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Buffalo DAC (ESS Sabre 9008)

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#1,141
Re: Vref Again

fmak said:
Russ

Why have you left out the lf filter before the LM4562 on the board in feeding Vref? Is there a drive issue?

Seems it may be useful to reinstate lf filtering to a low freq.

Gone back to my old setup with ESS well away from PSs. Bass is a little 'plumb' .
Click to expand...


I am sorry but you have lost me. 🙂 Probably my fault.

What LF filter did I leave out?

The VREF is itself a low pass with a very very low corner. 🙂

I actually added significantly more filtering.

The LED reference voiltage is the only thing that is being filtered. 🙂
 
#1,142
Hello Russ
I have told my friends about the improvement with the Mux. Obviously the Buffalo is doing better if it is fed with an already dejittered signal. Because they don't use the selector function, I wonder if the Wolfson board could do the same even better. The data sheet of the Wolfson 8804 chip gives 50ps compared to 200ps of the CS8416.
So can you recommend the Wolfson board for the buffalo as well?
Thanks
Andre
 
#1,145
Joshua_G said:
Will there be any benefit by adding WM8804 between the CS8416 and the Buffalo?
Click to expand...


IMO, no.

When we looked at jitter sidebands on the output the Sabre even a lowly (jittery) USB I2S input was virtually identical to ultra clean I2S. The way the Sabre does digital input is not like anything else out there. It is completely asynchronous. This is why the ESS master clock can be any frequency you like with a certain range. It is literally the only clock of significant importance regarding the final performance of the DAC (within reason).

Cheers!
Russ
 
#1,148
Re: Re: Vref Again

Russ White said:



I am sorry but you have lost me. 🙂 Probably my fault.

What LF filter did I leave out?

The VREF is itself a low pass with a very very low corner. 🙂

I actually added significantly more filtering.

The LED reference voiltage is the only thing that is being filtered. 🙂
Click to expand...


Sorry, what I meant was if Vref output is injected to the Vdd side of R4 by cutting the trace there, we end up with a compound filter. I don't know if this will be better???
 
#1,149
Re: Re: Re: Vref Again

fmak said:



Sorry, what I meant was if Vref output is injected to the Vdd side of R4 by cutting the trace there, we end up with a compound filter. I don't know if this will be better???
Click to expand...


I think I understand what you are asking. C6 is in parallel with the VREF filter cap, so it will basically adds to the capacitance. If you want you can remove C6 (and even R4 and C13), but I can't see any need. The only way leaving C6 in place will hurt is if you have significant inductance at the VREF cap as you would then have a "tank cct".

Cheers!
Russ
 
#1,150
Reduced R4 to 147R and Vref is now upto 3.45V.

So I think I will try it at that and see does it drop much. If it does I can change things another bit to bump it up. At least now I don't feel nervous about cutting the trace and not having a working supply.

So thanks Russ. I will be putting it in tonight and will report back later. I also will fit a volumite after that and see how it goes.

I'm getting near starting build number 2 now!!


Fran
 
#1,151
woodturner-fran said:
Reduced R4 to 147R and Vref is now upto 3.45V.

So I think I will try it at that and see does it drop much. If it does I can change things another bit to bump it up. At least now I don't feel nervous about cutting the trace and not having a working supply.

So thanks Russ. I will be putting it in tonight and will report back later. I also will fit a volumite after that and see how it goes.

I'm getting near starting build number 2 now!!


Fran
Click to expand...


3.45 should be just fine. 🙂

Have fun!
 
#1,152
Ok,

so I just installed it and it all seems to work. I've only just fired it up and there is sound at least.

One thing I do need to check... I connected it to VA and GND, which was at 7.2V, I get 3.450V at the output of the AVCC. Then when I connect it up to the opamp-pin-side of C6 I no longer get a voltage reading between there and ground. Is that correct?


heres the cut:

An externally hosted image should be here but it was not working when we last tested it.


Installation:

An externally hosted image should be here but it was not working when we last tested it.


and the whole thing.. starting to get busy in that case!

An externally hosted image should be here but it was not working when we last tested it.




Fran
 
#1,154
Yeah, its ok - 3.37V

What happened is that the lead of my DMM was halfway out of its socket. Mobve the lead around and it made contact when measuring the feed voltage, move it a different way to measure Vref and down it went.

What are the chances of that!!

All ok I think. Listening yet to come....


Fran
 
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