| Bass-Depth |
Hi ! :)
I want to build a Subwoofer for my Homecinema and thought of a LAB-Horn,the Lab Horn is really nice but i want a Subwoofer which goes down to 20Hz with more Output than a SVS PB12 Ultra 2
It's important for me to have a clear Bass so I only want to build a Horn ;)
Max.SPL @30Hz should be more than 120dB @ 1m
Please can you say which DIY-Sub would do all I'm dreaming of and isn't more expensive than the LAB-Horn???
David ;)
Sorry for my english...i'm from Austria ;) |
|
|
| johninCR |
| A LABhorn is only a 35hz horn. A true 20hz horn is huge. Plan on building something that utilizes a corner as part of the final flare to keep the size down. Personally, I would use a vertical array of drivers in a corner horn to make use of the vertical space that would otherwise be wasted and create a false corner that would actually be a huge horn without looking too intrusive. |
|
|
| planet10 |
| quote: | Originally posted by Bass-Depth
Please can you say which DIY-Sub would do all I'm dreaming of |
It will need to be BIG. Really BIG.
dave |
|
|
| Ron E |
That 20Hz horn will be larger than Ober Oesterreich ;)
I guess if you want to build a 20Hz horn, you should get Hornresp and spend a lot of time on "horny" forums. You can shorten the horn quite a bit and reduce the mouth area by the use of boundaries, but there is a limit to what you can do without making the response very ripply. In a high SPL environment, 35Hz is more than enough - the lower frequencies will just rattle stuff and waste amp power. I wouldn't knock the labhorn's extension until you heard it.
I lived in Austria a while back - in der Wachau. |
|
|
| quiet |
funny i thought the same thing - :)
still a vertical array using the hight of the room and a corner
or the hole wall..... seems like a good idea
20hz is loooow for a horn |
|
|
| simon5 |
I played with Hornresp a bit to help you.
Best results I had was with Acoustic Elegance AV15.
It's a Catenoidal horn.
Length of 6 meters and mouth area of 16612 cm^3 if it's a corner horn. You also need a rear compression chamber of 125 liters. Ripple is about ±3 dB with 110 dB sensivity with 2.83V RMS imput. I tried to design the smallest 20 Hz horn with ±3 dB ripple.
You'll need to be creative to build a catenoidal horn and to fold the 6 meter length in three so it can stand up in a corner of the room.
Good luck! |
|
|
| simon5 |
Just beaten what I said.
I used a Ascendant Audio Avalanche 18. I know it's discontinued but if you can get one...
Catenoidal horn
12100 cm^3 mouth area
5 meters long
250 liters rear chamber
In theory with a 800W RMS amplifier into 4 ohms, this horn could do 135+ dB from 20 Hz to 80 Hz. |
|
|
| rcw |
Back in the 70's an Australian electronics magazine had a feature about a man who had an extension built on his house in the shape of a 16Hz. horn, it had a listening area at the big end and an array off 15inch woofers at the small end.
The report was that it sounded quite impessive with organ music.
Anything less than this would seem to be an inedequate compromise. |
|
|
| planet10 |
| quote: | Originally posted by rcw
Back in the 70's an Australian electronics magazine had a feature about a man who had an extension built on his house in the shape of a 16Hz. horn, it had a listening area at the big end and an array off 15inch woofers at the small end. |
I had a customer (in the late '70s) with similar -- don't know how low it went, but he used a single B139.
dave |
|
|
| Brett |
| quote: | Originally posted by Ron E
You can shorten the horn quite a bit and reduce the mouth area by the use of boundaries, but there is a limit to what you can do without making the response very ripply. In a high SPL environment, 35Hz is more than enough - the lower frequencies will just rattle stuff and waste amp power. I wouldn't knock the labhorn's extension until you heard it. |
My LABs, corner loaded with a flare extension as per TD's suggestions got well into the 20's. Shook everything in my house, and the neighbours. I really don't beleive if you'd listened to them that you could realistically want for more. |
|
|
| slowmotion |
Hi all
I'm going for floor-to-ceiling corner horns ( two of them ) myself,
but I don't expect to go much under 30Hz.
We'll see in a year or so ;)
Seriously, I think about 30Hz is just about managable,
if you want to use proper horns. If you want to go down to
20Hz you probably have to build the horns as part of the house.
Good luck !
cheers ;) |
|
|
| johninCR |
What is the consensus regarding the use of a large chambered rear horn to achieve the extra low extension?
Designs like the Jensen Imperial are able to achieve extension far below the horn tuning this way. A corner array would be more impressive to look at if you can see the drivers. HornResp only goes to 99L for the chamber size for RLH's making modelling a big array impossible. Is there some rule of thumb for predicting the response from stacking horns if you know the response of a single unit? |
|
|
| Bass-Depth |
Thanks for your answers!!! ;)
Probably it would be enough with the Lab Horn but now my Sub is a Double 12" (one active one passive) which plays down to 25Hz @ -3dB...but it's not loud...this Sub is good for beeing in a 20m² room...
Has anyone of you ever heard an SVS PB12 Ultra2??? I want this deep bass of the SVS but more SPL and the Horn-Sounding Bass... ;)
David :cool: |
|
|
| moray james |
Would not a bank of reflex loaded 18 inch deivers do the job in a smaller area and be less complicated cabinet work? The pro's usually do this as it makes for a more portable rig.
