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Fix the filters and mixing resistors on terracren's YM2203 SSG channels A+B-tied-together and C being inadvertently swapped. Restore the A+B mixing resistor to 10K as it was previously. [Lord Nightmare]

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Lord-Nightmare 2024-07-16 17:41:34 -04:00
parent 66f0f7c6ef
commit 147f94e7dd
1 changed files with 25 additions and 25 deletions
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50
src/mame/nichibutsu/terracre.cpp
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@ -119,9 +119,9 @@ public:
, m_dacfilter2(*this, "dacfilter2")
, m_ymfilter(*this, "ymfilter")
, m_ssgmixer(*this, "ssgmixer")
, m_ssgfilter_abfilt(*this, "ssg_abfilt")
, m_ssgfilter_abgain(*this, "ssg_abgain")
, m_ssgfilter_cfilt(*this, "ssg_cfilt")
, m_ssgfilter_cgain(*this, "ssg_cgain")
, m_ssgfilter_abgain(*this, "ssg_abgain")
, m_bg_videoram(*this, "bg_videoram")
, m_fg_videoram(*this, "fg_videoram")
, m_coltable(*this, "palbank_prom")
@ -150,9 +150,9 @@ private:
required_device<filter_biquad_device> m_dacfilter2;
required_device<filter_biquad_device> m_ymfilter;
optional_device<mixer_device> m_ssgmixer;
optional_device<filter_biquad_device> m_ssgfilter_abfilt;
optional_device<filter_biquad_device> m_ssgfilter_abgain;
optional_device<filter_biquad_device> m_ssgfilter_cfilt;
optional_device<filter_biquad_device> m_ssgfilter_cgain;
optional_device<filter_biquad_device> m_ssgfilter_abgain;
required_shared_ptr<uint16_t> m_bg_videoram;
required_shared_ptr<uint16_t> m_fg_videoram;
@ -809,8 +809,8 @@ void terracre_state::ym2203(machine_config &config)
// R9 - Yamaha (digital/FM) - 1kohm = 0.3500 of total
// R12 - DAC1 - 2.2kohm = 0.1590 of total
// R8 - DAC2 - 1kohm = 0.3500 of total
// Yamaha (analog/SSG, channels A and B) - 3.3k = 0.1060
// Yamaha (analog/SSG, channel C) - 1k = 0.3500
// Yamaha (analog/SSG, channels A and B) - 10k = 0.0350
// Yamaha (analog/SSG, channel C) - 3.3k = 0.1060
// However, the actual volume output by the ym3014 dac and the r2r resistors
// is not the same range on each!
// The YM3014 dac has a DC offset of 1/2 VDD, then +- 1/4 VDD of signal,
@ -821,14 +821,14 @@ void terracre_state::ym2203(machine_config &config)
// The R2R dacs are full range, min of 0v and max of (almost) 5v, vpp of ~5.0v
// Because of this, we have to compensate as MAME's ymfm core outputs full range.
// Math: (assuming a constant current for each component)
// YMFM: 0.350000 * 0.5 = 0.175
// DAC1: 0.159000 * 1.0 = 0.159
// DAC2: 0.350000 * 1.0 = 0.350
// SSGA+B:0.106000 * 0.46 = 0.04876
// SSGC: 0.350000 * 0.23 = 0.0805
// Sum: 0.74081
// Multiply all 5 values by 1 / 0.74081 (i.e. 1.349873):
// ym: 0.236228; dac1: 0.21463; dac2: 0.472456, ssgA+B: 0.065819; ssg3: 0.108664)
// YMFM: 0.350000 * 0.5 = 0.1750
// DAC1: 0.159000 * 1.0 = 0.1590
// DAC2: 0.350000 * 1.0 = 0.3500
// SSGA+B:0.035000 * 0.46 = 0.0161
// SSGC: 0.106000 * 0.23 = 0.0244
// Sum: 0.7245
// Multiply all 5 values by 1 / 0.7245 (i.e. 1.380):
// ym: 0.2415; dac1: 0.2196; dac2: 0.4830, ssgA+B: 0.0222; ssgC: 0.0337
FILTER_BIQUAD(config, m_ymfilter).opamp_sk_lowpass_setup(RES_K(4.7), RES_K(4.7), RES_M(999.99), RES_R(0.001), CAP_N(3.3), CAP_N(1.0)); // R10, R11, nothing(infinite resistance), wire(short), C11, C12
m_ymfilter->add_route(ALL_OUTPUTS, "speaker", 1.0);
FILTER_BIQUAD(config, m_dacfilter1).opamp_sk_lowpass_setup(RES_K(22), RES_K(22), RES_M(999.99), RES_R(0.001), CAP_N(10), CAP_N(4.7)); // R17, R18, nothing(infinite resistance), wire(short), C19, C17
@ -840,12 +840,12 @@ void terracre_state::ym2203(machine_config &config)
// -4.54545 and a cutoff at effectively infinity, as it has nothing but parasitic
// capacitance as the capacitor part of said circuit. (YR12, YR15).
