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philly

I inquired about Genesis audio to Ace9921 on youtube. He seemed to know a lot about all the different Genesis revisions, so I asked about his opinions on getting the best sound from the system, pre/sans any modding. He blessed me with this awesome response:

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What you really need to be aware of is the different motherboard revisions in each of these systems. Here's the general rundown:

Genesis Model 1: In North America, there exist 7 different motherboard revisions: VA2, VA3, VA4, VA5, VA6, VA6.8 and VA7. Genesis Model 1s with VA7 motherboards are the ones to avoid; they sound like shit. The sound is distorted, low-quality and very hissy. All the other motherboard revisions sound the same: clear sound, very high bass, zero hissing, no distortion. The Genesis I use for my 10 Minutes of Video Game Music videos is a Genesis Model 1 with a VA3 motherboard.

Little note: any Genesis Model 1 with a VA2 motherboard will have screwed up Mono audio. Instead of the Mono audio output actually being Mono, it's actually just the right sound channel. The left sound channel is never mixed. The same is true with Japanese MegaDrives that have VA0 and VA1 motherboards.

Genesis Model 2: There exist 7 different motherboard revisions in this system as well: VA0, VA1, VA1.8, VA2, VA2.3, VA3 and VA4. Stay as far away as possible from Genesis Model 2s with VA0, VA1 or VA1.8 motherboards, as the sound is just as nasty as a Genesis Model 1 with a VA7 motherboard. The VA2 and VA2.3 motherboards aren't very good either. The sound is clear, but the volume balance is off, and the PSG is so badly out of tune Sega Master System games have heavily distorted sound. The out-of-tune PSG also makes Genesis games that use PSG sound wrong(Thunder Force games in particular). VA3 and VA4 are fine for sound, as they've got a very well-made sound circuit and the volume balance is almost perfect. VA3s have perfect volume balance while VA4s have slightly louder FM Synthesis than normal.

Genesis Model 3: Only 2 motherboard revisions exist: VA1 and VA2. I've never used a VA1 Genesis Model 3, but I can tell you that the sound off a VA2 Genesis Model 3, aside from being Mono only, is very clear. Its bass is rather weak, but the clarity is there. PSG is also slightly louder on the VA2 Genesis Model 3.

Sega CDX: There exists only one motherboard revision of the CDX as far as I know. Its sound is the clearest of all Genesis systems I've ever used, but it's rather weak compared to other Genesis systems. FM Synthesis is also a bit too loud.

Nomad: Again, only one motherboard revision exists to my knowledge. Believe it or not, the bass is actually STRONGER on the Nomad than on pre-VA7 Genesis Model 1s. PSG is just a touch louder than normal.

Here's a little something you might want to know: there exist 2 different types of Yamaha YM2612s(this is the chip responsible for FM Synthesis) on the Genesis: discrete YM2612 and ASIC-based YM2612. If you find a Genesis with no chip marked Yamaha YM2612, the chip is integrated within the big Sega ASIC on the motherboard, denoted Sega 315-xxxx. This list will tell you what YM2612 each model's motherboards contain:

Genesis Model 1: Discrete YM2612 in VA2 - VA6.8 motherboards, ASIC-based YM2612 in VA7 motherboard.

Genesis Model 2: Discrete YM2612 in VA2 and VA2.8 motherboards, ASIC-based YM2612 in all other revisions.

Genesis Model 3: ASIC-based YM2612 on all motherboards.

Sega CDX: ASIC-based YM2612 on all motherboards.

Sega Nomad: ASIC-based YM2612 on all motherboards.

The main difference between the two is that the ASIC-based YM2612 has a higher sampling rate than the discrete YM2612, resulting in clearer sound, but it usually sounds more "computerized," if you know what I mean. The discrete YM2612 also has more quantization noise than the ASIC-based YM2612. Quantization noise is most noticeable when music fades out, as you will hear that the notes last longer on a discrete YM2612 than an ASIC-based YM2612.

My personal recommendation is any Genesis Model 1 with a discrete YM2612. Sound is best on that. If you find a Genesis Model 1 that says HIGH DEFINITION GRAPHICS on the case, you're guaranteed to have a motherboard with a discrete YM2612. If you prefer the sound of an ASIC-based YM2612, get a Genesis Model 2 with a VA3 motherboard or a Nomad(NOTE: A Nomad is VERY expensive. Unless you can get one for cheap, don't bother hunting down a Nomad).

There's an easy way to recognize a VA3 Genesis Model 2. Take a look at this image:

http://img16.imageshack.us/img16/8452/g … mother.jpg

If you turn over a Genesis Model 2 and see this short metal plate, then you've got either a VA3 or VA4 motherboard in your Genesis Model 2. This one has a VA4 motherboard, which has 2 holes punched in the metal plate. Genesis Model 2s with a VA3 motherboard have no holes in the metal plate.

The true sound, however, is that of a Genesis/MegaDrive Model 1 with either a VA0, VA1, VA2, VA3, VA4, VA5, VA6 or VA6.8 motherboard. That's why I use a Genesis Model 1 with a VA3 motherboard. TMSS has nothing to do with the sound quality(it was introduced in motherboard revision VA6, FYI) as the sound circuit is exactly the same in all of these motherboard revision. Sega changed the sound circuit on the VA7 motherboard for a really shitty one that results in awful sound.

Before I forget: if you have a Sega CD and use its Stereo audio outputs, it eliminates some of the hissing from Genesis Model 2s with bad sound. It doesn't eliminate all of it, however.
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Oh and don't forget little-scale has some handy comparisons up here as well:
http://milkcrate.com.au/_other/sega_comparisons/

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oh man i love reading comparisons like this its so interesting.

