New Genesis - VA6.5 vs VA6.8?

[mikey.shake]

Hey, all... new acolyte to the Genesis/Mega Drive way. Always had love for the system, but my middle school years were based around the SNES. Bought a Genesis and the Sonic games about a decade ago, but got rid of them accidentally a few years back. Finally back in the saddle for the first time, sorta.

 

Somewhat inadvertently, I've ended up with a stack of Model 1s recently to go with the Mega Everdrive she'd gotten me as an early Christmas gift (and the 32X she surprised me with a couple days ago). One of them was a discount Model 1 we got today at a junk shop. So, along with those nifty peripherals, I've now got a set of Genesii as follows:

 

VA2 - Good video, some rainbow banding, but the sound out the front stereo jack has clipping and distortion. Non-TMSS (obviously). Haven't done enough analysis to see if the composite audio out is accurate or just one channel.

VA6 - TMSS, "High-Definition Graphics” model, discrete YM2612 chip, with an “Ext” port on the back. Great sound, good video, a little rainbow banding.

VA6.X - Non-HDG, discrete YM2612, no “Ext” port, but there is space for it, unlike the VA7 port layout. Great sound, good video, a little banding in Sonic's waterfalls. Can’t figure out if it’s a 6.5 or a 6.8. It’s got the discrete audio chip, but I’m not sure exactly what other factor determines the difference between these two revisions.

Can anybody fill me in on the VA6.5 / VA6.8 differences?

I'd ask for gaming suggestions, but there are a million of those threads. MUSHA, Truxton, Streets Of Rage/BK 1-3, Sonic 1-4, Bio Hazard Battle, Contra HardCorps, Gynoug, Gunstar Heroes, Space Harrier II, and many, many others have been helping make this holiday season a blast. And finally getting to play the whole SMS library is amazing. Any other suggestions for deep cuts? After a while, the same 50 games or so pop up on all the lists, but anyone have some really, REALLY hidden gems?

PS - the side expansion port was plugged with something that didn't fit aesthetically, and when I took it off and unscrewed it for a part number and found it was a "PC-80 Expansion Board", which was apparently something to plug into the VA0 Genesis 2s to make the 32X work with them. Not something I need, but an interesting bonus to find on the VA6.X, which was untested but only $10!

Edited December 13, 2015 by mikey.shake

[mikey.shake]

I guess I’m going to turn this into “New Owner - Genesis Model 1 Revisions Info”. I’m not tossing this around like a know-it-all n00b. This whole post is presented more as, “Is this correct? Can anyone offer any info or correction or clarification?"

In trying to educate ourselves about the revisions of the Model 1 Genesis, my friend and I studied that legendary, glorious post over on sega-16.com, so this is just my attempt to wrap our brains around our attempt to learn from some technical stuff that’s over our heads and concentrate it. For the real scoop, go HERE, to the Genesis Model Revisions mega-thread over at Sega-16 and get all the in-depth details.

Laying it all out, so we had a quick guide of what to look for, our team came up with this high-tech chart to help things:

[EDIT: The note on the chart is WRONG. The HDG models do not always have the discrete chip, because of the weirdness with VA6.5/6.8. Please imagine VA6.8 squeezed in just above VA7. Our mistake.]... but we can [still] deduce the following (totally) radical theories:

- “High-Definition Graphics” does not necessarily mean “non-TMSS” (because of the VA6.0).

- Non-TMSS consoles do not necessarily have superior sound to TMSS units, due to the VA2’s sound problems. (They’re significant, whether you use the stereo or composite outs - each has different issues.)

- “No 'HDG' logo” does not necessarily mean "bad sound". (The VA6.5 has no 'HDG' logo or EXT port, but has comparable sound circuitry to the earlier, "more desirable” VA3-VA6.0 "HDG" units.)

- Having a TMSS console does not necessarily eliminate rainbow banding. (I have a VA6.0 and what I believe to be a VA6.5 that both exhibit some rainbow banding in Sonic 1’s waterfalls, tested on multiple TVs.)

- Ultimately, the presence or absence of the "HDG" logo cannot solely determine TMSS from non-TMSS consoles, nor can it determine good sound from bad. Non-TMSS units do not have universally high-quality sound output design, and TMSS Model 1s do not necessarily have inferior sound to a non-TMSS Model 1."

Phew.

------------------------------

Looking back, here’s our notes on each of the different versions, translated from bullet points. (We didn’t distinguish the VA6 intricacies on the chart.)

VA2 - Non-TMSS US launch consoles. Everyone seems to say "'High-Definition Graphics' models always have good sound”, but the VA2 has significant sound problems, making it the exception to the “non-TMSS always has better sound” common-knowledge rule-of-thumb. Much like its predecessors in the Japan-released VA0 and VA1 Mega Drives, there’s the preamp is too powerful for the stereo out and some (?) models are missing one channel from the composite audio out mix.

VA3-5 - Not sure on the specifics between these. People seem to say that the VA4 is maybe slightly harder to find than others. These fix the flawed audio problems of the (VA0-)VA2 board, and since they 1) have fixed audio and 2) are non-TMSS (and therefore say “HDG”), these seem to be the most desirable Genesis consoles for many collectors, even though they aren't the first US revision (the VA2s).