Ask Tom Danley he knows how to move a lot of air at low frequencies. Would be interested to hear his ideas. Regards Moray James. |
|
|
| mwmkravchenko |
I ripped this off the DIY-Systems site under the bass horn link:
Additional info to take into account
Until now only a small part is explained, there is more to it! Now we mainly know how to calculate the actual horn it is useful to know how two horns beside each other have influence on the response, and how the driver cabinet (the back chamber) has influence on the speakers parameters when adapted to the horn.
When the mouth area Am of two horns are placed beside each other then the result will be a better performance in the lowest bass because the area is now doubled. The next formula can be used to see if we can lower the frequency Fg by the enlargement of Am.
Mind in the calculation where you want to place the horn, by placement in the corner the surface Amt must be multiplied by 8 !
Basic formula for calculating the lowest frequency radiated by the horn...
An advantage is that the new horn can be calculated as being shorter. Because we work in stereo the efficiency is 6dB higher (two speakers instead of one) and the power capabilities (mechanical and electrical) improves.
What has changed is the larger (total) throat area Ah. In reverse you could say its the smaller (half) mouth area Am. The bigger the throath- or the smaller the mouth area the shorter the hornlength.
Suppose a Fg of 30Hz is wanted, according to the next formula the mouth area Am (m²) will be:
Calculating the horn mouth area...
Placed in a corner the result will be 1.32 m². When two horns with their mouth close to eachother are used, the result can be divided by 2 (0.658 m²). By calculating the contour (flair) of the horn it becomes clear that for the same Fg a shorter horn is sufficient. Of course it is possible to use more than one speaker in a horn, Ah is then multiplied by the amount of speakers.
The advantage of more speakers is that the power (mechanical and electrical) improves, the throath can be enlarged (shorter horn) and, not less importent, the speaker selection is less critical.
It is found here: http://www.diy-systems.com/
Bass horn design section
Hope this helps
Mark |
|
|
| simon5 |
| quote: | Originally posted by Bass-Depth
Has anyone of you ever heard an SVS PB12 Ultra2??? I want this deep bass of the SVS but more SPL and the Horn-Sounding Bass... |
SVS PB12 Ultra2 is not that hard to beat with a huge ported box. You won't have the horn sound, but it will be deeper and louder than the PB12. |
|
|
| johninCR |
Mark,
That info jives exactly with some modelling I've done in HornResp. eg a 6ft tall corner horn with 8 $22/ea Pioneers , PE# 290-063 with an Fs of 40hz, shows a peak sensitivity of 110db at 90hz, dropping smoothly to 107db at 40hz, 105db at 30hz, and 100db at 20hz. That's an RLH with a 99L chamber and I believe a larger chamber would go even lower. With only a 1.7m horn length and 700cm throat (50% of Sd) and a 37hz flare rate, it would fit in about the same floor space as a typical boxed sub. At 30hz it would come close to Bass-depths requirements, but at lower frequencies he'd run out of excursion quickly.
I just wish HornResp could handle larger RLH chambers because I'd love to model a floor to ceiling corner horn with more appropriate larger drivers, like 8 12's or 6 15's. |
|
|
| xstephanx |
Clean deep bass and no one said tline?
Tline can usually get VERY useable spl about an octave below tuning
but to go on the safe side, lets design a tline for 30hz instead of 40
so
speed of sound (330 m/s roughly for average air elasticity)/ frequency(30hz)= (330/30=11) soo 11 meters is how long a FULL wavelength of 30hz is, but with a tl you can get away with only 1/4 wavelengths.
11x.25= 2.75, a relatively feasable length, especially when you consider that this is a straight 1/4wave pipe, when you start getting into things like tapering, you should be able to reduce the length EVEN MORE
Stuffing to reduce length is a controvertial subject, ive heard reasonable arguments put forth by both schools of thought, so throw some in, but dont count on it too much.
The only downside to a tl as opposed to a horn is the efficiency really, tls and hrons are really different, horns are practical for high frequency, high efficiency reproduction, while a tl is more a low frequency lower efficiency route.
Oh, and hrons have colorations as well, ive heard alot of people say hey preffer a transmission line over a horn sound. |
|
|
| Bare |
I think you guys are just 'wanking' here
What you fantasize about is perhaps considerably beyond your expectations in real life.
A few months back/last Fall ? Dr Edgar published /posted Images of Genuine 30hz horn(s) built on comission for some undisclosed Military purpose. Given their pedigree they likely did meet their design specifications.
These were Huge, monstrous in fact, as in they would not fit within in a regular house shape.
Just the thing to listen to Hip Hop with, in yer Mom's basement :-) |
|
|
| johninCR |
| Wanking? No one said anything about a no compromise 30hz horn designed for free air use. |
|
|
| mwmkravchenko |
YOu should all be yanked outa here!
Man what do you have to do to get some respect in this place;) !
Some of the gentleman posting know their stuff. John does, as does RCW and Dave. They are not yankers. Nor am I ! Built more horns than most gents on this forum. R&D'ed fullrange drivers and back loaded horns for a couple of clients. By driver I mean the whole driver! If that makes me a yanker than yanker I am!
Mark |
|
|
| johninCR |
Mark,
Thanks for the compliment, but I'm just a noob. I do learn quick though. |
|
|
| BassAwdyO |
| quote: | | Dr Edgar published /posted Images of Genuine 30hz horn(s) built on comission for some undisclosed Military purpose. Given their pedigree they likely did meet their design specifications. |
Probably not folded....
If your horn isnt so big that it cant fit through your door, then its not too big!
If you want to hear about some real testing eqiupment look at some of the stuff Tom Danley has done....
who is this Dr. Edgar anyway?
