Suggestions to improve old audio note dac 4

[chaccone]

I have one of this : audionote_dac4

any suggestions to improve this dac?

Some options i have been advised so far include
a. removing analogue filter (do i need to add in a resistor to replace the filter?)
b. replacing the I/V filter with Trans 496 or 497 but too expensive for me.
c. changing the voltage regulator and diodes
d. adding snubber circuits to the power supply stage

However I am not familiar with diy and would like to seek advice on how these would change the sound of the dac and which are the ones that will give the most benefit.

thanks so much in advance

 

[abraxalito]

Input S/PDIF grounding change - does the black wire of the twisted pair go to the groundfill? If so then try other grounding points where the common-mode currents aren't routed through the analog groundfill too.

Are the internal opamps being used in the AD1865? If so then external opamps will probably do a better job - try LM6171.

Lowering the PSU impedance at the DAC may well bring improvements - only two smallish 'lytics I can see there.

Replace the S/PDIF trafo with something with lower interwinding capacitance - the one in the picture looks to be bifilar wound = high capacitance.

 

[QSerraTico_Tico]

mods

Hi,
Try to find an AD1865N-K, sounds better.
Also replace CS8414 by CS8412 if you only play redbook.
Use Wildmonkeysects loopfilter on the CS8412.
Use MAX913 on digital input, forget the transformer.
Etc. etc.

 

[batteryman]

I have one of this : audionote_dac4

any suggestions to improve this dac?

Some options i have been advised so far include
a. removing analogue filter (do i need to add in a resistor to replace the filter?)
b. replacing the I/V filter with Trans 496 or 497 but too expensive for me.
c. changing the voltage regulator and diodes
d. adding snubber circuits to the power supply stage

However I am not familiar with diy and would like to seek advice on how these would change the sound of the dac and which are the ones that will give the most benefit.

thanks so much in advance

I used a pair of Sowter transformer with my Dac 1, and removed the valve stage - not needed with the transformers. No filtering apart from what the transformers provide.

The ones I had were type 9545 meant for a pair of differentially connected tda1541a on a Chinese dac board. (and are now used with it again as I prefer the TDA541 sound over the AD1865)

 

[gumo73]

improving Power stage

I think you can increase SNR off power stage putting a filter
pigreco Resistor Capacitor Resistor ans a small inductor on
power input cable and increase SNR on the stage with LM7805 by other design off power control

 

[gumo73]

bit resolution

Bit resolution if you have about 2.5V at output on the signal
transformer 1LSB is nearest 38uV at 16bit word input .
This mean you need a power stage with a SNR more than
85-90dB.
Is hard to made but not impossible.

 

[chaccone]

do i need to add a resistor with the transformer and how do i determine the value ? can you share how i can add the sowter and how it change the sound. thanks

I used a pair of Sowter transformer with my Dac 1, and removed the valve stage - not needed with the transformers. No filtering apart from what the transformers provide.

The ones I had were type 9545 meant for a pair of differentially connected tda1541a on a Chinese dac board. (and are now used with it again as I prefer the TDA541 sound over the AD1865)

 

[gumo73]

not good idea

do i need to add a resistor with the transformer and how do i determine the value ? can you share how i can add the sowter and how it change the sound. thanks

Removing Valve stage is not a best idea you need a slow value of output impedance
for a good driving of coaxial cables ...they have Z=75ohm
I think you need work on Power of this stage and fit global transfer function of the
analogue stage.