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 James-F » 2016-9-20 @ 16:25

Yes, the SB 1.0 1.5 and 2.0 has the same simple 3.2kHz low pass filter as the SBPro (or should I say the other way around).
You can listen to the GODS track on the SB 2.0 HERE or HERE.

It is only on the SB16 Creative introduced the dynamic brickwall filter, and it sounds different to the SBPro.
DOSBox emulates the SBPro filter even in SB16 mode.
The sound of the filter is all part of the nostalgia.

You are searching for 0805 (2012) 4.7nF SMD Capacitor.
Like THIS ONE for example, which seems to be the most reliable.
EDIT: 6.8nF will be even more accurate.

PS.
It is "Into, the Wonderful". :lol:
Last edited by James-F on 2016-9-21 @ 08:56, edited 2 times in total.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby PhilsComputerLab » 2016-9-20 @ 16:37

Done, ordered a few :)
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-20 @ 16:42

A few? I see you bought 5...
A single buy is 100pcs, that makes it 500 capacitors for your disposal, if something goes wrong with soldering the TWO. :lol: :lol: :lol: :lol:
They are cheaper than the paper strip that holds them.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby carlostex » 2016-9-20 @ 16:48

James-F wrote:Beware of SMD caps from ebay, they can be empty or the wrong value.
Make sure you have something to measure them.


Nah, i don't buy caps on eBay. I get my stuff from Mouser or Farnell. I suspect i will have to order parts from there in the future so i'll grab some various value SMD ceramics from there. Can you tell me the size of them? They seem bigger than 0805 package...
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby carlostex » 2016-9-20 @ 16:50

James-F wrote:You are searching for 0805 (2012) 4.7nF SMD Capacitor.
Like THIS ONE for example, which seems to be the most reliable.


Lol at me for not reading the whole thread... :lol:
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-20 @ 16:52

Mouser or Farnell are good.
They are 0805 (2012) I personally measured with a caliper.

This particular seller on Ebay looks like a reliable source too.
Make sure you buy only ONE to get 100pcs.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby Cloudschatze » 2016-9-20 @ 16:58

James-F wrote:The lowpass filter DOES exist and it is enabled by default but the SMD cap is so small (250pF) that it has no effect on sound.

This is one of the scenarios I'd suggested yesterday. Thank-you for doing the leg-work to test and validate all of this, James. :)
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby PhilsComputerLab » 2016-9-20 @ 17:05

James-F wrote:A few? I see you bought 5...
A single buy is 100pcs, that makes it 500 capacitors for your disposal, if something goes wrong with soldering the TWO. :lol: :lol: :lol: :lol:
They are cheaper than the paper strip that holds them.


LoL 500? Haha
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-20 @ 17:08

Cloudschatze wrote:This is one of the scenarios I'd suggested yesterday. Thank-you for doing the leg-work to test and validate all of this, James. :)

No, Thank YOU for motivating me to test this.
Not only did we tested and validated it, but we also found a solution that makes YMF71x one heck of a SBPro clone.

This after spending a couple of hundreds of $ on sound cards in the last two months... :dead:
That is just my luck, it seems like a reoccurring pattern that I find the item I owned first was actually the best one after spending loads of money.
If the all mighty wants it that way, I shall accept it. :happy:
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby clueless1 » 2016-9-21 @ 10:54

James, have you tested the line-out vs speaker-out on the YMF71x? Conventional wisdom has always said that line-out is preferred, but I've had my Audician jumpered for speaker-out (amplified) for a few months and it still is quieter (less hiss) than the CT2800.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby firage » 2016-9-21 @ 12:15

You probably know to check the basics for variables. The self-noise of the speakers in the case of differing input levels, and noise introduced through any of the analog inputs:
-CD
-AUX
-PC Speaker
-mic
-daughterboard
-line in.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-21 @ 12:26

Speaker-out jumper switches the line-out jack to the big amplifier IC that is designed to pump more current and higher voltage to speakers, and may distort (or worse) a line-in.
It is intended for connecting 4-16 ohm speakers straight to the line-out of the sound card without an amplifier or any device in between.
I can't stress that enough, never miss-match or connect the wrong equipment to the wrong jack.