VA6 - The first implementation of TMSS. This one’s complicated, because there were apparently other changes within this revision that cross over several categories

- VA6 (VA6.0) - The first model to have TMSS, but it still has “HDG” on the face, and still has the EXT port on the back. First model to have the shorter FCC ID. (TMSS/HDG/EXT/discrete YM2612)

- VA6.5 - The first sub-revision seems to be most commonly referred to as the VA6.5. As near as I can tell, it’s the same as the VA6.0, but with no “HDG” on the face and it drops the EXT port from the back (though there could be smaller differences above my head). The other ports are still laid out as though it were there. There’s a big plastic “gap” on the left side of the channel switch. (Check out the pics on the Sega-16 thread.) Importantly, this still has a discrete YM2612, making it a “TMSS, non-HDG” Model 1 that still has the desirable, earlier “non-TMSS” sound circuitry. (TMSS/no-HDG/no-EXT/discrete YM2612)

- VA6.8 - We're unclear on the differences between the VA6.5 and VA6.8, but THINK it’s that the VA6.8 began using the “inferior” later sound circuitry as a step toward the VA7. Someone please comment below so we have this info collected as many places as possible for posterity? [(TMSS/no-HDG/no-EXT/integrated ASIC)?]

VA7 - TMSS, non-HDG, no EXT port on back, and an integrated ASIC audio processor. The output ports in the back have been redesigned to a new layout that doesn’t leave the “space” where the EXT port used to be (see that Sega-16 thread for reference). In this model the discrete YM2612 sound chip is replaced by an integrated ASIC sound processor. The video output is said to be an improvement from earlier versions. These seem to be the reason some people just avoid “non-HDG” Model 1s. It’s my understanding that they’re *almost* a VA0 Genesis 2 in a Model 1 body.

---------------------------

I know virtually nothing about Genesis 2s, except that the first few VAs (0-2?) had lousy sound like the Model 1 VA7, but that the later revisions of the Genesis 2 (VA3-4?) were supposed to be vastly improved, and excellent consoles. I’ll have to dive in and learn more than just “look for the 3/4 metal plate through the bottom”.

So that’s what we came up with here.. does anyone have anything they can correct or add?

Edited December 14, 2015 by mikey.shake

[R.Bear]

There is actually nothing wrong with the VA6.8 audio, it also includes the same discrete chip present in the older revisions. As far as I know the only one out of the Mega Drive 1/ Genesis 1 models to have the same borked audio set-up that the early Mega Drive 2 / Genesis 2 is the VA7 model.

 

Audio from my VA6.8 Mega Drive 1:

 

 

The main one to avoid is the VA7, but as said above the VA2's are known to have various issues as well.

 

From what I've read online, the main difference between the VA6 and 6.8 is the video encoder chip.

Edited December 22, 2015 by R.Bear

[mikey.shake]

Nifty, thank you for clearing that up!

 

I've done some more digging, and it seems mine is a 6.5, because it's got the through-hole CXA1145 video encoder (as opposed to the surface-mount) but also has the "sealed-over" back spot where the EXT port used to be and no "HDG" logo. That clip of yours certainly sounds good, and sounds nothing like the VA7s and early M2s I've heard!

 

I hear the VA7 *is* good for modding, but with the three others I've got (and the VA4 Model 2 I found the other day for a pittance -- I looked for the "punch out" holes in the 3/4 motherboard), I'm probably not in the market.

 

And if I'm correct, I get to strap a 32X to one of them on Christmas morning...

[R.Bear]

Forgot that I uploaded this one actually:

 

 

A comparison between the same VA6.8 as in the video above and a Model 2 Mega Drive, you can hear for yourself how bad the VA7 / Model 2 MD sound chip is by comparison lol.

 

Yeah it is possible to improve the sound on the VA7's and Model 2 consoles but it is a fairly extensive mod, I believe its called the "Crystal clear audio mod" but by default these consoles sound nasty.

 

I've got a few different consoles, 2x HDG VA6 (a Genesis and the other is a Japanese MD).

 

The better sounding model 2's seem to be quite uncommon, I only ever see (and own) the nasty sounding Model 2's lol. From what I've read and seen in comparisons though even the "better" model 2's still aren't as good as the pre-VA7 model 1's. They are a big improvement over the older model 2's though.

[Rick Dangerous]

Always love a good discussion of genesis motherboard revisions. I play it safe and stick with a model 1 high definition. But if you plug in a 32x into any genesis you will get high quality video (but not sure about sound.)

 

What i'd really like to know, is more about Model 2 motherboard revisions.

 

I have a Model 2 with the 3/4 motherboard, but it doesn't have the desirable metal tabs missing.

 

ALSO:

 

Supposedly there is a holy grail Model 2 out there (about 1 in 50 model 2s) that has both high quality video chip AND audio chip on the motherboard. My dream is to track one of those down someday...

 

Here is a good start:

 

http://www.sega-16.com/forum/showthread.php?7796-GUIDE-Telling-apart-good-Genesis-1s-and-Genesis-2s-from-bad-ones

Edited January 22, 2016 by travistouchdown