I think a good no comprimise horn could be built into an attic. The folding could be much less complex depending on the attic space itself, and size is probably not an issue(assuming a large attic). It couldnt be removed and moved somewhere else, but I'm sure you could get just about any flare rate and cutoff you desire. |
|
|
| planet10 |
| quote: | Originally posted by BassAwdyO
who is this Dr. Edgar anyway? |
Mr. Modern Day Tractrix....
dave |
|
|
| rcw |
I think it is now well established that below a particular frequency a horn acts just like a single ported bandpass box, and that if you want it to act as an acoustic transformer down to the lowest frequencies then it must be of the dimensions mentioned for the military application, and no amount of hand waving, or indeed using ones hand for other purposes will change it.
I always think that the bass horn fans in fact like the look mystique and idea of horns, but in thinking that this aesthetic appreciation is somehow not appropriate or manly try to put forth sound technical sounding reasons for horns, instead of stating the simple fact that it is the aesthtic and mystique of horns that attracts them.
Don Keele showed long ago that in terms of bass for space reflex loaded direct radiators with filter assistance win hands down, and no use of hands in whatever manner will change this.
The major trouble is that a box with a hole in lacks all of the glamour and all the other afformentioned properties possed by horns, thus horns will always win in these stakes, I just wish that sometimes horn lovers would come clean and admit thats the attraction. |
|
|
| Steve Eddy |
| quote: | Originally posted by rcw
Don Keele showed long ago that in terms of bass for space reflex loaded direct radiators with filter assistance win hands down, and no use of hands in whatever manner will change this. |
I'm sure in terms of simple frequency response it does win hands down (though I can't think of any reason why a horn system couldn't be filter assisted as well). But I suspect that there's more to horns than simple frequency response and that what attracts many to horns is more than just aesthetic and mystique.
| quote: | | The major trouble is that a box with a hole in lacks all of the glamour and all the other afformentioned properties possed by horns, thus horns will always win in these stakes, I just wish that sometimes horn lovers would come clean and admit thats the attraction. |
I don't mind admitting that that's part of the attraction for me (being the holistic kind o' guy that I am), but not the entire reason. There's something more.
se |
|
|
| Coolin |
| quote: | Originally posted by Steve Eddy
I don't mind admitting that that's part of the attraction for me (being the holistic kind o' guy that I am), but not the entire reason. There's something more.
se |
I agree.
With non bass horns its the directionality that makes them different but with bass horns and long wavelengths theoretically there shouldnt be much difference.
We will find out soon though as i,m also going to make one. |
|
|
| Brett |
| quote: | Originally posted by rcw
I always think that the bass horn fans in fact like the look mystique and idea of horns, but in thinking that this aesthetic appreciation is somehow not appropriate or manly try to put forth sound technical sounding reasons for horns, instead of stating the simple fact that it is the aesthtic and mystique of horns that attracts them.
Don Keele showed long ago that in terms of bass for space reflex loaded direct radiators with filter assistance win hands down, and no use of hands in whatever manner will change this.
The major trouble is that a box with a hole in lacks all of the glamour and all the other afformentioned properties possed by horns, thus horns will always win in these stakes, I just wish that sometimes horn lovers would come clean and admit thats the attraction. |
Whilst you are entitled to your opinion, in my opinion, it's a load of bollocks.
I've never heard anything even come close to the horn rig I had in terms of ease of presentation, dynamic ability and the ability to present a realistic size and scope to the music. Never heard a ported box(es) of any size begin to equal their performance.
As for being aesthetic based, when I used my Khorns they blended in to the room quite well so that few people noticed them quite unlite a set of floor or standmounted speakers 5 feet out into the room. When the rig developed into what it was at the end, the 'big' boxes were a set of LABhorns, placed on stands so that they fired down and into the corner. They were painted (with a roller) flat white so they matched the walls. There were framed pictures hung on them and they looked like a large wall unit. The midbass looked like a box until you sat in front of it and noticed there was a flare inside it. The mid/high horn looked like a horn though, but wasn't that big (~400mm dia x 400 deep)
I miss my horns a lot, but I can't get them into my current house so I sold a lot of the flares and components off. My KEFs are fine and enjoyable, but sooooooo lacking ultimately compared to what I had. When I move back to my house (I moved to do the work that means something to me), I'll build another horn rig. |
|
|
| mike.e |
RCW : It isnt for the majority of laymen to decide that something is true simply because it seems to make sense,Id leave that to to the AES guys. But yes a BP4 does seem to approximate the horn below Fc. Have you seen the distortion measurements vs frequency here->
http://homepages.paradise.net.nz/sbk1/ssi.htm
Re DB keele,yes its true but if you cant afford multiple 18"s with appropriate EQ isntead of your single HT woofer on a massive horn its no use. (bearing in mind that we are talking HT not midbass)
You could just chuck the largest flare extender you can fit onto a labhorn size unit - FR can be worked out with hornresp.(single 18"/ 2 x 12"s or similar)
For HT I wouldnt have a cutoff any higher than 25hz or so. I wouldnt be expecting 16hz horn loaded.
http://www.speakerstore.nl/forum/viewtopic.php?t=121
http://www.diyaudio.com/forums/show...9502&highlight= |
|
|
| rcw |
I would expect no other reaction than that from someone who describes such observations as "bollocks" Brett, and then goes on to describe the sound of his horns in subjectivist aesthetic terms.
Perhaps in your case it is some sort of British understated aesthetic. |
|
|
| mwmkravchenko |
Small size and low frequency output together cannot be accomplished with a horn. THat's a statement we all have to agree is true.
