Dear Romy and all,

I’ve been lurking here for a few months and - after a sceptical start! - I have found this site an Invaluable Help. Many many thanks to Romy and all involved. My system is now starting to sing and make nice noises for the first time in 15 years… but more about that another time.

My first post is to ask some advice. I’m about to start conversion of my barn here in rural England. Planning permission has been granted and engineers are about to be asked to design the footings (foundations). It’s a good sized room - 23 by 33 feet with a double-height open-vaulted roof.

The question - and I have to decide very soon. Shall I design in an underground bass horn – and if so, what sort. Stereo? Mono? Probably only going up as high as 30-35hz And where should the exits be. I’m assuming that the best positioning for my speakers will be across the short wall - about 3-6 feet into the room. I will have the option of hanging mid bass horns from the roof – time aligned of course. I am thinking of some underground horns that would exit either in the middle of the room or at the sides (slightly more awkward). Or should I forget about bass horns and just have some nice sealed boxed at line-arrays from floor to ceiling beside the big windows.

I’m not a bass freak at all. Actually I couldn’t care less! But this is a once in a lifetime decision and I don’t want to be digging up concrete and underfloor heating in a few years time!

Opinions would be most welcome…

All best wishes

James

Actually it is very interesting question and I almost feel you pain for decision you will be making. I do not think that anyone would be able to express any arbitral opinion about the subject, as least an opinion that worth to follow. You see, building such a system is a self-contained creative process and it I will include many wrong decisions that you most likely will be dong. Those wrong decisions are perfectly normal and not one will underused your “mistakes” accept you. Navigation sound in that that type of installation is a process of DOING THE THINGS, then observing the results and REACTING UPON THE RESULTS. I do not believe that there are people who can foresee the results in this type arrangement as you are planning to build. I will pass some of my very general observations but please take them with certain skepticism. First of all I never built those types of installations and second: I do not fell that any generalizations in your case worth consider as a “doctrine”.

Generally I do not believe in bass horns. There two major reasons (there are some minor as well): time alignment and the bothering me “closed bottom”. With time alignment is simple: I just do not know how to delay a full range signals to synchro it with a few milliseconds of delay that happens in a bass horn. The second reason is more complicated. The sealed enclosure I call “opened bottom” enclosures. What I mean is that there are no conceptual limitations in lower response. The limitations in sealed box are tactical: how much power you have, how much your drivers will handle, what is the relation of volume and Fs, how driver damped by amplifier and many others. However, there is no self-restricting boundary in there. With any other LF solutions (horn, open baffles, 4th order, ported and so on) there are always strategic limitations by nature of the design… would it be size of the baffle, size of the mouth or tuning of a port). With sealed box you can always burn some power, use the LF section on transition slope or even EQ (with open bottom only) your bass (works very well). With any other solutions (besides sealed box) those “further actions” are not available. Those are some of my motivations why I do not like the idea of bass horns and prefer the sealed enclosures

Saying it I have to add that the “recommendations” would also vary with the level at witch you target. If you look to get a pressure rising at LF (it is hoe most of the bass horn sound on bad hand) then any bass horn will do. It is very easy to get that “sewer pipe type of bass“ from a bass horns… the question what to do next? No one knows. The Morons are deaf do not recognize that they have that “sewer pipe type of bass“ but even when the do  recognize then who the hell know how to fix it? Not to mention that fixing implies a large cement mixing machine and a wasted half of summer. Sounds like a plan for actions, doesn’t it? Sill, I have to add that if the bass horn and a sealed enclosure are done IDENTICALLY PROPERLY then for the SAME FREQUENCY the bass horn do sound better.

Saying that I do admit that you are absolutely correct saying that it is a lifetime decision. You will never do it twice and therefore here is the rational that I would consider if I were at your place: I can always threw a pair of sealed arrays in my listening room, however I will not be able to add bass horn AFTER I made my barn conversion. So, you might find a reason within yourself to go for bass horns and if the bass horn direction will not deliver to you the results that you would like THEN discard the project, make a good sauna in those horns and put the sealed array into the game. A intestinally do not expires a direction I would go personally if I were you – it will be your call.  However, I will give you some point for both directions.

