FlipC said:
Apparently I wasn't clear enough. The easiest way is to input the driver's specs and use HR's DRIVER ARRANGEMENT Tool to do all the summing calcs for you, then do the design based on corner loading since you're summing four cabs, and finally, divide all its area dims by four.
It doesn't look like a good design to me, what with the huge LF 'bump'.
Stuffing can extend the LF gain BW by lowering the horn's Q (flattening its roll off slope), but at the expense of severely reduced acoustic efficiency over the rest of its gain BW, so not a good plan for a prosound app.
No.
Anyway, here's my take on it with each cab being ~538 L net and only 800 W total to reach Xmax, so thermal power compression should be low:
GM
Attachments
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divide all areas by four
/quote
Wouldn't you multiply areas by 4? or am I not understanding correctly?
(S1 would be 2400 in my example)
http://www.diyaudio.com/forums/attachment.php?s=&postid=1598913&stamp=1220191730
I think what screamers is trying to get at, is that TH seem to couple and you get more than just 6db for every doubling of power/cabinets.
For example, in my TH. I measured 102.5db 2.83v@40hz@1m with one cabinet. However I kicked it up to 20v with 4 cabinets, and got 114db@10m. All else being equal, I would have expected 114.5db@28.3v@10m with 4 cabinets. Somehow I got 2.5db for 'free'
I haven't seen a good way in hornresp to explain why I got what I did, and I think that's the root of screamers question.
divide all areas by four
/quote
Wouldn't you multiply areas by 4? or am I not understanding correctly?
(S1 would be 2400 in my example)
http://www.diyaudio.com/forums/attachment.php?s=&postid=1598913&stamp=1220191730
I think what screamers is trying to get at, is that TH seem to couple and you get more than just 6db for every doubling of power/cabinets.
For example, in my TH. I measured 102.5db 2.83v@40hz@1m with one cabinet. However I kicked it up to 20v with 4 cabinets, and got 114db@10m. All else being equal, I would have expected 114.5db@28.3v@10m with 4 cabinets. Somehow I got 2.5db for 'free'
I haven't seen a good way in hornresp to explain why I got what I did, and I think that's the root of screamers question.
jbell said:
??? The design is based on four drivers, so as you take away drivers the areas must be reduced otherwise as you stack the individual cabs it will be far larger with a much wider gain BW than simmed.
If OTOH you design based on a single driver and multiply it by the number of drivers/cabs you want, then again you'll typically wind up with a much larger array with a wider gain BW than desired which is not a performance goal in a prosound app. Quite the contrary.
Anyway, what does my response to FlipC have to do with screamers' posts? Frankly, since I'm not 'up to speed' yet with Akabak I've ignored them for the most part since there's other folks here who use it.
Regardless, my SWAG on your 'free' SPL is that as you increase the number of horns its summed directivity increases, ergo on axis SPL, so backing up to 20 m where the stack should be a point source at 40 Hz and remeasuring with 40 V will probably be more in line with theory. Not many 'free lunches' in audio.
GM
Indeedscreamersusa said:
An externally hosted image should be here but it was not working when we last tested it.
It also happens to horn loaded drivers when driven too hard. That´s why horn-loading drivers with light cones (which are usually not as rugged as heavy ones) is a bad idea most of the times.
Is that a Definimax 12"? I always thought they were pretty rugged, but I guess that's more in terms of power handling rather than cone strength... I hope to use 4x Definimax 12's for some sort of TH tuned to somewhere between 30 and 35Hz, but I also need to get to grips with simming multiple cabs in HR (All the info I need is here and in the huge TH thread, I just need to find the time to get it all figured out in my head and HR. ). I'm guessing I should be safe tho if I don't exceed Xmax and avoid cooking the voicecoil, but I'll also have to consider compression ratio also... What's a safe ballpark figure? I'm guessing 3:1?It´s an omega pro (which is recommended by eminence for horns or scoops) which used to work quite fine in a TH for over a year now... Until some DJ didn´t know where to stop...
The Definimax is more rugged, though... It certainly would be a better choice when going for max levels in pro-sound.
