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 Subiectul mesajului: Direct radiating low-mid options
MesajScris: Sâm Feb 11, 2006 2:31 am 
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Hi guys,

I know you all want a horn loaded low mid and so do I eventually but I'm still thinking I can make a suitable direct radiating complement to the mid and high horns I've got in mind.

I'd be interested in your opinions please on the following driver config options:

Imagine

The first is a dipole config. D&B use a similar arrangement in their Q series which sounds very nice. If they can use a pair of 10's up to 1.2kHz I'm sure I can get a pair of 12's to sound good up to 400Hz where the 8" will take over. It also allows the mid and high horns to be mounted on a baffle reducing diffraction problems and securing them in the cab.

The second option is one Nexus3 and I both came up with seperately. Using this config there might be some loading gain from the V shape but causes problems with the mid and high horns.

Something to think about anyway....


Sus
   
 


 Subiectul mesajului:
MesajScris: Dum Feb 12, 2006 9:52 am 
With 400hz wave having a length of 215mm,I think that at the very top end of their operation,the 12"s will exhibit some kind of lobing/reflection either way.Their DI will be slightly raised in this band but not much.

Il go take a look at the d&b one.


Sus
  
 
 Subiectul mesajului:
MesajScris: Dum Feb 12, 2006 3:40 pm 
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If you look at the polar plots for the d&b boxes, there is some lobing in the vertical plane, however it doesn't look bad enough to actually be a problem.


Sus
   
 
 Subiectul mesajului:
MesajScris: Mar Feb 14, 2006 3:12 am 
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Here's another one I've come up with. Haven't looked into it too much but might be another option. I think Staipers BP-Horn is a good configuration and could be made to work with 12" drivers. It might be easier just to stick the mid horn at the top of the box and have a long thin box but here's what it would look like in the middle.

I've decided having the high-mid horn 'floating' in the mouth would just cause trouble.

Imagine


Sus
   
 
 Subiectul mesajului:
MesajScris: Mar Feb 14, 2006 10:08 am 
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Director General 0766332366
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Membru din: Joi Oct 27, 2005 7:33 pm
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if we make the enclosure trapezoidal the drivers will NOT FIT

I already thought about this kind of placement.

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Sus
   
 
 Subiectul mesajului:
MesajScris: Mar Feb 14, 2006 11:15 am 
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Surely it depends what angle the trapezoid is and how wide you make the cab overall? It will fit, just might make for a larger than desired cabinet. Which is one reason I started looking at direct radiating options. Unfortunately though, very small and very loud don't go well together.

There's no need to snap, it was only an idea I was throwing around late last night after looking at:
Imagine
Imagine


Sus
   
 
 Subiectul mesajului:
MesajScris: Mar Feb 14, 2006 11:35 am 
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ceharden scrie:
There's no need to snap, it was only an idea I was throwing around late last night after looking at:


I'm sorry if it came out that way, I was not intended. :oops:

I merely pointed out a prolem that I've confrunted with when I designed the cartboard prototype

I've looked at that design you have in the pictures it's very nice

I have something to show you too :wink:

_________________
ing. Mircea Bartic
Director general

Poweraudio Romania
Str. Gheorghe Sincai, Nr.26 Bistrita
Telefon: 0766332366
E-mail: office@poweraudio.ro
www.poweraudio.ro
facebook.com/poweraudio.romania


Sus
   
 
 Subiectul mesajului:
MesajScris: Mar Feb 14, 2006 11:53 am 
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Director General 0766332366
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Imagine
Imagine
Imagine
Imagine
Imagine

_________________
ing. Mircea Bartic
Director general

Poweraudio Romania
Str. Gheorghe Sincai, Nr.26 Bistrita
Telefon: 0766332366
E-mail: office@poweraudio.ro
www.poweraudio.ro
facebook.com/poweraudio.romania


Sus
   
 
 Subiectul mesajului:
MesajScris: Mar Feb 14, 2006 1:00 pm 
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ceharden scrie:
Here's another one I've come up with.
Imagine

following reading about edge difractions etc i also came to the conclusion that having a floating mid and high section could result in problems, so i also considered baffle mounting the mid and high horns, side by side.

not surprisingly then my current thinking looks exactly like what ceharden has just drawn. issues arising include the difficulties encountered in building the throat for the 12" drivers (getting the front chamber down to ~3l and making a nice transition from compression chamber to horn proper is tricky with inverted drivers, but the possible benefits have meant that i haven't abandoned this layout) and the fact that the hf horn can not be dragged back to align with the high mid driver.

of course, we could still do this and stick the hf into the top 12" flare, facilitating the use of a passive crossover, in my mind still a very worthwhile goal. on another positive note, the whole bifurcation argument goes out of the window with this layout so we can be fairly sure we will be modelling the horn(s) correctly.

i'm glad we are wandering back into the realms of hornloaded mid bass. i totally see your point ceharden that a proper beastly 135 dB narrow dispersion array cab will be complete overkill for most of the events that you do, for that reason a dr mid bass suddenly seems not just attractive but it becomes the obvious choice. casting back to the design objectives though, wasn't the reason for starting this project the lack of an arrayable all horn top box to complement the awesome array of bass cabinets on offer?

that eaw cabinet is a triumph of layout and component density and it throws up some very interesting ideas. sadly, i think the prorietary mouldings on the high mid and hf waveguides are fairly essential for the correct operation of the box and also let us not forget that will have an exceedingly wide horizontal and very narrow vertical dispersion pattern, not quite what we are after. the mid bass element is fascinating isn't it, there appears to be a slot entry horn for the first part, but then the remaining length of the chambers are parallel walled and full of obstructions, very odd. still, quite an inspiring sight.

james.

