Multichannel Systems MEA-System Manual - Manual (Page 16)

The MEA2100 amplifier with blanking circuit is a 60- or 120-channel headstage with a hardware
defined bandwidth. Default settings for the hardware filter will be 1 Hz to 3 kHz. However,
a different bandwidth can be achieved by an additional software program, called “MEA2100
Configuration”, no hardware modification is necessary. The hardware defined bandwidth marks
the upper and lower limit of the frequency range, fine tuning within this range can be done with
software filters in MC_Rack.
Note: To change the hardware filter settings without changing the firmware, you can use the add
on software “MEA2100 Configuration”.
Please see the manual for the “MEA2100 Configuration” software in the Appendix. The MEA2100-
System has a fixed hardware gain of 10. However, due to the large resolution of 24 bit, it is
possible to adjust the actual signal input range used for recording in a wide range from +/- 812 μV
to a maximum of +/- 227 mV. The 24 bits are distributed among this complete voltage range.
The standard gain of a MEA1060 amplifier is 1200, which is fine for most applications, but MCS
also provides amplifiers with a gain of your choice (from 100 to 5000) as well. In MEA2100 the
bandwidth of the filter settings on the headstage are adjustable via the software program
“MEA2100 Configuration”. For large signals (for example, from heart preparations), you need
a lower gain to prevent a saturation of the amplifier. Please note that the gain is a fixed hardware
property; and that you cannot change the gain of the amplifier by software controls.
Please note that the ratio of the output signal to the input signal, that is, the gain, is not
a fixed parameter for the complete bandwidth. The gain that was specified for the amplifier,
for example, 1200, is not fully reached at the borders of the amplifier's pass band. The general
rule is, that at the lower and upper limit of the frequency band, the gain is
2 / 2 , that is
approximately 70 %, of the full gain. Therefore, you should use a bandwidth that is at a safe
distance of the signals of interest. Outside the pass band, the gain decreases with the frequency
and finally approaches zero.
For information on the gain and filters of the (USB-) MEA amplifiers, please see the appropriate
amplifier manual. For more information on gain and filters in general, please refer to standard
literature or contact your local retailer.
3.4.3 Data Acquisition
Recording from up to 240 channels is easy with the respective hardware and the MC_Rack
software or with LTP-Director, Cardio2D. The MEA2100-System and USB-MEA data acquisition
devices provide the possibility to record from up to 240 electrodes with the designated software.
You configure the input voltage range from +/- 400 mV to +/- 4 V and the sampling rate with
software control in the MC_Rack program. Please refer to the MC_Rack help or manual for
more information.
The input voltage range affects your dynamic range, that is, the lower the input voltage range,
the higher is the voltage resolution.
DC Offset correction
An offset correction is generally not necessary, because the intrinsic DC offsets of the MCS
amplifier outputs and the data acquisition are very low in comparison to the signals of interest.
You can use the MC_Rack offset correction feature to remove even this low offset and reset
all channels to zero. Please refer to the MC_Rack help or manual for more information.
Note: If you observe a large offset on any channel(s), you should contact your local retailer for
troubleshooting. The offset correction is not intended for removing large offsets, because the
offset correction will decrease the input voltage range.