Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Discussion about old sound cards, MIDI devices and sound related accessories.

Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby PhilsComputerLab » 2017-5-27 @ 11:57

My CD Audio comes out separate, I built myself a rear bracket with RCA ports. But FM would be affected that's true. All my MIDI gear is external though.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2017-5-27 @ 12:06

I wouldn't say soldering two small smt capacitors is harder than building a bracket or adding a dedicated in-line equalizer.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby PhilsComputerLab » 2017-5-27 @ 13:24

James-F wrote:I wouldn't say soldering two small smt capacitors is harder than building a bracket or adding a dedicated in-line equalizer.


No, but it's permanent and I prefer something I can adjust on the fly.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby PhilsComputerLab » 2017-6-06 @ 13:48

I know that James has mentioned this tool already, I only got around to trying it out today. It's the Sound Blaster Pro Volume Control TSR. It likely works with all SB Pro 2 compatible cards?

Anyway, it's a TSR that lets you control the mixer from within games. It has a lot of features, so read the documentation. Works very well and I find it useful for capturing to set the volume quickly for example.

http://www.vogonsdrivers.com/getfile.ph ... enustate=0
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Acill » 2017-7-19 @ 23:44

Hi everyone! I was asked to do this mod for someone and just wanted to share. Very cool stuff. I usually work on restoring classic machines like the Atari ST, Amiga and consoles. This was a first. I had no idea old PC gear was this popular!

Shared photos are here: https://photos.app.goo.gl/pPfulsBh4Id03s6j1
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Maxx1234 » 2017-8-14 @ 02:38

Concerning the Audician 32 Plus DOS Mixer (setupsa.exe v2.20 from the Win9X Driver v4.06.2343), can anyone verify if the following WSS Mixer items are correctly identified?
WSS MONO IN: Voice Modem Input Volume
INPUT VOL L/R: Wavetable Daughterboard Volume

The rest are as indicated below:
WSS LINE L/R: Line Input Volume
WSS AUX1 L/R: Analog CD Audio Input Volume
WSS AUX2 L/R: FM Synthesizer Volume
WAVE VOL L/R: Wave Volume
MASTER VOL L/R: Master Volume (keep at 12 for optimal line-level output, as recommended in a previous post)

Thank you in advance.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby timitt » 2018-1-17 @ 19:41

My SM178 rev 3 card had problem that it's left channel started to cause some scratching sounds even when not playing anything from it. I tried to replace capacitors (electrolytic ones) one by one, but it did not really help.

Then I read this topic and decided to try to turn input filter off and realised that it was related to that. So I decided to mod my sound card with James-F instructions (mostly because I started to think that filter capacitor might be broken).

And it certainly was the problem. Now my sound card works perfectly and also sounds much better as it has those 6.8nF caps.

Here is what I changed (as I have different layout): https://imgur.com/s3EUoaK

So many thanks to James-F for his valuable work!

And also thanks to everyone else for all information this topic contains about good settings with mixer (and separate driver package from Phil).
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby KCompRoom2000 » 2018-1-20 @ 09:08

Just changed the SB Pro mixer value to 1 in the SETUPSA program on my Pentium 1 build, and it seems to have helped, but there's a catch for the minority who happen to be using their YMF71x card on a Windows 3.1x machine, changing the values with the SETUPSA DOS utility can hose your SYSTEM.INI file, thus losing the ability to play sound on Windows.

Luckily, not all hope is lost since the utility makes a backup of the SYSTEM.INI file as SYSTEM.E00, so if this happens to you, the solution for fixing it is to simply restore the old SYSTEM.INI by typing in "COPY SYSTEM.E00 SYSTEM.INI" inside your Windows directory in DOS.

If you haven't changed the SB Pro mixer setting with SETUPSA because you're afraid it'll hose your Windows installation, there's another way to change it, simply open OPL3SA.INI (inside the same directory as SETUPSA.EXE) with either Notepad (assuming you're in Windows) or EDIT (assuming you're in DOS) and check the SB mixer values inside the file, go down until you find the SBMixMainL and SBMixMainR values as shown below:
Code: Select all
SBMixMainL=1
SBMixMainR=1

If that number is not 1, change it.

NOTE: There are other values for the SB components in the OPL3SA.INI file (like SBMixFML/SBMixFMR, SBMixLineL/SBMixLineR, and some others), but it appears that the SETUPSA utility doesn't change those values if you're changing the Main value as described in this topic, so I'm not sure if those need to be changed to 1 or not.

I apologize if I got something wrong in this post, it's late at night already so it's possible that I forgot something. If you notice a problem with my guide, let me know and I'll fix it.
1988-96:SL-54U5|P233MMX|64MB|Virge325|YMF719-S
1995-98:P2B-VE|C433|192MB|Rage Pro|Voodoo2|CT4500/32M
1998-01:GX150MT|PIII-S 1400|384MB|GF4Ti4200|CT4670
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Ace » 2018-2-05 @ 18:02

As much as I'm a sucker for the real SoundBlaster Pro 2.0 CT1600, I'm going to revisit the YMF71x for sure after reading all that's gone on in this thread. That low-pass filter mod is the first thing I will do on one of my YMF719 cards; I really don't like the sound of unfiltered PCM out of the SoundBlaster Pro.

I must ask: If I attach my NEC XR385 to either of my YMF719 cards, the audio is SEVERELY overblown and gets very badly distorted. I get the same thing on various ESS AudioDrive cards and some of my OPTi chipset-based cards, but not on SoundBlaster 16s nor on the Diamond Monster Sound MX300. Is this down to lack of proper attenuation on the wavetable header or just the XR385 having overly loud output?

