Tiido wrote on 2021-01-19, 21:34:

C46, 50 and 52 should be as high as you can find, I used 10µF. Bigger = better, less noise etc.
C45, 47 and 48 are 0.1µF but can also be 10µF or something else big. I took the parts from around CQM and its DAC stuff.
C41 I moved from C37, R13 from R9. This moves the CQM clock parts to OPL3L side, the MicroClock PLL generates the right stuff.

Bless you. I'm still waiting for another YMF289B-S and YAC516-E to arrive to get the CT3600 done, but when it does, I'll give it a shot.

In the meantime, I also have a CT2950 that I've tried to de-CQM, and while the CQM bits are removed and I've added components as shown in the posts above, FM sound isn't detected when poking 388h, and nothing plays back out of it in DIAGNOSE; I'm assuming maybe my solder job on the YMF289B-S was poor, since it's not detected at all, and the YAC516-E looks okay. Those fine pins are a pain in the ass. I'll have to give it another run of solder and see how it goes.

Yeah, the tiny pins of the YMF289B-S are pretty annoying to try to solder by hand. I had to redo one of my cards three times(!) before it worked as expected. Keep at it, and good luck! 😀

Eep386 wrote on 2021-01-26, 05:49:

Yeah, the tiny pins of the YMF289B-S are pretty annoying to try to solder by hand. I had to redo one of my cards three times(!) before it worked as expected. Keep at it, and good luck! 😀

After redoing it twice and fearing lifting or burning a pad, I had someone much more competent with a soldering iron than I take a pass at it.

It works like a champ now. Next up: the CT3600!

The CT3600 was a bit of a disaster. Soldering the YMF289B-S and YAC516-E on was actually much, much better than my job on the CT2950, but I got a little overzealous with the heatgun in the end and popped one of the vias in a trace shared between the OPL and the CQM chip, and blistered the board a bit. After that, the card wouldn't show up in the BIOS (or Windows). The CQM chip was missing anyways, and the trace was from the DSP to the OPL, and then the OPL to the CQM chip, but the via was after the OPL, I don't think that was what was giving me grief, but i patched it just in case.

More likely I did some damage to one of the caps around there, so I pulled all of the caps I'd installed off and replaced them with new ones. (I just stuffed 10uF caps in all of the filter spots since I had enough.) The computer would reboot continuously after the POST screen for a bit, so I pulled the card back out and touched up all the solder joints.

After a not-insignificant amount of screwing around, it works. 10uF caps for the filters was the right choice: FM sounds great!

That makes two (reasonably) successful CQMectomies. Thanks for the help, Eeep386 and Tiido; couldn't have done it without you two!

For anyone with an early(?) CT3600 with the weird bodge wire and missing caps between the clock generator and the DSP (and the two surface-mount bodge caps on the back), this is all I did to mine:

Ouch! Thank goodness you were able to salvage it and get it de-CQMed in the end!
I sometimes butcher my parts too 🙁

That visual map is incredibly helpful for visualizing what needs to be done for that particular card; maybe we should make one for every card that can be de-CQM'ed? At the very least, maybe someone could do something similar and point me towards what needs to be desoldered and soldered onto this card that I am planning to ruin? 😀

appiah4 wrote on 2018-01-02, 13:32:

Nice project but I kind of disagree with OPL3 being the holy grail of FM Synthesis, to me ESFM and even Crystal FM sound better, and CQM is not worse than OPL3, just different. Also, OPL3 by itself means nothing, the kind of filtering different OPL3 cards have tend to produce completely different sounds anyway, late Vibra/OPL3 SB16s' FM synthesis sounds as far from the SB Pro 2.0 sound as ESFM does. Some of Creative's own OPL3 cards have no bass response. Some have very muffled sounds. I commend what you did here but not sure I find it necessary 😀

It depends on the game.
Like, for example, Crystal-FM doesn't work in most Sierra adventure games, as they were designed to be Yamaha/Creative OPL compatible.
A really good example of this in Quest for Glory 3, when you first leave Tarna and the music plays a drum-roll stinger before it transitions into the map theme.

On a real OPL or decent clone, it sounds like a drum roll. A sharp and snappy drum roll, but a drum roll.
On Crystal-FM, it sounds like a drum roll done on alarm bells. It's horrible.

