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Sega Mega Drive 60hz mod


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Hi. I've modded my Sega Mega Drive to switch to 60hz and always wondered why the sound is lower pitched than all the emulators out there then realised the game runs that little bit slower the other day when both the ntsc version was playing on the emulator and the console was on 60hz at the same time but the music was falling behind. The lower pitch obviously means it's going slower. Is there anything I can do to get it going at the full speed or am I going to have to try get a Genesis?

 

I've seen that I'll be only getting 59.3hz instead of 59.9hz on my PAL console. I only have colour because of my RGB cable but it's black and white on composite and rf. I've seen oscillator mods but would they make any difference to the game speed?

 

I know it's literally a fraction but it affects the smoothness if I use an LCD TV and also the lower pitch sound kind of gets me. I'd be using a CRT anyway because that's the best option but still it's better to have it work right :)

 

Any help appreciated.

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Maybe the mod has "told" the system it is a 60HZ system, but the clock are all still running at the 50Hz speeds. This would result in a slow down of all the timing elements.

 

I am about to mod my Megadrive so I can run my repro carts. I'll be interested to see if it does the same.

 

P.S. I don't know the answer, but I'm always happy throw wild speculation into a conversation.

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As mentioned, the 60Hz mod only changes the Hz, not the colour encoding. So it's outputting a PAL60 signal which is why some TV's get confused and only display in black & white. This is where the crystal mod comes in to play, it also alters the colour encoding to NTSC.

 

I've never noticed any difference in audio though.

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The audio is lower pitched on PAL vs NTSC. You'll only notice if it's a game you usually play a lot. For an example of what I mean just load up GENS and then run a game and listen to the music. Then set GENS to PAL Europe instead and reload the game and you should hear what I mean. It's definitely lower on the PAL version than the NTSC version. A lot of people probably wouldn't notice though. I'd imagine it's probably different clock speeds that cause it to happen.
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I definitely notice the difference between 50Hz and 60Hz, audio, game speed and resolution.

 

What I meant is I've never noticed a difference in audio between 60Hz PAL and 60Hz NTSC. E.g. A Japanese Mega Drive conpared to an Aussie 60Hz modded Mega Drive.

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Ah, I overlooked the emulator bit. That will be the cause of the discrepancy, emulators seldom have 100% accurate timing. A big annoyance with the Blaze/ATT Games Mega Drive clones is the horrid sound emulation.

 

I think you'll find there's no difference between genuine consoles.

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Ignore the emulator - I’ve lost count of the amount of Mega Drives and Genesis consoles I’ve modded over the years, pitch should remain the same but speed decreases by up to 17.5% on PAL consoles depending on how the game’s coded. Some games will automatically retime the music correctly IIRC - pretty sure Sonic 2 PAL music is identical or close enough if booting it on 60hz. Most games this isn’t the case, and some games break if you change refresh rate mid-game like Streets of Rage 2 - PAL cart is PAL and Japanese compatible, but not US. If you want it to run in 60hz and English boot it in Japanese mode then flip your language switch at any stage. Once it writes to the video output the region differences will overwrite any visual anomalies.

 

And yes, refresh rate is slightly off on modded consoles, only way to correct this is to address the master clock.

 

Master clock mods may offer some options, but as Frank said you need to apply an extra mod to the video encoder to adjust the logic on the CXA1145 to push it into PAL/NTSC colour encoding if you’re not using RGB.

 

 

Sent from my iPhone using Aussie Arcade

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