Like firage said, the hiss/noise comes form one of the mixer variables.
Mute one by one and find which one makes the noise.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby carlostex » 2016-9-21 @ 12:32

So 6.8nF is the best value for the caps?
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-21 @ 12:36

4.7nF or 6.8nF will do, both are miles of improvement over unmodded card.
6.8nF is ever so slightly more accurate, almost no difference.
Don't overheat the pad, it will unstick from the board and the trace to the YMF chip is hair-thin... :-D
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby clueless1 » 2016-9-21 @ 13:08

James-F wrote:Speaker-out jumper switches the line-out jack to the big amplifier IC that is designed to pump more current and higher voltage to speakers, and may distort (or worse) a line-in.
It is intended for connecting 4-16 ohm speakers straight to the line-out of the sound card without an amplifier or any device in between.
I can't stress that enough, never miss-match or connect the wrong equipment to the wrong jack.

Like firage said, the hiss/noise comes form one of the mixer variables.
Mute one by one and find which one makes the noise.

The point I was trying to make was not about the CT2800 hiss and how to solve it--it was how quiet the Audician is even when jumpered to speaker out. I use powered desktop speakers. No issues with distortion, etc. The only difference I noticed when jumpering to speaker out was the volume jumped up about 30% (estimated), which I compensate for at the speaker volume knob.

My question was, have you compared line-out to speaker-out to measure actual differences and quantify conventional wisdom?
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-21 @ 13:23

Here are some frequency analysis of DOSBox, CT1600, and modded YMF71x with 6.8nF.
LPF Comparison.png

With 4.7nF the YMF was slightly higher than DOSBox, but now it is exactly like the CT1600 up till 5kHz and slightly lower than DOSBox above 5k.
I think 6.8nF is the ideal Cap, and it sound excellent.

Here is how Unfiltered looks/sounds for comparison:
Unfiltered.png


My question was, have you compared line-out to speaker-out to measure actual differences and quantify conventional wisdom?

Why do you assume that the signal path through the amplifier chip will sound any better or quieter? It will not.
But I will measure the frequency response for science, and edit this post.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby clueless1 » 2016-9-21 @ 13:33

James-F wrote:
My question was, have you compared line-out to speaker-out to measure actual differences and quantify conventional wisdom?

Why do you assume that the signal path through the amplifier chip will sound any better or quieter? It will not.
But I will measure the frequency response for science, and edit this post.

I did not say that it would be better or quieter with the internal amp. I did notice, though, that it did not sound worse, which contradicts what I have read/heard from other sources. I expected noticeably worse audio quality, but only noticed ~30% higher output at the same speaker volume with no change in audio quality.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby James-F » 2016-9-21 @ 13:40

The frequency response is identical between SPKR and LINE out.
SPKR: -5.3db, LINE-24db, there is a 20db boost whe using the SPKR jumper.
Moreover, When on SPKR mode there is distortion in the audio path if the Master VOL is set to 15, lowering it to 12 clears the distortion.

20db gain is 10 times the voltage gain, so from 0.3V typical line level to 3V speaker driving level.
I do not recommend enabling the SPKR jumper on anything besides those 90s amplifier-less (passive) speakers.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby clueless1 » 2016-9-21 @ 13:45

James-F wrote:The frequency response is identical between SPKR and LINE out.
SPKR: -5.3db, LINE-24db, there is a 20db boost whe using the SPKR jumper.

Thank you for checking, James. :) Good to know my ears aren't going as bad as I thought.

James-F wrote:Moreover, When on SPKR mode there is distortion in the audio path if the Master VOL is set to 15, lowering it to 12 clears the distortion.
Ahh...my Master was already set to 12, so that makes sense.

James-F wrote:20db gain is 10V of voltage gain.

Can you help me understand why that is bad? 10V doesn't seem like an amount that would hurt anything, but I'm pretty uneducated on the topic.
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Re: Yamaha YMF71x SB Pro Mixer Bug Issue Fix

Postby firage » 2016-9-21 @ 13:59

Any amp is going to hurt the signal, the only question is how much. Phil's Audician 32 Plus shows the same TEA2025B amp that's in most old Creative cards, pretty solid old design for portable cassette players. If the quality beats the gain stages you have in your active speakers or recording gear, it'll be an improvement of course.
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