serve you better. 

I think part of the reason a lot of systems opt for horns is that there's more of a 'colour by numbers' feel to the established horn designs. You know where you stand with a Hog, or an HD15, they're 'known entities'. There's one optimised way to build them and clear recommendations of suitable drivers. If you decide to build a reflex system it can feel harder to differentiate between available design options and settle on the best choice.

The optimal reflex system is rarely represented as a free plan because the highest performance reflex drivers are really expensive and considered inaccessible to the average DIYer. Most of the free reflex plans are designed to be flexible across a wide range of drivers, so to get a reflex system that can realistically compete with a horn system for output you first of all need to spend a lot on drivers and second you need to develop your own design for them, which isn't as hard as it sounds but isn't easy either.


Not cheap at 430 quid, but if you can source an amp with ~5000w per channel to drive them you could get 138dB at 44Hz in a 220 litre 2x18" reflex enclosure. You'd be hard pushed to find a horn system that can compete favourably with that for all round size/weight to performance ratio and system flexibility, but for cost/performance, horns win always.


Edited by Hemisphere - 03 April 2018 at 7:45am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jngggggggg Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2018 at 4:34pm
I also am trying to spec a system that can play flat to 30hz. I know a lot of people advocate that this level of lf performance is unwarranted and not necessary but it's something I believe to be necessary for our type of sound and following
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mini-mad Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2018 at 6:04pm
It's not that it isn't warranted, it's just those extra 10hz of depth you want will add hundreds of £££ to the price stage of your system for the sake of " I want it a little deeper"

You're more then welcome to build/buy a system flat to 30hz.... it's just by no means should you delude yourself that this will be a cheap exercise

If it sounds like a gorilla is trying to escape, turn it down.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2018 at 7:02pm
Well a stack of Hogs can get close enough to 30 for most purposes, but for 150 people a true 30Hz hog stack would be overkill.


That's the sort of frequency response you can expect from a Hog. 30Hz point is -10dB. A couple of them corner loaded might approach -3dB and would be more than enough for your needs. If you felt otherwise afterwards you could build more. Flat to 30 you would need like 8 of them.

That said, the Hog scoop only plays to about 130dB in that sim. A beefier driver might bring it up a few dB, but reflex is still a legitimate option in that case with many benefits. A BMS 18n862 system, 330 litre 218 enclosure with 3000w driven into each driver would offer 134dB at 45Hz, 130dB at 30Hz.

The cones would be moving 44mm peak to peak in that arrangement, which believe it or not is within the low distortion excursion capacity of that woofer (having a 'true' xmax of 19mm, or 23mm by standard inflation) if you designed the enclosure such that the movement of the cones was clearly visible in operation, that would make for an impressive visual spectacle. On the more esoteric side of things, the timbre of a cone moving that much air while reproducing music gives it's own edge to the sound (which you may or may not find desirable).

Of course the 18n862 could be loaded to a Hog as well with silly results, but the question is, do you actually need that for your 150 capacity crowd? 

A two box system of single 18" 165 litre reflex bins, driven by a single NU6000 to 128dB peak SPL (134dB total system output or 140dB corner loaded) with -4dB at 30Hz would be a really solid starting point for a high fidelity system that plays low, and could be expanded as necessary. You could have four of those bins or two doubles in a space 35-40% smaller than a pair of Hogs, and achieve similar SPL levels.

The other advantage of a reflex system like that is that it's much more rider/rental friendly if you ever want to do basically anything with it other than your main application. Wouldn't it be nice to be able to pop a couple of compact single 18" bins and some monitor/midtops in the back seat of a car and do something casual with them once in a while? You won't have that option with a Hog system.

Edit: The system proposals I'm making are really 'best case scenario' ultra-compact options. You can buy two high quality 18" reflex drivers for the price of the models listed and achieve similar SPL or a few dB more, but it would take up twice as much space. At least. If not 3 or 4 times (cheaper drivers tend to prefer bigger reflex boxes, but they are more efficient). It depends what your priorities are and if you would stand to gain anything from a truly portable system or not. Those single 18" bins would be between 1/4 (B&C 18DS115) and 1/3 (BMS 18n862) the size of a Hog scoop.


Edited by Hemisphere - 03 April 2018 at 7:43pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jngggggggg Quote  Post ReplyReply Direct Link To This Post Posted: 04 April 2018 at 5:00am
damn Hemisphere! you make a guy question - why would anyone in today's world pick a horn over that!! hah
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 04 April 2018 at 7:04am
Well, I've made a very one sided argument to try and illustrate that a reflex system can go low and loud, but a horn system can go just as low and much louder, with the same amount of investment in drivers (and it can go quite a bit louder even with a much smaller investment in drivers), if that's what you require, and the box size isn't an issue for you. I just don't believe even half as many people require that as think they do.

