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In the Forum: Horn-Loaded Speakers
In the Thread: 45Hz Bass Horn
Post Subject: 45Hz Bass HornPosted by jessie.dazzle on: 9/19/2006
Hello Romy and everyone here,
Thanks again for your thoughts on the large horns.
It seems best to start a new thread, as previous threads dealing with the "10-Footer" originally began as discussions of other subjects. Romy, you may want to move previous posts regarding the large horn to this thread as well (you can find them in the 5-Ch Melq, and Evaluation of Tractrix threads).
Quote from Romy : "...the 45Hz...should have a chamber of mach larger size, enabling to tune the driver for 80-90Hz. I know it sounds ridiculous to make a huge horn and waste it for a high crossover point. Still you might find it very beneficial for Sound. People usually do not do it (and I understand why) but you might experiment with it and you might discover then with "enough" space under crossover point the upper bass "might" sound very “opened”. You might go then to a lover crossover point by juts masking out the back chamber. It is hard to predict how high the 45Hz horn will be working..."
Contrary to what is mentioned above, when I calculate to tune the rear chamber volume for 80Hz, I get a SMALLER chamber volume than when I calculate for 40Hz. Beginner that I am, it is entirely possible that I'm missing something. In any case I understand that you mean to suggest tuning for 80 - 90 Hz.
I calculated rear chamber volume via the formula below (with throat area in square meters, velocity of sound in meters/sec).
Throat Area X Velocity of Sound
-------------------------------------
2Pi X Horn Cutoff Frequency
Formula available here (scroll down to "Compression Chambers", Second formula, as there are no T/S parameters for the AK151) :
http://melhuish.org/audio/horndesign.html
Is this an acceptable formula for REAR chamber volume calculation?
Regarding throat area : I don't have a question, but will post what I plan to use and leave it open for posssible comments. Though the AK151 is a 15 inch driver, the effective piston area measures about 11 inches (28 cm) in diameter. I took 2/3 of this dimension to arrive at a throat diameter of 7.33 inches.
Thanks in advance for any clarification/thoughts. Again, I hope one day to contribute back to this site with photo-documentation of the build process.
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