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Brooklyn, NY

Excellent stuff man - I could never find a straight answer for all of the models!

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matt's mind

this is super great and concise

thank you big_smile

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Sweeeeeeden

How does this correlate to TmEE's crystal audio mod? Can the "bad" PCB revisions be saved?

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philly

I don't know! It'd be cool to hear if TmEE has advice on certain models for his mod. smile

I did some sampling from animal style's CCAM modded console, and there was unfortunately some distortion in the right audio channel. I can provide an example later tonight. I don't know if there's some weird mistake with this particular implementation of the CCAM, or if the model involved is part of the problem. I guess the next step is to find out what revision model 2 joey has, I didn't bother finding out before...

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Milwaukee, WI

hmmm, my guess is that a CCAM Model 2's would all sound the same... Its the same ASIC revisions and the CCAM replaces the audio signal path, so unless the noise is caused by power or some other issues I would think the CCAM would be dandy.  I'm probably entirely wrong here though sad

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philly
Theta_Frost wrote:

hmmm, my guess is that a CCAM Model 2's would all sound the same... Its the same ASIC revisions...

But above it says that it depends on the revision of the Model 2. So they're not all the same ASIC revision, if you have a Model 2 VA2 and VA2.8 (apparently), they're discrete 2612s...

Last edited by bucky (Sep 14, 2010 9:29 pm)

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Milwaukee, WI

Well crap ha.  I bought two model 2's and neither are VA3's  One is VA1 something and the other I haven't cracked open yet.  I'll do sound comparisons, but now I'm after two VA3's.  (Hit me up wink )

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Estonia, Mahtra

CCAM is for machines with Sega 315-5476, 5660, 5700 and 5708 ASICs. But it should work nicely with 315-5960, and it also works with the ASIC in VA2 Genny3, but you need 100K resistors instead of 22K ones on the FM input lines.

As long as all your transistors are equal and resistors accurate (small differences will cause distortion) then you should not get issues with sound quality. I once mixed different manufactuer transistors and had to corrigate resistor values to get both channels equal...

Last edited by TmEE (Sep 19, 2010 7:23 pm)

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philly

Awesome, thank you!

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i would love to hear a detailed side by side comparisons of all of the models. It would be interesting to here all the differences.

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Milwaukee, WI

Sorry for the bump but I've had a few burning questions.  In the ASIC based Model 2's what causes the difference in sound quality?  Does it have to do with the signal path of the audio or the actual ASIC revisions?  I'm going to replace all the capacitors on my VA1 but for instance, would a VA1 with CCAM sound the same as a VA3?  This is good information to know, so I don't go and waste money on finding two VA3's.

Last edited by Theta_Frost (Jan 24, 2011 3:32 am)

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New York City

Been dragged to this upon opening my Genesis and finding a VA7... I find the reports on its shitty sound being truly exaggerated. Seriously, it's not THAT bad at all. I connected it yesterday to my stereo and there was NO hissing, and decent bass sound.

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Discovered this thread on google today. Occasion is that I dug out and dusted off my Genesis model 1 after becoming very dissatisfied with the genesis audio quality on my Genesis 2/SegaCD2/32X rig. Comparing the two, I did like the sound better on the Gen 1, but it still didn't seem "better enough" based on the comparo clip on the Genesis' wikipedia page. I remembered hearing that some of the very late Model 1s actually had the cheaper mixing circuit a la the model 2, but I didn't know how to tell whether I had the good one or bad one.

Soooo, I found this, read the whole thing (very informative!) also checked out the milkcrate comparo linked at the end (great sample tune!) grabbed a screwdriver and would go on to discover that my Genesis 1 contained motherboard USA VA7.....crap! :-(

Giving it a listen on my home stereo* using the headphone out on the Genesis (using a stereo mini to LR RCA cable), I do have to disagree with the assessment that VA7 is overly hissy, or lacks in bass output. It seemed fine in those respects. -However- I do notice a lot of scratchiness and flatness in the high end, no brilliance that characterizes the superior mixing hardware (per the wikipedia clip). Comparing my Genesis 1 to the wikipedia clip, my Gen 1 sounded much closer to the Gen 2 than the Gen 1 in the example, so I would agree with the overall sentiment that the VA7 does not sound particularly good.

I have a friend who has a Gen 1 with the "High Definition Graphics" decal, which this article says is a sure-bet to have the better audio circuitry...rest assured I will get to work on trying to work a trade with him post haste! :-D

Thank you for this very informative article! I've been greatly benefitted by it!

God Bless!

-J

p.s. Another important question: If I get the HDGFX branded Gen 1, hook it up to the Sega CD model 2, and the 32X, use the headphone jack from the Genesis into the Sega CD, and then then LR RCA cables from the Sega CD into the Stereo, will I still reap the benefits that the Gen 1 offers, or will the Sega CD/32X rob me of that? Lemme know! Thanks!

* =If you are interested in specifics on my stereo (the specifics of my test environment, as it were), PM me.

Last edited by JaySeeDoubleYou (Oct 14, 2011 4:09 am)

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rochester, ny

something else to add - here's how to read and understand the serial numbers on the bottom of model one's.

the first digit of the serial number identifies what factory produced that particular genesis. i know at 3 is taiwan and i assume 1 must be japan but i'm not sure of that.

the second digit is the year it was made. 9 means 1989. 0 means 1990, 1 means 1991, etc.

the third digit is usually a roman numeral indicating which production run produced this.

the rest of the numbers is what # this was in the production run. this is either 5 or 6 digits.

someone correct me if i'm wrong but i'm pretty sure this is how it works.