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With the QDA-13 you have quadratic diffusion and activated carbon diaphragmatic absorption combined in one unit. Quadratic diffusion from 300 hz. – 3,400 hz. coupled with 3 low frequency activated carbon absorbers. The bottom absorber begins absorbing at 35 hz. and goes to 50hz. Behind the diffusor section, we have 2 activated carbon, diaphragmatic absorbers that are broadband absorbers beginning at 40 hz. and going through 100 hz. Consult our Riverbank test data below for performance specifics. Both frequecy absorption curves on the ACDA-10 and ACDA-12 apply to this product. Units are completely finished in furniture grade veneers with light, medium, and dark stains. Units are 60″ high, 24.5″ wide, and 13″ deep. Each unit weighs 240 pounds.



Quadratic diffusion eliminates wall relections by spreading middle and high frequency energy out in fanlike array across our room. Diffusion is preferred over absorption because with absorption, sound energy is converted to heat and is lost forever. The wider the frequency response range in the diffusor, the more air, seperation, layers, and definition are added to our recordings and playback presentations. The activated carbon, diaphragmatic absorbers, absorb low frequency energy across the low frequency spectrum in a smooth and uniform rate and level. With this low frequency energy control, our bass energy in our recordings and presentations becomes more defined and seperated. Bass definition is critical to a balanced recording or presentation. It is the foundation upon which the middle and high frequencies rest upon. Instead of buying seperate diffusion and low frequency absorbing products to accomplish the above goals, you can have both in one unit. Our furniture grade veneers equal or exceed the quality levels found on today’s upper end speakers. With this performance level in the low, middle, and high frequency ranges of our music, we now have another component to add to our amplifiers and speakers.

Graphic Display of Test Results for Low Frequency, Activated Carbon, Diaphragmatic Absorbers (ACDA – 10)


Graphic Display of Test Results for Low Frequency, Activated Carbon, Diaphragmatic Absorbers (ACDA – 12)