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Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

My second try on digital side
My second try on digital side
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Old 1st January 2016, 04:41 PM   #11
sesebe is offline sesebe  Romania
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Default the case...

As I promised I put some pictures with the used housing.
It is custom made from steel painted on black.
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Old 20th December 2016, 10:59 AM   #12
Coris is offline Coris  Norway
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My second try on digital side
Impressive realisation...
I wonder only about the grounding point you use over the toroid central fixing screw. I assume this screw it is in contact with the metallic chassis on the bottom of the transformer.
The ground wire (yellow/green) you use and/or the rest of the wires connected in that point (pictures), it may form a turn (loop) and some AC currents it may be induced so into the ground connection, by the toroid coil itself... Such wiring/connection is to be avoided when using a toroid. Do you not have problems by choosing a such ground connection?
Personally I would like to connect the ground wires right on the chassis, and let free the top of the toroid screw (as recommended when using a such type transformer)...
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Old 20th December 2016, 05:45 PM   #13
sesebe is offline sesebe  Romania
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No problem Coris, the audio analog part are galvanic isolated.
I explained at the beginning that the digital part of the schematic are completely isolated by the DAC, filters, and volume control - the analog part of the equipment.
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Old 22nd December 2016, 12:47 AM   #14
sesebe is offline sesebe  Romania
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I read your explanation again and you are right but fortunately because I have galvanic isolation I have no problem with this power supply noise probably is induced in the Earth connection. At the first opportunity, when I will open again, I will change my connection to the Earth.

Thanks for giving me attention.
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Old 18th March 2017, 08:29 PM   #15
sesebe is offline sesebe  Romania
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I corrected the ground connection Coris, thank you!
I change the connection point to the screw that fix the power socket.

I do not noticed any change in sound. but it is better to be correct routed.

Last edited by sesebe; 18th March 2017 at 08:31 PM.
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Old 20th March 2017, 08:33 PM   #16
dreamth is offline dreamth  United Kingdom
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I had the opportunity to meet Bogdan and listen @sesebe's DAC yesterday on two systems:
first one was a diy speaker system run on a fairly good Yamaha amplifier , which wasn't finished on the subwoofer side, but for the most part of the job the sound was cristal clear, delivering a good punch and well defined over 200hz while the base suffered a bit because he's using two subwoofers and his listening room is less than perfect causing some resonances at around 200hz as @sesebe showed me when taking some real measurements with a microphone.He's still fighting with his speaker's filters, but i allready know that his system simply needs a specialized room for listenings , his living room being far less than perfect for a fine tuning.
Second ...i just used my Bayerdynamics DT880 pro and his Samson studio headphones and the sound was really good on the dac headphones output .
Well...we don't have the most expensive gear to evaluate audio systems , but we did well enough for a first .
I 'm glad that i met him and i found a really passioned audio guy.
His means might look modest, but the degree of dedication and passion for a good sound was really impressive.
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Old 15th February 2019, 07:57 PM   #17
sesebe is offline sesebe  Romania
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Hello all,

It is time to design an improved new version of my DAC and I'm thinking maybe to change the DAC chip that I used.
Can you recommend a different DAC chip that I can use?
I still have some desires:
  • I do not want something from ES family, if possible
    I do not want something with current output
    I do not want something with integrated filtering on analog side
Please explain the reason, why would I choose that DAC chip.
If there are already this discussion please redirect me to that topics.
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Old 15th February 2019, 09:44 PM   #18
dreamth is offline dreamth  United Kingdom
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What would you think about trying any iout dac and a balanced version of my i/v stage idea with lower noise high hfe pnp transistors , better op-amps like your lm4562 and passive filtering ? I'd like to see someone else giving a try to my idea even if the results would be less than ideal.


Best way to mod cheap cd-players-enhancing the noise


The sims with a LT1115 and bc337/40 as input transistors show about 85...88db thd with predominantly even harmonic content dependent on the input transistor bias and feedback with a simple sine input. I would recommend to try the tape-head coupling just for fun, but , if you want to give it a try , please try first a better spice model than mine for an i/v section suitable to your high end dac's and tell me what you think about that!

Don't change your dac yet! I've listened to your dac and it was good sounding already.
One day i found an old Toshiba cd player and what amazed me was the passive filter attached right at the output of the DAC.
You can see it in my attachment and because we had some discussions in the past about what you could measure at the output of a digital system , maybe you'd take a further step to actually improve a filtering system than just "swapping dac chips " .I know that you're a very competent engineer who has the right tools to measure that noise too
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Old 15th February 2019, 10:17 PM   #19
dreamth is offline dreamth  United Kingdom
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Sorry, i just realized that you have a v-out dac.The toshiba player in the photo had a 16 bit v-out dac , probably way noisier than yours. I can't delete my previous post now.
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Old 16th February 2019, 02:38 AM   #20
abraxalito is online now abraxalito  United Kingdom
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The choice is fairly narrow with that set of constraints - how about LTC1650?
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