Thanks. My first post (using blogspot) was 3/19/2009
How does the AKM compares with the ES?
4 years eh ? It shows !
It's hard to say about AKM vs ES. At first listen I'd say ES was the more impressive but this is through headphones where dynamics and stereo image are less obvious and THD, noise and detail are what are easy to hear for me. The AKM seems fine but until I actually get to plug them both into the hifi with the same source etc, then it isn't fair to comment.
One thing I've noticed is that some op amps get very hot in the first stage - I definitely think that EVM circuit causes some to oscillate as the calculator predicted. Just adding 1000pF across the postive input shunt cap should fix that.
Also, once I have finished it and picked out a final choice of op amp, I'll be removing the sockets and getting them as close to the board as possible.
cheers
It's hard to say about AKM vs ES. At first listen I'd say ES was the more impressive but this is through headphones where dynamics and stereo image are less obvious and THD, noise and detail are what are easy to hear for me. The AKM seems fine but until I actually get to plug them both into the hifi with the same source etc, then it isn't fair to comment.
One thing I've noticed is that some op amps get very hot in the first stage - I definitely think that EVM circuit causes some to oscillate as the calculator predicted. Just adding 1000pF across the postive input shunt cap should fix that.
Also, once I have finished it and picked out a final choice of op amp, I'll be removing the sockets and getting them as close to the board as possible.
cheers
Quick update. I fitted the extra 1000pF and the details improved a little but it made no difference to some op amps overheating.
The DAC needs high sample rates - 44.1Khz sounds very digital - 96Khz is excellent. However, there seems to be a problem with 192Khz - I just get noise. I need to investigate that when I have more time.
I also made an ultra low noise power supply for DVCC using an RC filter, an adp7104 9V reg and a potential divider/cap multiplier. It sounds better than the TPS47_ EVM ! Details are so clear and the background is deep and dark. Sounds great through HD650.
As always, details on the blog ;-) just click the signature...
The DAC needs high sample rates - 44.1Khz sounds very digital - 96Khz is excellent. However, there seems to be a problem with 192Khz - I just get noise. I need to investigate that when I have more time.
I also made an ultra low noise power supply for DVCC using an RC filter, an adp7104 9V reg and a potential divider/cap multiplier. It sounds better than the TPS47_ EVM ! Details are so clear and the background is deep and dark. Sounds great through HD650.
As always, details on the blog ;-) just click the signature...
The on-board regulation is done. I found a place to mount an adp7104 to use for avcc where it won''t create any problems with power crossing or close-paralleling signal lines that don't already exist. The only place I could find was in the centre. I didn't notice any change in sound quality. Now the board only needs one supply so that's simpler and easier. Here's a pic - better one on the blog. She's nearly finished...
An externally hosted image should be here but it was not working when we last tested it.
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New PCB version has much shorter trace to the major decouple capacitor,
and uses the latest 1229 batch code AK4399!
the sound is much better than the old 1007 and 0825 AK4399 batch code,
I don't know the sound improvement is from the new PCB layout or the new 1229 batch code chip. but newest batch code chip should be always better
and uses the latest 1229 batch code AK4399!
the sound is much better than the old 1007 and 0825 AK4399 batch code,
I don't know the sound improvement is from the new PCB layout or the new 1229 batch code chip. but newest batch code chip should be always better
An externally hosted image should be here but it was not working when we last tested it.
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AK4399 sounds really good eh ? This is mine - I have a temporary hookup with a cm6631a (cheapo thing on Taobao, not as good as yours) and Acko's isolator and re-clocker. The re-clock really works ! The iso is an adum3440 and it's not that great but the re-clock fixes it.
I filled the vias and soldered the 4 opa827 op amps into the board (no sockets).
I filled the vias and soldered the 4 opa827 op amps into the board (no sockets).
An externally hosted image should be here but it was not working when we last tested it.
New PCB version has much shorter trace to the major decouple capacitor,
and uses the latest 1229 batch code AK4399!
the sound is much better than the old 1007 and 0825 AK4399 batch code,
I don't know the sound improvement is from the new PCB layout or the new 1229 batch code chip. but newest batch code chip should be always better
An externally hosted image should be here but it was not working when we last tested it.
Where can I get one?
CM6631/a has some secret apart from the power supply ultralow noise linear regulator and low ppm oscillator is needed, there is a very important 12k resistor used for reference, most people only follow datasheet and use 1% but I found that it must use thin film resistor! Originally I also use thick film 1% reference resistor in the prototype and after use thin film in another prototype accidentlly...wow, it's like listening a whole new chip. and it should told why extra reclocker will work, it's like why some people can told use double conversion and add one more SPDIF layer will sound better. the spdif layer do reclock the signal. If the original is already good enough, the extra layer benefit should not cover it's disadvantage. The above 6631 resistor is not a secret anymore because a new usb to i2s pcb will be available soon
I haven't try opa827 with AK4399 yet, but the very experience OPA627 is the best and cheap 5534 is the second best, very special. unbelievable but it's real.
apart from the power supply ultralow noise linear regulator and low ppm oscillator is needed, there is a very important 12k resistor used for reference, most people only follow datasheet and use 1% but I found that it must use thin film resistor! Originally I also use thick film 1% reference resistor in the prototype and after use thin film in another prototype accidentlly...wow, it's like listening a whole new chip. and it should told why extra reclocker will work, it's like why some people can told use double conversion and add one more SPDIF layer will sound better. the spdif layer do reclock the signal. If the original is already good enough, the extra layer benefit should not cover it's disadvantage. The above 6631 resistor is not a secret anymore because a new usb to i2s pcb will be available soonI haven't try opa827 with AK4399 yet, but the very experience OPA627 is the best and cheap 5534 is the second best, very special. unbelievable but it's real.
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I think you're right - the re-clock means the quality of the cm is not so critical, so no need to upgrade resistors to thin film for this use.
Yes, 5534 sound good ! 627 are one of my favourite op amps. But for my headphone use, the 827 gave the best sound balance.
I look forward to seeing the new CM ! I hope you do one with an ES9023 dac ic. it's amazingly good for such a cheap IC, especially with a 50mhz saw oscillator as mclk.
Yes, 5534 sound good ! 627 are one of my favourite op amps. But for my headphone use, the 827 gave the best sound balance.
I look forward to seeing the new CM ! I hope you do one with an ES9023 dac ic. it's amazingly good for such a cheap IC, especially with a 50mhz saw oscillator as mclk.
the source is absolute critical, reclock can help but also add noise/jitter etc. Mostly, I think good source is better than reclock of a bad source. The new usb i2s is based on another famous chipset
cm 44.1 and 48 bck is work at 128x lrck, es9018 like bck = 64x lrck and the universal shifter of my latest toy nos dac also need 64x lrck ...although 32bit i2s need bck = 128x lrck but there are not 32bit cd USB has requirment on D+/D- trace impendence,
http://www.usb.org/developers/docs/hs_usb_pdg_r1_0.pdf
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