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Old 14th August 2015, 08:24 AM   #3271
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Join Date: Aug 2015
Location: United Kingdom
Would it be possible to replace the opamps in the buffer stage with, say, the OPA827?
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Old 14th August 2015, 08:57 AM   #3272
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Location: Lierde
It has been done with another opamp LME49990
Check first if the OPA827 can work in the same circuit.
My RefSpeaker
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Old 14th August 2015, 09:27 AM   #3273
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Also, could anyone give any advice as to how my implementation of the Soekris board is going to go: Bucket's Technology Blog

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Old 15th August 2015, 02:10 AM   #3274
soekris is offline soekris  Denmark
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Done with next version of dam1021 firmware, all issues fixed and new filters and functionality added except:

1) Still a thump when powering off, but can be reduced to 1/3.
2) DSD support is for next revision, maybe two months outs.

But it's late here in Denmark and I have to get up tomorrow and take my kids to Air Show. So watch for the actual release tomorrow evening.
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Old 15th August 2015, 11:58 AM   #3275
canda is offline canda  Hong Kong
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Good News!
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Old 16th August 2015, 02:42 AM   #3276
soekris is offline soekris  Denmark
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Finally it's here, the first major dam1021 firmware update. I have named it version 0.99, please let me know if there are any issues, small or large. The plan is then to release version 1.00 in a week or two.

Firmware update on the dam1021 is done using the RS232 serial port, either by one large file or three separate files: ----> all firmware/filters --> fpga firmware ----> dac filters ---> uC firmware

To update the dam1021 firmware, you need to have the rs232 serial port connected and working with terminal emulator software. Enter the uManager by typing +++. You should then get the uManager prompt, then you type

# download

Start download session using Xmodem CRC protocol, when all downloaded then type command to update the uC with new firmware

# update

You can then enter uManager again and verify revision 0.99 firmware is loaded.

Revision 0.99 firmware have the following bug fixes / improvements / new functions:

* PLL Clock Sync at sample rate change cut down to less than 0.2 second
* Isolated Serial port now works, note that port is at 3.3V cmos level
* Serial Port now interrupt driven, no character loss at high speed
* Volume Control now is -80db to +10 db, and phase bug fixed
* Volume Control also now have zero crossing detect
* Power Off plop can be reduced to 1/3 by adding a single 27K4 resistors, see picture attachment
* FIR1 filters doubled in size, so max 2032 coeff @ 44K/48K, 1016 @ 88/96K, 508 @ 176/192K, 127 @ 352/384K
* You can now select four sets of filters, named Linear, Mixed, Minimum and Soft.
* FIR1 coefficients are now 1.31 format, filters should be good down to around -150 db
* Stock filter now have improved deemphasis filter
* Input Source Select bug fixed
* New mode setting: Normal, Inverted, Balanced Left, Balanced Right
* The tiny bug on signal saturation on -full scale fixed
* Should now be possible to do balanced and crossovers by parallel the inputs and connecting the isolated serial ports together, more details to follow

To do: DSD support, will add that in a couple of months.

To experiments with filters, the filter .txt file and updated mkrom utility is here, note that FIR1 coefficients now have to be < 1, but are now checked by mkrom utility.
Attached Images
File Type: jpg dam1021_top3_plop.JPG (83.4 KB, 2006 views)
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Old 16th August 2015, 03:14 AM   #3277
ylingf is offline ylingf  United States
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Join Date: Jun 2004
Location: New Jersey, US
Thank you Soren! I am having problem downloading mkrom.exe though.
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Old 16th August 2015, 05:49 AM   #3278
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Join Date: Feb 2003
Location: West Coast of Norway
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Old 16th August 2015, 06:37 AM   #3279
Foodie is offline Foodie  Finland
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Join Date: Jan 2014
Hi Soren, and thank you for new firmware!

I updated the firmare and can see the new version in uManager. I had working set before with volume potentiometer. For some reason after update, I do not get any sound. I've set volume -99 from uManager. I can see signal lock from i2s, but no sound.

Any ideas?
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Old 16th August 2015, 06:45 AM   #3280
Foodie is offline Foodie  Finland
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Join Date: Jan 2014
Restarting helped. Got it working now!
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