A nice dac to complement the Aleph-X.

[uli]

Lucas + Leve,
I didn´t know that it´s such an issue to get MAT´s in the US!
In Europe they are quite common for hi-end DIY projects.
according to AnalogDevices (former PMI) they cost 6,- USD
if you buy 100+
I´m on rework of my DAC, it´s basically a hypertweaked
'elektor' design, with different psu and 'my' analog output
which is a mixture of NP´s D1 and some bipolar stories.
As the software for the used GAL is available for about 15,-USD
I will draw the complete circuit (CS8414, DF1704 or -6, 4x PCM1704) and maybe some PCB work.
Maybe AD is willing to tell you where to buy MAT´s, maybe the
guys from AudioXpress (www.audioxpress.com) can tell you.

Uli

[nibolo]

Originally posted by Nelson Pass
I don't see why you wouldn't want to simply use the
I/V converter from the D1. Schematics at www.passlabs.com

Is it possible to use this design with nonoversampling filterless dac.
I´m already almost build a dac based on TDA1541A and your I/V, but its not finished yet.
Was that a bad idea?

[LBHajdu]

Nibolo,
The D1 does not care about oversampling, nonoversampling, 16bit, 24bit. All the D1 cares about is that the dac outputs current (as the TDA1541A does) and that that current is somewhere in the neighborhood of 2mA. The TDA1541A outputs 4mA I don’t know if that’s too much or not, but it’s a lot easer to accommodate the circuit for too much current then for too little. However if your building both halves of the d1 you will need two TDA1541A’s per channel in inverted phase thats 4 dacs for a 2 ch system.

On a somewhat different subject, could someone report as to if they hear any difference between 16bit and 24bit dacs. The only reason I am interested in 24bit is future proofing and some DVDs like the extended addition of “The lord of rings” comes with stereo recordings on the DVD. I don’t know if these recording are in 16 or 24bit.

uli,
I look forward to your circuit. What’s a GAL?

[uli]

GAL is short for Gate Array Logic I think, its something
instead of a graveyard of former 74LS ...

You design a graveyard of logical gates (74LS) and then
a smart digital guy shows up and says:
Youre a dinosaur man, today we programm all that ****
in a GAL, PAL, PLA some weird microcontroler...

The complete circuit has just this 'controler', the Crystal
receiver and the TEXAS DF1704 and 4x PCM1704.
My last ones were from BURRBROWN, hope the Texas ones
sound equal!
(and some peripherals of coarse )

I decided not to use the DF1706, I split the circuit into
4 PCB´s: Left, Right, Digital in, PSU. The digiboard will
be easily exchangeable (CS8414, DF1704, GAL-22V10)

Uli

[pquadrat]

Hi all,

Because you said that "IT IS NOT INTENDED AS A PROJECT" and we are all very respectful.

here is one more less respectful (in terms of a D1 project) person.
I am currently building a DAC with the D1 output stage. It uses a DIR1703 as a receiver, Analog Devices AD1896A upsampler to 96kHz, DF1706 as digital filter and to seperate the channels, and four PCM1704 DACs for symetrical output.
Now I have to think about the lower output current of the PCM1704 (1.2mA max) compared to the 2mA of the PCM63. What to change to get full level output again?

I odered a proto PCB for this last week, so if all works out well, I can tell something about it in about for weeks.

Peter

[Jarno]

Hi Peter,

You're a very busy guy Peter!
If you are making an upsampling DAC and already ordered boards for it I'm interested!

How are things at the Ono front?

Greetings,

Jarno.

[uli]

Originally posted by pquadrat
Hi all,




Now I have to think about the lower output current of the PCM1704 (1.2mA max) compared to the 2mA of the PCM63. What to change to get full level output again?

Peter

Hi Peter,
swap the 1k5 resistor with 2k5 (2/1.2 x1.5), problem:
You should go to +40V or lower the bias to 6mA (swap the 3k3
with 5k1 or so) otherwise the drain of the first Fet is at about
5V which is a little bit lo.

Uli

[uli]

Originally posted by uli


The complete circuit has just this 'controler', the Crystal
receiver and the TEXAS DF1704 and 4x PCM1704.
My last ones were from BURRBROWN, hope the Texas ones
sound equal!
(and some peripherals of coarse )

I decided not to use the DF1706, I split the circuit into
4 PCB´s: Left, Right, Digital in, PSU. The digiboard will
be easily exchangeable (CS8414, DF1704, GAL-22V10)

Uli

I also decided not to use such things as AD1896 as the CS8414
and DF1704 are designed for 96kHz. The DF1704 puts out 768kHz
(8 times oversampling) same as DF1706 (192kHz 4times OS)
As there are no devices on the market for 192kHz (and no software) IMHO it makes no sense to fill up the enclosure with
expensive stuff, where increase in quality is at least questionable.
BTW the DIR1703 is primarily designed to support DeltaSigma
Converters, and they are too questionable. I believe the only
alternate choice for the PCM1704U-K are the "Ultra Analog"
converters but somewhere must be a point where to stop
putting money into that unit. This extramoney I will put into better
cables speakers....

PS: when changing the resistor from 1k5 to 2k5 the parallelcap
must be changed to 1.5nF (exactly 1.62) to stay at the same
-3dB frequency.

Uli

[pquadrat]

I also decided not to use such things as AD1896 as the CS8414
and DF1704 are designed for 96kHz. The DF1704 puts out 768kHz
(8 times oversampling) same as DF1706 (192kHz 4times OS)
As there are no devices on the market for 192kHz (and no software) IMHO it makes no sense to fill up the enclosure with
expensive stuff, where increase in quality is at least questionable.
BTW the DIR1703 is primarily designed to support DeltaSigma
Converters

The AD1896 can work fine at 96kHz output Fs, the same is for the DF1706. Differences between DF1704 and DF1706 are the 3.3V opertating voltage of the 1706, missing internal pull-up Rs on the 1706 and that the 1706 CAN do 4-times oversampling from 192kHz. But it can still do the 8x OS from 96kHz. And the 1706 is available from TIs sample program
Reason for me to take the AD1896 were the slightly better specs. The only way to use the AD1896 with 192kHz is to use it in slave mode, means that it is clocked from another device.
I do not know if there is a problem with the DIR1703 with this design. I am not aware of diferences to the crystal receiver chips, but would like to know.
I was told that the DIR1703 has good jitter suppression.

-peter

[uli]

Originally posted by pquadrat


.... And the 1706 is available from TIs sample program
.....


-peter

Hi Peter,
convinced!

5 minutes ago I ordered my free (!!!!!) samples from TI.
That is kinda argument

Uli