General Description:
The Forssell Technologies MADA-2 is an extremely high quality two channel Analog to Digital
Converter (ADC) and two channel Digital to Analog Converter (DAC) housed in a 1U rack mount
enclosure. The MADA-2 can be powered from 115 or 230 volt 50/60 Hz line voltages. An internally
mounted switch selects which line voltage can be used.
The MADA-2 has AES3 and SPDIF digital inputs and outputs, as well as a Word Clock input and
output. Analog inputs and outputs are balanced and floating so that they can used with either balanced
or unbalanced signals. Using the MADA-2 with unbalanced analog signal sources will result is slightly
worst distortion figures when compared with a balanced analog signal source. No such compromise in
performance exists for the analog outputs.
Analog to Digital (ADC) Section Description:
The ADC section of MADA-2 is a high quality two channel Analog to Digital Converter. The MADA-
2 is designed for the most demanding applications, where capturing musical performances with accuracy
and honesty is required. Output sample rates from 44.1k to 192k Fs are selected with a single front
panel switch and with LED indicators showing the selected sample rate. Digital “clipping” is indicated
with a single front panel LED that latches on until the “reset” switch is pressed. The MADA-2 analog
circuitry features an all Class A discrete JFET with no IC opamps used in the signal path. The analog
inputs use high quality XLR connectors. The digital outputs provided are AES3 (XLR), SPDIF (RCA),
WC Sync input and Word Clock output (BNC) are provided. An additional Word Clock output is
available as an option. The MADA-2 digital output word length is fixed at 24 bits.
The MADA-2 uses a 32 bit asynchronous decimation filter to provide various standard output sample
rates from 44.1K to 192k. The actual low jitter sampling clock that controls the AD converter chip
timing is permanently set to sample at 196.3 kFs regardless of output sampling rate selection. This
process is called Asynchronous Sample Rate Conversion (ASRC) and is performed by a 32 bit sample
rate converter. The output from the ASRC circuitry is 24 bit at the selected output sample rate.
Please note that there are no provisions for word length reduction, or level metering with this
converter.
Word Clock Output:
The MADA-2 has a single low jitter word clock output available on a rear panel mounted BNC
connector. This output is designed to operate into a 75 ohm terminated coaxial cable. The output
voltage is TTL compatible. The WC output follows the output sample rate, as selected by the front
panel control. Additional WC outputs are provided on the MADA board, but the user would have to
install their own connectors and wire them to the MADA board.
Output Sample Rate selection:
The output sample rate of the MADA-2 is selected by the single front panel mounted “Select” switch.
The LEDs to the right of this switch indicate the output sample rate currently selected. The MADA-2
does
not
remember this setting when power is removed. If your sample rate is other than 44.1k
, then
you must reset the output sample rate to the desired sample rate each time the unit is powered up.
“Over” LED:
The front panel mounted red “Over” LED lights when any channel reaches a digital signal level that is
within 0.1 dB of digital full scale for more than two sample periods. Once lighted, the over LED will
remain lighted until the “reset” switch is press. The reset switch only effects the “Over” LED and does
