GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Macondo 3.0

Post Subject: I have my reasons.Posted by Romy the Cat on: 7/4/2023

ArmAlex wrote:
Hi Romy, In this picture it looks that attic opening's distance to listening position is very close to distance of chair to the main speakers. Time alignment?

ArmAlex, very good question. The position of the exit of the open baffle was well considered and chosen deliberately. The first thing first, that picture above is a bit misleading. It is a wide-angle lens, and it makes the distance between the listening spot and main loudspeakers too large. In reality the exit from infinite-baffle is just slightly smaller.

The infinite-baffle exit is not position at the location absolute time alignment because I would like to reserve this position for the exit of the midbass horn if I chose to build is in future. The infinite-baffle is crossed at 20Hz with wavelength 63 feet. A few feet here or there will make significantly less difference than it would be a let's say crossover point of 60 Hertz of mid base horn. Also, and it is the most important argument the exit of the infinite baffle is made and the architectural corner of ceiling. It is not the end of the room, in fact it is in the middle of the room, but it has two ceilings, and I placed the baffle in the end of just one ceiling. Consistently that is location when I had a maximum low frequency gain in a room from listening position, i did measure it. So, from one side I have time alignment which is at 20 cycles less critical and from other side I have a good 10 decibel gain from low frequency, that certainly made amplifiers to create less voltage and drivers’ diaphragm have less excursion. What would you choose? Here is a tip, something that I did. If you measure gate and loss of the signal for time alignment at 20 cycles, then a few feet would have absolutely no dent on the amplitude of your response. So, 10 decibels of gain that I got from room in my view overweight everything. If you want to experiment with this, you can do what I did and use my magical device. I use the magical Sunfire True Junior Subwoofer. It is super compact sub that can go very low and very manageable. I hooked it to all imaginable places of my rooms to see how room response to the different LF source’s locations. I use strictly empirical methods to do my predictions. Under no circumstances any human being should pay attention to the Sunfire sub sound, it is atrocious. However, as an acoustic pressure generating machine it is very comfortable tool at least to me.
The infinite-baffle in red the prospective mouth of the bass horn in blue

Macondo3.0_AtticFull.jpg

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