Sealed array will work ONLY across a long wall. While thinking about the arrays and the drivers think about amplification. The amplification-drivers interaction in high-quality dedicated LF sections sis very much under-looked area. Consider multi-sectioned arrays with one driver per section. This also economical as you might start with less sections and then pile them up as you find it necessary. The arrays must be positioned outside of your MF sections.

In case of the bass horns let visualize what we deal with. If for instance you go for 25Hz horn with 18” throat then (for tractrix profile that you would likely NOT wiling to use) you would need roughly an exit area of 150000 sq cm, which is a circle with 4.3m diameter or it’s square equivalent. The horn will be around 9m, with ~ 9mSec delay (depends of the temperature outside… unless you will thermo-stabilize the horns :-) Further, any serious solution implies use of TWO HORNS. The mouthed of the hone must be outside of your MF sections. You might position the mouths of the horns at the side’s of the barn and by doing it you will minimize the time delays. It is a VERY good solution but having 23 by 33 feet room you have no space to play with it is you do for 25Hz horn. The image below will give you an idea how it might be done:

However, if it delays might be fixed as it shown above then it will set the entire system to operate in far-field setting. You have to consider it and see is you like the far-field arrangements (I do not). Also, the position of mouths of the horns near a middle of the room and near the listening position do resolves the delays problem but at the same time do creates some other troubles.

So, as your see there are a lot of thing to consider. Not the last would be your thoughts about the rest of loudspeakers that will be using and how they will be integrated in context of your ether line-arrays or the bass-horns. I can only promise you what whatever decision you will go for you will be sorry.. :-) Nevertheless, there is a slight mercantile advantage to go for the bass horns. After you finish the project you can make some money by selling admission tickets into your barn to those crazy British audio-freaks demonstrating to them and to their wifes that … “it could be worse”…

Dominic wrote:

I'd put your sub horns above your head. There are some big issues with that but you save a lot on concrete engineering, and assuming space remains in future you could apply what you learned from the overhead wood horns to a more refined bass setup. Obviously doing it twice isn't perfect but the opportunity to get it right seems worth it. It might make some sense to try a foreshortened horn approach, ie large throat like John Dreyer's system here: http://aca.gr/pop_dreyer.htm I don't see a good way to avoid the far field listening position with a straight front horn, one can only hope to mitigate the distance a little bit. It'd be much better i think to shorten the horn from the back and lose a bit of loading than modifying the mouth and mangling the wave front. The science of the acoustics of subsonic horns in the context of an audio installation in an eclosed space is essentially undiscovered country. Several people have tried to do it but as far as i know they've all had major complaints, either of their own or by listeners. Either that or they depend on delay circuits; and still have complaints from purists. Everybody up to now has been experimenting. I keep wondering about what the horn faces, the size of the mouth often approaches other dimensions of the space, or is actually very close to the on axis wall/floor/ceiling.

The John Dreyer's solution is definitely very elegant but he went for a large throat to make the horn shorter. It is not a criminal action by itself but the question is: at which frequency this horn stops to act and horn and start to act as a direct radiator? To answer this it would be necessary to see where the horn stops to give 6dB gain… To measure it in context of a room and to filters out the room's mode is VERY complicated. The brilliant part of what John Dreyer did was that even when his horns stops loading the driver then he has a good line-array at the lower frequencies… Still, if I have Dreyer’s design in my room I would be wondering what kind drivers I might put in this horns. Using 5X515G I would have way better horn-bass but using 5X515B I would have way better direct-radiator’s, lover bass… So, go figure….

Johan Dreyer wrote:

What I need is a compression driver with a 3 inch throat that can do 100 -1000Hz.Forget ALE 126-It craps out at 500.