The statements about output below Fs are convienient for the point at which they are measured. That is below Fs. Above Fs a horn will produce more volume with less power input than any other box configuration period. That is part of the allure!
The other part is it's dynamic range. Granted a huge bank of Vented sub monkey coffins can be coaxed into submission with enough kilowatts to become dynamic. I have both done it and heard it. Frightening! But the volume of the boxes and the cost of the rig driving them is not negligable.
But a smaller complement of drivers with power orders of magnitude lower will outperform the monkey coffins if they are coupled to a horn. ( horse coffin ) ( have to be fair to monkeys ) The trade off is the size. The design limited bandwidth to is a definite tradeoff. ( allthough there are definite design limits to reflex designs to ) But the realistic punch and apparent limitless power is very alluring.
As someone who spent a good many years playing in the back row of an orchestra. I say that hands down a horn portrays the reproduced sound with the greater realism.
Food for thought
MArk |
|
|
| Cortez |
> Small size and low frequency output together cannot be accomplished with a horn.
Well, it depends...
Lets take an infinite, open-air acoustical environment.
We have a cone, and we want to radiate sine soundwaves.
(The cone now just radiate in one direction for simplicity)
At a given frequency the efficiency of sound radiation depends
on the size of the cone. For a lower frequency a bigger cone
is ideal, cause a low freq sound means slow air-movements, and
therefore a lot of time to the air to escape far from the cone
in every direction. Therefore air will rather just move instead
of compression and pressure-variation (generating sound).
Increasing the frequency the radiation is getting even more directed,
cause for the air particulars its easier to radiate the sound in the
cone's axle, instead to propagate it all around the cone.
Now then, its clear that for great bass we need a cone as huge as possible.
But (and thats the point) in a closed place this work a bit different.
In this case we need more power to radiate, cause we must compress the air
in this place a bit. (The walls and the corners push back the waves...)
So there is an important thing, that peoples often forget:
Where do we want to achieve the bass improvements with our horn ?
Remark, that a BR enclosure can also help a lot in bass reproduction,
although it has just a little port. Now then, the are two extremity of
sound radiating:
- small area & big amplitude
- huge area & tiny amplitude
A panel-loudspeaker is rather the second type and a dynamic
speaker with coil and magnet is rather the first type.
With an average subwoofer speaker we have a finite power, and the speaker
alone can radiate low freqs with just a small efficiency.
Now with a horn we can make a transform between the two extremity above.
And we should do this too, cause in a closed air-space there is an optimum
horn-sizing for a given speaker. Not the horn with the biggest mouth is
definitely the optimum. |
|
|
| johninCR |
| Again I ask, what is the consensus regarding a large chambered rear horn in order to achieve true subwoofer extension in a relatively compact horn size? It seems to work well in cabs like the Jensen Imperial. |
|
|
| Cortez |
What is the consensus ? Nothing. These are complex things,
specially at low freqs, e.g. the room plays a big role in this.
Otherwise what do you exactly ? There are a lot of sub-horn plans on the net. |
|
|
| BassAwdyO |
| Why is it that I always hear RCW saying that a horn approximates a 4th order bandpass below the cutoff. What does a 4th order bandpass approximate below it's cutoff? A SEALED BOX!!!! why cant you just say a horn approximates a SEALED BOX below its cutoff!!!! |
|
|
| johninCR |
Bass,
That's below the horn cutoff. The band pass cutoff can be much lower. This is also my point regarding using large chambered horns. For a sub all we need is a narrow bandwidth, eg 20hz to 80hz is just 2 octaves. If the lower end is really ported output with some loading, who cares as long as you get the extension. |
|
|
| BassAwdyO |
it is indeed a very narrow bandwidth, I see your point john.
why dont we use rear chambered back horns? well for one I dont have any clue how to design a good one, for two, it's still huge, and well maybe it still has the same bass reflex sound to it, i dont know. I've never heard one.... |
|
|
| rcw |
Another way of looking at it Bass is that the output from the horn at around and below cut of is the same as that from the port output of a reflex box having a driver of the same Qt as the driver mounted on its air chamber.
If you were to have complete isolation between the port out put and the driver output, then the horn out put is in fact the very high Q resonance that you get from a high qt driver in a reflex box that is also tuned high, this is in fact what a fourth order box is, a reflex with only port output. |
|
|
| GM |
| quote: | Originally posted by BassAwdyO
why dont we use rear chambered back horns? well for one I dont have any clue how to design a good one, for two, it's still huge, and well maybe it still has the same bass reflex sound to it, i dont know. I've never heard one.... |
Greets!
For the same reason you don't use a T/S max flat vented alignment in a corner app, unless a 'boomy' response is desired of course. ;)
They're easy enough to design, especially with Leach's math, though it's best to over-size the compression chamber a bit and reduce it if required. Basically, you just find the Vb that puts the driver's impedance peak at the horn's Fc (Fh).
Done right, it doesn't sound like either a sealed or vented design since it has way more gain, flatter response, but with a highly damped sysQ. With today's low Qts, high Xmax drivers, cheap power and digital EQ though, I don't see the point in a HI-FI sub app since plenty loud, low distortion performance down into the teens can be had using a multiple driver IB or several low Qts sealed cabs.
GM |
|
|
| mike.e |
| quote: | Originally posted by rcw
Another way of looking at it Bass is that the output from the horn at around and below cut of is the same as that from the port output of a reflex box having a driver of the same Qt as the driver mounted on its air chamber.
