CM6631 usb audio interface .... any good ? - Page 19 - diyAudio
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Old 9th February 2013, 04:47 PM   #181
wklie is offline wklie  Hong Kong
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Quote:
Originally Posted by luxury54 View Post
I don't quite understand the ASUS Essence One construction either, where supposedly their firmware and driver which enables only SPDIF and mutes I2S would have to feed also the DAC present in that soundcard...so that means that the internal DAC isn't receiving I2S from the CM6631? they went with SPDIF all the way including internal DAC?
I think I read from somewhere about a hypothesis that suggests Asus did this in order to support 88.2kHz and 176.4kHz with CM6631.
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Old 10th February 2013, 04:04 AM   #182
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Quote:
Originally Posted by KlipschKid View Post
Hi,


Anyway, have fun - I think that's really why you've bought them right ?
Yes indeed. And thanks for taking the time to educate me on this stuff.
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Old 10th February 2013, 12:38 PM   #183
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Quote:
Originally Posted by cogitech View Post
Yes indeed. And thanks for taking the time to educate me on this stuff.
I hope it is helping and I'm not teaching my grandmother to suck eggs !

A quick update on that case for the CM6631 - it doesn't quite fit because the oscillator is at the edge on one side, and there is a cap on the edge on the other side. So I had to grind down some of the internal guides in the case to make it fit. But in the meantime, I've lost the front plates, so I'll have to make my own, which is lots of trouble.

Anyway, the Potato 74G04 works very well - it doesn't seem to degrade the sound at all and it may even sound a bit better. Hard to say for sure without an A-B test, but for sure, it's an excellent part.

7404 G Series GHz TTL CMOS logic IC 14pin SOIC QTY-1 | eBay
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Old 10th February 2013, 10:23 PM   #184
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Hi Klipschkid,
Looks like your having fun ,lol.itie bittie spiders smt,lol.
So have you found any sonic or improvements in the sound from these mods?
Could you do a little guide line for us to follow ,Have you changed the power supply to a shunt or CCS and tried that also?
Keep it coming,lol. THANKS!
Regards,
NS
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Old 11th February 2013, 12:38 AM   #185
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Hi Pat,

Yeah the adp151 are a little fiddly... but 9uV noise and only two 1uF smd caps required so it's worth the trouble.

The Diyinhk cm6631 use LP5900 regulators - 6.5uV noise to 100Khz, 150mA output. The board uses around 130mA. There are also several ferrite/cap filters for RF noise, so the boards are not too fussy about what power they get. However, they do pass through noise from the source so keeping that down to 100uV or so is all that's needed, and especially noise at higher freqs.

So for the 31, with usb power, I have a small rc filter for RF ( 2.2R and 100uF ) and a capacitance multiplier on the input. These drop the voltage to 3.8V from 5V but they clean up the power nicely. The ground is still dirty - PC grounds always are.

For the 31A, it has a 30uV noise linear supply with two RC filters after it so that's more than good enough for the LP5900 to be able to do its job.

Apart from the Salas shunt, I'm not particularly a fan. Shunts are wasteful and something like the TL431 has 40uV or more noise. I have used an Lm317 + TL431 for a super shunt, and it's good for analogue but too noisy for digital. Shunt or series doesn't matter - what matters are the components in the design and the circuit layout, pcb quality etc. Noise, bandwidth, output impedance, stability etc can be determined as much by choosing different transistors as can the psu topology.

The good old LM723 is still one of the lowest noise regs available - 2.5uV noise - and can be configured as a shunt or series. But it's bandwidth and output impedance are way behind the times now.
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Old 11th February 2013, 03:46 AM   #186
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One final update - the Potato uses ~10mA to drive 1m of cat6 cable (into an SRC4192). The board uses a total of 144mA. I didn't notice any significant change in any respect between identical cat cables of different lengths - I tried 1m and 30cm. So, functionally, it's all finished.
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Old 11th February 2013, 10:03 AM   #187
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Quote:
Originally Posted by luxury54 View Post
I don't understand why CM decided to have only 1 of the outputs available at a time
Hi

I just tested this and found my CM6631 does both I2S and SPDIF outputs at the same time.

I have finished this now - just need to re-paint the case.

Click the image to open in full size.
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Old 13th February 2013, 05:26 PM   #188
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Hi to all,

I have one of Cm6631 usb to optical/spdif device and today its arrive. At first, I search for a driver, and one of the driver I found this topic works however, there is a issue about it. Seems like driver not fits exactly and while playing, sometimes there was a noise or "roll-of" the power seems to decreasing for one second or something.

Because of that I think maybe I try to update firmware, I downloaded FW update tool and worked on it however I think accidentally erase or damage the firmware on device. Computer doesnt recognize the device and fw update tool most of the time, 2-3 times it saw the device but while I press update, it says did but doesn't change anything. I have external power suppiler, usb cabloe for device etc. Is there anything (like re-flash firmware) I can do by myself to this device?

Thanks for your answers...
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Old 14th February 2013, 02:08 AM   #189
wklie is offline wklie  Hong Kong
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Quote:
Originally Posted by kuzeyboun View Post
I have one of Cm6631 usb to optical/spdif device ... Seems like driver not fits exactly and while playing, sometimes there was a noise or "roll-of" the power seems to decreasing for one second or something.

Because of that I think maybe I try to update firmware [problem...]
Did you do the update on Windows XP? Which firmware did you try - the 2203 from nutsaudio web page? Are you sure you have CM6631 instead of CM6631A?

Since your device no longer works, perhaps you may even try flashing the Asus Xonar Essence One firmware.

If you get it to work, I'd suggest you use an external power supply (if your converter has a DC input), or use a USB 2.0 hub that requires power.
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Old 14th February 2013, 05:17 AM   #190
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Quote:
Originally Posted by KlipschKid View Post
Hi

I just tested this and found my CM6631 does both I2S and SPDIF outputs at the same time.

I have finished this now - just need to re-paint the case.
Hi,
please tell us with what driver and in what configuration (Asio, KS) have you got simultaneous output on both I2S and SPDIF
thanks
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