In terms of "destroying cones" Compression Ratio between 2:1 and 3:1 are no problem. The higher the compression ratio, the more rugged the speaker has to be. The above design had 3:1 which obviously can destroy the 90g cone, a definimax might have survived... I have to add, that the level driven to the omega was so insane, it probably already distorted like hell - but since it was one of those GOA / Noise / Techno Events where people loose theyr hearing, nobody recognised what was going on... So this definitely is human failure (too bad I was in bed by then, I could have saved them....). QSC Amping with 2 kW was driven to the max and fed to the omega - crash...
The Definimax is more rugged, though... It certainly would be a better choice when going for max levels in pro-sound.
In terms of "destroying cones" Compression Ratio between 2:1 and 3:1 are no problem. The higher the compression ratio, the more rugged the speaker has to be. The above design had 3:1 which obviously can destroy the 90g cone, a definimax might have survived... I have to add, that the level driven to the omega was so insane, it probably already distorted like hell - but since it was one of those GOA / Noise / Techno Events where people loose theyr hearing, nobody recognised what was going on... So this definitely is human failure (too bad I was in bed by then, I could have saved them....). QSC Amping with 2 kW was driven to the max and fed to the omega - crash...
I asked eminence what the max safe compression ratio was for the 3015lf and the 4015. They don't have a rating for it and have no plans to do so either. They just claim lots of people are using them for horns. I guess it's just one of those things you hope you don't figure out the hard way.
That omega looks like a few EVprolines I had lying around here.
All killed by.......DJ's of course. Ironically, in EV boxes!!!
I'm at it again, building one more full of tricks and sauce, before I settle on one of the other two. Back to work.
That omega looks like a few EVprolines I had lying around here.
All killed by.......DJ's of course.
Ironically, in EV boxes!!! I'm at it again, building one more full of tricks and sauce, before I settle on one of the other two. Back to work.
2kW? I'm surprised cone actually stayed in the driver!Sabbelbacke said:
The Definimax does seem to sim quite well, and I've already built William Cowans 30Hz horn enclosure as "proof of concept", and even tho it's tunes to 30 Hz it works very well, it only seems to run out of xmax at 40Hz (with both sim and real life), so I'm hoping to reduce the size of the path and tune the box to 35Hz, which should increase output at the expense of low end extension.
I wonder earlier if TH's are any kinder to cones compared to traditional horns when they are both using the same compression ratio? Traditional horns with a sealed rear chamber can use that air like a 'spring' while the TH is actally using both sides of the cone to move air...
screamersusa said:I asked eminence what the max safe compression ratio was for the 3015lf and the 4015. They don't have a rating for it and have no plans to do so either. They just claim lots of people are using them for horns. I guess it's just one of those things you hope you don't figure out the hard way.
That omega looks like a few EVprolines I had lying around here.
All killed by.......DJ's of course.
For high CR you need a driver like the Ciare 12.00SW with a large high-BL coil and smaller diameter thick stiff straight-sided cone -- the replacement cones are said to be strong enough to stand on, and I've never heard of one being damaged even in a high CR horn like the Punisher with a big amp.
Ian
djk said:
I get 25hz xmax at 20w
38hz xmax at 65w with compression, about 45 without.
so far on a 3015.
I second the design and operator combination. Too many guys around here (Fla), trying to get too much out of a single pair of subs. By the time they finally listen and buy a couple of more, they've already bought 2 or three superpowered amps and reconed their speakers at least 2-3 times each. Sigh.
Improper replacements are a nightmare as well. I lost an AB1100a
in flames because one of two rental cabs I was using had an 80watt driver in it instead of it's original 350w eminence. I was PISSED! The 80w driver failed and shorted while under a 2 ohm load, since the AB1100A didn't see a proper short due to the other 3 drivers still running, there was no warning and no clip lights and the amp burst into flames 6 inches from my shins!
Kept burning after power was pulled. Got pics somewhere, be warned!!
No, that´s real lief in prososund rental business. You are awfully quick to jugde the design without even knowing what it is....