Johan Dreyer wrote:

Delays: My compression drivers sits in the mouth of the bass horn about 2m from the bass drivers i.e 6ms delay.I have tried but honestly cannot hear this. However moving the tweeters 1cm(0.03ms) is clearly audible.

Johan Dreyer wrote:

I call this the "pulsating room effect" Here there is a sensation of the air in the room actually pulsating to the sound.This is not boom but a sense of sheer energy being transmitted.Unlike music simply being played way too loud and being unpleasant this is simply an awareness of the power of a bass instrument and- more remarkable- the air in the recorded space being excited by the instruments(not only bass instruments).We have all heard how ,on a good mid horn , a brass instrument (especially saxophone or trumpet) can simply leave the horn and gigantically excite a room.Exactly like a live instrument next to you can startle by its sheer energy exciting a space( A Trombonist I know calls it "picking up the room").That is what happens on a basshorn too. Again I hear this effect in real life too. I think it is the horn matching the impedance of the drivers to the room

I know this effect but if it happen with bass horns then I do not call it “"pulsating room effect" but I rather call it “+1dB effect”. Some bass horns being placed in their rooms increase the density of pressure faster then the density of sound. It is bizarre concept of mine and no one understands it. Let try to explain it. Density and Pressure of tone has purpose and this purpose is described by artistic value of musical peace. With the expressive intentions of a given composition and the given interpretation there are always inner-reasons what density and what capacity of a note should be. In this case density, capacity and potency of a tone are almost the synonymous. However, not the Pressure. Pressure is an absentminded parameter that has relation to objective deviation of one volume over another but it has no relation to musical intentions. So, when you told that your have that “"pulsating room effect" across full MF range then I had no problem with it – it looks you are getting good sound out there. However, what you said that your have the same effect from basshorn I recognize it as a problem (your friend Trombonist with his "picking up the room" is very much irrelevant because he plays MF-HF instrument). The load a room with a dense, phase-perfect MF is wonderfully and we in a way experience it in “live” sound. (I said “in away” because in “live” sound we have also “space” and unlimited dynamics…., but it another subject) However, in “live” sound we never experience dense bass. Of course I’m talking about Sound of classical music, opera or any acoustic music not about the electrons surrogate).

You would argue, in fact you have said that you have heard this effect in real life too. However, who said the in real life we do not experience the problem with standing waves? The 30% of the sits in Boston symphony, partially near the walls and under the balconies have heavy standing waves problems and they crate that “pressurized bass” that I call “room clipping”. Take a string quartet and put it into a mid size rooms. Make then to play some rhythmic work, like Mozart or Hayden, and walk around them. You will see that at many locations cello will be not only louder but “pressurizing” with that “scuba-diver effect”. Sure it will be the “live” experience but will it be corrects? Not really. Those “clippings”, although they are “life” and “natural”, but they will take place NOT because the musical ideas but ONLY because the mechanical room-condition overriding the Sound. It is not good….

So, what from my point of view what be a duty of a properly performing lower basshorn? A basshorn should pressurize the room and create an environment that allows the MF to be “floated” ATOP of basshorn’s pressuranization. Thy basshorn’s out should act like a high density liquid that would permit the low density liquid (MF and HF) do not sink and to fly freely in a room. However, as soon the LF begin to inflict a listener with own ‘"pulsating room effect" then the value of LF should be minimized (at lest for the given listing position). John, try to reduce LF on your system. I know it is difficult to spend so much efforts and do not hear it. Furthermore you for a week or so will be experience some deficiency of LF. However, you will soon get use to and might dustcover that it does makes sense to keep it down, 0.5-1db below the moment when the "pulsating room effect" from basshorn will manifest itself. The only problem is that moving 6 feet away will change the entire setting for the  “+1dB effect”… 

Johan Dreyer wrote:

