Technics SH-9090P

Technics SH-9090

October   1 9 7 5 october 1975
1 9 7 8 1978

Big Universal Frequency Equalizer of the good kind (parametric) with two twists :

Twist °1
The twelve center frequencies can be individually shifted by as much as one octave so as to narrow or widen the actual "area" of intervention or even stack two controls over the same spot.

Twist °2
this is a monaural equalizer : you need two for stereo !

After that, the SH-9090P is a normal parametric EQ : variable Q (bandwidth) corrections but with Twist °1, this made a very versatile sound shaping item.
In fact, pushing it to its limits would bring you closer to a synthesizer than a normal equalizer as the f0 center frequencies can be shifted as follows :

10Hz : 5Hz...20Hz
30Hz : 15Hz...60Hz
60Hz : 30Hz...120Hz
125Hz : 62,5Hz...250Hz
250Hz : 125Hz...500Hz
500Hz : 250Hz...1Khz
1Khz : 500Hz...2Khz
2Khz : 1Khz...4Khz
4Khz : 2Hz...8Khz
8Khz : 4Khz...16Khz
16Khz : 8Khz...32Khz
32Khz : 16Khz...64Khz

... that's not frequency shifting anymore but a crazy rumba mixed with an electropop top and two rocky mountain swings !

Each of the twelve filters is made of one adder-substractor and two integrators or a high-pass filter, a bandpass filter and a low-pass filter operating in series.

Center frequency and Q changes come from changing resistances in the feedback loop, strapped between the two amp stages : - frequency settings act on negative feedback in the 1st amp stage, + frequency settings make the bandpass filter operate in parallel with the input resistance of the 2nd amp.

When at "0", the bandpass filter is gounded so all active elements are out of the signal path ; a high impedance buffer amp and an output amplifier with low output impedance are in to keep other components from influencing response of the SH-9090P : 10 Ohm at the unbal outputs !

Also in are Cannon (XLR) terminals (really balanced : hot / cold / ground), duplicates in unbalanced RCA plus a monitor output (unbal), mandatory 19" rack handles and printing on the top cover of the main curves for daily psychedelic trips.

The SH-9090P and SH-9090 seem to be the very same, aka 90P in Japan, the SH-9090P version being the USA export model - P for Professional, of course.

Sales-wise, Technics had more success with the identically engineered but reduced 2x5 bands SH-9010, aka 10E in Japan, and the later SH-8065.

Technics SH-9090P, image 1 Technics SH-9090P, image 2 Technics SH-9090P, image 3
Technics SH-9090P specifications
Title Value
Insertion loss : less than +0,5dB
Frequency response : 20Hz...20Khz (balanced, all controls to "0" ; +0 / -0,5dB)
15Hz...30Khz (unbalanced, all controls to "0" ; +0 / -0,5dB)
3Hz...80Khz (unbalanced, all controls to "0" ; +0 / -3dB)
Noise voltage : -88dBm (EQ in, bal.)
-90dBm (EQ in, unbal.)
-94dBm (EQ out, bal.)
-96dBm (EQ out, unbal.)
THD : less than 0,5%
Master level control : -6dB...0dB...+6dB
Band level control : -12dB...0dB...+12dB
Center frequency control : -1 octave...+1 octave
Bandwidth control : 0,7...7
Center frequencies : 10 / 30 / 60 / 125 / 125 / 500Hz
1 / 2 / 4 / 8 / 16 / 32Khz
Inputs : 100kOhm (bal)
50kOhm (unbal)
Outputs : 20 Ohm (bal)
10 Ohm (unbal)
Rated input voltage : 0dBm (bal)
0dBm (unbal)
Maximum output voltage : +24dBm (bal)
+20dBm (unbal)
PC : 20W (JP)
25W (US)
Dimensions : 45 x 19,3 x 42,6cm
Weight : 9,8kg.
List price : 200,000¥ ! (1975)
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