Thanks! These boards are inspired by diyaudio and Russian enthusiasts and their designs. With my "CRCRCRCRC always wins" thing 
It's just a single DAC board. I'll try to use it in different configurations
- feeding it with regular I2S
- parallel (simultaneous) I2S to lower the feed frequency and to be able to try 8x oversampling with different digital filters.
- go "ballanced" with single IC per channel - so every single TDA will output bipolar single channel. This way it will cancel odd harmonics as well as irregularities in PSU and DEM. Given i use same IC for "+" and "-" signals, these signals should match properly as they share the same silicon. I'll try both I2S formats too as long as i'll get free space in CPLD i use.
It will require a digital frontend which i didn't yet designed... I'll throw a CPLD for the "software" work - inverting, format conversions, SPDIF sync/async management and other things. I hope my "wannabees" will fit in the CPLD i choose .
It's just a single DAC board. I'll try to use it in different configurations
- feeding it with regular I2S
- parallel (simultaneous) I2S to lower the feed frequency and to be able to try 8x oversampling with different digital filters.
- go "ballanced" with single IC per channel - so every single TDA will output bipolar single channel. This way it will cancel odd harmonics as well as irregularities in PSU and DEM. Given i use same IC for "+" and "-" signals, these signals should match properly as they share the same silicon. I'll try both I2S formats too as long as i'll get free space in CPLD i use.
It will require a digital frontend which i didn't yet designed... I'll throw a CPLD for the "software" work - inverting, format conversions, SPDIF sync/async management and other things. I hope my "wannabees" will fit in the CPLD i choose
.
Thanks! These boards are inspired by diyaudio and Russian enthusiasts and their designs. With my "CRCRCRCRC always wins" thing
It's just a single DAC board. I'll try to use it in different configurations
- feeding it with regular I2S
- parallel (simultaneous) I2S to lower the feed frequency and to be able to try 8x oversampling with different digital filters.
- go "ballanced" with single IC per channel - so every single TDA will output bipolar single channel. This way it will cancel odd harmonics as well as irregularities in PSU and DEM. Given i use same IC for "+" and "-" signals, these signals should match properly as they share the same silicon. I'll try both I2S formats too as long as i'll get free space in CPLD i use.
It will require a digital frontend which i didn't yet designed... I'll throw a CPLD for the "software" work - inverting, format conversions, SPDIF sync/async management and other things. I hope my "wannabees" will fit in the CPLD i choose
I haven't decided on any digital frontend yet. The plan is to get 2-4 TDA's working together in the best possible way.
Looking at the DIR9001 reciever and hopefully I'll find a replacement for the SAA7220 as I would like to keep the oversampling.
I've got a ton of reading to do for this project so it is very long term.
I would like to be able to fit the Dacs, reciever and filter on a 100x160mm PCB if possible.
Clock, I/V etc will be separate boards to keep my options open.
I'll look at your site often to see how your project is comming along
There is a good DF, compatible with 1541 in 4x mode - CXD1244, CXD1144. Hard to find, but they are much better than 7220. They require 384Fs MCLK - a bit painful in general (for 256Fs guys), but pretty OK for you as DIR9001 supports it.
I won't turn my nose off 7220, but i'll try ASRC as an option of avoiding 7220 altogether. In general, ASRCs in upsampling mode do the same things as 7220. I've read somewhere that ASRCs are on par with DF1700 in their sonic performance - it means they ain't that bad
I won't turn my nose off 7220, but i'll try ASRC as an option of avoiding 7220 altogether. In general, ASRCs in upsampling mode do the same things as 7220. I've read somewhere that ASRCs are on par with DF1700 in their sonic performance - it means they ain't that bad
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There is a good DF, compatible with 1541 in 4x mode - CXD1244, CXD1144. Hard to find, but they are much better than 7220. They require 384Fs MCLK - a bit painful in general (for 256Fs guys), but pretty OK for you as DIR9001 supports it.
I won't turn my nose off 7220, but i'll try ASRC as an option of avoiding 7220 altogether. In general, ASRCs in upsampling mode do the same things as 7220. I've read somewhere that ASRCs are on par with DF1700 in their sonic performance - it means they ain't that bad
Thanks!
Found datasheet for one of them, the CXD1244.
ASRC? Sounds interesting...please educate me on that
I use the SAA7220 in my version of the analog metric dac(for now) it sounds great, but then I haven't heard it without the 7220.
Why are you wasting time chasing relics like the CXD parts? Read the datasheets. The max BCLK rate is 2.1 MHz. That implies a 48-bit frame, which is confirmed by counting clocks in the timing diagram. The DIR9001 outputs a 64-bit frame.
If you really want to play with first-generation digital audio, just buy an old CD player with CXD filters and piggyback more TDAs.
If you really want to play with first-generation digital audio, just buy an old CD player with CXD filters and piggyback more TDAs.
No, I was simply trying to say that if it can be done for SAA/TDA, it should be doable for CXD/TDA or AD1896/TDA. Not an adapter though, I'm(trying anyway) designing the PCB myself(with help from some friends).
Keeping my options open, and also learning eagle, I made several devices. I can't use both CXD and AD1896, but I made both devices(and bought them) to have options when the time comes to build this DAC. This is as much a learning experience for me as it is an attempt to make a DAC that might be even better than the Analog Metric I currently use.
Keeping my options open, and also learning eagle, I made several devices. I can't use both CXD and AD1896, but I made both devices(and bought them) to have options when the time comes to build this DAC. This is as much a learning experience for me as it is an attempt to make a DAC that might be even better than the Analog Metric I currently use.
You're the one who brought up the adapter idea. If you are going to design a circuit that uses a DIR9001 connected to a TDA1541, with or without an AD1896 or SAA7220, you don't need an adapter. Those chips speak the same language. The purpose of the CS8412/14 adapter you mentioned to to use a DIR9001 in place of a CS8412/14 in an existing PCB. Since you are designing a PCB for the DIR9001, there is nothing to adapt.
With a 44.1K input sample rate, the DIR9001 outputs a 64-bit frame that has a bit rate of 2.8 MHz. The maximum bit rate the CXD1244 can handle is 2.1 MHz. Converting a 64-bit, 2.8 MHz frame to a 48-bit, 2.1 Mhz frame is not trivial. But why bother? The CXD is decades-old technology using fixed point math and table-based interpolation. There are dozens of more modern chips that can do a better job without any interface issues.
With a 44.1K input sample rate, the DIR9001 outputs a 64-bit frame that has a bit rate of 2.8 MHz. The maximum bit rate the CXD1244 can handle is 2.1 MHz. Converting a 64-bit, 2.8 MHz frame to a 48-bit, 2.1 Mhz frame is not trivial. But why bother? The CXD is decades-old technology using fixed point math and table-based interpolation. There are dozens of more modern chips that can do a better job without any interface issues.
I know, just meant it as an example.
I'm the first to admit that my knowledge is limited at best.
What IC would you put between DIR9001 and 4pcs TDA1541A?
I am very grateful for all input, critique and ideas.
Also, english is not my first language so I might not be able to make myself understood as well as I'd want at times.
Nothing. The devotees of the TDA1541A seem to prefer it non-oversampled. The supposed benefits of oversampling CD audio are relaxed LP filter requirements and increased sample width. Oversampling the 16-bit TDA1541 gives only the first one.
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