I personally always use COG in such positions although I know other people prefer Film. I suspect there is little difference and any changes are inaudible.
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Here's my take on the AK4490 - only 2 days old and already sounds very good 
It's a full DIYINHK setup with LT3042 regs, all the basic mods that were discussed. I used all the FR caps that came with the kit except for +-12v supply where I put 330uf Jamicons I had lying around (the second one is on the bottom because it's too fat).
I plan to upgrade the caps to Silmic II for analog and maybe oscons for digital, and the opamp to AD4898, but also to improve the layout, shorten the wiring etc.
Would adding another small 6v transformer for the digital supply only make sense? For now the two 9v from the first transformer are connected to 3.3v digital and 3.3v analog, the 2x 9v from the second are connected to 7v analog left and right, and 2x 15v to +-12v.
It's a full DIYINHK setup with LT3042 regs, all the basic mods that were discussed. I used all the FR caps that came with the kit except for +-12v supply where I put 330uf Jamicons I had lying around (the second one is on the bottom because it's too fat).
I plan to upgrade the caps to Silmic II for analog and maybe oscons for digital, and the opamp to AD4898, but also to improve the layout, shorten the wiring etc.
Would adding another small 6v transformer for the digital supply only make sense? For now the two 9v from the first transformer are connected to 3.3v digital and 3.3v analog, the 2x 9v from the second are connected to 7v analog left and right, and 2x 15v to +-12v.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I've had a few enquiries about how I purchased my Yanasoft dual AK4497 board.
Mine was purchased on my behalf by a friend in Japan but it would be unfair to keep asking him for favours so I thought I would try out one of the Japanese proxy shopping web sites, in my case this one;
FROM JAPAN: Japanese auction and shopping proxy service
To try it out I ordered;
I can report that my purchases have been successful and I have just paid the shipping fee for the items to be delivered.
The obvious downside is that you'll pay a premium for items purchased this way because of the fees, but the site was easy to use and communication was very good, guiding you through each step of the process.
To purchase items you simply paste the URL of the item you want into the site and, once the site has worked its magic, you confirm the item is correct and add it to your basket.
Payment is in two stages, first for the goods themselves then, once everything is ready to ship out, a second payment to cover the fees and delivery. There are options for the fees, insurance, shipping.
Anyway, if you're interested in the Yanasoft boards it looks like this is the way to purchase them. The Yanasoft website offers some interesting projects, apart from the dual AK4497 there are dual AK4490 and AK4495 and a nice single AK4490 board. Here's the Yanasoft website, which Google Translate does a reasonable job on, certainly good enough to understand the information on the projects;
?????
Do note though that Yanasan only does short runs of the boards so you may have to wait for an item to be 'under distribution'.
Ray
Mine was purchased on my behalf by a friend in Japan but it would be unfair to keep asking him for favours so I thought I would try out one of the Japanese proxy shopping web sites, in my case this one;
FROM JAPAN: Japanese auction and shopping proxy service
To try it out I ordered;
- The LCD screen listed in the BOM for my AK4497 (from a Japanese parts supplier)
- DSD Principle PCBs from Yanasoft
I can report that my purchases have been successful and I have just paid the shipping fee for the items to be delivered.
The obvious downside is that you'll pay a premium for items purchased this way because of the fees, but the site was easy to use and communication was very good, guiding you through each step of the process.
To purchase items you simply paste the URL of the item you want into the site and, once the site has worked its magic, you confirm the item is correct and add it to your basket.
Payment is in two stages, first for the goods themselves then, once everything is ready to ship out, a second payment to cover the fees and delivery. There are options for the fees, insurance, shipping.
Anyway, if you're interested in the Yanasoft boards it looks like this is the way to purchase them. The Yanasoft website offers some interesting projects, apart from the dual AK4497 there are dual AK4490 and AK4495 and a nice single AK4490 board. Here's the Yanasoft website, which Google Translate does a reasonable job on, certainly good enough to understand the information on the projects;
?????
Do note though that Yanasan only does short runs of the boards so you may have to wait for an item to be 'under distribution'.
Ray
automatic DSD\PCM selection
The boards there has a separated PCM and DSD inputs. As well they doesn't automatically switch between PCM and DSD, need manual selecting.
It's possible to use their SRC front end, but reclocking everything to a fixed frequency or DSD isn't a good solution at all.
Any suggestions?
The boards there has a separated PCM and DSD inputs. As well they doesn't automatically switch between PCM and DSD, need manual selecting.
It's possible to use their SRC front end, but reclocking everything to a fixed frequency or DSD isn't a good solution at all.
Any suggestions?
As I recall, I'm not sure that is quite right. I think the AKs will auto-switch between incoming PCM and DSD in 'normal mode' but if you want to use the 'Direct DSD' mode you need to select it via the menu and that turns off the features of normal mode, such as the auto-detect, volume control etc.
Ray
According to 4497 datasaheet, DSD is not available in parallel mode (hardware setup) as for AK4495. In serial mode (software setup) DSD/PCM switching require a change on a internal register and a soft reset (another internal register).
So the uC which is steering the DAC needs to know weither the stream is DSD or PCM, and this information is not provided by the AKM DAC chips. For example this information is available on USB adapter Amanero connector pin 7 or JLSound I2S2USB pin 8.
That explains my recollection, I was using a JLSounds I2SoverUSB and their AK4490 DAC. Thanks
I'm pretty sure that (at least the 4490 that I'm playing around with) it does not, Ray.
In parallel mode (a.k.a. with no uC) they do not support DSD at all. In serial mode (I2C or SPI control) they do support DSD but you have to change a register in the chip. Otherwise DSD produces garbled audio. It doesn't matter if you choose normal mode or Direct DSD (but if I remember correctly, if you have selected Direct DSD but have set the DAC in PCM mode and sent it PCM, it outputs garbage).
It would be nice if I was mistaken, though.
If you have any ideas I would be happy to try them out on my test rig.
EDIT: Damn I'm a slow typer today..
As far as I know, PCM and DSD are raw data stream, they're mainly aimed to be D/A converted or digitally filtered. Raw data means that they're only what is called the 'payload'. There's no framing, preamble wich usually contains the information describing the nature of the payload. So the DAC has no practical way to decide weither it is PCM or DSD (or anything else...). This is why DSD/PCM detection is made at previous stage where the framing informations are available: at the USB level or within the DSP, etc...
I found nothing in the AK4497 datasheet about a output that tells you if you have a PCM or DSD digital input.
I really don't know how you can switch from one mode to another if don't have this information.
As showed above, you have separate inputs for DSD mode when DSDPATH=0 : DSDL, DSDR and DCLK.
You have also to setup the DSDPATH to 1 for identical inputs.
I really don't know how you can switch from one mode to another if don't have this information.
As showed above, you have separate inputs for DSD mode when DSDPATH=0 : DSDL, DSDR and DCLK.
You have also to setup the DSDPATH to 1 for identical inputs.
Nope, no dice. DSD requires register programming, same as every other DAC chip on the planet. The internal mathematics are too severe a change to allow for auto-switch.
Attachments
I hadn't noticed that the 4497 had separate pins for PCM and DSD.
That is very annoying.
Most (if not all) USB interfaces have a single combined I2S/DSD output. That will have to be split in two, and possibly buffered.
Most if not all USB receivers provide a "DSD signal" pin.
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