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Buffalo II

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A sine wave is a sine wave (or any other wave form) regardless of it's DC bias. Especially if it is differential. :)

It will simply have a DC bias very close to GND instead of at AVCC/2. If you don't understand these concepts your probably in way over your head. You may want to do some more research before undertaking your project.

You will have some DC offset no matter what unless you AC couple or use something other than a simple resistor. You could of course AC couple to the next stage. Completely up to you.
 
Russ, I clearly understand what is the offset for. Unfortuletally laconic info about ES9018 in network makes me wonder. This chip is really a voltage-output type with 195R in series (4 DACs per channel) BUT it is different from other voltage-output DACs because no one but this can be put in "current" mode - there is always minimal load resistance defined in DS.
Moreover, erlier information "to put ES9018 in current mode load should be less than ~700ohm" is misleading, because as you said even load of 5ohm will not geave a real current mode.
So If I connect output to GND (0R) there is no offset anymore and I wonder how it is possible to chip to generate current sine wave using single power supply.
If I connect output to "virtual ground" like inverting input of OPAMP should I use AVCC/2 for non-inverting input of OPAMP or tie it to GND?
 
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Russ, I clearly understand what is the offset for. Unfortuletally laconic info about ES9018 in network makes me wonder. This chip is really a voltage-output type with 195R in series (4 DACs per channel) BUT it is different from other voltage-output DACs because no one but this can be put in "current" mode - there is always minimal load resistance defined in DS.
Moreover, erlier information "to put ES9018 in current mode load should be less than ~700ohm" is misleading, because as you said even load of 5ohm will not geave a real current mode.
So If I connect output to GND (0R) there is no offset anymore and I wonder how it is possible to chip to generate current sine wave using single power supply.
If I connect output to "virtual ground" like inverting input of OPAMP should I use AVCC/2 for non-inverting input of OPAMP or tie it to GND?

I am having a hard time following you.

Where did you get that quote about ~700ohms?

As I said before if your using a resistor or an opamp the referenced voltage can be anything from 0 to 3.3v. It completely up to you. That is really basic stuff.

Also the DAC is not a voltage source with a 195R output impedance. It is a whole bunch of high impedance current sources in parallel that sum to 195R. :)
 
Sorry for that..
About 700ohm - it was mentioned somewhere can't find right now and it was probably regarded to ~700ohm output impedance od single DAC of ES9018 - so maybe when load is going under ~700ohm output starts to behave rather as current sournce and so on.
In case of BuffaloII with 4 DACs per channel this treshold is 195ohm?
My mistake.
 
Hi Russ,
I was lucky to purchese 2 Buffalo II modules and placids 2 weeks ago.
I am going to prepare Dual mono Buff II with tube output (balanced XLR).
Also I use AES/EBU 110 Ohm cable to connect transport with DAC.
What will be the best pin to attach the signal Spidf + G or DSD ?
How to do it in dual mono mode?
 
For those of you using AES/SPDIF. If you want to use both ends of the AES then you will want a good pulse transformer to turn it single ended. Otherwise just use one end.

You could also use our MUX module which takes AES input and does both SPDIF and I2S output. It also provides galvanic isolation.

If you are usuing SPDIF input you don't want to feed the same signal directly to both dual mono DACs. You will have a double termination. The SPDIF signal should only go to one DAC.

Instead of sending it to two (going direct into SPDIF both DACs) feed the SPDIF into DAC #1 normally with the SPDIF switch closed as usual. Then wire from GND and D1 on DAC #1 to GND and D1 on DAC#2 and keep the SPDIF switch *open* on DAC #2.

Now you have a single termination for the SPDIF and you will be feeding the second DAC with TTL signal from the comparator of the first. This works very well for me.

Cheers!
Russ
 
Now you have a single termination for the SPDIF and you will be feeding the second DAC with TTL signal from the comparator of the first. This works very well for me.

Cheers!
Russ
So how long can this conexion be or what kind of cables are recommended? I ask that for the posibility of making dual mono in diferent enclosures, so placing each one next to the power amp monoblocks next to each speaker.
 
I have had success by simply removing the 75 ohm termination resister from the first DAC and daisy chaining to the second with SPDIF.

The solution Russ put forth is likely better if both DACs reside in one box.

For AES a transformer is the way to go along with a T network to attenuate the level and match the impedances. below is a link to a calculator. Just enter 110 as the source and 75 as the load assuming a 1:1 transformer. About 15 db attenuation seems to work well.

T-Pad / H-Pad Calculator - Resistor Values for Attenuation
 
I have question about power supply. If i use 3.3 battery to power
AVCC instead AVCC Shunt Regulator module, is it possible to use
12V SLA battery to supply on-board low-noise digital power supplies( LT1763 )

Angel

12V is a very big drop for those regs. I don't think I would try it . It would likely work, but they will run *very* hot and may not last as long.

6V however would be just fine and much more comfortable so long as you power AVCC directly with 3.3V

Be sure that the supplies come up together.
 
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Dear Russ,
I was wondering if you could help me with understanding one thing.
I use AES/Ebu cable from my transport and I connected signal + (pin 2) to Spidf inputs on Buff II and ground (pin 1) to ground.
Also between the Pin 3 (- signal) and Pin 1 (ground) is small blue condensator.
Is that right? should I use something different?
Can I connect AES /ebu signal to DSD? and how if this is possible?
I was wondering how to use AES signal correcty to the Buff II boards.
Please help me understand and corrct me if I am wrong.
Thank you,
Christ
 
Thanks Russ for explaining Dual mono feeding.
This works exellent. Very coherent sound. Much better then separate feed.
I am still wondering how to use second wire (pin3) from AES
It is signal there. I dont want to just cancell it.
Is mux module the best solution?
I am searching only for the best .
Christ
 
Hey guess, new to the world of DIY dac's but not new to DIY amps. Im looking to build the BII and wondering how this dac ranks among the best you can buy? Thanks in advance guys.

Buff II ? This is the best I had.
I purchesed CEC TL combo, than EMM labs SE combo and lastly DCS Scarlatti combo.
They all are 24 bit max and sound is not natural. good, but not like 32 bit BII.
I spent a fortune to learn that extremely chip TP Buff II is the best.
It is that simple.
I was stupid to do not try Twisted Pear products (B II) before spening a fortune for junk.
Now I am very happy with my dual mono BII with tube output stage.
Christ
 
Can you post the schematic of your tube output stage?

Thanks

JD


Buff II ? This is the best I had.
I purchesed CEC TL combo, than EMM labs SE combo and lastly DCS Scarlatti combo.
They all are 24 bit max and sound is not natural. good, but not like 32 bit BII.
I spent a fortune to learn that extremely chip TP Buff II is the best.
It is that simple.
I was stupid to do not try Twisted Pear products (B II) before spening a fortune for junk.
Now I am very happy with my dual mono BII with tube output stage.
Christ
 
Dear Russ,
How to summate the signal in dual mono mode on each board?
I think on L and R is the same signal , but in opposite phase.
I connected R+ with L- and R- with L+ with silver wire on each board.
Is that right?
I use tubes balanced output stage and do not use IVY III which is I think doing the job normally.
Is there any better way to summate the signals in dual mono mode?
Thanks in advance!
Christ
 
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