The delay thing is a problem.I hear delays higher up as drivers become audible as individual speakers instead of a whole sound.I do not hear this in bass.I think you may be right about the arrays.They may simply create a whole room full of sound that makes the above effect inaudible.On the other hand they quite clearly image left right and depth too so I do not know. But how to hear it? In setup I ran a sine wave at crossover freq through the system and watched the mic response(at listening position) on an oscilloscope figuring I should see 2 spikes in the reproduced sine.I saw none. This is probably nonsense but it made me feel better. I would expect to hear wide ranging instruments to "split in two"at the crossover, but I do not hear that either.Instruments not in one "space" i.e lower notes deep in the horn and the higher component out front? I have not heard that either.Never mind the old tap dance efffect of old WE horns.I think that only happens higher up.Bottom line :neither I nor my friends hear it so I stopped worrying about it. Maybe somebody can.Then I 'll worry again.

I still feel that you shell hear it. You presented a case of time misalignment - when the drivers heard as two deistically different sources. This hardly has to do with time misalignment and has to do with other reasons. The timing misalignment could not be heard this way. The Haas effect and many other things will mask it out. The way to hear the misalignment is to observe imagine and stoppage of decays (Whatever I say in this paragraph is about misalignment in LF, in the HF the misalignment is very simple to spot). What I might suggest you to do is borrowing a digital delay machine. It is dirt-cheep (under $100 and up to 32mSec by 1 mSec) and you can even buy one. Do not expect to get any quality form them but you not need any. All that you need is to delay MF and to observe if the presentation of music will change. I presume it should… at least of was my experience….

wow. So much to digest here.

Further thoughts.

This is where I’m at.

1. It seems that I don’t have the space for optimum straight horns exiting directly onto the listening position as per Romy’s diagram. And besides, I like nearfield listening too.

2. The roof space needs to be reserved for the mid bass horns.

3. Yes. It’s a suck it and see question. I’m willing to go with my hunch, when I know what it is, and take the consequences.

4. One thing nobody has mentioned is using the room’s corners. Is this a no no? I’ve been trying use McBean to model a horn exiting into the corner – with a middle ‘mouth’ about 1m squared - and using a conical approximation as the room corner – with some nominal (very large) mouth size. Am I right that the corners are basically a conical expansion? But. McBean crashes with these numbers and takes my whole computer down with it. Quite dramatic really. Is this model at all relevant? I can’t see why not.

5. I’m becoming increasingly tempted to build some MORON horns. With a bit of luck, they might be useful. If not they can always just do the bangs and thumps for some ‘home theatre’ system that I’m unlikely to install. Last summer I pointed some 45hz tractrix horns at the corners and got good response down to at least 30hz. Setting the levels nice and low, I still got a very good ‘feel’ to the music. More ambiance and more space. Everything was moronic in this test so I should discount it. But I can’t help wondering…  

5. Digital delay. Yes, I know – a big topic. I’ve been listening recently to my UltraCurve 2496 through headphones used just as a delay. Digital in and Digital out. I cannot hear any change in sound at all. I've really tried. Luckily – but sadly – I’ve never owned any LPs in my life, so I’m not worried about an extra a/d-d/a in the chain. So I’m not ruling out digital delay completely . . . .

6. I’m worried. Romy – You say Line Arrays ONLY work on the long room dimension? Can you elaborate? Intuitively I can’t see why. And this was my Get Out Clause. This is worrying.

8. And another question. I’ve learned the slow way that funny mouth shapes and bends in horns really screw up things in seemingly unrelated parts of the audio spectrum. Is this still true of low bass?

Many thanks for all your empathy!

James

op.9 wrote:

One thing nobody has mentioned is using the room’s corners. Is this a no no? I’ve been trying use McBean to model a horn exiting into the corner – with a middle ‘mouth’ about 1m squared - and using a conical approximation as the room corner – with some nominal (very large) mouth size. Am I right that the corners are basically a conical expansion? But. McBean crashes with these numbers and takes my whole computer down with it. Quite dramatic really. Is this model at all relevant? I can’t see why not.

