Technical Information for some devices build and used while making researches on EVP in 1986
by Rolf-D. Ehrhardt

Real-Time Terz-Grafic-Analyser, 30 filters

                                        

Real-Time means:
the whole acoustic signal will be analysed at once - no sample and hold -

Range: 
20 Hz to 20 kHz - lower meanfrequency at 25 Hz - the upper 20 kHz - 30 Terzfilters over the range

Display:  
330 LED - 11 rows with 30 columns 
 
Input:  
Line in -  Electret-mike with adjustable sensitivity (50 - 75) - overall input amplifier 0 dB to 100 dB - overload signal

Pink-noise generator:  
25 Hz to 20 kHz, electronically generated

Terz-Grafic-Equalizer, 28 filters

Range:
20 Hz to 20 kHz - Filters from 31,5 Hz to 16 kHz - steps in Terz - 48 mm travel of linear poti - +/- 14 dB

Input:     10 kOhm - sensitivity via poti - By-Pass-Switch
Output:   10 kOhm - LED-overload-indicator

Parametric Equalizer