MD1 audio w/ mCD & 32x buffer amp circuit


Posted on Feb 5, 2014

Need some program to set it`s channels to the maximum level, or write the full scale to the DAC. Looking at the MD schematics, you`ll see that the audio is mixed together with relations of 0. 0431 for the PSG, 1 for the YM and 0. 0468 for the external audio sources (both 32x and CD) What I did with my audio amp was tapping all signals before going through the electrolithic


MD1 audio w/ mCD & 32x buffer amp circuit
Click here to download the full size of the above Circuit.

capacitors (and removing those caps, and everything after them, resistors, the sony amp, everything), Amp`ed the YM outputs by 28, and mixed them with the straight PSG and Ext audio, "without" amplification (actually there`s a trimmer to adjust the PSG level About the ADC filtering, a first-order low pass filter at 61kHz should be enough. It will give you 40dB attenuation for the 6. 1Mhz replica. This means that the spectral components around 6. 1Mhz (+/- 61kHz) will have a maximum of 7mV (ignoring noises and crap) They were powered by a linear 6Volt regulator (7806), completely separated from the MegaDrive logic and analog supplies, and draws about 30-40mA of current. Now I would do something different regarding the PSG: I would use separated opamps to fead each channel separately, even though their input would be the same: this reduces cross-signaling between audio channels. Oh yes there`s more stuff like control bits and bit inversion crap in this protocol. This means you have to do some signal processing between the ADC output and the SPDIF connector.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Portable Audio Amplifiers (TEA2025)
    RF modulator
    Telephone-sound-level-meter-monitor
    Dialed-phone-number-vocalizer
    Parts and schematic for an AM radio transmitter
    Nixie low voltage PSU
    AD8225 High Resolution Analog/Digital Converter (ADC)Circuit and Datasheet
    wifi radio with lcd display
    What is analog to digital converter ADC using LM324 IC
    SPDIF Monitor Circuit
    Using the MCU Timers
    TYN612 SENSITIVE & STANDARD(12A SCRs)
    Voice dimmer
    RF amplifier and filter for 144 MHz
    STEREO TV DECODER
    A Hartley Oscillator
    Battery discharge status indicator circuit



    Top