I do not believe in horn prediction programs. They are conditionally useful for MF but for bass they are completely bogus. My experience with various deaf idiots from AA (Bill Fitzmaurice, Wayne Parham and the rest of dirt) suggested that those horn prediction programs are crouch for brainless cretins who have no hearing or awareness to assess results and to act upon own senses. Also, would it possible the no one mention to your corners because with your objective of 20Hz -30Hz horn you are way beyond the dimensions of anything that could be called architecturally “ a corner”?

op.9 wrote:

I’m becoming increasingly tempted to build some MORON horns. With a bit of luck, they might be useful. If not they can always just do the bangs and thumps for some ‘home theatre’ system that I’m unlikely to install. Last summer I pointed some 45hz tractrix horns at the corners and got good response down to at least 30hz. Setting the levels nice and low, I still got a very good ‘feel’ to the music. More ambiance and more space. Everything was moronic in this test so I should discount it. But I can’t help wondering…

op.9 wrote:

Digital delay. Yes, I know – a big topic. I’ve been listening recently to my UltraCurve 2496 through headphones used just as a delay. Digital in and Digital out. I cannot hear any change in sound at all. I've really tried. Luckily – but sadly – I’ve never owned any LPs in my life, so I’m not worried about an extra a/d-d/a in the chain. So I’m not ruling out digital delay completely . . . .

op.9 wrote:

I’m worried. Romy – You say Line Arrays ONLY work on the long room dimension? Can you elaborate? Intuitively I can’t see why. And this was my Get Out Clause. This is worrying.

op.9 wrote:

And another question. I’ve learned the slow way that funny mouth shapes and bends in horns really screw up things in seemingly unrelated parts of the audio spectrum. Is this still true of low bass?

Bud wrote:

Just so you know about these folks. go to this site and page down for a bit till you find the horn installation topic.  http://www.royaldevice.com/custom3.htm

I see a big problem with this horn. The problem that from my point of view make the Royal Device’s efforts kind of… pointless. Paul asked the correct question: is it about better project or is about better Sound? If “Sound” then how should be perceive a good projects that have some “bad for Sound” solutions?

Anyhow, I disagree with those Royal Device guys. They read apparently a lot of old horn books and paperworks and picked from there a notion of front compression chamber. This is VERY common mistakes for beginners or for people who have cliché mentality instead of listening awareness. Yes, in the past all people who have written theories about horns stressed used of front compression chamber. However, in that past no one meant to use horn for high fidelity sound reproduction in homes and all the people carried was how to get more dB out of those things.  Listen any of the “old horns” and you will head what I mean. Yep, the front compression chamber do increase dB output but it does it via the “sonic boom”, ruining the quietly of sound. Why those Royal Device’s guys decided to make that intentional front compression chamber is beyond me.

Dear John,
I hope you don't mind me writing directly to you. I've been posting on Romy the Cat's audio board about the pros and cons of a bass horn in my new Barn Conversion. I'm probably not going to go ahead with it for various reasons. But I was thinking of installing Bass Line arrays below 40hz against the short wall of a 10m by 7m double height room with vaulted cieling. Probably 6 or 8 15" drivers in a sealed box per side. But - at this is the question, Romy seems sure that Line arrays will only work properly when used on the long dimension of the room. Is this correct? Intuitively I can't see why...
Your thoughts on this would be most welcome

Bass horns:

