Buffalo DAC (ESS Sabre 9008)

[Russ White]

Russ

You are prolific. Is this going to be available?

One question - is the previous vref based on the pnp transistor enough to drive the Buffalo LM4562? Or are you just developing a new feedback regulator?

My experience with the ALW regulator for general use is that a tracking preregulators improves performance significantly. The Teddy series pass prereg actually doesn't do anything extra.

Fred

Hi Fred, Thanks.

This regulator is designed to be used after a LCDPS.

The VREF alone is not meant to drive the LM4562 at all. It is there to provide the low noise 3.3V reference that the opamp tracks. The opamp *is* the VREG. The VREF's output impedance on its own is not stellar. It has to used with a very high input impedance, like the opamp.

With the exceptional PSRR of the LM4562 the LCDPS should work out very well. But you can use any regulator you like as long as you get a good low impedance 6 - 8V or so.

Try the VREF on the buffalo and see what you think. I am really liking it.

Cheers!
Russ

 

[Russ White]

Re: up and running!!

Hi

No big news, just wanted to say that my baby is up and running (including the new VREF). Everything worked as it should. Soldering and assembling was straight forward.
And what about the sound? All I can say: I'm very happy. To me it just sounds right - and that's fantastic.

Next thing will be a nice case - but first I'll have to sit down, take a deep breath and have some listenings.

Brian and Russ, thanks a lot for making this possible.

Cheers!
Mario

Wow! Very nice work!

I am glad you are enjoying it.

Cheers!
Russ

 

[glt]

Re: Extension of the idea...

Here is a low noise regulator based on the VREF idea above.

The output (pass) device can either be To-220 or TO-92 depending on what you need.

I added the capability to take feedback(Sense) from the load instead of the right at the output. You just extend RF to the further pad and wire the sense wire to the pad marked "Sense"

Russ, If this becomes a product (please, please) you can add a pad to the Vref so the same board so it can be used for a Vref or Vreg. Thanks!

 

[rolls]

Hello
I hope there is anybody around who can help.
Yesterday I was happy, because the AV Ref mod works very well.
Then I wanted to add the MUX, but it does not work at all.
I have checked everything:
layout in the net and on the board of the buffalo are different, I don't know which is correct, I have tried both, without success.
When I follow the I2S markings on the board, buffalo locks, but the LED on the MUX is dark, even If I connected the missing ground link (I have an early board).
I have connected input one, for this select 1 and 2 are tied to gnd.
switch 1 on buffalo is neg
I have left the switches on the mux untouched.
All the voltages are O.K.
I soldered the relays that their point is on the same corner as the small white dot on the board.
When I switch to SPDIF, buffalo works, but with added clicks sometimes.
Thank you!

André

 

[Russ White]

Hi Andre

If you put the I2S output of the MUX board against the I2S input of the buffalo board, the terminals will line up.

Here is a pic I hope will help.

I have GND connected elsewhere, thats why you don't see it.

Data,BCK,LRCK

Add GND if your MUX and Buffalo don't share a common supply.

 

[Russ White]

Also, you cannot leave the switches open. Try setting them like this.

 

[rolls]

Hello Russ
Buffalo and Mux are stacked,
but DOUT to D2
LRCK to D1
BKC to DCK is correct I think.
I just hear loud hiss with faint music.
Ground is everywhere. Relays are O.K?
thank you!
André

 

[Russ White]

If you have a very very early Buffalo (very first run) remember that D2 and DCK are swapped.

Also, isolate the MUX itself and make sure its locking. Is the LED installed backward?

 

[rolls]

My buffalo is from the second round, the one with the hosting company problems you had.
I have removed the mux now, unsoldered and checked the LED, flat side is connected separately to ground. selectors 1 and 2 still to ground, no lock!
Slowly I start to think about to replace it with another mux.
Thank you for your help
Andre

 

[Russ White]

Yes, it sound like the MUX might be suspect.

If it won't lock on its own, then there is no point to proceed with it.

I guess maybe it could be a solder bridge or a dry joint.

Very sorry your having trouble with it.

 

[rolls]

no problem, I will order a new one when you are back.
Thank you.
André

 

[avr300]

Noise problem solved

Hi guys..

I have been struggling with noise problems, cracks, pops, hiss, yes, some really nasty digital garbage.

Barely audible at normal listen level, but easy to hear when using headphones. Not constant, came and went, influenced by the touch of a finger or two.

This night I tried shielded cables between the Buffalo and the IVY - no difference.

I should say, that my setup is stacked.

Then I tried increasing the distance between the two PCB's. That did the trick. Further on I placed a shield between the two stackings.

Russ and Brian, I think stacking the Buffalo and the IVY needs to be reconsidered. The distance between them is too little with the supplied stacking hardware.

