**terra horn**

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

Just a bump to say 'Hey, where are the pictures you promised' 

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'

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...

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