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oberheim/dmx.cpp: Corrected HPFs. Converted audio path to voltages. Tidying. (#13562)

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* Corrected the calculation of the voice DC-block HPF.
* Audio streams are in voltages.
* Cross-checked component values with parts list, and corrected a couple of them.
* Also updating master volume and pitch adjustments on reset.
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m1macrophage 2025-04-06 08:41:28 -07:00 committed by GitHub
parent 79db8d2a59
commit 2c7efb2177
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1 changed files with 72 additions and 43 deletions
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115
src/mame/oberheim/dmx.cpp
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@ -176,9 +176,6 @@ struct dmx_voice_card_config
class dmx_voice_card_device : public device_t, public device_sound_interface
{
public:
// Default value of pitch adjustment trimpot.
static constexpr const s32 T1_DEFAULT_PERCENT = 50;
dmx_voice_card_device(const machine_config &mconfig, const char *tag, device_t *owner, const dmx_voice_card_config &config, required_memory_region *sample_rom) ATTR_COLD;
dmx_voice_card_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0) ATTR_COLD;
@ -219,8 +216,8 @@ private:
required_memory_region *m_sample_rom = nullptr;
std::vector<float> m_cv; // 555 CV (pin 5) voltage variations.
std::vector<attotime> m_sample_t; // Sample period variations.
s32 m_t1_percent = T1_DEFAULT_PERCENT;
std::vector<float> m_gain; // Gain variations.
s32 m_t1_percent = 0; // Tuning trimmer.
std::vector<float> m_iref; // DAC reference currents for gain variations.
std::vector<float> m_decay_r; // Decay resistance variations.
// Device state.
@ -280,13 +277,13 @@ void dmx_voice_card_device::trigger(bool tr0, bool tr1)
if (m_config.pitch_control)
select_pitch();
const float gain = has_gain_variations() ? m_gain[m_trigger_mode] : m_gain[0];
const float iref = has_gain_variations() ? m_iref[m_trigger_mode] : m_iref[0];
if (has_decay()) // Gain is controled by an envelope generator.
m_eg->set_instant_v(gain);
m_eg->set_instant_v(iref);
else // Constant gain.
m_dac_mult->set_fixed_cv(gain);
m_dac_mult->set_fixed_cv(iref);
LOGMASKED(LOG_SOUND, "Trigger: (%d, %d) %d, %f\n", tr0, tr1, m_trigger_mode, gain);
LOGMASKED(LOG_SOUND, "Trigger: (%d, %d) %d, %f uA\n", tr0, tr1, m_trigger_mode, iref * 1e6F);
}
void dmx_voice_card_device::set_pitch_adj(s32 t1_percent)
@ -298,13 +295,17 @@ void dmx_voice_card_device::set_pitch_adj(s32 t1_percent)
void dmx_voice_card_device::device_add_mconfig(machine_config &config)
{
// This multiplier relates the DAC reference current to the output voltage.
// Iout = dac value (normalized to -1 - 1) * 3.8 * Iref.
// Vout = Iout * R_current_to_voltage_converter.
static constexpr const double DAC_MULTIPLIER = 3.8 * RES_K(2.4); // R16, R11 on voice card.
static constexpr const double SK_R3 = RES_M(999.99);
static constexpr const double SK_R4 = RES_R(0.001);
TIMER(config, m_timer).configure_generic(FUNC(dmx_voice_card_device::clock_callback));
DAC76(config, m_dac, 0U);
VA_VCA(config, m_dac_mult);
m_dac->add_route(0, m_dac_mult, 1.0);
m_dac->add_route(0, m_dac_mult, DAC_MULTIPLIER);
if (has_decay())
{
@ -492,27 +493,27 @@ void dmx_voice_card_device::init_gain_and_decay_variations()
const float r17 = m_config.r17;
const float c3 = m_config.c3;
// Precompute gain variations.
m_gain.clear();
m_gain.push_back(MAX_IREF);
// Precompute gain variations. Different gains are set by supplying
// different reference currents to the MDAC.
m_iref.clear();
m_iref.push_back(MAX_IREF);
if (has_gain_variations()) // Configured gain variations.
