VOGONS


Sound Blaster: From best to worst

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Reply 180 of 184, by Tiido

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It depends a lot on what is going on in the particular machine and exact opamp itself as far as the floating opamps go. The high impedance inputs are going to react to whatever can disturb them (in this case seems mostly internal to opamp) and since the loop is open, maximal gain of the opamp is going to get used for these reactions and this is going to have effect other parts of the card through the power rails and capacitive effects. When some signal is ran through the card you'll get more revealing results, most likely in form of increased THD. Some cards will perform better than others with the fixes applied, it is good to see some quantification of it ~

I don't have any sort of working retrocomputing setup to do anything on for a while longer, much of my stuff is still packed away until there's space to deal with them (I moved to another country more than half a year ago)...

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 181 of 184, by Eep386

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It's entirely possible too that my other modifications are getting in the way of the results, too. I did replace a bunch of MC3403s with TL074/TL084 and some MC33079. The MC33079s actually made things slightly worse in terms of >1kHz noise - which was a result I wasn't expecting. (I do recall that many bipolar amps with low voltage noise tend to have much higher current noise, whereas the bifet amps like the TL07x are the other way around.)

You're right Tiido, I should have made recordings of an actual game being played. Maybe with the next Creative card. (Kind of sick of mussing with this thing, I basically reverted and then re-implemented the fixes.)

Life isn't long enough to re-enable every hidden option in every BIOS on every board... 🙁

Reply 182 of 184, by Tiido

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I actually had similar experience with one other card, I used a MC33079 and things suddenly got a lot more noisy, in addition the output current seemed to be too low and I got excess distortion from there... buuuuut those were ebay chips from china and they may very well have been relabeled LM324 or something such, which will be as bad as my results were 🤣

I actually meant a sinewave sweep rather than games, as it is easy to tell any additional components generated by the electronics on the graphs or spectrograms one can do. I generated a clean logarithmic sine sweep from 10Hz to 20kHz, in 16bit 44100Hz mono which should be possible to play on a variety of hardware. You can simply do a recording of it and then in your favorite audio editor do a spectrogram of it and see if there are any lines above the main fundamental and judge distortion performance on just that (although effects of your recording hardware can also get in the way).

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  • Filename
    LogSweep10-20000.flac
    File size
    247 KiB
    Downloads
    50 downloads
    File comment
    Logarithmic sine sweep 10...20000Hz
    File license
    Public domain

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 183 of 184, by Eep386

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Thanks for the sound clip, I'll use that for the next comparison.
Though for the next comparison I'll leave the stock op-amps on there, to eliminate the rolling amps as a cause of additional noise.
I'll just need to secure another SB16 (shouldn't be too difficult, almost every single one has floating amps).

Though even with the dead-silence results I got, I noticed an average 3-8dB overall improvement after fixing the amps. I can only imagine that the overall noise result with a signal playing is considerably better still.

Life isn't long enough to re-enable every hidden option in every BIOS on every board... 🙁

Reply 184 of 184, by uav1606

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Der Kuenringer wrote on 2020-09-13, 19:42:

Anyone ever seen AWE32 models CT3940 (Value, PnP) or CT3960 (PnP) in the wild?

There's a picture of the CT3960 here:
Sound Blaster AWE32 PnP (CT3960)

Maybe someone has a CT3991?