Yes, they do work and can work extremely well.  Probably the best authority on the planet when it comes to bass, period, is Tom Danley.  His first commercial success was a product that had to fit in a Land Rover and call elephants when it was first discovered that the communicated over great distances in the 20 Hz region.  It was the Packiderm 6 and was the predecessor to the Intersonics ServoDrive subwoofers that came out in the late 70's.  ( www.servodrive.com)  Since then, he created the acoustic suspension chamber that created perfect crystals on the space shuttle.  It requires 175 dB SPL.  He has been involved with two sound companies since ServoDrive, Sound Physics Laboratories (SPL) and he currently designs product for Danley Sound Labs (www.danleysoundlabs.com).
At Danley, his mid-high products are the best passive speakers in the professional sound reinforcement industry, in my opinion.  Let alone that he makes the best subs in the industry.  This link will give you an idea of Tom's world:
www.danleysoundlabs.com/forum/forums/thread-view.asp?tid=47&posts=1&start=1>>

Just Google-search Tom Danley and lab horn and see if you can dig up the article where somebody built-in Tom's lab horn in a rather large-scale (multiple drivers) application in a large room.  It would be 2 -5 years old by now.  It would be very similar to your application.

Bass Line Arrays:>>

More important than what wall they go on is what is the ratio of the room dimensions.  Regular room dimensions, like 10 X 20 X 40 aggravate isolated room modes where the room literally rings at low frequencies (think cathedrals).  There are ratios recommended by acoustical consultants that distribute modes to prevent this.  However, if you are stuck with your dimensions, then narrow-band notch filters can prevent your system from exciting them.  The trick is finding someone that can discern room ring modes from localized standing waves (In England, my friend Peter Mapp comes to mind).  They are not the same and you must look at time vs.. frequency, not frequency vs. dB to find them.  >>
The first mistake most make when doing a bass line array is stacking them together.  In order to act as a line source there are two requirements:>>
1) The array must be sufficiently long to provide the -3 dB/doubling of distance for more level from less cabinets at a given distance.>>To do this in your barn, I would suggest going from wall-to-wall across the short wall.  The reason for the short wall is two-fold: a) They will be aligned with the mid-highs on the same wall without the need for a digital delay to align them.  b) If you go wall-to-wall, then the side walls, if massive enough, will act as extended virtual sources, making the line array virtually infinite.  The more massive the side walls and the one behind the speakers, the better.  >>
2) The array elements must be within 1/2 wavelength of the highest frequency they reproduce.  >>
If you are using 15" woofers, I would crossover into your mid-highs at about 90 - 125 Hz.  At 100 Hz, 1/2 wavelength is 1128/100 = 11.28  11.28/2 = 5.64 ft. = 1.7 meters   So, at 7m, you could put 5 cabinets across the front wall on the floor (a 1/4-space loading for 12 dB more output than in free space) with the first and last in opposite corners.  This is a proper line source at long wavelengths.  If you want more level, use pairs instead of single cabinets.
If it were me, I wouldn't bother designing my own cabinets and selecting a driver with the right parameters.  Leave that to the home theater tweaks that convince themselves that expensive AC cords make a difference.  I'd use something like Danley TH-115's for level or TH-112's or DTS-20's for extreme lows (http://www.danleysoundlabs.com/DANLEY_productspagehome.html).  His old company SPL also has a couple of models I'd consider, like the B-Deap32 for level or the Contra Bass for extreme lows (www.servodrive.com/products.html).  >>
Danley Sound Labs mid-highs array together very well too.  But, in my opinion, the best sounding non-arraying high-output mid-high sound-reinforcement speakers in the industry are from a new company called KV2.  They will absolutely smoke products like JBL, EAW, and Meyer at half the price.  They are powered and they are as clean as studio monitors.  I handle them so I've heard them against all comers.  I call them loud Genelec's on a stick.  They are as low in distortion as many good studio monitors are and get stupid loud.  KV2 has a distributor in elace>ngland. lace>See if you can get a listen to them.  For very loud boxes, you will love them. www.kv2audio.com/Products/index.php>>

Hope this helps!