{
// The equations below were derived from Kirchhoff analysis and verified
// with simulations: https://tinyurl.com/22wxwh8h
// For trigger mode 1.
m_gain.push_back((r12 * r17 * VCC + R8 * r12 * VD + R8 * r17 * VD) /
m_iref.push_back((r12 * r17 * VCC + R8 * r12 * VD + R8 * r17 * VD) /
((R8 * r12 * r17) + (r12 * r17 * R9) + (R8 * r17 * R9) + (R8 * r12 * R9)));
// For trigger mode 2.
m_gain.push_back((r12 * VCC + R8 * VD) / (r12 * R8 + R8 * R9 + r12 * R9));
m_iref.push_back((r12 * VCC + R8 * VD) / (r12 * R8 + R8 * R9 + r12 * R9));
// For trigger mode 3.
m_gain.push_back(m_gain[0]);
m_iref.push_back(m_iref[0]);
}
for (int i = 0; i < m_gain.size(); ++i)
for (int i = 0; i < m_iref.size(); ++i)
{
LOGMASKED(LOG_VOLUME, "%s: Gain variation %d: %f uA, %f\n",
tag(), i, m_gain[i] * 1e6F, m_gain[i] / MAX_IREF);
m_gain[i] /= MAX_IREF; // Normalize.
LOGMASKED(LOG_VOLUME, "%s: Gain / Iref variation %d: %f uA\n",
tag(), i, m_iref[i] * 1e6F);
}
// Precompute decay resistance variations.
@ -785,6 +786,8 @@ public:
, m_metronome_timer(*this, "metronome_timer")
, m_buttons(*this, "buttons_%d", 0)
, m_faders(*this, "fader_p%d", 1)
, m_pitch_trimmers(*this, "pitch_adj_%d", 1)
, m_master_volume(*this, "fader_p10")
, m_switches(*this, "switches")
, m_external_triggers(*this, "external_triggers")
, m_output_select(*this, "output_select")
@ -829,11 +832,13 @@ private:
u8 buttons_r(offs_t offset);
u8 external_triggers_r();
u8 cassette_r();
u8 cassette_and_switch_r();
template<int GROUP> void gen_trigger_w(u8 data);
void update_output();
void update_mix_level(int voice);
void update_master_volume();
void update_pitch_adj(int voice);
void memory_map(address_map &map) ATTR_COLD;
void io_map(address_map &map) ATTR_COLD;
@ -845,7 +850,9 @@ private:
output_finder<> m_metronome_out;
required_device<timer_device> m_metronome_timer;
required_ioport_array<6> m_buttons;
required_ioport_array<10> m_faders;
required_ioport_array<9> m_faders;
required_ioport_array<8> m_pitch_trimmers;
required_ioport m_master_volume;
required_ioport m_switches; // Includes foot switches.
required_ioport m_external_triggers;
required_ioport m_output_select;
@ -1116,7 +1123,7 @@ u8 dmx_state::external_triggers_r()
return ~m_external_triggers->read();
}
u8 dmx_state::cassette_r()
u8 dmx_state::cassette_and_switch_r()
{
// All components are on the Processor Board.
// Inputs buffered by U19 (75LS244). This is a mix of cassette-related
@ -1200,13 +1207,13 @@ void dmx_state::update_mix_level(int voice)
assert(voice >= 0 && voice < NUM_MIXED_VOICES);
static constexpr const float P_MAX = RES_K(10); // Volume potentiometer.
static constexpr const float VC_R21 = RES_R(4.7); // R21 on voice cards.
static constexpr const float VC_R21 = RES_R(47); // R21 on voice cards.
static constexpr const float VC_C10 = CAP_U(33); // C10 on voice cards.
static constexpr const float PB_C24 = CAP_U(6.8); // C24 on processor board.
// Feedback resistors on the left and right summing op-amps (U1B, U1C).
static constexpr const float R_FEEDBACK_LEFT = RES_K(4.7); // R30.
static constexpr const float R_FEEDBACK_RIGHT = RES_K(4.7); // R29.
static constexpr const float R_FEEDBACK_LEFT = RES_K(27); // R30.
static constexpr const float R_FEEDBACK_RIGHT = RES_K(27); // R29.
const s32 pot_percent = m_faders[VOICE_TO_FADER_MAP[voice]]->read();
const float r_pot_bottom = P_MAX * pot_percent / 100.0F;
@ -1220,9 +1227,12 @@ void dmx_state::update_mix_level(int voice)
// -v_pot because the summing opamp mixer is inverting.
const float gain_left = -v_pot * R_FEEDBACK_LEFT / r_mix_left;
const float gain_right = -v_pot * R_FEEDBACK_RIGHT / r_mix_right;
// Resistance as seen from the output side of the DC-blocking capacitor.
const float rc_r = r_pot_top + r_gnd;
const float rc_c = (voice == METRONOME_INDEX) ? PB_C24 : VC_C10;
m_voice_rc[voice]->filter_rc_set_RC(filter_rc_device::HIGHPASS, r_gnd, 0, 0, rc_c);
m_voice_rc[voice]->filter_rc_set_RC(filter_rc_device::HIGHPASS, rc_r, 0, 0, rc_c);
m_left_mixer->set_input_gain(voice, gain_left);
m_right_mixer->set_input_gain(voice, gain_right);
@ -1230,6 +1240,27 @@ void dmx_state::update_mix_level(int voice)
voice, pot_percent, gain_left, gain_right, 1.0F / (2 * float(M_PI) * r_gnd * rc_c));
}
void dmx_state::update_master_volume()
{
// The audio pipeline operates on voltage magnitudes. This scaler normalizes
// the final output's range to approximately: -1 - 1.
