GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Jessie Dazzle Project

Post Subject: Upper-bass sweepsPosted by jessie.dazzle on: 3/6/2010

Since having replaced the 16 Ohm drivers in my upper-bass horns with 8 Ohm versions of the same driver, I gained enough upper-bass output that it is now possible to run all horns from the 8 Ohm taps (I was previously running upper-bass from the 16 Ohm taps in order to increase their output).

In the Mid-bass horns and real estate thread Debugging the upperbass I mentioned that in spite of this gain, I still hear the absence of the as yet not completed mid-bass horns.

In response to that comment, Romy wrote:

"...I still do not know why you have weakness in 80-160Hz octave. Your upperbass shall cover it perfectly fine. Can you post sweep of your upperbass alone with no crossover. Actually I would need 4 sweeps if you do not mind.

1) Regular slow sweep were 20-20000 is passed within 15-20 seconds from horn default position

2) Regular vibrating sweep were 20-20000 is passed within 10 seconds

3) Regular slow sweep were 20-20000 is passed within 15-20 seconds but from different location, from another perpendicular wall

4) Regular slow sweep with your other channels attached electrically but the horn are plugged and do not radiate sound.

I do think that you have some kind of bug as I feel that your upperbass shall not have the 80-160Hz problem..."

Here are the sweeps (all measurements done with no filters on the upper-bass horns; microphone placed in listening position about 12 feet away):

2x 115Hz horns 20-20KHz in small increments.jpg

Above: 1) Both upper-bass horns in their normal position, playing a succession of narrowly spaced tones from 20-20KHz

2x 115Hz horns 20-20KHz warble tones.jpg

Above: 2) Same as previous image, but this time playing a succession of not so narrowly spaced vibrating or warble tones from 20-20KHz
(I used recorded tones for the "vibrating" sweeps; they are not as closely spaced as the non-vibrating tones in the previous image, which were created using a tone generator)

1x 115Hz horn Left wall 20-20KHz in small increments.jpg

Above: A single upper-bass horn, playing a succession of narrowly spaced tones from 20-20KHz

1x 115Hz horn Right wall 20-20KHz in small increments.jpg

Above: 3) Same as previous image, but this time the horn was moved to an alternate position.

Above: 4) Both upper-bass horns in their normal position, playing a succession of narrowly spaced tones from 20-20KHz, with all mid and HF drivers connected, but physically muted.

I did one more sweep running the lower-bass modules as well, which indicated that they are taking over below the upper-bass horns, right about where they should. In light of this, it is unlikely that I am correct in stating that I was hearing a lack of output in the 80-160Hz octave.

To be continued...

jd*

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