Neither of the drivers I mentioned are optimal for the Hog Scoop, but they certainly go loud so I simmed them anyway, and they both deliver 135dB in half space, 146dB corner loaded. With a single 18" driver. (they don't do much below 35Hz though, unless you have a big stack).

Reflex with the same driver is 134dB corner loaded, so the Hog is more than twice as loud, and for 500w less amp power. If you're running outdoors on a severely limited genset and need to power 8 cabinets, or maybe you only have access to a single 13a outlet in a venue (which certainly happens!), being able to go 2dB louder than the reflex equivalent with just 10% of the amp power is a big deal. That can make the massive cabinets and accentuated room modes worth it. 

You can save a lot of money on drivers and you can save a lot of money on amps, but it's always a trade-off.






Edited by Hemisphere - 04 April 2018 at 7:20am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jngggggggg Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2018 at 4:03am
is there anywhere i can read more on types of room effects that one may encounter indoors. as you suspected, we do not have a "home" venue and as such, are always on the move. horn systems may expose us more to unmanageable rooms where us newbs cant tech the room correctly. ive heard of terms like cancellation, nodes, delay, reverb but know nothing of them - the saying of "quiet up close but going off outside" seriously worries me - i havent found any good sources to reference on room effects.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2018 at 10:13am
Cancellation can be very severe in a worst case scenario, and it's rare to encounter a worst case which can't be ameliorated to some degree by repositioning the rig, but it does happen, especially in pubs or other small venues that were never designed with stage acoustics in mind.

Think of each wall, ceiling or floor of a room as being a mirror for the sound in the same way that a smooth metal surface is a mirror for light. If you shine a red, green and blue spotlight at mirrors in the right positions they will reflect and combine to form a white spotlight, right? If you shift the mirror angles a little then some will remain white and the rest will break up into component and composite colours. 

The thing with sound is that the waveforms have a phase - an up cycle and a down cycle, so when they combine, unlike light, they don't always form a boosted signal. If the waveforms are sufficiently in phase when they combine after reflection then the sound is boosted. The peak of the reflected waveform combines with the peak of the original waveform, and the trough with the trough, and so it partially amplifies the signal - optimally by as much as double the original energy, or +3dB (in the case of a reflex. +5 or 6dB in the case of a horn, and that's what makes horns more volatile. Twice as volatile, basically).

When things really go wrong - total worst case scenario - is you have the combined forces of the walls, floor, and ceiling of the room all contributing to an 18dB dip in one place, and an 18dB boost in another (not sure if that's the exact number but it'll be in that ballpark), which is something akin to ten times the percieved volume in one place vs the other. Bass that's ten times quieter may as well not be there at all, and that's exactly how people perceive it when they walk around the room. You'd really need to work to make a room that bad, but you could easily hit 3, 4 or 6 times quieter bass with a horn loaded system. The Fletcher Munson 'Equal Loudness Contour' accentuates this effect. Due to the sensitivity characteristics of the ear, quieter bass is perceived as being even quieter than the actual dB level would suggest.

If you put a system in the corner of the room you've got a strong chance of boosts from both walls. There are way more possibilities to do it right than to do it wrong, and I'm making it sound much worse than it really is. These extreme peaks and dips won't be over vast areas, but if you're really unlucky they can certainly end up over critical areas (right in front of the stage ie, or by the bar or somewhere else which is consistently densely populated).

If the system has the bass headroom available, and horn loaded systems in small venues often do, the system operator or DJ might then attempt to compensate for the dips by EQ'ing up the bass, creating extreme boosts in other areas (like the rear of the venue or the car park, where the HF and mids are naturally attenuated) which aren't pleasant either (although to be honest I quite like them and if I came across one I would probably sit in it for a bit, but that's just me, I'm not normal, and my ears have paid the price for this).

Reflex systems aren't free of these effects, but they're approximately halved.

I'd recommend reading through this whole thread: https://forum.speakerplans.com/sub-placement_topic100807_page1.html

Charlysays was having issues with peaks and troughs with his Cubo system and he links to a number of Void Acoustics papers that discuss the issue in some detail with graphs and room simulations etc.



Edited by Hemisphere - 06 April 2018 at 10:35am
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