As for my own interests, I cannot stand the screechy, chirpy artifacts and mangled timbres that CQM assails my ears with.
https://en.wikipedia.org/w/index.php?title=Fi … _FM_vs._CQM.ogg
First half is OPL3 through a CT1770, second half CQM through some ViBRA16 thing before de-CQM. Filtering is different between the cards naturally.

appiah4 wrote on 2021-02-01, 13:52:

That visual map is incredibly helpful for visualizing what needs to be done for that particular card; maybe we should make one for every card that can be de-CQM'ed? At the very least, maybe someone could do something similar and point me towards what needs to be desoldered and soldered onto this card that I am planning to ruin? 😀

Is that a CT2940? There are OPL versions of the card in the wild:
https://imgur.com/gallery/8zRbN

-Brian

bbuchholtz wrote on 2021-02-03, 00:39:

Is that a CT2940? There are OPL versions of the card in the wild: https://imgur.com/gallery/8zRbN […]
Show full quote

appiah4 wrote on 2021-02-01, 13:52:

That visual map is incredibly helpful for visualizing what needs to be done for that particular card; maybe we should make one for every card that can be de-CQM'ed? At the very least, maybe someone could do something similar and point me towards what needs to be desoldered and soldered onto this card that I am planning to ruin? 😀

Is that a CT2940? There are OPL versions of the card in the wild:
https://imgur.com/gallery/8zRbN

-Brian

I know but I would need the values for added components..

appiah4 wrote on 2021-02-03, 10:41:

I know but I would need the values for added components..

I have the OPL version of the card. This weekend, I'll bust-out my soldering iron and LCZ.

-Brian

bbuchholtz wrote on 2021-02-03, 13:49:

appiah4 wrote on 2021-02-03, 10:41:

I know but I would need the values for added components..

I have the OPL version of the card. This weekend, I'll bust-out my soldering iron and LCZ.

-Brian

You sir are a hero 😀

For the CT2940...

Eep386 wrote on 2020-12-11, 02:12:

X3 needs to be populated with a 33.868MHz oscillator. R51 is 16 ohm, R52 and R53 are 47K, R57 is 3.9K, R65 is 1K. C71, C73, C95, […]
Show full quote

X3 needs to be populated with a 33.868MHz oscillator.
R51 is 16 ohm, R52 and R53 are 47K, R57 is 3.9K, R65 is 1K.
C71, C73, C95, C96, C97 and C98 are 100nF caps.
I think C112 and C113 are 15pF caps.
After fitting the YMF289B and YAC516-E chips, you then remove the CT1978 chip at U3 and the TDA1387 DAC chip at U1.

All the SMD caps and resistors except R51 are 0803 / 2012 metric size. R51 I don't know the exact size offhand, but it's one size up from 0803 / 2012 metric.

OPL version of the CT2940. I used a YHP H05-4276A, measured at 20kHz. Let me know if I missed anything.

-Brian

I followed kvanderlaag and Tiido posts and modded my CT3600. It worked at first attempt; then I redid some of capacitor SMDs for cleaner look and OPL3 became mute.

After some fiddling I was able to get some faint sound setting input in MixerSet to midi; I took capacitors off and measured them again all seem good, tried two others YAC512 dacs still sound is very faint.

I can check signals on YAC512 but not sure what levels it should ouput, I appreciate if anyone has suggestions or can provide me with levels from YAC512 and signal path to the mixer.

Check for short circuits. You can use a multimeter in continuity check mode.
It's possible a very fine solder bridge formed someplace. Do you have a good magnifying glass?

Eep386 wrote on 2022-05-09, 14:11:

Check for short circuits. You can use a multimeter in continuity check mode.
It's possible a very fine solder bridge formed someplace. Do you have a good magnifying glass?

Turned out that few legs of YAC516 including refH were loosely soldered so the chip was confused about output voltage range.
Some traces on top side of YAC516 are thick, ground, refH, etc so guys be careful to hold soldering iron longer on these pins, drag soldering is not enough solder along pins too.
Thanks for your help guys!

I have older AWE32 CT3900 with CT1747 OPL chip and there's no left footprint for Yamaha. How is this CT1747 compared to your hatred CQM?

RayeR wrote on 2022-11-03, 02:58:

I have older AWE32 CT3900 with CT1747 OPL chip and there's no left footprint for Yamaha. How is this CT1747 compared to your hatred CQM?

CT1747 is real OPL, it's not even comparable to CQM

Ok, but why they degraded the quality on newer cards? I would understand if they replaced 3rd party chip with theirs cheaper one but this OPL is already from Creative (at least by marking)...