Sound Blaster 16 Bugs and Deficiencies Summary

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

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Cloudschatze » 2018-9-28 @ 18:56

GL1zdA wrote:Soem SB16 cards have the AK4501-VS DAC - how does it compare to the CT1701 and the various CT1703 chips?

CT1701 = AKM AK4501-VS

The CT1703 is speculatively an AKM AK4503-VS. This would need to be confirmed with decapsulation.

GL1zdA wrote:...is OPL audio routed through the CT1701 on the CT2760? On the early SB16s the OPL3 audio would go through the Yamaha DAC to the mixer. But I can't see such DAC one on the CT1747 cards.

On applicable cards, the OPL output from the CT1747 is digitally routed through the EMU8000 and its corresponding TDA1387 or TDA1543 DAC. Hence the need to initialize the EMU8000 (via AWEUTIL) to get FM output, and the ability to apply EQ/Reverb/Chorus to those sounds.
User avatar
Cloudschatze
Oldbie
 
Posts: 1072
Joined: 2005-6-16 @ 14:32

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby GL1zdA » 2018-9-30 @ 20:28

Cloudschatze wrote:
GL1zdA wrote:...is OPL audio routed through the CT1701 on the CT2760? On the early SB16s the OPL3 audio would go through the Yamaha DAC to the mixer. But I can't see such DAC one on the CT1747 cards.

On applicable cards, the OPL output from the CT1747 is digitally routed through the EMU8000 and its corresponding TDA1387 or TDA1543 DAC. Hence the need to initialize the EMU8000 (via AWEUTIL) to get FM output, and the ability to apply EQ/Reverb/Chorus to those sounds.

Does this mean, that on the SB16 cards with CT1747 FM goes to the CT1701/CT1703?
User avatar
GL1zdA
Oldbie
 
Posts: 770
Joined: 2008-2-29 @ 10:41
Location: Warsaw, PL

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Cloudschatze » 2018-9-30 @ 21:01

GL1zdA wrote:
Cloudschatze wrote:
GL1zdA wrote:...is OPL audio routed through the CT1701 on the CT2760? On the early SB16s the OPL3 audio would go through the Yamaha DAC to the mixer. But I can't see such DAC one on the CT1747 cards.

On applicable cards, the OPL output from the CT1747 is digitally routed through the EMU8000 and its corresponding TDA1387 or TDA1543 DAC. Hence the need to initialize the EMU8000 (via AWEUTIL) to get FM output, and the ability to apply EQ/Reverb/Chorus to those sounds.

Does this mean, that on the SB16 cards with CT1747 FM goes to the CT1701/CT1703?

No, on such cards, the CT1747 is directly connected (I2S) to either a TDA1387 or TDA1543 DAC.
User avatar
Cloudschatze
Oldbie
 
Posts: 1072
Joined: 2005-6-16 @ 14:32

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby GL1zdA » 2018-9-30 @ 22:44

So the CT1701/CT1703 are for digital sound (speech in MIXERSET) only?
User avatar
GL1zdA
Oldbie
 
Posts: 770
Joined: 2008-2-29 @ 10:41
Location: Warsaw, PL

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Schyz » 2018-10-16 @ 10:23

Hi,

My experience, if it helps.

- The clicking DMA noise is not as bad, compared with the overall quality of the digital audio of the time, I'd say it's several orders of magnitude less annoying than other issues like the hanging note bug or the fake FM sound.

- "Stuttering with high-rate samples", I could never reproduce this issue, tested with AWE32 3900 (CT1747 chip) and both XG50DB and CM-500, and the games Duke Nukem 3D and Ultimate Doom, which (I think) have above 11KHz samples. Let me know if there is any solid way to reproduce these issues. I remember reading another user with a 3900 reporting the same.

- There is an additional issue, not exclusive to Creative but maybe important to consider in this topic: OPL3 compatibility with fast computers
In fast machines the OPL3 music will generate horrible noise. Some cards are worse than others, my 2760 starts behaving at 133MHz on some games, my 3900 is rock solid on 550Mhz with 100Mhz bus. Some motherboards, Asus especially, have an option on BIOS to set "8-bit I/O recovery time", and this can mitigate the issue, but the option is usually missing from other manufacturers.

I suspect one of the reasons for many sound card manufacturers to go for fake FM sound is to mitigate this issue. The CQM present in late AWE32 and AWE64 cards allows those to work flawlessly on faster machines of the time.

One last thing, I think this topic should be pinned in the audio section, the work done by James-F documenting the Sound Blaster issues is top quality and I wish I knew this info many years (and cards) ago.
Schyz
Newbie
 
Posts: 15
Joined: 2017-1-02 @ 00:30

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby appiah4 » 2018-10-16 @ 11:34

Yeah, this, and the other thread.
1989:A500|+512K|ACA500+|C1084S
1992:HIPPO-VL+|U5SX-33|8M|GD5428|CT2290|S2
1995:P5I430VX|P133|32M|S3T64+/MX2|V1|CT3980/32M
1998:S1573S|K6-2/400|64M|V2/SLI|CT4500/32M
2001:GA-6OXT|P3-1200|384M|GF3Ti200|MX300
2004:K8VD|3700+|2G|X1950PRO|SB0350
User avatar
appiah4
l33t
 
Posts: 3307
Joined: 2017-2-19 @ 07:36

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby The Serpent Rider » 2018-10-16 @ 18:36

- "Stuttering with high-rate samples", I could never reproduce this issue

It's not exactly stuttering. The bug will cause brief but very noticeable slowdown during the initial loading of the music track, after that performance will return to normal. It's somewhat annoying, but manageable.

to go for fake FM

Different implementation =/= fake. That said, the difference between some cheap ass CQM Vibra and AWE64 Gold can be quite drastic.