If you were to have complete isolation between the port out put and the driver output, then the horn out put is in fact the very high Q resonance that you get from a high qt driver in a reflex box that is also tuned high, this is in fact what a fourth order box is, a reflex with only port output. |
rcw : No doubt,horns are resonant,nothing is non resonant.
I find your view curious in its stance,but not unfounded.
So a horn only sounds as good as a BP4 but because its big it must sound betterAre you perhaps also saying that the transient response is nothing improved over BR or BP4 but simply low harmonic distortion due to driver loading??
Regarding subjectivity and mystical horns beating your BP4 ABX,Im sure if you were keen you could ABX it with a large enough sample size (you).
Im also sure that some people might think your comments about this as being nasty,but I see your technical point whether I agree with it or not.
Mike.e |
|
|
| mike.e |
| quote: | Originally posted by johninCR
Again I ask, what is the consensus regarding a large chambered rear horn in order to achieve true subwoofer extension in a relatively compact horn size? It seems to work well in cabs like the Jensen Imperial. |
Do you mean a BLH with a large front chamber?
You can design a horn with no wasted space,with a maximally flat FR for the boundarys present,and a driver of nominal linearity and Vd driving it and achieve the best result possible.
Realistically speaking,nothing hugely better can be done in the near future. This is why there is no labhorn beater. Just different compromises.
We are still looking at a horn in the 4000litre volume for the cutoff in question |
|
|
| rcw |
The point being that if you use a horn in that region it is neither fish nor fowl, neither a bandpass box or a horn, and not much chop at either.
You would at least in theory produce a much more optimum system if you built a dedicated bandpass box for that region, crossing over to a horn at around 80-100Hz.
At these frequencies you can make a straight horn that has exemplary
acoustic transformer performance and a mouth that's large enough.
This is something like the A7 type of box, without the compromise of trying to do two jobs with the one driver. |
|
|
| RobWells |
I believe RCW's saying that the eq'ing of a horn below its cutoff will give the horn the same characterstics as the bandpass box - but only below- it's cutoff frequency.
The difference is above the horns cutoff though. ie: build a horn with a cutoff at 30Hz, eq it flat to 25. 25 - 30Hz could well be similar to a BP enclosure, but as soon as the horn starts loading the similarities are gone. If you use a BP box all the way to 80Hz then you've got the BP signature right up to 80Hz. The region below 30Hz is pretty much 'unhearable' compared to the rest of the audio spectrum so I doubt you'd notice the difference on the horn. Also roomgain would ease the use of eq, as would the horns overall output, which would never be reached in a home environment.
Saying that, I'm planning on crossing the labs I'm building to sealed boxes at 30Hz/48dB/oct. But I want flat to 15Hz at least.;)
Rob |
|
|
| Circlomanen |
"when you do hook an amplifier to it things can frankly get as outrageous as you want them to. These hit extremely low. Paul and I measured a flat response still at 22 Hz."
Thats what Steve Deckert said about this little setup.
More about the Jensen Imperial:
"Along the journey we quickly found out that nothing man made that you could buy in any stereo shop could ever come remotely close to this cabinet as a subwoofer. It would make bass come out of almost anything. A 25 watt 10 inch pioneer woofer shook items off a neighbors shelf in the house across the street. Distance: 220 feet. It did that with one channel of a 22 watt class A receiver. The same woofer in the box it came out of with the same signal wouldn't shake a pencil, in fact, by comparison it was inaudible. It was in that moment I saw the light. It's been almost 20 years since and the passion it ignited actually created DECWARE. Since then, I've had the opportunity to hear most of the best speakers in the world. I bring that up because even today with all I've heard nothing in the consumer marketplace that's not custom built seems to be able to kick its ***.
In the years that followed we built several more of these cabinets and used them as subwoofers in large night clubs. This continued R&D gave us the opportunity to try a variety of things that otherwise would have been too costly. You're probably thinking who needs a bunch of thick heavy bass - night clubs always have sucky bass. Well, ironically the bass from the Imperial was just the opposite. Fast and effortless it was the benchmark of clean, flat, low bass
On one occasion a club owner wanted to hear what one would do in his own place so he called us up. On the spur of the moment we had to take what we had so we packed up a single Imperial, my frequency generator, and an old Harmon Kardon Reciever with one channel blown. Just before we got this call, we had been experiementing with a unique driver arangement. We removed the 15 inch woofer, and replaced it with a 12 inch woofer that was already mounted in a 1 cubic foot sealed cube. The response of the woofer in the cube was 3 dB down at 120 cycles. Basically ZERO bass. We installed this cube into the Imperial with the woofer facing the back of the encosure. The original 15 inch speaker opening was sealed. Installed the response was a bit different. Starting at the same 120 cycles and measuring the SPL at 90 dB in the room we slowly started to sweep the frequencies down until at 28.5 cycles the SPL had risen to 118 dB. That's a 28 dB of gain at 28.5 cycles! I really can't begin to describe what happens at that frequency when you hit that SPL, but it's serious. We saw a mouse stagger out of a crack in the concrete floor and die.
We gave the same demonstration in the night club for its owner, using only a single 12 inch woofer and 80 watts we were able to move the ash trays on 51 tables throughout the facility. It was an effective demonstration. He bought it, and we placed it into service with the 12 inch woofer that you couldn't move for the sealed box behind it - just to see how long it would last with 800 watts driving it all night long. The woofer lasted about 1 week and we got a service call. Upon inspection I was shocked to see 1/2 of the pulp speaker cone missing. It was all still inside the cube in the form of a powder. The largest fragment was less than 10 milimeters across. We saved that woofer for over 10 years just to look at it."
