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Old 21st February 2013, 05:24 PM   #201
Coris is offline Coris  Norway
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Here is a picture where is to be seen the exact pin for clock input. Else you may have more infos in the chip datasheet attached.
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Old 21st February 2013, 05:59 PM   #202
Corvus5 is offline Corvus5  Poland
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I didn't connect the clock directly to the pin. Playing with these legs with my tools is very hard. I connected it to the second smd element, the one near the old quartz positive pad. When changing sampling frequency from 44,1kHz to higher the sound gets slower, but playing 48kHz or 192kHz has the same speed. Bought the Vanguard from the only HK seller on ebay. I've got no access to the proper measurement devices. 24,574MHz may require oscilloscope with higher than 10MHz or 25MHz range. I already helped myself with the datasheet of the CMI8788, CS2000 and the eeprom with the xonar pin placement. The source linux drivers were also helpful.

I'll try to find better ground. The STX card is easier if they don't have the CS2000. I heard the newer STX may have the CS2000. On the STX the clock gives signal to the CMI8788. Then the CMI8788 multiplies it and feeds to the PCM1792.

The ST is more advances. The CMI8788 is not doing the multiplication. The CS2000 does the multiplication. It also lowers the jitter. That's why the clock change on the ST is not so much improvement like on the STX. When I speed the music for normal playback it's not much different in the tonal balance. The sound gets little smoother, there's no sharpening, it's also more precise. There are more sounds in the center which is more detailed than before reclocking. I expected much more, but well... I've got to fix this clock. On other forum there was a thread where after reclocking the sound was slowed down by 30%. Also I found some images on the net with wrong clock connection like the one using the eeprom on your image. They suggested to use the ground near the 7805 from which the power is taken.

I'm happy the card can still run. I fought it was dead like broken CMI8788 legs.
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Old 21st February 2013, 06:36 PM   #203
Corvus5 is offline Corvus5  Poland
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Fixed timings! It's a small xonar driver bug or internal CMI8788 bug (sometimes called the feature!). The fault was disconnecting eeprom during the CMI8788 operation. The card may report as xonar, but when disconnected, is switches to the default CMI8788 routines and clock selector. This may require faster clock. After restart, the card was reported as c-media. Fixed eeprom connection and now it's working. I don't hear any large improvement in the sound. Bit more sharp with slightly better imaging, more air between instruments. Most of this was already fixed with better cables and faster power management.
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Old 21st February 2013, 08:30 PM   #204
Corvus5 is offline Corvus5  Poland
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The frequency response seems strange. The recording is ok.
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Old 22nd February 2013, 09:21 AM   #205
Corvus5 is offline Corvus5  Poland
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Here's the comparison of the clocking with the wrong multiplier and one with proper multiplier.
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Old 22nd February 2013, 09:42 AM   #206
Corvus5 is offline Corvus5  Poland
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The noise comparison. After recklocking seems more noisy with more and larger spikes. And it's just noise measure. Maybe the master clock is being used when recording and the noise and spikes come from better quality clock or... worse quality, spikes are doubled. The clock may interfere with the 5V too.
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Old 22nd February 2013, 09:46 AM   #207
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Interesting. Is it reclocking or just "clocking"?
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Old 22nd February 2013, 09:51 AM   #208
Corvus5 is offline Corvus5  Poland
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Quote:
Originally Posted by bambadoo View Post
Interesting. Is it reclocking or just "clocking"?
I repeated the clocking procedure for the CMI8788. You may call the procedure re-clocking. For the circuit it's the clock for the CMI8788 and on my card the CS2000 does the recklocking by multiplication and conditioning.

In simple words: I changed the stock quartz to the vanguard tcxo oscillator.
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Old 22nd February 2013, 10:05 AM   #209
Corvus5 is offline Corvus5  Poland
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Oscillations appeared just on for the other forum user when he plugged the oscilloscope after applying vanguard on his board, however AFAIR he noticed the oscillations on the 5V xonar line.
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Old 22nd February 2013, 11:34 AM   #210
Corvus5 is offline Corvus5  Poland
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Fixed by playing with the system drivers. Now it's time to improve the oscillator. I heard they are very difficult to power and dedicated regulator is a must. The higher tones are too gray.
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