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**terra horn**

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tb_mike View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb_mike Quote  Post ReplyReply Direct Link To This Post Posted: 07 June 2005 at 11:55pm
Originally posted by _djk_ _djk_ wrote:

"Red herring. Any resistance present in the speaker cable will ruin manufacturers Dfactors of ten hundred billion ,down to 50 or so."

Crown Delta Omega 2000 has feedback sense leads to go directly to the drivers to negate speaker wire resistance.

Thats all good and nice sounding,but what are the practical results?

Saw a circuit in Electronics Australia suggesting how to do this.

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minaximal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minaximal Quote  Post ReplyReply Direct Link To This Post Posted: 08 June 2005 at 7:24am

the delta omega amp was also introduced in 1982, it doesnt look like they still bother employing the technology any more...?

i ran some tests on my horn for the last two days, and it seems that the (very old) cs1000 amp does start to drop its voltage;

 at ^45hz-30hz;  to 50v (300w) (@30hz) 8r bridged a bit after the hpf kicks in whilst still keeping nearly as close to clip with same sensitivity as at ^45~100hz where it is around 90v (1000w) maybe an extra -2db~3db on top of filter!? (L-R 24db at 28hz)

the amp was fairly constant maybe even picked up a bit after it dropped and stayed 40v at 26hz.  this wasnt the most scientific of tests, my laptop soundcard and sigjenny/cheap multimeter, may have introduced drops in gain, but pretty sure its mostly the amp, (or maybe inductance) is this a problem of other amps also.. cheaper components maybe? 

back to the horn though,

1/4watt! at 26hz makes the whole building shake, but 40v  at 26hz as stated above was the most the amp could throw at it also with the hpf set. and that was intense! everything started falling off the walls and shelves, and horn started vibrating around the room..(its 110kg at the mo')

strangely the only panel ressonances were from my house walls and some screw holes i made just after the throat whilst glueing the layers together,which i had forgotten to fill, which made the horn whistle, until i worked out where it was coming from i was a bit worried after that with only the two sheets of 4mm ply layerd up so far the panels seem fine.

need to rta it really (see if i can get the mic today).. surely if other amps drop voltage at lower frequencys rta's may not be that much to compare..

hopefully get photos today..



Edited by minaximal
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 08 June 2005 at 11:48am

Quote People are hearing differences between amps,I dont know how,Havent experienced it myself not enuf amps around

Most obvious difference would be the headroom of the amp. Most cheaper amps are made that way that they begin to distort long before you see the leds indicate clipping. With my own cheaper amps I can hear the distortion at +/- -6dB

Higher quality amps begin to distort much later, sometimes even already after it's clipping. Of course this will affect the sound and thus create a difference.

Wkr

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote rastaman Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2005 at 10:14pm
Just a bump to say 'Hey, where are the pictures you promised' 
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Phil B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2005 at 7:15am

Please tell me that this ain`t someone in your "terrahorn"?!!!

 

They`re gonna need that stretcher ......?

.p.

 



Edited by phildekked
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tb_mike View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb_mike Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2005 at 9:39pm
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minaximal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minaximal Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2005 at 7:25am

 

Originally posted by phildekked phildekked wrote:

Please tell me that this ain`t someone in your "terrahorn"?!!!

 

They`re gonna need that stretcher ......?

.p.

 

hehe, that photo's great, yer i tried crawling in also at a quiet point and then some jungle bassline came on and scared the sh*t outa me, felt like it blew me back out, becaues of the sound pressure. tom jones spent most of his time in there though gaurding it for us.

i have been away for a bit, and photos are still on gf's mac, i'll see what i can do.

i found out a few days after doing some tests that a niegbour four houses down on the other side of the road was freaking out because his whole house was rattling and rumbling, and he was running around between each room trying to find out what was háppeníng.. so it work quite well

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tb_mike View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb_mike Quote  Post ReplyReply Direct Link To This Post Posted: 26 June 2005 at 1:08am

bahaah thats the stuff!!

Even though 140dB of 32hz in your flat isnt that practical,I still crave it its ridiculous. My mind keeps reminding me 'build the jbl 2226 horn'

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Post Options Post Options   Thanks (0) Thanks(0)   Quote rastaman Quote  Post ReplyReply Direct Link To This Post Posted: 05 July 2005 at 12:41am
Just looking at the curved section picture with the guy lying in it, how many separate plys is that bonded together, from the photo it almost looks like you just bent a piece of 18mm plywood? Is it made up of lots of thinner layers, a la the HD15 and Scoops and so on.?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dj-panoramix Quote  Post ReplyReply Direct Link To This Post Posted: 02 March 2010 at 2:56am
what the exact external dimension ?
what are the HR input parameter(approximatively) ? because i can't get nothing that smooth in 2PI with 3,4meter long...
 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dj-panoramix Quote  Post ReplyReply Direct Link To This Post Posted: 02 March 2010 at 1:56pm
here's is my best result:
2PI:
0,5PI:
Input:
Excursion with 70V:
as you can see with 70V input the driver is in overexcursion, minaximal can you post your excursion plot for 70V ? 


Edited by dj-panoramix - 02 March 2010 at 1:57pm
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minaximal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minaximal Quote  Post ReplyReply Direct Link To This Post Posted: 02 March 2010 at 1:57pm
Originally posted by dj-panoramix dj-panoramix wrote:

what the exact external dimension ?
what are the HR input parameter(approximatively) ? because i can't get nothing that smooth in 2PI with 3,4meter long...
 
 
 


wow, 5 year old thread bump!..

do you really want to try and build something as difficult as the terrahorn?
I do pretend to be secretive and proffessional, as i make them for ££.

but anyway,

S1 = 400

S2 = 7400

i'll let you guess at the rest, albeit is just a normal hyperbolic horn, folded (bent) in an elegant way, to minimise in passband standing waves and refraction, due to inconsistent contour changes, hence the curves.

years ago when i started this, many believed a curved contour makes no difference for bass, i still beg to differ, (listen for yourself!) and look at the work of geddes on HOM's and wavefront propogation today, to see the widely accepted views now. (although he doesn't like basshorns)

also interestingly my initial response sweeps show the constructed horn seems to have a longer pathlength than reality, thats partly end correction factor, and the mirror image of the horn mouth on the floor, which would increase the effective mouth area as seen by the driver.

Ps, pd1850 or ciare ndc 18-5

al





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