In fast machines the OPL3 music will generate horrible noise

Never had any problems with generally quiet OPL3 cards on a 1ghz+ system.
User avatar
The Serpent Rider
Oldbie
 
Posts: 1318
Joined: 2017-3-25 @ 19:07
Location: Stagnant Demesne

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Schyz » 2018-10-17 @ 12:36

About the noise on fast machines, I'm not talking noise as in "there is some [ssshh] sound in the background, like a white noise", it's more like "why there is a 4 year-old kid messing with the electric guitar".

It depends on the games as well, some DOS games support fast machines better than others. Also it's more frequent to happen in real DOS mode than under Win9X. Give it a try with a real OPL3 and Monkey Island, running "monkey.exe a", bus 100 MHz and 1GHz CPU speed.

I've been able to reproduce this issue even with Adlib Tracker 2, but it has a setting that allows to increase the latency which fixes the problem("opl_latency=1"), of course games never offer this option.
Schyz
Newbie
 
Posts: 15
Joined: 2017-1-02 @ 00:30

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Scali » 2018-10-17 @ 12:42

Schyz wrote:I've been able to reproduce this issue even with Adlib Tracker 2, but it has a setting that allows to increase the latency which fixes the problem("opl_latency=1"), of course games never offer this option.


Sounds like the intrinsic problem in the design of the OPL2/OPL3 chips:
Writing to a register is fire-and-forget.
That is, the write on the bus completes quickly, but the synthesizer needs to complete a full cycle of processing before the written value is applied correctly.
Yamaha has documented the delays between register writes in absolute time.
Problem is, most software doesn't actually perform delays in absolute time, but rather performs a sequence of dummy register reads, under the assumption that a read takes a certain amount of time.
On very fast machines, these dummy reads complete too quickly, which means that the next register write is executed before the previous one was completed by the FM synthesizer. This leaves the chip in an undefined state, leading to all sorts of glitches and random noise.
Scali
l33t
 
Posts: 3999
Joined: 2014-12-13 @ 14:24

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Schyz » 2018-10-17 @ 13:22

I agree that this is probably more to blame on the game developers of the time than on the hardware, but at the same time it could be a factor to consider when purchasing a Sound Blaster, an AWE64 could be a better choice for a fast computer.

Also, I hope that awareness on the issue will prevent some OPL3 Sound Blasters to end up in the bin.
Schyz
Newbie
 
Posts: 15
Joined: 2017-1-02 @ 00:30

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Eep386 » 2019-2-05 @ 07:11

Cloudschatze wrote:
GL1zdA wrote:Soem SB16 cards have the AK4501-VS DAC - how does it compare to the CT1701 and the various CT1703 chips?

CT1701 = AKM AK4501-VS

The CT1703 is speculatively an AKM AK4503-VS. This would need to be confirmed with decapsulation.

I tried swapping a CT1701 on a SB16 SCSI board with a CT1703-T, and got no PCM sound, so I don't think it's compatible at any rate.
My synthesizer hierarchy: Novachord > DX-7 > YM2151 > YM3812 > CT1747/YMF262/YMF289 > CQM > PC Speaker > AudioPCI "FM" (retch)
User avatar
Eep386
Newbie
 
Posts: 91
Joined: 2012-9-14 @ 05:25
Location: Not far from Sacramento, CA

Re: Sound Blaster 16 Bugs and Deficiencies Summary

Postby Eep386 » 2019-5-07 @ 20:17

Apologies for reviving this ancient post, but I wanted to mention that the CT1703 series parts seem to be made by ROHM. Looking a little closer it seems Asahi Kasei might have also used ROHM as a fab/foundry, but I don't think the CT1703 is compatible with the CT1701.

Also, it is possible to de-CQM some cards with CQM synthesis. If there is a CT1978 present and there are empty pads for a YMF289 plus YAC516, the card in question can be de-CQM'ed. This will involve adding additional components as well, such as resistors, capacitors and in most cases a 33.868 MHz oscillator. (Some cards, such as the CT3600, instead need an 18 ohm resistor to connect the YMF289B chip's clock input to the onboard clock chip.) Unfortunately virtually every AWE64 in existence is forever stuck with this blight as the CQM function is built into the main chip.
My synthesizer hierarchy: Novachord > DX-7 > YM2151 > YM3812 > CT1747/YMF262/YMF289 > CQM > PC Speaker > AudioPCI "FM" (retch)
User avatar
Eep386
Newbie
 
Posts: 91
Joined: 2012-9-14 @ 05:25
Location: Not far from Sacramento, CA

Previous

Return to Sound

Who is online

Users browsing this forum: Neonstar, Rawrl and 1 guest