New Documentation: An authoritative reference on the YM2612

AamirM · Post by **AamirM** » Sat Jan 31, 2009 8:33 am

Another thing to test would be the Spiderman intro sound I've been bugging everyone about for a while

. I don't know if its a problem with the envelope generator or whether Genesis does something special when output reaches a certain level. I found a fix for it using a hack by messing with the TL writes (if I add a certain fixed value, 0xF, to TL of the operators). It makes it sound like the recording by TmEE/Kega. Steve, would you take a look? plz plz plz

Huge · Post by **Huge** » Sat Jan 31, 2009 10:48 am

AamirM wrote:Another thing to test would be the Spiderman intro sound I've been bugging everyone about for a while . I don't know if its a problem with the envelope generator or whether Genesis does something special when output reaches a certain level. I found a fix for it using a hack by messing with the TL writes (if I add a certain fixed value, 0xF, to TL of the operators). It makes it sound like the recording by TmEE/Kega. Steve, would you take a look? plz plz plz

Which Spiderman, the Animated Series one? I thought it just uses the channel 3 glitch, like Comix Zone.

AamirM · Post by **AamirM** » Sat Jan 31, 2009 10:52 am

Spiderman Separation Anxiety. There is a problem in the intro, on channel 3 and 6.

HardWareMan · Post by **HardWareMan** » Sat Jan 31, 2009 2:03 pm

GManiac wrote:...Hmmm, I listened to "Super Stripe" from CCAM'ed MD2 and... I don't like it

Me too. But we can not compare the taste?
My turn to share some records.
http://rapidshare.com/files/192035241/AftBrn2.rar.html
http://rapidshare.com/files/192021501/WavPlay.rar.html
Record takes from unmodded MD1 (YM2612+SEGA 315-5313, board IC BD M5 PAL VA4) in 60Hz mode.

As the saying goes - feel the difference.

Nemesis · Post by **Nemesis** » Sat Jan 31, 2009 2:22 pm

AamirM wrote:Spiderman Separation Anxiety. There is a problem in the intro, on channel 3 and 6.

Ahh yes, I think I know the instruments you're talking about. I looked into that a bit. Little known fact: Even when the LFO is disabled, amplitude (and frequency?) modulation are still applied, but the LFO waveform itself is locked. In the problem track on Spiderman, the instruments on channels 3 and 6 have AM sensitivity set to max, with amplitude modulation enabled on all operators. Whatever value the LFO is frozen at, it applies a large amount of attenuation to the instrument, making it much softer. Phase modulation may also be affecting the pitch. I haven't done full tests on this behaviour, as I haven't started work on the LFO yet.

Nemesis · Post by **Nemesis** » Sat Jan 31, 2009 2:58 pm

Record takes from unmodded MD1 (YM2612+SEGA 315-5313, board IC BD M5 PAL VA4) in 60Hz mode.

Ahh, that's more like it.

That's the exact model I do most of my testing on.

HardWareMan · Post by **HardWareMan** » Sat Jan 31, 2009 3:09 pm

Nemesis wrote:
Record takes from unmodded MD1 (YM2612+SEGA 315-5313, board IC BD M5 PAL VA4) in 60Hz mode.
Ahh, that's more like it. That's the exact model I do most of my testing on.

Cool! That mean we have same result in audio because we have same analog part. I can do more audio tests if anybody need this.

After Burner 2 used PSG as DAC sets highest possible frequency and controls it amplitude (16 levels). And this frequency can be heared in headphones. But, when I try to record it by soundcart this high frequency seems to cut-off by filter in soundcart. Or something like that. That frequency very close to channel change frequency (that was I showed at oscillograph screen). And YM2612 output mixes with PSG output before preamp, which do filtering of high frequences. So that to high frequences can affect to each other and produce many harmonic frequences, wich make sound much complex, then we can imagine.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Sat Jan 31, 2009 3:52 pm

GManiac wrote:Why are you both talking about PSG and that PSG at high volume muffles/damps YM2612 or cancelling some of YM2612's output? I said that in 2nd test I CUT OUT all writings to PSG and tones 1, 2 from VGM file and played this VGM on hardware and you can see that emulator still playing the same as with all tones and PSG.

