Audio problem with MegaFlashRom SCC+ and a Sanyo Wavy-70FD

Page 1/6
| 2 | 3 | 4 | 5 | 6

By Gustau Pérez-Querol

Resident (59)

Gustau Pérez-Querol's picture

03-07-2015, 09:30

Hi,

I have a Wavy 70FD. Recently I bought the MegaFlashRom SCC (MFRS) from Manuel Pazos. I was aware of the audio problems with the MFRC and the NMS-82[5|8]0s. To our suprise (mine and Manuel's) the SCC audio level is lower than the PSG audio level. An to make things even stranger, an original Konami SCC sounds just fine (both SCC and PSG audio levels get mixed fine).

I tried the MFRS with an NMS-8245 and everything went fine.

Manuel (@Gullian) suggested the same fix needed by the NMS-8250 (that is, placing a 100nF capacitor plus a 1,2kohm resistance in the the cartridge) but no joy. In fact, with 100nF it'd appear the resistance has little impact, because I tried lower values of it (the resistance) but little changed.

Anyone else is having the same problem. Any idea on how to proceed any further? I'd say to increase the value of the capacitor, but I'm not an expert on electronics.

I could post pics of the Wavy, if that can be of any help.

Thanks!

Login or register to post comments

By OeiOeiVogeltje

Paragon (1366)

OeiOeiVogeltje's picture

03-07-2015, 22:50

i had two wavy 70FD and i had the same problem
so im pretty sure now its not related you YOUR wavy but to ALL of them

By syn

Paragon (1975)

syn's picture

03-07-2015, 23:54

I have wavy phc70 fd2 (with 2 drives) and I have the same problem with playsoniq SCC, volume is WAY too low.

I think the reason is that playsoniq and the newer megaflashrom scc+'s are FPGA SCCs (as in not original SCC chips). I have yet to buy a megaflashrom scc+sd so I cant verify if I have this problem as well but I am pretty sure the sound would also be softer. Although it was discussed a long time ago in another topic, some ppl do have reasonably normal volume balance, so maybe there have been differences between batches of the sanyos. If anyone wanna borrow me a mfrscc+ I can test it.

By Grauw

Ascended (9341)

Grauw's picture

04-07-2015, 00:17

syn wrote:

I have yet to buy a megaflashrom scc+sd

o.O

By Daemos

Paragon (1713)

Daemos's picture

04-07-2015, 00:21

Placing in a resistor and capacitor will not magically fix audio problems related to bad mixing or too low volumes. To fix these kind of problems you can either change the attenuation level of the HW itself which is not easily done or do a active amplification between the HW and the MSX.

However, if the problem for the phc70 is the same as for the NMS8250 a more complex fix is required.

By Gustau Pérez-Querol

Resident (59)

Gustau Pérez-Querol's picture

05-07-2015, 11:46

HI,

hopefully it is not the same problem the nms 8250 has, because the nms 8250 or 8280 models had problems with regular SCC cartridges too.

The wavy has only problems with the megaflashrom-scc+, regular konami cartridges (I tried nemesis2,3,king's valley 2 and salamander) do sound just fine.

Patching the cartridge with the capacitor+resistance (1,2nF+1,2kohm) makes scc audio levels to be more audible and nearly reaching the wavy PSG audio levels. I think it is a mixing problem and I wonder if changing the capacitor would make it any better.

By roadfighter

Champion (401)

roadfighter's picture

05-07-2015, 12:52

Gustau Pérez-Querol wrote:

To our surprise (mine and Manuel's) the SCC audio level is lower than the PSG audio level.
Manuel (@Gullian) suggested the same fix needed by the NMS-8250 (that is, placing a 100nF capacitor plus a 1,2kohm resistance in the the cartridge) but no joy.
Thanks!

I am confused, you state that the audio level is lower than the PSG, so why are you putting a resistor and a condensator in the cartridge ?
You dont want to lower the volume of the cartridge but increase it ? right ?

By roadfighter

Champion (401)

roadfighter's picture

05-07-2015, 12:58

Daemos wrote:

Placing in a resistor and capacitor will not magically fix audio problems related to bad mixing or too low volumes. To fix these kind of problems you can either change the attenuation level of the HW itself which is not easily done or do a active amplification between the HW and the MSX.
However, if the problem for the phc70 is the same as for the NMS8250 a more complex fix is required.

I agree this makes a lot more sense then a resistor and a condensator.

By Gustau Pérez-Querol

Resident (59)

Gustau Pérez-Querol's picture

05-07-2015, 22:02

Hi @roadfighter and thanks for your reply.

I'm not an expert on this, but I do agree it's a bit strange.

The fact is that with unmodified megaflashrom scc+ the SCC audio level is quite lower than the PSG level (in fact, I'd say I can't hear the SCC at all). I tried the same audio track with the openmsx without scc (I have a disk with all the scc tracks on it) to check whether it was the PSG or SCC and the test gave me the same audio than the wavy+megaflashrom scc+ (that is, just PSG).

Manuel (@Guillian) suggested placing a capacitor (100nF) and a resistance (1,2kohm) in the cartridge, that made the SCC audio level to be closer to the PSG audio levels (but not enough). It would appear that lowering the resistance was also making a the SCC audio level to raise a bit (but also not enough).

Reviewing the problem the 8280 has (that is, the PSG level is lower than the SCC level, instead the problem I'm havinig) I do agree I don't understand why that fix would work with the wavy and the megaflashrom, because is PSG which is way louder than the SCC generated by the cartridge. However, I can confirm that it has some impact.

I'm not an expert on this and I have to say I'm a bit lost right now. Any idea would be appreciated. I can provide photos of the wavy if that helps.

By Daemos

Paragon (1713)

Daemos's picture

05-07-2015, 23:24

If anyone can give me a link to the schematics of the computer I can have a look for you and maybe design something that actually will fix the problem.

By Gustau Pérez-Querol

Resident (59)

Gustau Pérez-Querol's picture

06-07-2015, 07:52

Thank you @Daemos,

I don't have the schematics, but I can provide you with photos of the motherboard. I can also measure components values' with a tester if needed.

Page 1/6
| 2 | 3 | 4 | 5 | 6