VOGONS


First post, by Tiido

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MIDI boards based on Dream SAM9733 and SAM9407 (and possibly others) default to high enough master volume that they digitally clip, causing unwanted distortion. I made a little DOS util (in QB45) that sends a custom master volume command to the MIDI device and sets it to a sane level where there's no more distortion happening. Most games seem not to clip much but I have a handful of MIDI files that made these things sound absolutely awful and they're the reason I began looking into it hahaha. After the volume fix they're completely fine ~
You will likely have to boost the sound card input level to compensate for the loudness loss, but it'll be worth it ~

Anyway you can grab it here : http://www.tmeeco.eu/TKAYBSC/DREAMFIX.EXE

Default port is 330, to override it use Pxxx command line parameter where xxx is new address in hex.
Default volume is 4F, to override it use Vxx where xx is a hex value between 00 to 7F (7F being chip default).

I'll make some recordings soon.

Last edited by Tiido on 2019-10-08, 01:02. Edited 2 times in total.

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Reply 2 of 14, by Tiido

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Here's some recordings from SAM9733 using the Roland clone ROM, straight from digital output from the sound chip via SPDIF at original sample rate of 37500Hz (via a modification) of one MIDI file I have that was most offensive :
Original : (FLAC) (OGG)
Fixed : (FLAC) (OGG)

Here's same track from hardware using SAM9733 with CleanWave32 ROM, this time analog output via my sound card (the cracking is not caused by the sound card itself, but overflow in digital domain on the sound chip) :
Original : (FLAC) (OGG)
Fixed : (FLAC) (OGG)

MIDI file itself

Games don't really have much issues, there's only mild clipping distortion heard at stuff such as Duke Nukem 3D title for example though CleanWave32 board does crack in many tracks in Doom and probably other places too... I'm not sure how that sort of issue got missed...

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
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Reply 3 of 14, by keropi

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quite an improvement, original is just broken
I also wonder how this was not detected back then... wtf!

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Reply 4 of 14, by Tiido

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It turns out CleanWave32 problem stems from another fault : CleanWave32 distortion fix

This util is till useful for reducing digital clipping problems as the default master volume is very high on these devices.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 5 of 14, by ahyeadude

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This definitely reduces the volume on my Yucatan FX. I'm not sure if I had clipping issues though since I run the output from the CHiLL to an external mixer where I can turn it down. What does changing the music/midi volume in a game do? It doesn't seem to override this master setting (which is good, just curious how it works).

Reply 6 of 14, by Tiido

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I'm just sending a Dream specific NRPNs to the chip that controls the Master Volume of SAM9733, it shouldn't get in the way of anything else.

By default the volume is very high and there's good amount of digital clipping going on prior to data entering the DAC on the card with many tracks, you can easily see in the recordings how the peaks are completely flattened with default volume.

Last edited by Tiido on 2020-11-27, 07:14. Edited 1 time in total.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 7 of 14, by dreamblaster

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ahyeadude wrote on 2020-09-25, 01:08:

This definitely reduces the volume on my Yucatan FX. I'm not sure if I had clipping issues though since I run the output from the CHiLL to an external mixer where I can turn it down. What does changing the music/midi volume in a game do? It doesn't seem to override this master setting (which is good, just curious how it works).

So this works well for you ?
Did you notice any clipping issues before, any trouble in any game ?

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Reply 8 of 14, by keropi

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Just in case anyone has issues running Tiido's DREAMFIX here is the SysEx message that sets volume to 4F: B0 63 37 62 07 06 4F
I am attaching it along with the old DUMP.EXE , usage is: DUMP DREAMFIX.SYX

Attachments

  • Filename
    DreamFix_SysEx.zip
    File size
    17.57 KiB
    Downloads
    56 downloads
    File comment
    DreamFix SysEx volume fix + dump.exe
    File license
    Public domain

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Reply 10 of 14, by keropi

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Rawit wrote on 2021-03-29, 20:57:

Is it possible to do the same (Sysex) for the equalizer? Currently using the Yucatan Presets. I checked the SAM9793 user guide (can't find the 9733 one) but I'm not able to figure out the logic.

IIRC on the Yucatan page there are some midi files to download that do exactly this: eq setup
These can't be in .syx form, they are .mid that play no sound but do setup things

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Reply 11 of 14, by Rawit

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Yes I have those currently in use. I checked the MIDs to see what Sysex was being used but MIDI events are used instead. I was hoping there would be a Sysex option for added flexibility and additional tools to use.

YouTube

Reply 12 of 14, by Bancho

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I tested this fix out on a Miditech Pianobox which uses Dream SAM2635 although I'm not sure what patch set is use (Most likely a Cleanwave set).

I noticed real bad distortion on the Endgame Track for Descent (especially in the middle of the track). The Fix brings the volume down a tonne and stops the distortion. Dream really must boost their volumes on the chips!

I recorded the track at exact same volume and you can clearly hear the difference!

Attachments

  • Filename
    EndgameDreamFix.ogg
    File size
    2.43 MiB
    Downloads
    6 downloads
    File comment
    Dream Fix Applied
    File license
    Public domain
  • Filename
    EndgameNoFix.ogg
    File size
    2.56 MiB
    Downloads
    3 downloads
    File comment
    No Dream Fix
    File license
    Public domain
  • Compare.PNG
    Filename
    Compare.PNG
    File size
    77.65 KiB
    Views
    295 views
    File license
    Public domain

Reply 13 of 14, by Tiido

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That is a significant improvement for the middle part that was really suffering ~

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 14 of 14, by Rawit

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Based on Hummtaro's presets for the Yucatan FX I've created another preset midi that might work in this case as well. It sets the equalizer values to 0 and turn it off while keeping volume at 127.

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