Read the whole article here
http://www.decware.com/imperial.htm |
|
|
| Cortez |
| Have they created something speacial and more, then a simple, but huge horn with strong speakers ? |
|
|
| rcw |
The point that I was trying to make Rob is that a single ported bandpass box has the same second order roll off as a sealed box below its f3 and you can design it so that it is 6db. more efficient.
This means that you can get 6db. more output from the same amplifier driver combination, i.e. you will need 4 sealed boxes and drivers and four times the power for the same output.
If you apply the same sort of equalisation then you can expect to get the same frequency responce and output as you get from 4 sealed box es as you get from the single second order bandpass box with the same equalisation, all the time noting that in fact your horn is acting exactly like the bandpass box in the same range anyway.
The difference being that the overall system is smaller and more ideal in its performance since you can design each section for optimum performance over its range instead of fiddling the horn box in such a way as that compromises its performance in order to make it smaller.
The only benefit accruing from this being that you maintain the illusion that it still is a horn when in fact it is some sort of psudo horn/ bandpass device that is not particularly good at either. |
|
|
| RobWells |
Hi RCW,
I believe that you'd only need 2 drivers, and twice the power to get +6dB, as long as they're close enough to couple acoustically.
The argument you have put forwards is for conditions below the horns cutoff. Above the cutoff then the horn will surely pull forwards from the 4th order box in performance, no ?
ie: Bretts labs 30Hz - 80Hz will have better performance than a 4th order BP box 30Hz - 80Hz. But below the 30Hz mark Bretts 4x12 drivers in the labs will have similar performance to the BP box.
Just trying to understand what you were saying earlier.
Personally I've always just added a second driver rather than port, but thats just my preference. I don't think there will be a sonic difference below 30Hz either way.
Rob. |
|
|
| RobWells |
| quote: | Originally posted by Cortez
Have they created something speacial and more, then a simple, but huge horn with strong speakers ? |
They look like big scoops to me.
Rob. |
|
|
| mwmkravchenko |
I'll try some modeling to. Maybe our two hamsters spinning on squeaky wheels will come up with something. The idea of lowering the limit of the horns response is great. But it has to be done with the same clean sound that we crave from the beasts. With what I have read it is really an expanded version of reactance annulling. The idea being that there could be a smooth roll off of 12 db/octave below the horn system cutoff. Come to think about it why could it not be equalized a bit and get the true sub cut off?
Regarding the size of boxes and the pic posted.
Sure there are smaller horn subs. I have studied a great many. Some are even reflex loaded below horn cutoff. They have definite peaks and dips in their output. The boxes are manageable in size.
I said what I did because from the direct radiator side of the argument they will come up with a 4 cubic foot over amped and Eq'd that has response to 14hz. They exist. And they have output down to the basement and volume to match. The kicker is the amount of power that they require. Kilowatts! Plus there is a difference in the distortion components the two different boxes produce. Short of using a servo.
But then again if you use a level playing field a servo could be incorporated in a horn to. The servo combined with John's idea would get the most bang for the buck. There is also Graham Maynard's phase coherent low end Eq circuit. The point to keep in mind is that the response below horn cutoff decline steeply at 24 db/octave. With an enlarged rear enclosure it should roll off at 12 db/octave. The active Eq will take a lot of power but work.
Mark |
|
|
| johninCR |
I don't understand the emphasis on EQ'g a horn below cutoff in the last few posts. Isn't that just begging for excursion problems? On the other hand enlarging the chamber on a rear horn moves the point where excursion increases rapidly to a lower frequency.
Is the Imperial a scoop? If take a scoop and make it's horn length 2m and make it's chamber size well over 100L, then yes. I think that changes the sonics quite a bit compared to typical scoops. |
|
|
| RobWells |
| quote: | Originally posted by johninCR
I don't understand the emphasis on EQ'g a horn below cutoff in the last few posts. Isn't that just begging for excursion problems? On the other hand enlarging the chamber on a rear horn moves the point where excursion increases rapidly to a lower frequency.
Is the Imperial a scoop? If take a scoop and make it's horn length 2m and make it's chamber size well over 100L, then yes. I think that changes the sonics quite a bit compared to typical scoops. |
I think its more that in a home environment the horn will never get near its x-max. This allows a fair bit of boost before problems arise.
I won't be boosting the labs I'm building - they'll be crossed right on the lower limit of the horn loading.
Re: the imperial. I haven't seen inside one - I think I'd have to pay for the plans. The 21" scoop I linked to has a 2.44 metre length, and a very quick rough calc gives approx 75L rear chamber. (If the rear chamber is what I think it is on the plan:D )
Whats the mouth size on the imperial ? - The scoop I linked to has a mouth of 3984 cm2, and it states in groups of 4 the loading is down to 28Hz. (35Hz for 1 unit)
Cheers,
Rob. |
|
|
| Magnetar |
I use three sub horns loaded against the front wall and concrete slab floor. They get down into the teens at 125 db levels no problem. Mine are loaded with three eighteen inch JBL 2242H's.
Stargate Horn System (Obsolete)
 |
|
|
| Magnetar |
Here is one I built designed to go up against a wall. It has a 25 Hz flare and is loaded with a JBL 2241 18" woofer. It requires a 6 db boost at 20 cycles to get below 20 with authority.
 |
|
|
| johninCR |
Rob,
I came up with about the same chamber size for that 21" super scooper, but that's for a 21" driver and the imperial was designed for a single 15". The scoops are designed for max efficiency, however, the Imperial was originally designed as a full range unit, so they sacrificed some efficiency for deeper extension which was a better match for the acoustic XO between the front radiation and horn output at about 90hz. BTW the imperial's mouth is 7600cm2 and it was designed for in wall installation and use as a single unit in mono.
