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Modifying the Subbu V3 DAC

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#662
Good, you need a low value very small SMD cap near the pins for decoupling, even 1206 SMD packages are too large for effective decoupling at quite low frequencies, the smaller the package the better the decoupling. The frequencies of concern are found by deriving the knee frequency from the devices rise time, the faster the rise time the more concern you pay to your decoupling. It is sad to see otherwise nice modern DAC designs spoilt by the use of through hole decoupling caps.
 
#663
marce said:
Good, you need a low value very small SMD cap near the pins for decoupling, even 1206 SMD packages are too large for effective decoupling at quite low frequencies, the smaller the package the better the decoupling. The frequencies of concern are found by deriving the knee frequency from the devices rise time, the faster the rise time the more concern you pay to your decoupling. It is sad to see otherwise nice modern DAC designs spoilt by the use of through hole decoupling caps.
Click to expand...

Using 0805. I thought smaller than these would be difficult at C17.
 
#664
darshanjoshi said:
I want to try the original BOM. How does it matter using 16v vs 25v vs 35v ? Would i get better Ripple Current using higher voltage caps?
Click to expand...

It can change the sonic result in relation to your system, better to follow the BOM as the work of choice was already made. To really know one has to try the values. In case of doubt take the lowest sized package or the lowest pitch leg or even better the one which feet with pcb pitchs aera planned for the BOM cap 🙂 so the minimum voltage needed for the design.

If I remember the Sal was choosed by J-P/Subbu as an improvement over the Silmic II but also the result vary according your own system around the DAC. You can also read the whole thread if not already for some tweaks members shared after "extensive" tests as well. Most of the time the complete caps values are writed.😀
 
#665
marce said:
Good, you need a low value very small SMD cap near the pins for decoupling, even 1206 SMD packages are too large for effective decoupling at quite low frequencies, the smaller the package the better the decoupling. The frequencies of concern are found by deriving the knee frequency from the devices rise time, the faster the rise time the more concern you pay to your decoupling. It is sad to see otherwise nice modern DAC designs spoilt by the use of through hole decoupling caps.
Click to expand...

Hi Marce, I believe there is an exception in the Subbu DAC : the neg decoupling of the ESS dac chip : the 0.1 uF and 1 uF are better with the Wima MKT of the BOM and even better with a Black-Gate 1 uF Std or BG N... at least at ears.

My eyes and fingers give up at 0605 smd cap size max :magnify:...
 
#666
Does someone already try to swap the spidf chip for uf-l plugs ? If yes is better to keep the I2S serie résistors of the design or the extra length of an external USB-I2S links is "enough" resistiv ?

I have 2 Subbu boards so I can have a reference point...
 
#667
darshanjoshi said:
Using 0805. I thought smaller than these would be difficult at C17.
Click to expand...

Yes, and with the design may not have a huge difference, I did play about with my own version of the layout with my SI tools and power integrity tools and differences were minor, I used 0603s on my layout.
The separate power islands for each device make this a much better design than many, isolated power islands done properly help isolate the areas of circuitry and make the layout less prone to bad decoupling...
 
#668
Marce, if you send me your own layout pcb (unpopulated) I will tell you in PM if it sounds better than my "Vodoo SUBBU tweaké" 😀 and Blessed à Notre Dame !

(I have two, so I can have a reference and take the two chips from the other) !
 
#670
Maybe someone could help, Need a new Dac for the Linkplayboard A28 wifi, which is a Slave i2S device and does not supply a SysClk,
So how to use ESS9023 or 5102 and what PCB precautions to take. I would like to keep the Wifi Mod and Dac on the same board with onboard regulators so that the Dac board and the Wifi Module can be the daughter board.
 
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