PSG is not causing any distortions, its that PSG is used to play samples, and the result is failrly silent... now FM has to be made silent aswell so you could actually hear the samples from PSG... BUT not having too high accuracy, things become quite aliased at lower volume levels.
I can disable PSG from my MD2 (by disconneting PSG input from the audio mod) and things will be exactly like they are, just without samples...

TmEE, can you desribe in detail what model did you use? I used Asian PAL MD2 (Chinese clone) MK 1631-07 and European MD1 PAL 1600-05 and they sound identical (MD2 sounds a bit clearer).

Its an European MD2 model MK-1631-50 with IC BD VA1 PAL board, and 315-5660-02 system ASIC.
http://www.fileden.com/files/2008/4/21/1876835/5E6A.jpg
http://www.hot.ee/tmeeco/MYSMD2.JPG

HardWareMan wrote:Me too. But we can not compare the taste?
My turn to share some records.
http://rapidshare.com/files/192035241/AftBrn2.rar.html
http://rapidshare.com/files/192021501/WavPlay.rar.html
Record takes from unmodded MD1 (YM2612+SEGA 315-5313, board IC BD M5 PAL VA4) in 60Hz mode.

As the saying goes - feel the difference.

I also have exact same model MD1 that HardWareMan has, but without some of the mods he has in his MD1

Your recordings sound quite bright, my anything from my MD1 sounds much darker (more filtered)...

Maybe my very long cables have something to do with it (6 meter shielded cable...)

HardWareMan · Post by **HardWareMan** » Sat Jan 31, 2009 4:33 pm

TmEE co.(TM) wrote:I also have exact same model MD1 that HardWareMan has, but without some of the mods he has in his MD1

Wich mods you mean? Adding region selector, PAL/NTSC selector and hardware pause? Nothing was change with analog audio part.

TmEE co.(TM) wrote:Your recordings sound quite bright, my anything from my MD1 sounds much darker (more filtered)...

Very interesting. Why so?

TmEE co.(TM) wrote:Maybe my very long cables have something to do with it (6 meter shielded cable...)

I think capacitance of 6m qualitative cable can't spoil quality of sound. I used 10m of such cable and have no problems even in video quality. Or you used some cheap of one?

GManiac · Post by **GManiac** » Sat Jan 31, 2009 4:37 pm

HardWareMan wrote:As the saying goes - feel the difference.

HardWareMan wrote:Cool! That mean we have same result in audio because we have same analog part. I can do more audio tests if anybody need this.

It's strange because I have the same MD1 as you, its date is 05 May 92 (but Chinese assembly), and yours - 20 May. But your one sounds clearer

Probably you know about this link
http://arcade.ym2149.com/megadrive/index.html
His MD1 is dated on 04 June 92.
I recorded "Datarum" on my MD1 and it sounded just like his recording. Also someone provided recording BGM 02 from SoR2 and the result was the same.
Here are comparisons:
http://shedevr.org.ru/ghost/Datarum_Super_Stripe.rar
HardWareMan, can you provide the whole recording or only these seconds from Datarum recording:
part 1: from nearly 19.58 to 29.36 (length = 9.78)
part 2: from nearly 4:38.67 to 4:41.13 (length = 2.46)
Differences between models are most noticeable on this sections.

TmEE co.(TM) wrote:I can disable PSG from my MD2 (by disconneting PSG input from the audio mod) and things will be exactly like they are, just without samples...

Do you mean those things will sound loudly or not?
I think there's no necessity to disable PSG, you could playback my VGM on console (link is in previous post).

TmEE co.(TM) wrote:Your recordings sound quite bright, my anything from my MD1 sounds much darker (more filtered)...

I said the same

and problem is not in cable. Maybe he is concealing something?

HardWareMan · Post by **HardWareMan** » Sat Jan 31, 2009 5:16 pm

GManiac wrote:
HardWareMan wrote:As the saying goes - feel the difference.