static constexpr const float VOLTAGE_TO_SOUND_SCALER = 0.04F;
const s32 volume_value = m_master_volume->read();
const float gain = VOLTAGE_TO_SOUND_SCALER * volume_value / 100.0F;
m_left_mixer->set_output_gain(0, gain);
m_right_mixer->set_output_gain(0, gain);
LOGMASKED(LOG_FADERS, "Master volume changed: %d - %f\n", volume_value, gain);
}
void dmx_state::update_pitch_adj(int voice)
{
const s32 trimmer_value = m_pitch_trimmers[VOICE_TO_FADER_MAP[voice]]->read();
// Using "100 -" so that larger values increase pitch.
m_voices[voice]->set_pitch_adj(100 - trimmer_value);
LOGMASKED(LOG_PITCH, "Voice %d pitch adjustment changed: %d\n", voice, trimmer_value);
}
void dmx_state::memory_map(address_map &map)
{
// Component designations refer to the Processor Board.
@ -1259,7 +1290,7 @@ void dmx_state::io_map(address_map &map)
// Read decoding done by U9 (74LS42) on the Switch Board.
map(0x00, 0x05).mirror(0x78).r(FUNC(dmx_state::buttons_r)); // IORD*
map(0x06, 0x06).mirror(0x78).r(FUNC(dmx_state::external_triggers_r)); // SW6*
map(0x07, 0x07).mirror(0x78).r(FUNC(dmx_state::cassette_r)); // CASI*
map(0x07, 0x07).mirror(0x78).r(FUNC(dmx_state::cassette_and_switch_r)); // CASI*
}
void dmx_state::machine_start()
@ -1282,8 +1313,11 @@ void dmx_state::machine_start()
void dmx_state::machine_reset()
{
update_output();
update_master_volume();
for (int i = 0; i < NUM_MIXED_VOICES; ++i)
update_mix_level(i);
for (int i = 0; i < NUM_VOICE_CARDS; ++i)
update_pitch_adj(i);
}
void dmx_state::dmx(machine_config &config)
@ -1374,17 +1408,12 @@ DECLARE_INPUT_CHANGED_MEMBER(dmx_state::voice_volume_changed)
DECLARE_INPUT_CHANGED_MEMBER(dmx_state::master_volume_changed)
{
const float gain = newval / 100.0F;
m_left_mixer->set_output_gain(0, gain);
m_right_mixer->set_output_gain(0, gain);
LOGMASKED(LOG_FADERS, "Master volume changed: %d\n", newval);
update_master_volume();
}
DECLARE_INPUT_CHANGED_MEMBER(dmx_state::pitch_adj_changed)
{
// Using "100 -" so that larger values increase pitch.
m_voices[param]->set_pitch_adj(100 - newval);
LOGMASKED(LOG_PITCH, "Voice %d pitch adjustment changed: %d\n", param, newval);
update_pitch_adj(param);
}
INPUT_PORTS_START(dmx)
@ -1522,35 +1551,35 @@ INPUT_PORTS_START(dmx)
// as "PITCH ADJ."
PORT_START("pitch_adj_1")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "BASS pitch")
PORT_ADJUSTER(50, "BASS pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_BASS)
PORT_START("pitch_adj_2")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "SNARE pitch")
PORT_ADJUSTER(50, "SNARE pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_SNARE)
PORT_START("pitch_adj_3")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "HI-HAT pitch")
PORT_ADJUSTER(50, "HI-HAT pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_HIHAT)
PORT_START("pitch_adj_4")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "TOM1 pitch")
PORT_ADJUSTER(50, "TOM1 pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_SMALL_TOMS)
PORT_START("pitch_adj_5")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "TOM2 pitch")
PORT_ADJUSTER(50, "TOM2 pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_LARGE_TOMS)
PORT_START("pitch_adj_6")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "CYMBAL pitch")
PORT_ADJUSTER(50, "CYMBAL pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_CYMBAL)
PORT_START("pitch_adj_7")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "PERC1 pitch")
PORT_ADJUSTER(50, "PERC1 pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_PERC1)
PORT_START("pitch_adj_8")
PORT_ADJUSTER(dmx_voice_card_device::T1_DEFAULT_PERCENT, "PERC2 pitch")
PORT_ADJUSTER(50, "PERC2 pitch")
PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(dmx_state::pitch_adj_changed), dmx_state::VC_PERC2)
INPUT_PORTS_END