06479: kchampvs, kchampvs2, karatevs: ADPCM samples are distorted

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06479	Sound	Minor	Always	Jan 27, 2017, 03:04	Jun 19, 2017, 04:40

Tester	Tafoid	View Status	Public	Platform	MAME (Official Binary)
Assigned To	AJR	Resolution	Fixed	OS	Windows Vista/7/8 (64-bit)
Status [?]	Resolved			Driver	dataeast/kchamp.cpp
Version	0.182	Fixed in Version	0.187	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06479: kchampvs, kchampvs2, karatevs: ADPCM samples are distorted
Description	There was change in source to add a "74LS157 Quad 2-to-1 Multiplexer" to accurately reflect sound but the new implementation has distortion/muffling of the samples
Steps To Reproduce
Additional Information	Change here caused the issue: https://github.com/mamedev/mame/pull/1951 Sound from original coinop linked there for comparison
Github Commit

Flags
Regression Version	0.182
Affected Sets / Systems	kchampvs, kchampvs2, karatevs

Attached Files

No.13563 AJR Developer Jan 28, 2017, 01:15	I've been able to fix this experimentally by improving the accuracy of VCK output. However, this will break a lot of other drivers that don't check the VCK state. The old implementation always outputs 1 on what is supposed to be the active low state, even though it's far more common for VCK to be directly hooked up to the clock input of a 7474 (as the kchampvs schematics indicate), which triggers on rising edge.

No.13563

AJR

Developer

Jan 28, 2017, 01:15

I've been able to fix this experimentally by improving the accuracy of VCK output. However, this will break a lot of other drivers that don't check the VCK state. The old implementation always outputs 1 on what is supposed to be the active low state, even though it's far more common for VCK to be directly hooked up to the clock input of a 7474 (as the kchampvs schematics indicate), which triggers on rising edge.