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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

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#2,723
Søren,

I think I've found what looks like a bug in the Volume control.
Polarity is inverted at V-01, V-21, V-41 and V-61. I didn't test V-81 but I'd imagine the same thing occurs at that point too.
The other issue - only checked at V-41 - is that there is an incorrect step in attenuation. Please ignore the absolute level - it is the steps that matter 🙂

V-40 = -38.79dB true peak level
V-41 = -41.75dB true peak level <<<< should be approx. 39.80dB
V-42 = -40.82dB true peak level

So the level at V-41 is roughly what it should be at V-43. I've heard this incorrect step previously at around V-20ish so I'm guessing the misstep occurs at the same points as the polarity inversion.

I have posted some in information in the filter thread but it's a bit off-topic there, so please excuse the duplicated content...
 
#2,724
Just to add, the initial tests were done with the volume pot disabled in uManager and volume changed via serial port.

A quick "by ear" test with the pot enabled indicates that the volume step bug is audible around V-41. It's possible to hear the the step down in volume from V-42 -> V-41, then a very noticeable step up in volume from V-41 -> V-40. There is also a tendency for the output to "click" at this point when changing volume.

The same happens at V-22/V-21/V-20 and V-02/V-01/V-00... I had to turn down the level by 20dB/40dB in player software to check this but the same discontinuity in output level is definitely audible.
 
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#2,725
spzzzzkt said:
Just to add, the initial tests were done with the volume pot disabled in uManager and volume changed via serial port.

A quick "by ear" test with the pot enabled indicates that the volume step bug is audible around V-41. It's possible to hear the the step down in volume from V-42 -> V-41, then a very noticeable step up in volume from V-41 -> V-40. There is also a tendency for the output to "click" at this point when changing volume.

The same happens at V-22/V-21/V-20 and V-02/V-01/V-00... I had to turn down the level by 20dB/40dB in player software to check this but the same discontinuity in output level is definitely audible.
Click to expand...

Probably a math problem, let me investigate and fix it.
 
#2,727
bambadoo said:
Hi Soren. Since this is probably a math problem. Would it be possible to implement the possibility to invert phase via a command in umanager for instance?

Best regards
Click to expand...

In my pursuit of highest resolution volume control I manage to get an integer overflow at -1, -21, -41, -61 and -81 db, resulting in incorrect and inverted volume multiplier.... Incredible that nobody have noticed until now, thanks Paul for bringing it to my attention.... Data looks like this:

V-42 00002089
V-41 FFFFE2F8
V-40 000028F5
V-02 000CB599
V-01 FFF4A900
V+00 00100000

Already fixed, will be included in the next firmware release, in the near future...

And yes, phase invert is easy to implement as the volume multiplier is signed, will also be implemented in next release.
 
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#2,728
soekris said:
In my pursuit of highest resolution volume control I manage to get an integer overflow at -1, -21, -41, -61 and -81 db, resulting in incorrect and inverted volume multiplier.... Incredible that nobody have noticed until now, thanks Paul for bringing it to my attention.... Data looks like this:

V-42 00002089
V-41 FFFFE2F8
V-40 000028F5
V-02 000CB599
V-01 FFF4A900
V+00 00100000

Already fixed, will be included in the next firmware release, in the near future...

And yes, phase invert is easy to implement as the volume multiplier is signed, will also be implemented in next release.
Click to expand...

Thanks very much, SOEKRIS, for the upcoming polarity switch and all of the other imminent improvements.

I thought I was perceiving something inexplicable and now thanks to spzzzzkt's research an explanation is found. I thought I had lost acuity!

spzzzkt - what an invaluable resource you have been to this project!
 
#2,732

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#2,734
soekris said:
In my pursuit of highest resolution volume control I manage to get an integer overflow at -1, -21, -41, -61 and -81 db, resulting in incorrect and inverted volume multiplier.... Incredible that nobody have noticed until now, thanks Paul for bringing it to my attention.... Data looks like this:

V-42 00002089
V-41 FFFFE2F8
V-40 000028F5
V-02 000CB599
V-01 FFF4A900
V+00 00100000

Already fixed, will be included in the next firmware release, in the near future...

And yes, phase invert is easy to implement as the volume multiplier is signed, will also be implemented in next release.
Click to expand...

soekris,

May we have list of fixed issues and new features of next firmware release?
Will DoP included?
 
#2,736
Likely fixes and features in next firmware.

From previous posts by Søren in this thread:

- Input select bug fix
http://www.diyaudio.com/forums/vend...-magnitude-24-bit-384-khz-39.html#post4240798

- Isolated RS232 port at 3.3V digital levels enabled. New feature
http://www.diyaudio.com/forums/vend...-magnitude-24-bit-384-khz-38.html#post4237213

- Volume overflow bug fix
http://www.diyaudio.com/forums/vend...-magnitude-24-bit-384-khz-55.html#post4334047

From the filter brewing thread:

Four user selectable filters per sample rate - New Feature
http://www.diyaudio.com/forums/digi...filter-brewing-soekris-r2r-4.html#post4234913

Corrected de-emphasis curve for 44.1/48 (thanks to Pos!) Enhancement.
fwiw I include these in most of the filters I've done recently.
http://www.diyaudio.com/forums/digi...filter-brewing-soekris-r2r-6.html#post4242876

Increase resolution of filter coefficients from 2.30 to 1.34. Possible doubling of maximum filter length. Enhancement
http://www.diyaudio.com/forums/digi...ilter-brewing-soekris-r2r-20.html#post4318822
 
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#2,737
rickmcinnis - filter brewing said:
Or another balanced line stage after the single-ended output. For those of us with op-amp phobia!
Click to expand...
I have build up a pcb with DRV134 - it's the standard schematics of BB and I'm using Wima foil capacitors - all plugged on the SE output. Impedance matching is not ideal but the sound is very promising without loosing the SE magic.
 
#2,738
inMotion said:
I have build up a pcb with DRV134 - it's the standard schematics of BB and I'm using Wima foil capacitors - all plugged on the SE output. Impedance matching is not ideal but the sound is very promising without loosing the SE magic.
Click to expand...

Much of the recent discussion about implementing these DAC's can be found in these two threads...

http://www.diyaudio.com/forums/digital-line-level/270014-output-stage-soekris-r2r.html

http://www.diyaudio.com/forums/digital-line-level/267948-soekris-s-dac-implementations.html
 
#2,739
spzzzzkt said:
Do you think Søren might crack and answer the question if you keep asking the same thing, over and over and over? 🙄
Click to expand...

Spzzzzkt,

Thanks your consolidation to bug fix although it may not be full list.

Board start shipped few months.
As I understand, it is a commercial product instead of a DIYer product.
There are some issues reported.
Thanks Søren pay much effort to fix it.
I think it is comprehensible for consumer like me to learn FW upgrade schedule.

Hope Søren can share more on this topic.
 
#2,740
wkw9811 said:
Spzzzzkt,

Thanks your consolidation to bug fix although it may not be full list.

Board start shipped few months.
As I understand, it is a commercial product instead of a DIYer product.
There are some issues reported.
Thanks Søren pay much effort to fix it.
I think it is comprehensible for consumer like me to learn FW upgrade schedule.

Hope Søren can share more on this topic.
Click to expand...

Here is a challenge that might keep you occupied while you are waiting for a response:

Find one example of commercial audio product where the vendor gives an exact log of fixes included in a firmware update before the update is released or a time schedule for when the update will be released.

It might take you a while, because no-one I know of is stupid enough to do so...
 
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