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4079 Equalising
Amplifier
4088 Limiter / Compressor
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4079
Equalising Amplifier
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This board provides 20dB of lift and
cut at Bass (150Hz) and Treble (4.5kHz) frequencies.
Controls may, if required, be fitted directly on the
pcb (Electrospeed sell suitable PCB mount lin controls).
An auxiliary output is provided from the first stage
(pre-eq) for by-pass or other purposes.
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| Stock
no. 01-145 |
4079 Price: |
£25 |
| Technical
Specifications |
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Dimensions |
25 x 112 x
15 mm |
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Supply |
+/- 12v DC
@ 20mA |
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Response |
25Hz - 20kHz
+/- 0.5dB (controls centred)
Bass Mid = 150Hz Treble Mid = 4.5kHz
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4088
Limiter / Compressor |
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The
4088 is a general purpose compressor card, featuring
true RMS signal detection within the control loop and
eight selectable compression slopes, from 1.27:1 to
10:1. Another useful feature is that at 6dB of compression
the input and output levels remain constant, which means
that the compression slope can be changed without the
necessity to re-adjust gains. (see fig.)
The compression slope can either be selected by the
DIL switch on the card or via a 16 way DIL header and
front panel switch. |
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There is an on-board LED to indicate
the onset of compression with provision to connect
an external LED if required with no necessity for
any change to the 4088 pcb.
The threshold can be set by VR2 on the PCB to allow
for input levels of between +10 and -10 dbm, for 6dB
of compression. The other pre-set (VR1) is factory
set to minimise the VCA distortion.
Another useful addition is a separate VCA control
pin, (4b), to enable the 4088 to be used as a VCA
card with external control. This require approx. -30mv/dB
of attenuation.
Because of the RMS rectifier characteristic of the
control loop, independent adjustment of attack and
release times is not possible. The capacitor C6 can
be changed to accommodate different attack/release
times if desired. This is approx. 127dB/sec. The release
rate can be calculated for other values of C6 by using
the formula 1267/C(uF) dB/sec, where C is the value
of C6.
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| Stock
no. 01-150 |
4088
Price: |
£75 |
| Technical
Specifications |
| · |
Dimensions |
67 x 114 x
15 mm |
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Supply |
+/- 12v to
+/- 15v DC @ 30mA |
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