HardWareMan wrote:Cool! That mean we have same result in audio because we have same analog part. I can do more audio tests if anybody need this.
It's strange because I have the same MD1 as you, its date is 05 May 92 (but Chinese assembly), and yours - 20 May. But your one sounds clearer
Probably you know about this link
http://arcade.ym2149.com/megadrive/index.html
His MD1 is dated on 04 June 92.
I recorded "Datarum" on my MD1 and it sounded just like his recording. Also someone provided recording BGM 02 from SoR2 and the result was the same.
Here are comparisons:
http://shedevr.org.ru/ghost/Datarum_Super_Stripe.rar
HardWareMan, can you provide the whole recording or only these seconds from Datarum recording:
part 1: from nearly 19.58 to 29.36 (length = 9.78)
part 2: from nearly 4:38.67 to 4:41.13 (length = 2.46)
Differences between models are most noticeable on this sections.

Done. There no problem do it with my "Super 3in1 Trax" PD ROM.

http://rapidshare.com/files/192104633/Datarum.rar

While recording Datarum noticed an interesting feature: record sounds different from the direct signal. Such a scheme: MD1 is connected to the line input, and listening to headphones with pre-amplifier connected to the output of a sound card. Sound card is Creative Audigy model SB0090. I try to record at 44kHz and at 48kHz - no difference, but still different than direct signal. And matter is not in the frequency range, the upper of which cut-off at ADC sampling. There is something else...
The truth is out there (C) Cris Carter

TmEE co.(TM) · Post by **TmEE co.(TM)** » Sat Jan 31, 2009 5:16 pm

My MD1 is 08 May 1992... I'll do some recordings and provide a pic or two...

GManiac · Post by **GManiac** » Sat Jan 31, 2009 5:33 pm

HardWareMan wrote: Done. There no problem do it with my "Super 3in1 Trax" PD ROM.
http://rapidshare.com/files/192104633/Datarum.rar

It's awesome!

Your playback is the best, it's better than CCAMed MD2's and still doesn't sound too sharply or poignantly.
Maybe I have bad specimen of MD1? I intend to purchase first Japanese model and I hope it'll be as good as yours.

HardWareMan wrote:Sound card is Creative Audigy model SB0090. I try to record at 44kHz and at 48kHz - no difference, but still different than direct signal.

As Nemesis said, he notices something on oscillogram at 192 kHz rate. It seems the best option is to use sound card with 384 kHz ADC, but it's very high grade of sound cards.
Also when I recorded James Bond tracks at 96 kHz, I noticed some strange lines on spectrogram. Later I'll show them.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Sat Jan 31, 2009 5:38 pm

My Yamaha YMF71x type card could do 500KHz 16bit stereo (or perhaps 1MHz 16bit mono) sampling according to datasheet where its said that the DAC and ADC can handle 2MBytes of data per second... Windows(95) drivers don't allow me to use rates above 64KHz...

And the Datarum recording of HWM does not sound as bright as the recordings of the AfterBurner songs....

HardWareMan · Post by **HardWareMan** » Sat Jan 31, 2009 5:41 pm

GManiac wrote:
HardWareMan wrote: Done. There no problem do it with my "Super 3in1 Trax" PD ROM.
http://rapidshare.com/files/192104633/Datarum.rar
It's awesome! Your playback is the best, it's better than CCAMed MD2's and still doesn't sound too sharply or poignantly.
Maybe I have bad specimen of MD1? I intend to purchase first Japanese model and I hope it'll be as good as yours.

Everything can be corrected. If your MD have same sound chips, then there can be preamp filtering error. Some of passive elements may have allowed more than +-20%. And for amplifier frequency loopback it is enough to cut-off something more, than need.

GManiac wrote:
HardWareMan wrote:Sound card is Creative Audigy model SB0090. I try to record at 44kHz and at 48kHz - no difference, but still different than direct signal.
As Nemesis said, he notices something on oscillogram at 192 kHz rate. It seems the best option is to use sound card with 384 kHz ADC, but it's very high grade of sound cards.
Also when I recorded James Bond tracks at 96 kHz, I noticed some strange lines on spectrogram. Later I'll show them.

Well, I always said that. Even at that dead russian forum "emu-russia", remember that?