John A. Murray

Your email is fascinating and hugely interesting. Thanks for being so free with your expertise.
And thanks too for introducing me to Danly. The DTS-20 looks quite incredible. Just might solve the problem at a stroke.
I just have one more question. If, as you suggest, I use the short wall in a horizontal array (my side walls are 30 inches thick stone!) How do I deal with stereo? One channel on top of the other? or mono in the middle and 2 either side as stereo in a single array?
Also it seems to me that if I use both corners and the roof 'corner' (the barn will be open to the rafters) below 40hz then that would constitute an array too? And maybe load the room every well? Ok, I'm sorry that's 4 questions.

James,
There is no stereo for subwoofers because we cannot perceive stereo at extremely long wavelengths.  Our ears are 5 - 6 inches apart.  Even from the side the longest wavelength that will have even a 90-degree phase difference (1/4 wavelength) relative to each ear is that of a 564-Hz signal (6 inches = 1/2 ft.  1/2 ft. X 4 = 2 ft. 1128 ft./2 ft. = 564 Hz).  If the phase difference is less that 90 degrees, it becomes more difficult to discern the directional location of the source.  You will say, "But I can localize where my subwoofer is when it's playing, even with my eyes closed."   Not without the short wavelength components of harmonic distortion, you can't.  Try playing a very low distortion sub at a relatively low volume.  Blindfold someone, spin them and see if they can tell where the sub is....

Long answer to a short question, mono-sum your subs.  That's why there's a 1 in 5.1

Concerning including the barn's "roof corner," as an array component, I think you've missed something here.  First, depending on your sub type, use them up to 80 or 125 Hz as the manufacturer recommends.  They are the best component for that frequency range.  Your mid-high box's LF speaker will not do that range better than the subs, especially if it's at a high volume.  Second, a bass line source array would be a straight line of sources on 1.7m centers.  Sticking a sub in the roof would not be part of a line array across the front wall at floor level.  Since it is up high and farther from most listeners, it would also begin to smear the bass in time.  However, you could put subs all over the place to even out ringing room modes, but the bass would loose definition, tightness, impact.  This is a time smearing, distorted impulse response issue.  Just put them across the front wall and, if needed, have a good tech measure and notch out any bothersome room ring modes with 1/6th- to 1/10th-octave filters.

And don't listen to any smoke-and-mirrors shaman that tells you rubbish about narrow-band filters causing phase distortion.  If the signal in the room has a narrow (2-3 Hz wide) ring mode, it has a nasty phase shift that mother nature packs along with it.  The filter dampen the amplitude of the ringing and improve the phase.

That is what proper equalization does as well.  If a speaker has a peaking resonance, equalization removes the amplitude problem and cancels the peak's phase shift with the opposite shift in phase.  All IIR filters, be they transducers or electronic filters, have a minimum-phase component that is the amplitude's partner.  All good speakers are equalized because no transducer, as a fixed-diameter moving piston, has a flat frequency response.  Mother nature says no, despite what any company's marketing department may want you to believe.  In the home high-fi world, they just put the EQ filtering components inside the speaker cabinet on the crossover network board.  That way "he who abhors EQ and all its nasty phase shift" is blissfully ignorant.

As for putting what I'm saying on that message board, go ahead.  I haven't had any hate mail for a while now.......

Cheers!

John A. Murray

James,  you said that “Romy seems sure that Line arrays will only work properly when used on the long dimension of the room”, still you do not defined what it “only work properly”. Wherever you put the woofers they will work – the question would be where they produces less alinearity and where will inflict more positive influence to imaging. I say that along a long wall.  The LF arrays along a long wall produce better (WAY better) imaging and crate less standing waves in a room. The expense of the pro false is fine but I see a little correlation with what we do in hoe audio. I personally was successful with arrays only across the long walls. As far as I know the none-moronic high-end companies that the make the LF line-array-like speakers came to the same conclusions - I mean the Dunlavy speakers and the Australasian Duntech. Anyhow, James it will be very sample to check. When you bring the arrays home try both long and short wall positions. Listening for the imagine and the looking of your TRA will clearly tell you what to do.

