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In the Forum: Horn-Loaded Speakers
In the Thread: Midbass impedance bumps -- why and what to do?
Post Subject: The horns are like a Toilet?Posted by Romy the Cat on: 10/25/2010
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 noviygera wrote:
Question, Romy:
Why do you suggest to add the extension on the back, not the front, as B. Edgar suggested. He specifically commented that the MOUTH area is too small and said the throat size was OK?

Herman, the mouth area determines the LF cut off, the ration between mouth area and throat area determines horn LF equalization. Bruce recommendation to extend mouth is incorrect. Extending mouth you will make a completely different horn and will be forced to change back chamber. You will end u[p with a horn that will have 5-10Hz lower but it will make it absolutely not useable in context of the Edgar setup as the mouth will be cover the MF driver. The problem with 80Hz hour is not that it need to become 60Hz horn but that it need to output 80Hz but properly, with proper equalization and with proper sound. The Bruce’s 80Hz horn is too short with too large throat. By extending the horn in the back you will continue the descending curve and will end up with smaller throat, and by this you will change the EQ of the horn. If Bruce feel that the MOUTH area is too small for 80Hz (even for 1/8 size) then it would be better do not call the horn as “80Hz horn”.

Anyhow, I did not look at the Bruce’s 80Hz horn math but just looking at it the horn strikes me as very short horn. Be advised that extending the horn in the back will not address all problems as you need to think about time-aliment, drivers integration, location of the channels and the channels vignetteing. Pay attention how Macondo is gone – it provides a lot of answers and outcome of long thinking and many experiments how to optimize multichannel horn installation. I do not propose the Macondo configuration - it takes years of playing with it in order to understand that there are no other proper configurations – but I do propose to start with the way how Macondo started L take pen and paper and begin to draw the location of the channels.
 
When I was redoing my bathroom then my plumber measured all new appliances and give me an AutoCAD drawing of my new bathroom with all appliances vertically installed. He begin to break walls and run pipes only after we have an absolute agreement what and where will be installed and how it will be related to each other. How would you feel if you are a plumber and I after you are done and tiles are laid I asked you to put a shower of opposite wall of to place a jacuzzi in place of bidet? I think an advice to “fix” horn by extending it’s month is very much from the same ploy….

The Cat

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