Hello
It's hard to find any digital filter chip other than the SAA7220.
The TDA1541A, wen it's well implement, can be much excellent.
I did look at non-oversampling TDA1541A but it really need a sharp analog filtering at the output or there is lot of intermodulation from the 44.1khz and so doing noise down to audio frequencies.
I have eard the PCM1794, the sound was good but the soundstage was more flat than the TDA1541A, I also eard a WM8741 and it was better than the PCM1794 but the soundstage was also more flat than the TDA1541A. And the
TDA1541A have a more involving sound, especially in some opera the voice are so good or with some jazz music.
For now I use my Adcom-GCD-600 cd player, I've put a better clock and a better power supply and I've put OPA627 at the output of the TDA1541A to replace the mid-fi opamps that was there. 10 years ago the OPA627 was more affordable and I still have some of those opamps.
Thank
Bye
Gaetan
It's hard to find any digital filter chip other than the SAA7220.
The TDA1541A, wen it's well implement, can be much excellent.
I did look at non-oversampling TDA1541A but it really need a sharp analog filtering at the output or there is lot of intermodulation from the 44.1khz and so doing noise down to audio frequencies.
I have eard the PCM1794, the sound was good but the soundstage was more flat than the TDA1541A, I also eard a WM8741 and it was better than the PCM1794 but the soundstage was also more flat than the TDA1541A. And the
TDA1541A have a more involving sound, especially in some opera the voice are so good or with some jazz music.
For now I use my Adcom-GCD-600 cd player, I've put a better clock and a better power supply and I've put OPA627 at the output of the TDA1541A to replace the mid-fi opamps that was there. 10 years ago the OPA627 was more affordable and I still have some of those opamps.
Thank
Bye
Gaetan
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<shameless plug> My own digital filter will be along in the next few months, hopefully before the end of the summer.</shameless plug>
In the meantime have you looked at NPC or Yamaha for digital filters? I used to use SM5813 (from memory). Is this family of chips still available? Or the Yamaha ones like YM3414 or YSF210 (I'm quoting these all from memory so I could have got wrong part numbers). TI also has DF1704 and DF1706.
Yes, I'm convinced that's the case - it has such a loyal following who can't all be barking up the wrong tree!
Agree. You'd need a very linear I/V stage and even then the Nyquist violations are not pretty.
Hello
Maby a NOS dac with a 22khz low pass filter followed by a 44.1khz notch filter ?
I've put an image of the 44.1khz notch filter circuit alone with the frequency response graph.
Thank
Bye
Gaetan
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Hello
Seem very interesting, I may be interest.
Is it a PIC chip that you programed to do digital filtering for the TDA1541A ?
Thank
Bye
Gaetan
Pretty good guess - actually not a PIC but an ARM.The final chip isn't decided yet but either an LPC1113 or LPC1313. They need a bit of external circuitry as neither has I2S interface natively.
Hello
I'm not good in programing those chips, so your lucky to succeed in those.
Which chips you will use for the I2S interface ?
Keep me in touch.
Thank
Bye
Gaetan
Its brought back a lot of fun I used to have programming 68k assembler
You don't need to program to use it, I'll put the source and object code on line. Also I plan to ask a friend to sell complete units based on the design.At the moment, 74HC595 but I'm having severe problems interfacing those with the LPC1313. If I'm able to use the LPC1113 (which runs slower) then maybe I can do away with the 595s as this part has two serial interfaces.
Will do - thanks for your interest
@Gaetan - DF1706; DF1704;
@abraxalito - good luck with your endeavour. I would use a dedicated audio DSP (like AD's Sharc family or even TI's TMS320C5xxx family) but that's just me, lazy - usually they came with free audio codecs.
@abraxalito - good luck with your endeavour. I would use a dedicated audio DSP (like AD's Sharc family or even TI's TMS320C5xxx family) but that's just me, lazy - usually they came with free audio codecs.
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Those dedicated DSPs don't suit my requirements. First they're physically too large to fit within the footprint of the SAA7220 - I plan to make this a plug and play module. Second they're rather expensive because they're overkill for this purpose. Third they're probably too power hungry - the ADI part certainly is. It specifies a max draw of 500mA @ 1.2V core voltage. One of the problems of the SAA7220 is its 180mA (5V) draw, I was looking for a solution which would significantly reduce this, not increase it. There's no way I want to add in a SMPSU to generate such a low core voltage in this sensitive audio application.
I could go on, but probably you get the picture. Anyway thanks for your best wishes
I could go on, but probably you get the picture. Anyway thanks for your best wishes
Hi Gaetan
Interesting that you should ask - just in the past few days I've dusted off my ARM Cortex-M development tools and began looking into DSP again. Only yesterday I coaxed audio out of one of these STM32F030 CPUs : STM32F030F4P6???/?????/???-???
Its maximum clock rate is 48MHz, probably not quite fast enough for doing 4X OS in the same way as the SAA7220. But the next step up (ordered, on the way) is one of these : STM32G030K8T6???STM32G030????Cortex-M0+??G0???-???. The price is higher as its a much newer part (STM32G030) but I expect the cost to fall to a similar level to the F030 in future. It clocks up to 64MHz and has a slightly more efficient CPU (Cortex M0+) so I think it'll be up to the task of 4X OS.
Stay tuned.
Interesting that you should ask - just in the past few days I've dusted off my ARM Cortex-M development tools and began looking into DSP again. Only yesterday I coaxed audio out of one of these STM32F030 CPUs : STM32F030F4P6???/?????/???-???
Its maximum clock rate is 48MHz, probably not quite fast enough for doing 4X OS in the same way as the SAA7220. But the next step up (ordered, on the way) is one of these : STM32G030K8T6???STM32G030????Cortex-M0+??G0???-???. The price is higher as its a much newer part (STM32G030) but I expect the cost to fall to a similar level to the F030 in future. It clocks up to 64MHz and has a slightly more efficient CPU (Cortex M0+) so I think it'll be up to the task of 4X OS.
Stay tuned.
Here's the thread where I plan to develop the digital filter : Cheap ARM MCUs for RBCD audio
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