// Technically there may be some capacitance from YC3, although that is intended to be part of the SK filter below.
FILTER_BIQUAD(config, m_ssgfilter_abgain).opamp_mfb_lowpass_setup(RES_K(4.7), 0.0, RES_K(10), 0.0, CAP_N(22)/100.0); // YR12, N/A(short), YR15, N/A(unpopulated), (parasitic capacitance from YC3)
m_ssgfilter_abgain->add_route(ALL_OUTPUTS, "speaker", 1.0);
FILTER_BIQUAD(config, m_ssgfilter_cgain).opamp_mfb_lowpass_setup(RES_K(4.7), 0.0, RES_K(10), 0.0, CAP_N(22)/100.0); // YR12, N/A(short), YR15, N/A(unpopulated), (parasitic capacitance from YC3)
m_ssgfilter_cgain->add_route(ALL_OUTPUTS, "speaker", 1.0);
// This filter is a 2nd order sallen-key lowpass, unity gain.
FILTER_BIQUAD(config, m_ssgfilter_abfilt).opamp_sk_lowpass_setup(RES_K(10), RES_K(10), RES_M(999.99), RES_R(0.001), CAP_N(22), CAP_N(10)); // YR3, YR5, nothing(infinite resistance), wire(short), YC3, YC6
m_ssgfilter_abfilt->add_route(ALL_OUTPUTS, m_ssgfilter_abgain, 1.0);
FILTER_BIQUAD(config, m_ssgfilter_cfilt).opamp_sk_lowpass_setup(RES_K(10), RES_K(10), RES_M(999.99), RES_R(0.001), CAP_N(22), CAP_N(10)); // YR3, YR5, nothing(infinite resistance), wire(short), YC3, YC6
m_ssgfilter_cfilt->add_route(ALL_OUTPUTS, m_ssgfilter_cgain, 1.0);
// This filter is a first order inverting op-amp lowpass circuit with a gain of -4.54545 and a
// cutoff at 10.1hz (YR8, YR7, YC1).
@ -853,20 +853,20 @@ void terracre_state::ym2203(machine_config &config)
// near/bypassing YR7 was left unpopulated.
// It turns out this cap is mathematically redundant vs the cap at YC1, and serves the
// exact same purpose for calculating the cutoff.
FILTER_BIQUAD(config, m_ssgfilter_cgain).opamp_mfb_lowpass_setup(RES_K(33), 0.0, RES_K(150), 0.0, CAP_N(100)); // YR8, N/A(short), YR7, N/A(unpopulated), YC1
m_ssgfilter_cgain->add_route(ALL_OUTPUTS, "speaker", 1.0);
FILTER_BIQUAD(config, m_ssgfilter_abgain).opamp_mfb_lowpass_setup(RES_K(33), 0.0, RES_K(150), 0.0, CAP_N(100)); // YR8, N/A(short), YR7, N/A(unpopulated), YC1
m_ssgfilter_abgain->add_route(ALL_OUTPUTS, "speaker", 1.0);
MIXER(config, m_ssgmixer);
m_ssgmixer->add_route(0, m_ssgfilter_abfilt, 0.065819);
m_ssgmixer->add_route(0, m_ssgfilter_cfilt, 0.033666);
ym2203_device &ym1(YM2203(config, "ym1", XTAL(16'000'000) / 4)); // 4MHz verified on PCB
ym1.add_route(0, m_ssgmixer, 1.0);
ym1.add_route(1, m_ssgmixer, 1.0);
ym1.add_route(2, m_ssgfilter_cgain, 0.108664);
ym1.add_route(3, m_ymfilter, 0.2362);
ym1.add_route(2, m_ssgfilter_abgain, 0.022219);
ym1.add_route(3, m_ymfilter, 0.241517);
DAC_8BIT_R2R(config, "dac1", 0).add_route(ALL_OUTPUTS, m_dacfilter1, 0.2146); // SIP R2R DAC @ RA-1 with 74HC374P latch
DAC_8BIT_R2R(config, "dac2", 0).add_route(ALL_OUTPUTS, m_dacfilter2, 0.4725); // SIP R2R DAC @ RA-2 with 74HC374P latch
DAC_8BIT_R2R(config, "dac1", 0).add_route(ALL_OUTPUTS, m_dacfilter1, 0.219561); // SIP R2R DAC @ RA-1 with 74HC374P latch
DAC_8BIT_R2R(config, "dac2", 0).add_route(ALL_OUTPUTS, m_dacfilter2, 0.483035); // SIP R2R DAC @ RA-2 with 74HC374P latch
}
void terracre_state::amazon_base(machine_config &config)