Very interesting new RTFS SiRRAH  absorber/diffuser. I've asked Ben van Leliveld to share some insights. Do check the photos of practical implementation in quite a few upper echelon high-end audio systems and impressive pro-audio high-end studios/recording locations: "The SiRRAH absorber - diffuser are developed by RTFS Mr. Farshid Shlawadian, acoustical engineer. Already 6 years ago I was searching for a modern diffuser with consistent behaviour to be used in professional sound studio’s as well as home applications e.g.listening rooms, home cinema. We use the SiRRAH in the large demo room of Chattelin Audio Systems. Also most of the clients of my company Acoustic Matters do use them. Recently the new high-end mix and mastering studio of the label TRPTK ( uses them extensively." 

The basic is specially formed acoustical foam that can break if you press it to hard. RTFS has developed a special coating called BREA. The magic is with this coating. Low and mid frequencies will pass this coating and gets absorbed. Higher frequencies are diffused on a very consistent and fluent way. As from 100cm (appr. 3 feet) these SiRRAH’s do not have a sound of its own so you can actually sit nearby a SiRRAH which is not the case with traditional RPG diffusors were the critical distance is > 250cm

The SiRRAH’s can be easily attached by a square 10 x 10cm magnet so you can carefully get those in position and remove them easily which is a benefit in professional surroundings. The EU retail price is € 249,90,- and you can choose out of 4 colors: white, grey, red and black.

Also applied in the Northstar Recording Services studio. Tonmeister Bert van der Wolf (Challenge Classics)

Sometimes musicians also like to use SiRRAH's in this case at the recording of a Stradivarius (!) Cello from 1686.

Below the TRPTK studio in The Netherlands - city of Utrecht.

Contact: Ben van Leliveld ( - +31 6 53354337