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Sus
   
 
 Subiectul mesajului:
MesajScris: Mie Feb 15, 2006 4:55 am 
that top eaw photo looks like an amp!.. crazy

the edge defraction thing is what always slightly put me off the xtro's design,but then again if its only a small space taken up in relation to horn mouth and the flare could compensate then maybe it would be less obtrusive than it looks, (if the external flare of the cd horn isnt smooth enough maybe a moulding could cover it to blend with the mid flare better) or even half cut into the flare to act as half a baffle, i'm sure walt would have something to say about it.

i dont see getting the compression/throat chamber to 3 litres as a prob if the throat walls very closely track the outer edge of of the driver chassis, maybe add wood on the walls to almost go into the cage.

it would be good if someone did some tef type measurments on reverse mounted compared to forward for upper frequency resp,

i am worried going up to 400hz with the magnet as an obstruction. you dont scoop sand with a spade upside down, should you scoop air with the convex side of a cone.. would the air particles in the immediate vicinity of the cone slide past rather than get pushed, perhaps that would help to load the farthest corners from horn mouth first, and speed air flow there; to catch up with the pathlength differential from center point of cone?? compression and rebound (maybe more relevant above 400hz)

21cm 1/4 wave and high D.I. may not be a problem when the horn layout at throat angle/slot? could compensate, to load the horn.. wheres timber!!

sorry for the rant.. dont know id if its that relevant...


Sus
  
 
 Subiectul mesajului:
MesajScris: Mie Feb 15, 2006 5:11 am 
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Regarding my direct radiating rambles, as long as no-one objects I would like to continue to bounce ideas around which may not necessarily be in line with the original design aims. My main interest in this project is the high mid horn around which I would like to design a cabinet.

I don't think there is anything wrong with the outcome of this project being several varying designs, optimised for certain applications. Most of you want silly SPL, narrow dispersion etc which is fine and at some point I might need that too. I fully intend to contribute to a design which meets the majority of your needs, however what I build for my own use might end up being something slightly different!

I'll have a more detailed look at that horn/driver layout myself to see what is possible. I'm starting to like designing in Visio (haven't got into proper CAD yet) cos you can move stuff round to see what fits where.

I'll leave you with a thought, just got back from working a gig in London. EM Acoustics Quake subwoofer....... as a... Drum Fill!!!


Sus
   
 
 Subiectul mesajului:
MesajScris: Vin Feb 17, 2006 12:11 am 
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been thinking lots about the reverse driver loading, and about construction methods in general. whilst i'm scared of fibreglass, i also think it represents a wonderful opportunity to pursue new shapes and forms to realise our goals. i had been looking at all timber construction because i'm that kind of ludite, but if we want to make some kind of really clever shape chamber around the motor, fibreglass could really help. making complex shapes like that from timber could end up very heavy, perhaps less with extensive use of very thin ply supported by polyeurethane foam?

anyway. reverse loading. i think that from first appearences neo drivers lend themselves to this technique more than ferrites as there is a more direct and even path from the cone past the magnet. even so, there is still much varaition in units. check out the sn12b against the 12ndl76, whilst the spidery shape means it is hard to lock down the chamber volume with simple shapes, but the magnet and back of the chassis look much more like a natural phase plug.

james

Imagine
Imagine

_________________
mardy hippy.


Sus
   
 
 Subiectul mesajului:
MesajScris: Dum Feb 26, 2006 3:23 pm 
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Got a chance on Saturday to take a good look at some F1 Res 4's and 18" BPH's (not sure of the F1 model no.)

I reckon it might be possible to do a reverse driver version of the Res4 folded 12". If you take the 12NDL76 and build a nicely shaped foam wedge which fits onto the magnet (maintaining ventilation of course) it should approximate the phase plug used by F1. The horn length they use seems to be about 60-70cm with crossovers at 114 and 445Hz.

The mid horn is some piece of work isn't it! To make a single horn do 445Hz to almost 6k is definitely impressive. I did however notice that it ran out of headroom well before any other part of the system, something definitely to take note of, suggesting that using a twin 12" horn would probably way outrun the high-mid and high sections.


Sus
   
 
 Subiectul mesajului:
MesajScris: Dum Feb 26, 2006 8:14 pm 
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Hello,

I have used the Res4/Res5. The 12" section is the first to ran out of steam. The amps really have to work hard to get enough SPL out of the 12" section.

Best regards,

Walt


Sus
   
 
 Subiectul mesajului:
MesajScris: Dum Feb 26, 2006 9:58 pm 
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That is interesting to hear although not surprising. Must have been something odd about the setup I saw. On the controller the high-mids appeared to be slamming into the limiter on vocal peaks while the other sections had a decent amount of headroom left.


Sus
   
 
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