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The BenchMaster 8 series of variable filters are now in their
5th generation,
two channels of high performance analogue filter, plenty of gain, signal level
indication, and flexible input front end all in a
compact solid 1U high package. This versatile instrument has set the standards for laboratory and industrial filtering,
providing a reliable general purpose filter instrument with a range of filter frequency and characteristic options to suit virtually all applications.
BenchMaster 8's use specially manufactured components to ensure close tolerances
and good channel matching. The latest version is a complete redesign, giving
improvements in signal to noise ratios, overall noise, and a clearer front
panel. Modern manufacturing techniques allow us to offer quick deliveries.
Summary Specification
| Channels |
2 |
| Control |
Manual front panel all functions |
| Frequency |
0.01 Hz - 99.9 kHz |
| Gain |
x1,2,5,10,20,50,100,200,500
(+54 dB) per channel |
| Filters |
Switchable Hi/Lo - with
Butterworth / Pulse / Flat modifiers |
| Filter Responses - 6 |
8.03,
8.05, 8.07,
8.09 8.13 8.41 |
| Input Coupling |
AC / DC / single ended
/ differential |
| IEPE |
Yes 4mA 24V |
| Size |
1U 19" |
| Power |
90 -120 / 180-240 Vac 50/60Hz
Optional 9 - 30 V DC, with AC 'power brick' |
The use of the filter response modifiers and the series /
parallel mode, give two independent high/lowpass channels, which can be
combined to give the following response types:
 +
Lowpass and separate Lowpass |
 +
Highpass and separate Highpass |
+
Lowpass and separate Highpass |
+
Highpass and separate Lowpass |
| Highpass
and Lowpass in series = Bandpass |
| Lowpass and
modified Lowpass in series = true double strength filtering |
| Highpass
and Lowpass in parallel = Bandstop |
Highpass
and Lowpass in parallel = narrow Bandstop (Notch) |
All the curves above were measured on a standard BenchMaster 8.03, by using
a combination of the series/parallel control and the filter response
modifiers.
Frequency Range 0.01Hz to 99.9kHz
The BenchMaster 8 offers a cut-off frequency range of 0.01Hz to 99.9kHz, covered by five three-digit
ranges. Frequency is set with three rotary decade switches and a range switch.
Lowpass / Highpass
Each channel can be independently set to high or low pass, over the range 0.01
Hz to 99.9 kHz.
Flexible Input
Single ended or differential input can be set, with overload indication on the
input signals. Input signals can be DC or AC coupled, with matched coupling for
AC differential input. A 24V DC 4mA source for IEPE transducers is provided,
with LED indication of correct operation of the transducer. Green shows correct
operation, red shows short circuit, and nothing indicates open circuit.
Input Gain
The BenchMaster 8 has two stages of input gain, x1, 2, 5 (0,+6,+14 dB), as
precision differential amplification controlled as one front panel switch, then
x 1, 10, 100 (0,+20,+40 dB) as a separate switch control. This combination is
easy to use and allows amplification of small signals. This amplification is
applied to the signal before the filter stages. The filter stages can be
bypassed, so the BenchMaster 8 can be used as a pure amplifier, and in if
required the two channels can linked in series to give x 250 000 (+108 dB)
gain.
Signal Level Indication
To help optimise the gain settings, the BenchMaster 8 has a 4 level signal
indicator. This indicator has a fast rise time and a slow decay, so it can show
sharper peaks in the signal.
| Signal Level |
Indication |
| 0 - 2 Volts |
○ |
| 2 - 6 Volts |
● |
| 6 - 9.5 Volts |
●
|
| >9.5 Volts |
●
|
Three Switchable Response Modifiers
Each BenchMaster 8 has 3 filter modifier settings,
Butterworth, Flat, and Pulse.
'pulse' modifier, a minimum overshoot response, the normal operating position
for the Bessel response 8.07 and 8.09.
'flat' modifier, with a flattened amplitude response up to the cut-off
frequency, the normal operating position for responses 8.13 and 8.41.
'but' modifier, provides a -3dB at cut off type response, the normal operating
position for the Butterworth response 8.03 and 8.05.
The use of these modifiers makes for a very versatile filter, especially when
coupled with the Series/Parallel mode. For Bessel (8.07 and 8.09) and
Butterworth filters (8.03 and 8.05) the use of the flat setting allows 2
filters in series to provide correct shape double strength filters. Without
these modifiers 2 Butterworth filters in series would have -6dB at cut off,
but with one filter in the series, set to 'flat' the correct -3 dB at cutoff
is maintained. This allows 96 dB/octave Butterworth filters to be set on a
BenchMaster 8.03.
Frequency Range 0.01Hz to 99.9kHz
The BenchMaster 8 offers a cut-off frequency range of 0.01Hz to 99.9kHz, covered by five three-digit
ranges. Frequency is set with three rotary decade switches and a range switch.
Six Models
BenchMaster 8.05 - 4 Pole Butterworth response
24 dB/Octave. ( Data
sheet Response 8.05 )
BenchMaster 8.03 - 8 Pole Butterworth
response 48dB/Octave. ( Data
sheet Response 8.03 )
BenchMaster 8.07 - 4 Pole Bessel response
BenchMaster 8.09 - 8 Pole Bessel response
BenchMaster 8.41 - General Purpose, very flat to
cut off, linear phase.
BenchMaster 8.13 - Sharp Elliptic type
filter. -93dB at twice cutoff. ( Data
sheet Response 8.13 )
Amplitude click for larger images Phase
Easy Manual Control
The BenchMaster 8 is designed for easy manual operation.
DC Power (optional)
9-30V DC input is
available as an option. Power input by 'XLR' type connector, with an AC 'power brick' to power the unit from mains
when available.
Please check our page about DC
Power.
Other Features
The BenchMaster 8 is manufactured using the latest surface
mount technology, independent linear power supplies for the logic and analogue
circuits. The BenchMaster 8 is housed in a solid aluminium case, ready for
rack mounting, and with handles which protect the front panel controls. The
front panel is laser cut and marked stainless steel, and most of the internal
and external fasteners are stainless steel, vibration resistant where
possible.
This latest version is a complete redesign, and one that all the staff at Kemo
have contributed to, it is a product we feel proud of, and after over 40 years
of building filters one that has some expertise built into it.
Ordering Information
Please order as:-
BenchMaster 8.05, 4 pole Butterworth
BenchMaster 8.03, 8 pole Butterworth
BenchMaster 8.09, 4 pole Bessel
BenchMaster 8.07, 8 pole Bessel
BenchMaster 8.13, 8 pole sharp anti-aliasing type filter
BenchMaster 8.41, 8 pole general purpose linear phase filter
SPECIAL NOTE - a BenchMaster 8 can be supplied with any two filters from the
above selection, so a unit can be supplied with one 8.03 channel and one 8.41
channel.
Please specify if Optional
DC power is required.
BenchMaster 8 pdf data sheet (75 kB)
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