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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
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Old 10th October 2018, 03:23 PM   #7701
spikestabber is offline spikestabber  Canada
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Join Date: Feb 2015
Quote:
Originally Posted by Keetesyflush View Post
Ok, so quick update from my troubleshooting. I measured the shift registers and got some really wacky voltages back. Really low, like +/-0.4v on all 4 rows.

Well, I ended up hooking up directly to an 8vac transformer instead of the 12v power supply I was using and it worked! Everything, including the shift registers, measured correctly and I got glorious sound!

So, pretty sure the power supply is the problem. Got a different one arriving in a few weeks and hopefully will be in business.

Thanks so much for the pointers. Measuring the shift registers was what got me on the right track
Did you figure out what was wrong with your power supply? You said a 12VDC supply but you definitely need the negative component of that supply for it to work with a common ground. As in +/-12V.

EDIT: Another common fault is using a pair of 12V supplies to get a bipolar one but for that to work the transformer windings have to be completely isolated from eachother without a centre tap. The centre tap in this case just creates a short circuit. One can also run the boards on +/-7VDC if you are only using the raw output and not the opamp buffered one.
__________________
Soekris dam1021-12v2 dual-mono balanced: https://imgur.com/a/fD68M Update: https://imgur.com/gIn6Nkx
Hypex nc400: https://imgur.com/iORCyna | Overkill TT2USB: https://imgur.com/a/p6OiS

Last edited by spikestabber; 10th October 2018 at 03:28 PM.
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Old 13th October 2018, 08:22 PM   #7702
androa76 is offline androa76  Slovenia
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Join Date: Mar 2007
Location: Maribor
Soekris please for explanation.
I already asked but will again.
Why is at SOFT filter at firmware 1.19 frequency response rising till 20khz ? Is it deemphasis in script?
In comparisson i put pictures of 1khz, 10khz and 20khz SOFT sine wave and 10khz vs 20khz MINIMUM filter sine wave where we see normal falling response at that frequency.
Attached Images
File Type: jpg Soft 1vs 10 vs 20khz.jpg (252.0 KB, 368 views)
File Type: jpg Minimum 1khz vs 20khz.jpg (162.0 KB, 371 views)

Last edited by androa76; 13th October 2018 at 08:46 PM.
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Old 16th October 2018, 08:36 PM   #7703
androa76 is offline androa76  Slovenia
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Join Date: Mar 2007
Location: Maribor
Can anybody tell me if i can upload old 2k filter F5, F6 into 1.19 firmware or i must downgrade firmware to 1.09? Thank you.
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Old 16th October 2018, 09:19 PM   #7704
androa76 is offline androa76  Slovenia
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Join Date: Mar 2007
Location: Maribor
Any expalnation why Soren use on all designs smd decoupling caps also on GND pin?
So near VDD 3,3V on dam1021 uses 4,7uf smd and near gnd pin 0.1uf? Why 100nf so far away on the other side of clock?
Picture is from dam 1121 but similar as dam1021.
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File Type: jpg CLOCK.jpg (105.0 KB, 284 views)
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Old 16th October 2018, 10:13 PM   #7705
arnd13 is offline arnd13  Germany
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Hi Søren,

can you give us an ETA for final 1.20 Firmware and Filters (dam1021).

THX a lot
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Old 19th October 2018, 11:15 AM   #7706
janho12345 is offline janho12345  Germany
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Join Date: Mar 2016
Location: BW /Germany
Anyone here tried hooking up two dam1021 to one Toslink?!

Doesn't work for me. I just wired them in parallel but nothing.
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Old 19th October 2018, 07:23 PM   #7707
restrav is offline restrav  United States
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Join Date: Sep 2018
please reply to my email for support. any one of the six that i have sent over the last month will do. I dont understand why i have not received any communication regarding the DAc that i sent for repair but please consider getting back to me.
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Old 21st October 2018, 08:39 AM   #7708
spikestabber is offline spikestabber  Canada
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So further modding on,

I've bypassed the 7x05 regulators and set the DIYINHK regulators to 5V accordingly for the entire stack. This also requires the removal of the output muting shunts and R392 resistor. Probably a good idea if you don't trust these shunts in the audio path anyway, I will likely be building a new relay based mute circuit...

Remounted Sparko 3.3V regulators to be much better by using the old serial pin header area for its 3 pins, because they are now being fed 5V they no longer need active heatsinking so the footprint area is much smaller to mount them.

I did this by raising the DOUT pin on the U39 serial interface on the serial header pin that I had to steal for the regulator pin.
The first pin being connected to the ground plane gets you the first pin for the regulator, jumpered the other two regulator pins straight to the pads for the old 3.3LDO.
I tried removing the U32 IC first but that resulted in failure as serial commands no longer reached the board, it seems the RX commands pass back through this chip and some initialization routine requires both the DIN/ROUT pins from the FPGA to be connected or forwarding the data after some set period of time after startup... Soren, is there a good explanation of this? I read the datasheet for the serial converter but it doesn't tell me a whole lot about your code unfortunately. Shorting out the 2 pins for DIN and ROUT allowed the FPGA to receive volume commands after startup, however if these pins are shorted at startup it simply will not lock until the short is removed.

Removed lowpass caps on the r-2r output finally after a few years of being on the fence about it.... just do this, arguably the biggest difference of all, just get rid of them, forever!

I was originally going to run the +/-5V direct via sparko regulators but didn't bother with the added complexity simply because the DIYINHK units appear to output just as clean power or better. There becomes a point where I don't believe there is a whole lot more to milk out of this thing barring going full on battery type setup but thats way outside of my practicality standards.

Now to do more listening. It will be difficult to tell how much each mod did what with regards to the improved SQ, however its likely the lowpass cap removal made the largest difference. Anything from the shunt removal and regulator bypass remains to be heard.
__________________
Soekris dam1021-12v2 dual-mono balanced: https://imgur.com/a/fD68M Update: https://imgur.com/gIn6Nkx
Hypex nc400: https://imgur.com/iORCyna | Overkill TT2USB: https://imgur.com/a/p6OiS
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Old 21st October 2018, 11:57 AM   #7709
androa76 is offline androa76  Slovenia
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Can you tell in a few words what was improved??? In which way... more 3d more relaxed ..? thank you Davorin
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Old 21st October 2018, 06:49 PM   #7710
spikestabber is offline spikestabber  Canada
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Quote:
Originally Posted by androa76 View Post
Can you tell in a few words what was improved??? In which way... more 3d more relaxed ..? thank you Davorin
I would say more relaxed, there was some points where I found both highs and bass to be a bit emphasized however it feels more relaxed, in a good way. I measured the vref but its noise is lower than my ds1054/1104 can measure which itself isn't a bad thing.

I want to do some much higher listening levels later.
__________________
Soekris dam1021-12v2 dual-mono balanced: https://imgur.com/a/fD68M Update: https://imgur.com/gIn6Nkx
Hypex nc400: https://imgur.com/iORCyna | Overkill TT2USB: https://imgur.com/a/p6OiS
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