Also, are there any YMF71x cards with PC speaker passthrough support? I'm considering using one for a friend who I will put together a DOS build for out of spare parts I don't need, but the cards I have don't seem to have an input for PC speaker passthrough. What about modding a card that doesn't have PC speaker passthrough? How would one go about doing that?
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby CkRtech » 2018-2-05 @ 22:50

Yo Ace!

I can't answer regarding the difference between the SB16/MX300 and the YMF719 cards' wavetable header, but it is rather interesting - the external CHiLL MIDI interface board available on serdashop basically jumpers to select if the L and R output go straight through, through one 47k resistor or through a second 47k resistor (with a third tied to ground). http://serdaco.com/files/BUILDINSTRUCTIONS_CHILLBOARD.pdf.

I have a YMF719, SB16, and MX300 + a couple of Wave Blasters, but I don't have an XR385, so I have never encountered nor messed with the output level conundrum. Also interesting that the XR385 has analog audio input as well. Is there a difference between the analog input on the SB16 header vs the YMF719 header, and does it screw up any mixing on the XR385?
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Tiido » 2018-2-06 @ 06:12

DB60XG (aka XR712) and XR385 have very loud output, over 5Vpp which will clip most sound card inputs and has the theoretical ability to even damage them. Ideally you reduce the gain on the module to unity, matter of changing two resistors.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Ace » 2018-2-06 @ 14:53

OVER 5Vpp?! :exclamation:

No wonder it's so badly distorted on most cards. Why so loud? Is it because those cards don't properly attenuate the incoming audio signal on the WaveBlaster header or because the >5Vpp output of those Yamaha/NEC daughterboards is significantly out of spec for the WaveBlaster header?
Also, I know the SoundBlaster Pro DAC can have its low-pass filter cutoff frequency altered, but what about the YMF289 in the chip? The output is a bit too harsh for my liking, and I would like to lower the cutoff frequency to where FM is as muffled as it is on the SoundBlaster Pro 2.0 CT1600.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2018-2-07 @ 05:24

The SBPro2 output is a simple 2nd order Butterworth at 3.2kHz at output, but the variable frequency filter is only for the inputs.
The FM is not filtered on the YMF289, but neither on the SB16.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Ace » 2018-2-07 @ 14:27

Is there some way to filter the YMF719's OPL3 short of using a low-pass filter on the final output? That's what I'm asking as I find the sound a bit too harsh from the chip's integrated YMF289 just like I find the sound too harsh from any SoundBlaster 16 with OPL3. I see pins for a treble capacitor on the YMF715, at least (should be fairly similar compared to the YMF719), though I'm not entirely sure how those affect the audio output.
Since you mention the SoundBlaster Pro 2.0's output, aside from modding the card, can the Line In be made less muffled? Every time I pass another card or a MIDI module through the Line In, there is a quite noticeable amount of low-pass filtering.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2018-2-07 @ 17:35

The FM is integrated on the YMF chip, so there is no analog path to tinker with.
You can disable the Line-In filtering with the command line SPBro mixer, the YMF does not have this input filtering unless modded for larger caps on the ADFLTR lines (datasheet).
http://gd.tuwien.ac.at/linux/alsa/datas ... 3sa3ee.pdf
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Tiido » 2018-2-07 @ 21:34

Pins 97 and 98 on YMF715 and YMF719 are FM/i2s DAC sample/hold capacitors, you can increase their value and get darker output that way. On YMF711 and YMF718 the equivalent are pins 95 and 96.

Stock capacitors are 1000pF on most cards I have looked at, you'll want to try double perhaps. For best performance you'll want to use NP0 / C0G type ceramics or polyproyplene or polystyrene film capacitors.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby ahyeadude » 2018-11-03 @ 04:12

Thanks for all of these great posts! Helped me out tremendously in getting my ATC-6631 (YMF-719E-S) setup.

For those with the ATC-6631, the SBPro filter capacitors are C19 and C20. You can follow the traces from pin 99 and 100 out of the YMF-719 to be sure. All the pictures I've seen online of the ATC-6631 look to be labeled the same.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby ahyeadude » 2018-11-08 @ 05:03

So ran into another issue on my ATC-6631. The CD Audio volume seemed really really low, even with the mixer setting at 7. I tried multiple drives, so that wasn't the issue. Looking at the input circuitry, there is a 1k ohm resistor in series and then there is a high pass filter with a 220 ohm resistor and 1.6 uF capacitor. I removed all of these and bridged direct and the volume is now correct and sounds fine. The resistors were in-spec, but I can't confirm those capacitors were, though they match.

Any ideas? Is it okay to remove that high pass filter? Are there other component values I can use to still have the filter, but not crush the volume to unusable levels?
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Tiido » 2018-11-08 @ 10:51

Most CD drives etc. already have their DC blocking caps in the path, but ones that don't will cause you to have very distorted sound if connected to the card that lacks these DC blocking capacitors as the DC offset that the inputs must maintain get pulled to something totally off.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby ahyeadude » 2018-11-09 @ 02:57

Thanks for the info. I did notice that when changing CD input mixer volume that there were pops. So I went back to the drawing board and ended up keeping the 1k ohm in-line resistor and reduced the decoupling capacitor to 1uF. I also left out the 220 ohm resistor to ground because that was the source of the decreased volume. I tried a 1k and that was tolerable, but it was definitely cutting out the lower frequencies (hence the high pass filter). It sounds perfect without, so I just left it out. The decoupling capacitor eliminated any popping on volume changes.

I am not sure why they felt the need to have such a harsh filter on the input.
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