I do not agree with John Murray’s “In order to act as a line source”.  I do not know also how he can advise on a crossover point without having a whole picture what you do.  Also I very much disagree that LF channels care no stereo information. Perhaps if you build a LF resonator that sits below 20Hz with 4th order then it might be the case. But an auditable sound does care stereo. John illustration about the ears is correct but we do not perceive LF by ears.

Make an experiment and confirm for yourself. Take an playback the goes in it’s room down to 40Hz. Add to it a regular consumer subwoofer, crossed relatively sharply at 40H for instance. Place the subwoofer on the right. Then take a good stereo recording with an orchestra that position with all cellos and double bases are at extreme right from a conductor. Play the playback and get some reference. Not move the subwoofer on the left. Pay attention how higgledy misbalanced the Sound become. I mean everything is the same but you for whatever reasons feel very space-disoriented and you will have that feeling the something is not right. Try it, I did it many times. BTW, there is an irony in it. If you “get” that in the given recording the basses should be on the right then immoderate turn yourself back to the soundstage will give you a feeling of short relaxation….

As a "sound man" friend has often said, the idea with pro installations is to start with plenty of volume and go from there, using a "board" to equalize for desired effects.  And as you know, many if not most pro installations also use surround effects to suit.  Of course the "board" is not just for traveling shows, but it is generally used even in "fixed" installations, in concert venues and the like, with the sound pretty much tailored to each event.

Well, YMMV, but I have to say that, although it was "educational", I did not enjoy time spent with a multi-band equalizer.  Likely my OCD personality figured in, but I about drove myself nuts with the thing.

If I were so lucky as to have your "problem", I would seriously think about putting some kind of defeat-able casters (or something) under LF units, because you are probably going to want to move the units around for a while (maybe quite a while) as you get your system dialed in.

John obviously knows his business, but practically speaking you will in any case have to adjust your own Hi-Fi system to your own tastes, and a certain amount of flexibility may well turn out to be a blessing.  Again, YMMV, but I can't recommend the full-tilt "board" thing for hi-fi.

If you think you might want to try surround and/or minimal EQ, you might also track down Gordon Holt, who has stuck steadfastly with this for almost two decades now.  He is a longtime concert recordist, and he has written quite a lot on the subject as it relates to home hi-fi.

Best regards,
Paul S

op.9 wrote:

the horns come out of a rakk dac with lundahl LL1674 passive outputs the midbass use a behringer DEQ2496 (26cm delay) modified with passive outputs.

http://www.GoodSoundClub.com/TreeItem.aspx?PostID=775 

in particularly pay attention to the Jean-Michel Le Cléac'h comments. A few years ago I was bitching that DEQ2496 sound like crap and here was the Jean-Michel reply. I think he is in on something and could be very correct:

Hello,

If you just took the Behringer and put it in you system as you said I am not surprise that it sounded bad.
Did you put any attenuators (by example -20dB) or step-down transformers on the outputs in order that the ADC (if you use analog inputs) and the DAC could operate at their best? If you didn't I agree that your trial was disapponting.
When I first replaced my previous active Kaneda crossover, which one used discrete stages and was excellent with the BSS FDS388 I was really disappointed. The sound was dirty, noisy, harsh... then I measured how many volts RMS I had on the input: 80mV. This meant that I had +37dB digital noise added. Then I put step down transformers and attenuators on every outputs and feed the inputs at high level (attention to clipping!)this was the best crossover I ever possessed. Please notice taht I have also tarnsformers at the input and that the crossover input lines and output lines are balanced.
Many members of the discussion group in French of which I am moderator then did the same: putting attenuators or step-down transformers on the outputs and most of them report excellent sound. Did all of them are nuts and must also suffer your mockery?

Best regards,
Jean-Michel Le Cléac'h, Paris, France

I do not want to convert this subject into the DEQ2496 but I thigh that you might find the reference useful.