The route I'd like to try eventually is an rear loaded horn array, at least to find out if what HornResp is telling me is real, and that is strong output more than an octave below Fs. If I can find someone to give me 24-32 of the CSS WR125ST's, I could make a sub unnecessary except for subsonic HT content. |
|
|
| GM |
| quote: | Originally posted by RobWells
They look like big scoops to me.
Rob. |
Greets!
Depends on the 'scoop's' design gain/BW. If a typical BLH designed for wide BW such as the Imperial's, then it's nothing more than a BR with a huge expanding vent, ergo has a relatively large filter chamber/throat and terminating at a shorter length/larger mouth. Limited BW 'scoops' are closer to being compression driven, with higher gain over a narrower BW via a smaller filter chamber/throat and longer pathlength to get to the minimum aceptable mouth area.
The former has greater acoustic (box) efficiency, while the latter has greater acoustic power, ergo lower distortion/higher SQ until the driver goes into thermal power or mechanical overload, which can be at quite low power if the CR is high, so only prosound drivers designed for the app/abuse should be used IMO, even in a HI-FI/HT app as half roll surround suspended drivers sound really obnoxious when they deform. Obviously, any driver suitable for a BR/TL app will work in a typical wide BW design BLH.
GM |
|
|
| DeonC |
Would the DECWARE Imperial plans work with a single Tannoy 15-inch dual-concentric per side? Just curious. :D ;)
Thanks,
Deon |
|
|
| RobWells |
| quote: | Originally posted by johninCR
Rob,
I came up with about the same chamber size for that 21" super scooper, but that's for a 21" driver and the imperial was designed for a single 15". The scoops are designed for max efficiency, however, the Imperial was originally designed as a full range unit, so they sacrificed some efficiency for deeper extension which was a better match for the acoustic XO between the front radiation and horn output at about 90hz. BTW the imperial's mouth is 7600cm2 and it was designed for in wall installation and use as a single unit in mono.
The route I'd like to try eventually is an rear loaded horn array, at least to find out if what HornResp is telling me is real, and that is strong output more than an octave below Fs. If I can find someone to give me 24-32 of the CSS WR125ST's, I could make a sub unnecessary except for subsonic HT content. |
Hi John,
The photo of the imperials that was posted had 2 x 15's (I think they're 15's) per cab. Therefore I was thinking it would need more rear chamber than a single 21"
Thanks for the input GM. Nice to have your experience chiming in.
Rob |
|
|
| RobWells |
Magnetar,
The first pic you posted - That type of horn looks pretty perfect for a home theater app. Just place them wall to wall and put the screen in front.
Rob. |
|
|
| Magnetar |
| quote: | Originally posted by RobWells
Magnetar,
The first pic you posted - That type of horn looks pretty perfect for a home theater app. Just place them wall to wall and put the screen in front.
Rob. |
The basshorns are behind this screen.
 |
|
|
| RobWells |
:cool: Those main horns make the screen look small ! How big is it ?
What are your feelings on eq'ing horns below the cutoff ?
Rob. |
|
|
| Magnetar |
| quote: | Originally posted by RobWells
:cool: Those main horns make the screen look small ! How big is it ?
What are your feelings on eq'ing horns below the cutoff ?
Rob. |
Back then I used a 7' 4:3 screen - now I use narrower speakers and built a 10' screen.
I believe if you build a horn for the deep bass you should use the room to it's full advantage - 1/8th space loading (corner) is a big plus and normally will use up less living space. Eq is fine as long as you don't over drive the driver and expect miracles with too small of a horn. My triple subs use a lowpass single pole lowpass at 30 cycles built into the front end of the bass amps. The JBL 2242's in the three horns have a combined sensitivity of around 112 db/W/M at 20 cycles. They are AWESOME basshorn drivers! I use 220 watt watts/ three channels with a mono input to all three horns, plus use a Paradigm X30 with variable low pass and 0 to 180 degree phase adjustment infront of the amps to fine tune to the main speakers. It will reproduce a thunderstorm with little to no compromise. It can be scary - the air pressure in my room can be overwhelming. |
|
|
| Circlomanen |
| quote: | | It will reproduce a thunderstorm with little to no compromise. It can be scary - the air pressure in my room can be overwhelming. |
:devilr: :D :D :D |
|
|
| AndrewT |
Hi Magnetar,
I have asked this question before and appreciated the feedback but I would like to hear your opinion.
How long are your horns?
The bass horn is very long and this effectively delays the bass signal. You mention a continuously variable phase control on the bass horn? Does this appear to bring the bass signals back in time with the main speakers or does it just avoid the suck out around the crossover band? with the resultant slow bass because all the main speaker signals arrive waaay ahead of the bass?
Hi all,
If I use an 18 inch driver in the sub-bass horn 6m to 7m(20 to 25feet) long driving a 3.6sqm (42sqft) mouth into the corner of a 160cubm (4500cubft) room will I get some room gain at very low frequencies? I think I will have a lot a spare capacity in power and volume terms, so does that mean I can apply a linkwitz transform to pull up the low frequency response for AV use? For music I will settle for a response down to 20 Hz.
