Frequency Response of JVC Nivico 9425W amplifier

It sounds great when this amplifier is connected to the linoleum Pleiades Auratone 5C type speaker.


With a Pleiades 2N3055 flat? frequency response amplifier the Pleiades linoleum Auratone 5C type cube speaker gives an acoustic frequency response of + or - 3dB from 100Hz to 14KHz.


When the JVC amplifier is connected the low end goes down to about 60Hz. A significant change.


It is almost unbelievable how the radio growing up as a kid with comes to aid at such a moment. In fact it had been completely destroyed it. But the one surviving comes from dear grandparents who had bought the same model at the same time. This one escaped the curiosity destruction appetite.


So what is its frequency response? How much does it boost at low frequencies?


Signal path, setup:


Alan Parsons sound check 2 CD at warble tone of 1/3 octave bands - Sony Walkman at line out bridged - JVC Nivico 9425W, AUX in, Ear out - Rohde & Schwarz psophometer UPGS in parallel with linoleum Pleiades Auratone 5C type speaker.


For the acoustic frequency response see previous post, the is the ac electrical potential frequency response across amp out or speaker terminals.


Reference voltage is taken as -15dB.


20Hz -25dB
25Hz -10dB
31.5Hz -8dB
40Hz +2dB
50Hz +5dB
63Hz +5.5dB
80Hz +8dB
100Hz +7dB
125Hz +6dB
160Hz +5dB
200Hz +4dB
250Hz +4dB
315Hz +3
400Hz +2dB
500Hz +1dB
630Hz +1dB
800Hz 0dB
1KHz 0dB
1.25KHz -1dB
1.6KHz -1dB
2KHz -1dB
2.5KHz -1dB
3.15KHz -0.5dB
4KHz 0dB
5KHz +0.5dB
6.3KHz 1.5dB
8KHz 2dB
10KHz (2.5 to 3.5)dB
12.5KHz 2.5dB
16KHz -0.5dB
20KHz -11dB


Same test but instead using the test CD from Hellenic magazine Ηχος (sound) & Hi-Fi with sine waves instead of warble tones.


20Hz -29dB                                                   -33dB
23.1Hz -19dB                                                 -20dB
63Hz +5dB                                                     +4dB
80Hz 6dB                                                        +4.5dB
125Hz 5.5dB                                                  +5.5dB
160Hz 5dB                                                       +5dB
250Hz 4dB                                                     +4.5dB                            
315Hz 3.2dB                                                  +3.8dB
500Hz 2dB                                                      +2dB
800Hz 0.5dB                                                  +0.5dB
1KHz 0dB                                                       0dB
1.25KHz 0dB                                                   0 dB
2KHz 0dB                                                        -0.5dB
3.15KHz 0dB                                                   0dB
4KHz +0.5dB                                                   0dB
5KHz +1.25dB                                                 +1dB
8KHz +3dB                                                      +2.5dB
10KHz +4dB                                                    +3.5dB
16KHz +0.5dB                                                 +0.5dB
20KHz -8dB                                                      --4dB


The right column is the same text performed the day after with a 4R7 wire wound resistor connected to amp output instead of speaker. Not sure if the settings, volume, tone control on the JVC amp are exactly the same.