Yes, of course.
It seems one of my friends owns an old PC with serial port, I will try with it.
Andrea,
I doubt your hardware or firmware is defect, never seen that to be the case... But I have seen plenty having problem with their serial communication setup, it can be tricky if you're not that computer proficient....
As you asked in an email, you're welcome to ship it to me, but be prepared to pay for shipping and for my time.
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And btw, oversampling is really not bad as some think, it's just a solution to a problem, either you use sharp complex analog filters, or you oversample and use simple soft analog filters. Guess what I prefer....
Anybody remember the japanese CD players with sharp analog filters, then Philips came with their oversampling....
And with the custom filter possible with the dam1021, emulation non oversampling is just making a filter with 1,1,1,1,1,1,1,1 filter coefficients which is exactly the same as non oversampling, not some quasi....
In a digital transmission system you really need those filters to avoid aliasing products, which in best case can just change the sound, in worst case can blow your speaker and/or amplifier....
I doubt your hardware or firmware is defect, never seen that to be the case... But I have seen plenty having problem with their serial communication setup, it can be tricky if you're not that computer proficient....
As you asked in an email, you're welcome to ship it to me, but be prepared to pay for shipping and for my time.
----
And btw, oversampling is really not bad as some think, it's just a solution to a problem, either you use sharp complex analog filters, or you oversample and use simple soft analog filters. Guess what I prefer....
Anybody remember the japanese CD players with sharp analog filters, then Philips came with their oversampling....
And with the custom filter possible with the dam1021, emulation non oversampling is just making a filter with 1,1,1,1,1,1,1,1 filter coefficients which is exactly the same as non oversampling, not some quasi....
In a digital transmission system you really need those filters to avoid aliasing products, which in best case can just change the sound, in worst case can blow your speaker and/or amplifier....
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Except for that sticky issue with the serial port. But once that obstacle is overcome...
Succeded.
Finaly I have solved the issue using an old PC with built in serial port.
So I have loaded the NOS filter kindly provided from koala887 (thank you).
The only issue is that I have bought 3 adapters and none of them has worked.
It's not simple to find and old PC with serial port because modern PC does not provide such port.
So I would suggest to implement a USB port on the next revision of the DAM1021 because all modern PC has one and the communication it's much simpler for the user.
The filter works correctly as shown in the attached picture.
I'm able to play pure DC sample, indeed I have measured around 1Vdc peak at half power, only 23th bit switched on.
Now I can measure the accuracy of my DAM1021 to calculate the digital calibration in order to correct DAC linearity.
Thank you all for your support.
Finaly I have solved the issue using an old PC with built in serial port.
So I have loaded the NOS filter kindly provided from koala887 (thank you).
The only issue is that I have bought 3 adapters and none of them has worked.
It's not simple to find and old PC with serial port because modern PC does not provide such port.
So I would suggest to implement a USB port on the next revision of the DAM1021 because all modern PC has one and the communication it's much simpler for the user.
The filter works correctly as shown in the attached picture.
I'm able to play pure DC sample, indeed I have measured around 1Vdc peak at half power, only 23th bit switched on.
Now I can measure the accuracy of my DAM1021 to calculate the digital calibration in order to correct DAC linearity.
Thank you all for your support.
Attachments
Solved, but as I have already wrote I would suggest a better manageable USB port in the next revision of the DAM.
About oversampling I respect your thought but mine is a little different.
I have built several NOS DAC with a simple single capacitor LPF, no broken drivers until now and they sound very well for my taste.
And moreover you can oversample in software if you like this way.
And as I also already wrote, a USB Port add cost and complexity and need drivers.... A Serial port is an old well tested standard and actually pretty simple, I'll recommend getting one of the USB Adapters I use and recommend.... Most of the chinese ones are crap.
Or you could have both, the dac2541 actually have a builtin USB to serial interface chip, sharing the same USB Port....
Of course, I also listen to music with the filter. I've tested a lot of filters before, but none sounded as realistic as the nos. removing the dc filter also provides a better spatial representation.
Maybe I should mention that my dac is heavily modified. Fpga and Clock have their own Lifepo4 supply, the switching regulator is replaced by a linear regulator. Instead of the + -5V regulator I used 4 shunt regulators, as well as a special vref mod. All areas of the dac (transformer, power supply, r2r ladder, output stage) are shielded from each other.
This may also be the reason why the nos filter sounds better in my case.
Not much complexity and cost, we have used a PIC18LF4550 with built-in USB port (6 Euro micro) without any problem.
Driver is well tested and works very fine.
Using dotnet core you can develop your own multi-platform application to communicate with the micro, it's enough simple.
DAC2541 is not a diy device.
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Using a PIC is just more firmware and software, more complexity....
Why not just use a EUR 1.5 FTDI FT230X, if you could get any ?
dac2541 is just an example of what you could do, I have plenty of building blocks in my drawer....
Soeren, could you please make full firmware 1.24 available for download? I rolled back 1021 rev7 to earlier version in an attempt to troubleshoot an issue (temporary loss of SPDIF2 IN lock after rotating volume pot sometimes) and it looks like versions prior to 1.24 do not work with rev7, there is no lock and -2V on outputs.
I do not understand why you have this aversion to an alleged complexity which, however, in my opinion does not exist.
The major complexity, at least in our case, was the FPGA firmware and not the micro firmware or the Windows app.
Moreover yours is a commercial product so if it was more user friendly would not be bad.
…of which yours, in the true DIY spirit, not being a commercial product, you will release the source code, so everybody will be able to improve and adapt
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…of which yours, in the true DIY spirit, not being a commercial product, you will release the source code, so everybody will be able to improve and adapt
Not being a commercial product we have implemented the user friendly USB port.
About the source code, as you know, I'm not the only one who decides.
Sorry I prefer respecting Roberto's willing rather than your willing since you are the only one who asks for the source code to be public.
I can hear you don't get what it involves each time you change something, or introduce something, in this case, another uC with its firmware and its Windows software.
I already have firmware for two FPGA types, uC firmware, filter files with its tools, plus the schematics and PCB layout for now how many products, over multiple revisions....
Each time I add or change something it also requires testing. So no thanks, I have enough work already. For me to change something, it really need to add value, not just make it easier for you and your bunch of crappy USB interfaces.
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