It must be radiated HF which in some way upsets the IVY.

It's just so much more revealing now, it's absolutely dead silent when it's supposed to be.

Even the sibilance is gone - which I claimed had been introduced along with the ...... wait a second ......., digital garbage radiated from the XO down into the caps, the caps of the shunt cap mod.

Anyway, look at the picture, sorry for making it ugly, but it surely sings like ... now.

Big smile -

 

[eaoyama]

That's so strange, nothing like this is happen here.

and all my pcbs are close, including the toroidal transformer.

 

[Russ White]

Here is another interesting cct

This one biases the VREF CCS with the output of the pass device.

Its kinda circular feeback.

Its good for 3.3V.

I think it will have even better noise rejection.

PSRR is actually not shabby either.

This is one I will be testing very soon.

You could drive AVCC on each channel with one of these.

R5 and D3 I put in to limit current, but they may not be necessary for all applications.

Cheers!
Russ

 

[rolls]

Hi Russ
you may not believe it, but my Mux works now!
Two strange things had happened at the same time:
Mux started to lock with another player on my workbench. Later I found out, that Buffalo and Mux probably don't use the same signal for locking. With my Denon player, Buffalo stays always locked, but Mux just locks when a disc is playing.
But even this way there was just hiss with Mux. Accidentally I found the trick:
When I flipped the tiny SPDIF input switch on the buffalo, there was music!!
Very strange, I wonder if you have an explanation.
Now the sound is better, it is a bigger step than with the AV ref mod.
Thank you for your great products.

André

 

[fmak]

Re: Single Side PCB PDFs for VREF

Here is the VREF with bipolar CCS on a small single side PCB.

The zip includes everything you should need.

Cheers!
Russ

If anyone is making pcbs, please count me in for 6. (other useds as well).

Russ, you took the supply from VA of Buffalo to isolate this from VD?
Also, can you post a pic of where you cut on the underside?

One comment; the Vref has to be set at 3.4V for the supply unloaded as loading it with 30k of opamp input impedance brings the voltage down to 3.3V.

Thanks

Fred

 

[dday_one]

Re: Here is another interesting cct

This one biases the VREF CCS with the output of the pass device.

This is one I will be testing very soon.

You could drive AVCC on each channel with one of these.

R5 and D3 I put in to limit current, but they may not be necessary for all applications.

Cheers!
Russ

Hi Russ,

Do you think this one will be better than the previous one (the one posted with the DT files)?

Thanks for sharing btw, regards,

Lennert

 

[LTK]

Re: Here is another interesting cct

This one biases the VREF CCS with the output of the pass device.

Its kinda circular feeback.

Its good for 3.3V.

I think it will have even better noise rejection.

PSRR is actually not shabby either.

This is one I will be testing very soon.

You could drive AVCC on each channel with one of these.

R5 and D3 I put in to limit current, but they may not be necessary for all applications.

Cheers!
Russ

Be very interested to hear your results with this one Russ

 

[Russ White]

Hi Russ
you may not believe it, but my Mux works now!
Two strange things had happened at the same time:
Mux started to lock with another player on my workbench. Later I found out, that Buffalo and Mux probably don't use the same signal for locking. With my Denon player, Buffalo stays always locked, but Mux just locks when a disc is playing.
But even this way there was just hiss with Mux. Accidentally I found the trick:
When I flipped the tiny SPDIF input switch on the buffalo, there was music!!
Very strange, I wonder if you have an explanation.
Now the sound is better, it is a bigger step than with the AV ref mod.
Thank you for your great products.

Andr�

Yes, I can tell you why it was happening. The "SPDIF" switch pulls D1 to the comparator output. So when using I2S you have to open that switch.

I am glad it is working.

Cheers!
Russ

 

[Russ White]

Re: Re: Single Side PCB PDFs for VREF

If anyone is making pcbs, please count me in for 6. (other useds as well).

Russ, you took the supply from VA of Buffalo to isolate this from VD?
Also, can you post a pic of where you cut on the underside?

One comment; the Vref has to be set at 3.4V for the supply unloaded as loading it with 30k of opamp input impedance brings the voltage down to 3.3V.

Thanks

Fred

Yes take the supply from VA if you want complete isolation from VD. That is what I do.

I attached an image for the cut. It is marked black.

Good observation on the voltage. The datasheet says the absolute maximum of AVCC is 3.8V so just stay well below that. I have been using 3.5V on my latest tests(the last schematic I posted) with no issues. It at the voltage because I was to lazy to adjust it down and I wanted to see if there were any problems using it.

In practice 3.35 to 3.4V would be great and more safe.

:EDIT: here is the pic :EDIT:

Cheers!
Russ