How do you adjust Linkwitz to take account of room gain? Trial and error or something more technical? |
|
|
| DeonC |
Hi guys
I thought you might enjoy this: a picture of a pair of Jensen Imperial horns with a Hartley 24" driver in each! :bigeyes: :bigeyes: :bigeyes: Now that ought to get you real low with real ease!! :cannotbe: :D
Enjoy,
Deon |
|
|
| DeonC |
BTW, in case you were wondering, these bad boys are a mere 97" tall (that's about 2.5m tall in metric). :bigeyes: :cannotbe: Now that is my type of sub. :devilr:
Deon |
|
|
| Cortez |
| Well, its not a too complex design at all... :) |
|
|
| Circlotron |
Man-eating speakers :bigeyes: :bigeyes: :bigeyes:
No thanks! :whazzat:
;) |
|
|
| Circlomanen |
| quote: | | I thought you might enjoy this: a picture of a pair of Jensen Imperial horns with a Hartley 24" driver in each! Now that ought to get you real low with real ease!! |
I wonder how an upscaled Imperial with :
would sound? |
|
|
| Bass-Depth |
A Tuba 36 plays even down to 20Hz and should also play loud and clean ;)
David :D |
|
|
| Magnetar |
| quote: | Originally posted by AndrewT
Hi Magnetar,
I have asked this question before and appreciated the feedback but I would like to hear your opinion.
How long are your horns?
The bass horn is very long and this effectively delays the bass signal. You mention a continuously variable phase control on the bass horn? Does this appear to bring the bass signals back in time with the main speakers or does it just avoid the suck out around the crossover band? with the resultant slow bass because all the main speaker signals arrive waaay ahead of the bass?
Hi all,
If I use an 18 inch driver in the sub-bass horn 6m to 7m(20 to 25feet) long driving a 3.6sqm (42sqft) mouth into the corner of a 160cubm (4500cubft) room will I get some room gain at very low frequencies? I think I will have a lot a spare capacity in power and volume terms, so does that mean I can apply a linkwitz transform to pull up the low frequency response for AV use? For music I will settle for a response down to 20 Hz.
How do you adjust Linkwitz to take account of room gain? Trial and error or something more technical? |
Hello, what I'm using is three horns combined together side-by-side sharing the same 42 square foot mouth in 1/8th space, because of this configuration the path can be as little as 7' or as long as 21' - it would be very difficult to model, although wizards like John Sheerin that visits this forum could do it.
The phase control does avoid suckout but you have to understand there is three drivers seperated by 13-28' each that span across the whole front of the room which does vary the time and phase at the listening position (and room modes overlap, reinforce, cancel, ect) so it really dpends where you are in the room and where the main bass drivers are. I feel the power, dynamics, articulation and depth with this subwoofer system is worth the paranoia of knowing there is a delay from the mains. I have uses a digital delay on the mains and didn't like it. I normally only run these up to 40-60 Hz.
Corner loading will give you higher output and less ripple in the bass with a smaller horn! It is the way to go if you have solid corners. If you model in the McBean program in 1/8th space compared to 1/4 or 1/2 you will see a pretty good simulation of what the differences are.
I also feel front loaded horns like mine are considerably better sounding than the backloaded horns I have seen posted here. It does however come down to much more than front loaded versus backloaded - IE the Imperial is not relly a horn subwoofer, it is more of a direct radiator with backwave reinforcement in the bass. Probably a better cjoice for someone who wants to crossover above 80 cycles, but not as good for what I want out of my subs, |
|
|
| Bass-Depth |
| Are there plans in this forum for Speakers which are loud enough to play with one or two Tuba 36 also as PA-Speakers but with clean sound like a super Hifi-speaker? |
|
|
| mike.e |
| 24" scoop - not the most efficient use of space IMAO |
|
|
| freddi |
although dB# did not beat expectations/rules , briefly tried a 416 in funky Karlson tuned ~28-30hz per eXemplar w. a couple of pvc elbows - didn't have proper bandpass filter centered @30 as they used - so kluged w. old EV Interface box and a funky k12 w. ancient Allied-Knight-Jensen - maybe good (not "thick") tone was due to low-mass Altec - but played very well on better theatre organ cds with nice decay vs a B6 reflex w. - uh Eminence/Dayton 15 - system ran mono w. thrift store 15W/channel receiver room was only 14x22 - guess lower tuning added ~7-8dB in 20-32Hz then boost another 6 on C note -maybe not what folks would call SOTA but... ducts were not well received on K-forum so it was trashed.
eXemplar sub
 |
|
|
| qi |
| quote: | Originally posted by Bass-Depth
Are there plans in this forum for Speakers which are loud enough to play with one or two Tuba 36 also as PA-Speakers but with clean sound like a super Hifi-speaker? |
My two cents...
I would go with the largest TUBA 36 plan with the horizontal (BR) slot option to get into the teens.
I would cross them over (36db active) at 50hz to this DIY design...
http://sparkgap.homestead.com/DIYHedlunds.html
I would use a single high quality capacitor at 4k to HEIL AMTs (or equivalent) |
|
|
| qi |
| quote: | Originally posted by Bass-Depth
Are there plans in this forum for Speakers which are loud enough to play with one or two Tuba 36 also as PA-Speakers but with clean sound like a super Hifi-speaker? |
Here is another candidate, and there will be DIY plans posted "real soon"...
http://www.hornloudspeaker.de/
It looks similar to the Carfrae Little Big Horn |
|
|
| mike.e |
True. You can EQ anything to varying degrees,it just depends how much you understand what is happening,and what your requirements demand.
Personally I wouldnt since generally the subwoofers are the most demanding.
He doesnt mention excursion,only power. Hornresp clearly shows the excursion below Fc,which is probably similar to a sealed box. |
|
|
|
