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Mr White's "Opus", designing a simple balanced DAC

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#1,281
Clutz said:
In my Opus DAC kit, I received two LCDPS instead of an LCDPS and a bipolar supply (for the balsie). Can I use a LCDPS power supply for the balsie?
Click to expand...


First sorry for the mistake, we can rectify it for you.

But yes, actually you can use the LCDPS to power Ballsie, and it will work quite well. I am currently using it to power my headphone amp as a a bipolar supply.

All you need to do in join GND from one output with + from the other, the two in the center work well for this. the you can take either of those joined terminals as GND (0V).

The other +and GND will actually be V+ and V- respectively.

Then just adjust the pots until you get +/- 15V

Cheers!
Russ
 
#1,283
I'm sorry if these Q's have already been answered, but this thread is huge, and I cant seem to find the right answers

With the Dual mono version of this setup? Do I need two power supplies? (ie two Toroids or LCDPS kits? etc)

What VA rating Toroid is recommended for a dual mono OPUS?

What is the best way to power the METRONOME and SPDIF modules? (from the same LCDPS?)

I am concerned how to wire a dual mono setup, I saw the datasheet, but could someone provide a rough sketch how the outputs for the left and right channel from the dual dacs are meant to be wired? (to two rca plugs)

Also can someone recommend a good Brand/Type and gauge of hookup wire for signal/power
 
#1,284
With the Dual mono version of this setup? Do I need two power supplies? (ie two Toroids or LCDPS kits? etc)
Click to expand...

No, one power supply is fine.

What VA rating Toroid is recommended for a dual mono OPUS?
Click to expand...

Each Opus module draws <100mA, so a 15-30VA trafo should easily power several modules.

What is the best way to power the METRONOME and SPDIF modules? (from the same LCDPS?)
Click to expand...

Yes, same supply. Often people will use one side of the supply for the analog portion of the dac(s) and the pther side for the digital portion of the dac and any other digital modules (receiver, toslink, metronome etc).

I am concerned how to wire a dual mono setup, I saw the datasheet, but could someone provide a rough sketch how the outputs for the left and right channel from the dual dacs are meant to be wired? (to two rca plugs)
Click to expand...

I think I have a diagram around here somewhere, let me look.

Also can someone recommend a good Brand/Type and gauge of hookup wire for signal/power
Click to expand...

I'll let someone else answer this. I used cheapo PVC wire for mine.
 
#1,285
I've got a Dual OPUS & Metronome on order and I was wondering about which transformer to use.

In my spares box I have a 60VA 18V with dual secondaries and a 120VA 15V with dual secondaries.

I know that TPA sell a tranny with 15V windings but I would prefer to use my 60VA transformer due to it smaller physical size. Would this create too much of a problem? The heatsinks on the power supply look pretty beefy to me and the current draw is pretty low. Or would I be better off just using the 15V secondaries and try to squeeze the bigger transformer in the box?

What do you think?????
 
#1,286
waltona said:
I've got a Dual OPUS & Metronome on order and I was wondering about which transformer to use.

In my spares box I have a 60VA 18V with dual secondaries and a 120VA 15V with dual secondaries.

I know that TPA sell a tranny with 15V windings but I would prefer to use my 60VA transformer due to it smaller physical size. Would this create too much of a problem? The heatsinks on the power supply look pretty beefy to me and the current draw is pretty low. Or would I be better off just using the 15V secondaries and try to squeeze the bigger transformer in the box?

What do you think?????
Click to expand...

You won't come close to maxing out either transformer, so I would just choose which ever one you think fits best.

You should be in good shape either way.

Cheers!
Russ
 
#1,292
Brian, Russ,

I have build another Opus DAC with double 8740's and a metronome and want to ask you this:
It sounds ok but some music causes static tics/noise. Very strange. It is not there in single 8740 mode.
I took the metronome out and it seemed better. Very confusing.
PSU= isolated Balsie supply(dc-dc)
Isolated +5V digital lines are fed either with 9V or/and the 3.3V boards with 5V.
isolated +9V supply for the analog 5V line.
What else to do?

PS The DAC boards are version 1+2
other boards version 1
metronome board is upright just for testing.

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


An externally hosted image should be here but it was not working when we last tested it.
 
#1,294
Hi Bert-

Usually this type of noise is caused by interference between the power wiring and the I2S wiring, or power wiring too close to clock traces on the board(s).

From your pictures, my guess is that the source of your noise is one of the wires in this picture:
 

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#1,296
waltona said:
BGT, is that the 4cm high hifi200 box? I was wondering if it would be high enough for the OPUS power supply. Look as though it is.
Click to expand...


Waltona, it is the 4cm high box. Although the Opus psu fitted it got too hot because I could only use 1 power supply.
With double 8740's and the metronome I got too much heat because of the losses from going from the 12V for the Balsie to the 3.3V for the Metronome. So I made a power supply with smps regulators+a DC-DC for the Balsie. So now it stays really cool. No heat at all.
 
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