Signalyst DSC1

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#301
oK Nautibuoy 🙂
The first thing I will do is try to derive a schematic from the PCB, particularly the output stage around the transformers.
Click to expand...
I didn't understand, please tell me what do you plan to do?

The transformers are the I/V stage (and perhaps gain as well)?
Click to expand...
If i tell right, dsc1 is R/2nR dac.
So there is negative voltage in outputs of shift register.
AD844 sums all bits and inverts voltage.

Is I/V transformer usable here?
Is there rather need V/V transformer? 😕
 
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#303
nautibuoy said:
I plan to understand the understand the changes that have been made to the original circuit first. No plans beyond that at the moment, other than to finish the assembly of my DSC1.
Click to expand...

i understand you plan to understand the understand the changes.
If i tell right, dsc1 is R/2nR dac.
So there is negative voltage in outputs of shift register.
AD844 sums all bits and inverts voltage.
Click to expand...
After some thinking it should have current in input of AD844.
So I/V transformer is the good one.
 
#304
nautibuoy said:
I obviously can't speak for Jussi but he is on record as having no interest in producing hardware and he placed his original DSC1 under the CERN Open Hardware Agreement

Signalyst

which says "anyone should be able to see the source (the design documentation in case of hardware), study it, modify it and share it."

CERN Open Hardware Licence - Cernohl - Open Hardware Repository

The Chinese kit producer seems to credit Jussi through reference to his original schematics and recommendation to use HQPlayer. Where they're not playing ball is by failing to respect the CERN licence terms with respect to sharing they're modifications; they should be distributing their updated schematics and, I believe, board layouts.

Ray
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Yes, agreed on all counts.

Terry
 
#306
Some news i share to vulgarize the functioning of DSC1 DAC.

Here three main step of dsc1:
An externally hosted image should be here but it was not working when we last tested it.

Digital signal coming from HQ player is transformed in analog signal thanx to 74AHCT595. The sum is done by AD844 ( in addition to isolate).


The analog curve is smoothed by fourth order low pass filter.
An externally hosted image should be here but it was not working when we last tested it.

Both Sallen Key 2nd order low pass filter have a gain=1.


To finish with the last step of dac:
An externally hosted image should be here but it was not working when we last tested it.

I do not understand reason of this op amp.
If R806 was installed, it could be a non inverting amplifier...
Someone has an idea about it?
 
#308
I should be more visible.

Frank513 said:
Some news i share to vulgarize the functioning of DSC1 DAC.

Here three main step of dsc1:
837904Image3.png

Digital signal coming from HQ player is transformed in analog signal thanx to 74AHCT595. The sum is done by AD844 ( in addition to isolate).


The analog curve is smoothed by fourth order low pass filter.
723763Image1.png

Both Sallen Key 2nd order low pass filter have a gain=1.


To finish with the last step of dac:
830583Image2.png

I do not understand reason of this op amp.
If R806 was installed, it could be a non inverting amplifier...
Someone has an idea about it?
Click to expand...
 
#315
nautibuoy said:
I've had positive experience, in fact I have a Broskie ACF-2 buffer that might find its way into a DAC project...

ACF-2 Aikido Cathode Follower Kit

Ray
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Thanx, ok good news!
I read your thread with this Aikido Acf2.
Very interesting your project.
I want build something similar at your.
A pre-amp dac with if possible no op amp, only tube.
And this Aikido pcb looks good too:
Aikido Noval Stereo PCB & Kit

For PSU parts, i aim tube diode rectifier.
 
#317
nautibuoy said:
Are you sure you're not thinking of my project with the Broskie BCF?

I've gone with the ACF-2 buffer because I don't think I need gain and its bipolar B+ supply should mean I can do without coupling capacitors.

Ray
Click to expand...

Yes you right, it was Broskie BCF.
How do you determine is you have enough gain?
Do you plan to drive direct power amplifier?
 
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