QDA – 13 Quadratic Diffusor Absorber


The QDA-13 are two units within one. First, a quadratic diffuser based upon prime number 13 with a diffusion frequency response starting at 285 Hz. and going through 3,450 Hz. Behind the prime 13 quadratic diffuser is our activated carbon broadband low frequency absorber from 30 Hz. – 400 Hz. At the base of the QDA-13 is our more frequency specific carbon absorber from 30 Hz. – 50 Hz. The QDA measures 27″ w x 60″ h x 12″ deep and weighs 275 lbs.

ACDA-10 Riverbank Test Result

ACDA-12 Riverbank Test Result

The Quadratic Diffusion in the QDA takes your sound and spreads it out across your room in the way nature intended you to hear it without your room getting in the way. Your room prevents this naturally occurring sound-field from happening because it has 4 walls, a floor, and a ceiling. Diffusion minimizes the reflections that want to destroy your precious direct sound from your speakers. Whilst reflections from room surfaces help you localize and define sound and distance, these reflections must be managed through diffusion so that the reflections do not get in the way of the sound coming from your speakers. This is why your ears are longer than they are wide.

With the QDA you will finally get to experience the involvement that your expensive speakers are producing but which your room is stopping you from hearing. Through no fault of your own you have become so used to, and accepting, of poor diffusion in your room that your ears and eyes will open wide when you hear Quadratic Diffusion for the first time…Seriously, words fail to describe just what an impact diffusion has until you try it for yourself!

If you order the QDA today you will also get

  • A free one 30 minute phone or video consultation on your room mode issues with me, the products inventor, Dennis Foley
  • A 100% risk free 30 day money back guarantee
  • And castors so you can move the units in and out of your room if your listening room serves multiple purposes.

Request Quote

These units have special handling and shipping requirements, due to their weight and size. Please call us on 520-392-9486 or click HERE to contact us so we can assist you further.

SKU: 000010446 Categories: ,

Additional information

Weight 225 lbs
Dimensions 30.5 × 60 × 13 in


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