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Old 23rd February 2013, 04:15 AM   #51
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Anyone know what vcml/vcmr should be ? The datasheet says "normally connected to vss" and it says that vss1-4 are connected to gnd, so vcml/r should be 0V ? There's only one reference to it that I can find.

The fact I can get noise of various kinds indicates to me that the analogue stage is working, and that it is the digital side that has a fault. Nonetheless, I've been over everything on this DAC several times now and found no fault.

I've spent over 10 hours debugging it and I can do no more. I have no clue why it doesn't work. There are hi-res photos on my blog - better than this site will allow - just click on the photo. www.myl8test.wordpress.com/audio/ak4399-dac/ The photo looks like pin1 and 2 are bridged with solder but actually that is not the case - funny angle or lighting or something.

Last edited by KlipschKid; 23rd February 2013 at 04:27 AM.
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Old 23rd February 2013, 05:59 AM   #52
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vcml/vcmr is ~2.25V when playing music and ~0V when i2s is disconnected
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Old 23rd February 2013, 07:36 AM   #53
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I was hoping to get hit with something blindingly obvious rather than have to give up - I'll check the i2s again. Thank you !
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Old 23rd February 2013, 09:08 AM   #54
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Hi,

It's working - what a relief.

Problem 1 - my CM6631 i2s has stopped working (but the spdif still works ?!). Something else to fix.

Problem 2 - the wm8805 only works if the AKM board is reset every time. I did not try the reset with this connected before. I have dif2 low for this too.

....so many hours wasted because of these two problems, but the AKM works. Thank you for your help ! It is very much appreciated.

The Lme47710ha sound horrible. LT1028 are much better but the treble has thd. OpA627 are "normal". I'll try more another time.

I had fitted 220R instead of 620R. This increases gain in that stage to ~3.5 and the output is high enough for hd650 at an excessive level.

Thanks again for your help !
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Old 23rd February 2013, 09:40 AM   #55
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PS My best effort at local decoupling. Only the digital is on the pin but the rest are quite close. Is it worth adding 100nF smd across the 10uF on vcml/vcmr ?

Click the image to open in full size.
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Old 23rd February 2013, 10:20 AM   #56
Piersma is offline Piersma  Netherlands
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Default Inputs

Does this AKM board have USB and SPDIF inputs, or only USB?

thanks,

Piersma
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Old 23rd February 2013, 01:03 PM   #57
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Hi,

This DAC requires I2S or MSB or LSB or DSD input. I2S is the most common. If you want usb only, then I can recommend this as the best value for money (from the same seller, and no, I don't know him :

24bit 192kHz USB to I2S / SPDIF PCB CM6631 with ultralow noise 6.5uV regulator | eBay

and if you want both then this

Multi-input/converter module for DAC 8805X-J | eBay

although raindrop_Hui sells some real crap, its not too bad.
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Old 23rd February 2013, 03:43 PM   #58
glt is offline glt  United States
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The old reset trick!

I am glad you had it working. Thanks for being the pioneer on these diyinhk boards :-)
BTW, I checked your blog. Good start.



Quote:
Originally Posted by KlipschKid View Post
Hi,

It's working - what a relief.

Problem 1 - my CM6631 i2s has stopped working (but the spdif still works ?!). Something else to fix.

Problem 2 - the wm8805 only works if the AKM board is reset every time. I did not try the reset with this connected before. I have dif2 low for this too.

....so many hours wasted because of these two problems, but the AKM works. Thank you for your help ! It is very much appreciated.

The Lme47710ha sound horrible. LT1028 are much better but the treble has thd. OpA627 are "normal". I'll try more another time.

I had fitted 220R instead of 620R. This increases gain in that stage to ~3.5 and the output is high enough for hd650 at an excessive level.

Thanks again for your help !
__________________
www.hifiduino.wordpress.com
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Old 24th February 2013, 07:37 AM   #59
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Haha... yeah, that old trick was new to me ! Every DAC I've played with just started playing music as soon as it got the i2s connected.

I found my cat6 cable is the fault, not the cm6631. I've never had a cat cable fail on me before either.

Also, with the cm6631, no reset is necessary, it works immediately, so only the wolfson wants a reset. I'll have to look into why.

The DAC sounds good, but as Diyinhk says, the mids can be a little strident with the wrong op amps. So, op amp rolling once again. Since I'm going to use this to drive headphones, I have LM7321 in the second stage, and at the mo, I'm listening to ad8597 in the first stage. The trick is to get sets that suit the headphones - HD650 and PXC250 - rather than amps and speakers.

Thanks for the kind words about the blog - man, its time consuming getting it set up but now it is easy enough to navigate and add extra stuff too so, yeah... a start ! I'm now even more impressed with yours - that's got to have taken ages to get it looking that good.

cheers
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Old 25th February 2013, 03:37 AM   #60
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Another update is on the blog, but briefly, I tried adding a ferrite and using cfb. It either didn't work (oscillation) or worked but didn't sound as good as LM7321. I use opa827 in the first stage, but NE5534 are surprisingly nice too, and soooo cheap. This could be a real bargain DAC with the right choice of parts.

Click the image to open in full size.

The last thing to do is solder the vias, and add a receiver. I found an SRC4392 so I thought I'd give it a try. It looks mediocre but the output I2S lines haven't been messed with so it could sound okay.

Click the image to open in full size.
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