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OLD THREAD DAC End by Andrea Ciuffoli

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#281
My choise about power supply transformers has been:

LS70-1 0-15X2(0.8A) 0-12X1(0.8A)
R80-55 0-9 X2 (3A),0-250(200mA)

from Ebay shop:

50W R Core Transformer,115V//230V, for Preamp,DAC/R26-x su eBay.it Transformers, Vintage Electronics, Electronics

I will test soon.

Probably with the same money it is possible to get one custom made toroidal by Bartolucci (Ricerca e Sviluppo - Bartolucci Transformers - Welcome to Ricerca e Sviluppo - Bartolucci Transformers)

I consider 200mA (0.2A) the minimun for the 250v and also 220-230v are good.
 
#282

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#283
In the output stage board for any resistor on the signal path there are 2 resistors.

The best choice for the resistors is the Caddock but a good and less expensive choice is to use 2 resistors in parallel with opposite phase (inverted colors).

I suggest to use MK132 Caddock on DAC output (200ohm).
 
#284
audiodesign said:
In the output stage board for any resistor on the signal path there are 2 resistors.

The best choice for the resistors is the Caddock but a good and less expensive choice is to use 2 resistors in parallel with opposite phase (inverted colors).

I suggest to use MK132 Caddock on DAC output (200ohm).
Click to expand...

If you want to get the "best" resistor, you could also use the TX2575 from Texas Components.

I have outstanding results with this one in my DAC projekt! :nod:
 

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#288
In the Italian webpage of Bartolucci there are the differences:

Standard:
Lamierini ricotti in grani orientati, medio alta permeabilità -> core medium-high permeability
Rendimento 92% -> efficiency 92%
Bassa corrente di magnetizzazione -> Low current magnetization
Max riscaldamento lavoro Temp.Amb. +12° C -> Max heating Temp. +12° C

Special:
Lamierini ricotti in grani orientati, alta permeabilità -> core high permeability
Rendimento 96% -> efficiency 96%
Bassissima corrente di magnetizzazione -> extra low current magnetization
Max riscaldamento lavoro Temp.Amb. +8° C -> Max heating Temp. +8° C

but these are very expensive, I spoken about toroidal series
 
#291
I think the 0,1 parallel to the 220µF are not necessary, if Oscons or other super low Esr caps are used.
If someone really wants to add them, they can easily be soldered underneath the PCB, directly to the capacitors.

@Andrea
I'm asking myself if there are not too many caps after the regulators, which should already provide a clean and nice source.
And are those little TL431 regs really necessary? Is all this for decoupling the rails from each other, or is there another reason?
Probably you tried it and it was better...
 
#296
Plan for board completion

Plan for board completion

Dear All,
Firstly I would thank for your trust in myself and andrea in this design.

For a perfect completion, I may opt to have you all to take a look at the circuit and layout before I send it to printing plant.

Regarding schedule, the printing will start by January 18 and it will take 8 days. Plus two days for shipping to me, I can ship the boards out to you by January 28. This implies a 4 days delay compared to initial plan.

Regarding Paypal’s lock-up, the main reason is Paypal wants to see the evidence of shipping, which is yet available. I’m talking now with Paypal to sort out the situation.

For a solid, professional and hi-end boards are what I am striving for.
 
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