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R1's TESTS...







Roundffusor1's  Critical  Measurements  made  by  the  inventor

Measurement setup

1.    The source - a loudspeaker IMF Professional Reference Standard MK IV (a 2,5 m long transmission line loudspeaker, down to 17 Hz), positioned at 3,8 meters and 45 degrees lateral to the 12 grouped R1's axis - a matrix of 3 R1 horizontally by 4 vertically- driven by an amplifier (one channel, 130W, class A) directly from a TEF20 unit.

2. The sensors

a. a PVR1 - OMNI ELECTRET mike , laterally covered with protective air plastic foil in order not to touch the R1's body.

b. a miniature 3 grams Bruel accelerometer model 4500, serial nr.1804165, driven by the TEF20 towards a DeltraTron power supply WB 1372.

A calibration was not necessary, what was asked was:

a. the relative levels between the loudspeaker's wood cabin - at the lateral wall at the woofer height [the accelerometer glued using double face adhesive tape ]and two places upon the outside R1's surface, and

b. the relative levels between a multitude of positions, recorded by the above mike inside the R1's column long of 232 cm, the loudspeaker being at 3,8 meters away from the center of the R1's grouped surface .




When and How does the grouped R1 work ? Why is so important to know ?


A. Accelerometer measurements  

level1 - This  is a normal music listening level  


level 2 - Here is a higher signal level than level1  

Here above are shown the results from the highest signal level applied to de loudspeaker, relative to the two above measurements levels - 1 and 2.

* with white - the recorder signal from the accelerometer glued upon the loudspeaker's wood cabin

** other colors- the recorded signals from the accelerometer, glued upon the two different R1's surfaces - exactly in the middle of each R1, at the cross point.


Conclusions 1

A.  Accelerometer's measurements

1. In all situations, the displacements recorded by the accelerometer on the loudspeaker's wood cabinet were bigger than that sensed on two different [ but grouped] R1. Please note that each IMF speaker weights about 47 Kg and each R1 less than 2 Kg.

2. Somehow, the spectral irregularities recorded on the wood cabin's surface are filtered out upon the R1's surface. This means that at any source's levels, the R1's plastic body resonate somehow less than heavy loudspeaker's cabin, the small displacements waves are following the speaker's ones. 

B. Microphone measurements taken inside of the R1's columns  

The microphone took measurements from both lateral column of 3 vertically columns of R1  

The microphone took measurements from the central column of a 3 vertically R1's columns ( in the matrix of 3 horizontally x 4  vertically)  

Conclusions 2

B.  Microphone's measurements

1. The low frequency point were the grouped R1 are changing towards the mid and high frequency is 181 Hz.

2. It is clear that the R1 must be kept absolutely empty and not be filled with any kind of porous material, the air back absorption - complex Helmholtz resonator with very large aperture - being between 10 and 25 dB lower that the low frequencies inside the columns and of course, the whole, lower than the field level in the room. And all this, is done practically simultaneously with the incident sound, because our hearing system cannot perceive...when. This ''when'', in my opinion is the human perception's delay. So the said...real time, is not quite that. About this when, more at { such things are impossible ? }

3. The back air absorption is almost linear and this explain the same almost linear frequency responses. We speak about linearity but in fact is the musical bass surplus which is reduced by the grouped R1 surface,  for a certain room and audio system and song.

The recorded phase is remarkable stable at all points of measurements.

The superposition principle is somehow accomplished practically, even if extremely hard to be mathematically modeled.

4. As described earlier in the site, each R1's column, behave differently, reacting dynamically with the rooms modes and the always changing stereo signal, much more being done for low frequencies into the lateral R1's columns and less towards the R1's grouped surface center.

Please note, that in the microphone's measurement case, the frequency resolution is higher at 22.3 Hz than the 52.2 Hz in the accelerometer's case.

For clarity, all measurements were smoothed to 33% or 1/3 octave.


Roundffusor1's published, independent aural tests , all in Greek language.

 >  'Hxos-Eikona'': R1's Test

> AV Pro's article: R1's Test

>  Radio-Link's article: R1's Test 

>  Radio-Link - Zainea Liviu Interview



Much better acoustics : Big  recording studios or live stage performances

A simple example of a wide open trapezoid geometry made from grouped R1 ,

embracing the performers and directing the sound field towards the microphones or public



Company address : Mr. Zainea Liviu Nikolae / ESR,  14 Peresiadou street, TK11141 Athens, Greece    

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