Of course the people operating didn´t bother to calculate anything.... if they did and if they knew what they were doing, nothing would have happened. The same enclosure type is runnig fine for many years in different locations, this simply is a case of hooking up the wrong amplifier, putting it to bridge mode and the wish to be the loudest DJ in the place....
That´s what happens when DJs excess theyr authority and start changing amp setups after the engineer has left the building. Those people have to pay, get banned from the business and are far from sane
. This only happens every few years, but it happens - you would be astonished what kinds of people are out there in pro sound rental business... That´s what insurrances are for - for human / operator failure and guys doing something they are not supposed to.
"You are awfully quick to jugde the design without even knowing what it is.... "
Really?
"It´s an omega pro (which is recommended by eminence for horns or scoops) which used to work quite fine in a TH for over a year now... "
You stated it was an Omega Pro in a TH.
The picture shows an Omega Pro 15A, 4.8mm x-max, 12.2mm Xlim.
I've calculated thousands of boxes of all types, there is no box that goes below 50hz that will not exceed x-max with that driver with 2KW.
Really?
"It´s an omega pro (which is recommended by eminence for horns or scoops) which used to work quite fine in a TH for over a year now... "
You stated it was an Omega Pro in a TH.
The picture shows an Omega Pro 15A, 4.8mm x-max, 12.2mm Xlim.
I've calculated thousands of boxes of all types, there is no box that goes below 50hz that will not exceed x-max with that driver with 2KW.
djk said:
Yes.
You don't know anything about the actual design, the used high-pass filters, the controlling, limiting, stacking, the normaly given power on this cab, the cabs passband, etc... All you know that this driver, I quote myself:
was destroyed in a horn design because some insane DJs hooked up the wrong amp and didn't know where to stop. Every driver has a limit, regardless of the design its used in... Most of our customers in need of reconing or replacements own cabs with a high reputation - so every broken Speaker is a design flaw? Come on... Of course - sticking the wrong speaker in the wrong cab raises the chance of destroying it more quickly. But again, you don´t have any information on the circumstances..
Nothing is said about the actual situation when the driver was destroyed besides too much input power and DJs exceeding their authority are to blame. Still, after giving more insight above, you are making assumptions that this is a design flaw....
So yes, you judge quick.
This clearly was the fault of some DJs fiddling around with the system in a situation where they where not allowed to touch anything but their mixing console...
Nobody said that the driver would be running within the specs when driven with 2kW... Please read carefully before concluding... And once again, you don't know about the alignement of the cab, so stop making assumptions
In the time you simulated all your designs, I actually build "a few" over the last 20 years, so stop being so snobbish. Please.
The point of my post was to illustrate how a driver can look when driven too hard in a horn not to be insulted that the used cab is a design flaw.
BTW. You changed "60Hz" to "50Hz"... in your post. why?
Well, you both say it was the operator, the dj in this case, who made the error. Additionally, if it is a design failure can be answered yes and no, depending on the viewpoint. Yes, because the design wasnt up to the situation it was placed in. No, because the situation it was placed in was not the right one for the design.
MaVo said:Well, you both say it was the operator, the dj in this case, who made the error. Additionally, if it is a design failure can be answered yes and no, depending on the viewpoint. Yes, because the design wasnt up to the situation it was placed in. No, because the situation it was placed in was not the right one for the design.
Nicely put.Of course, arguing like this would make every situation where something gets broken a design flaw
What about human error? Filling diesel in a Otto-type engine is a design flaw? ok, back to topic.
In my observation, if a speaker mounted in a ported or closed design is driven too hard, the cone destruction (if there is any, sometimes the voice coil just burns - you don´t "see" much of a damage there) looks different. Ripped of dust cabs or single cracks may happen, even the spider or the surrounding might be torn of. But never have I seen a cone fragmentation of this magnitude in a single direct-radiation design.
Sabbelbacke said:
I have seen it a couple of times.
But it is mostly due to mousture. A cone that has been wet once can rip apart in small fragments when it is driven hard a week or two after the event.
Talking about DJs...
Tonite i worked at a club whose profile is to not have a DJ, they use an ipod on shuffle and livemusic instead.
-Take a look at the bottom of the flyer
