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

[Erlend Sæterdal]

Originally Posted by Magura

Yeah, that's a bit far to travel, at least for a cup of coffee


You should however consider popping by for this:

www.class-a-labs.com/News-Events

Rumor has it, that it will be a rather international event.


Magura

Yes I will consider it.
By the way the sound of my Dac/Pre is stunning. I do not think I have ever heard anything even near it.

[Magura]

So much more reason for inviting you


Magura

[Stanga]

Can the OPUS be controlled via a PIC microcontroller? Has anyone written a set of code to do that? I am very much interested in that idea. I am no good in programming, but I use PICBASIC PRO for some simple things. It had crossed my mind whether the use of a PIC to access the OPUS software functionality could be achieved.

[glt]

Not PIC but with Arduino (ATMEL). Documented in my blog.

[dali05]

Hi,

As i am new to DIY i have spent hours trying to find information how to set up my dualmono opus / IVY correctly. The problems i have is regarding the IVY II boards.

I have 2 Opus Ver 2 boards each feeding an IVY II in Dualmono. The amplifier is based around the Hypex Ucd400HG HxR module.

The easy part, replace R13 - R16 2K resistors on IVY to 1K.

The hard part.

The Hypex modules has an input impedance of 100K and an input cap to prevent DC. So, do i need to change the output impedance on the IVY and what changes is needed to make the IVY II DC coupled?

Russ mentioned that he preferred using the IVY without the analog filtering on the IVY leaving it to Opus. In this case, which components do i leave out?

Anything else that i dont know of to improve the IVY board in my configuration.

Any answer, tips and trix will be greatly appreciated.

Thanks,

[glt]

R13-R16 are for the balanced to single-ended converter, so it won't affect your set up since you are feeding balanced to the Hypex.

Leaving out C1-C4 removes the low pass filter

In theory IVY will remove the DC offset, so the input cap in Hypex is not needed. (But I would leave it there). I feed my Hypex Amp (180hg) straight from OPUS. So the capacitor blocks the DC offset coming out of OPUS.

The wolfson data sheet recommends a low pass filter at the output of the DAC, so I added an RC circuit to the input of the hypex amp with cut-off of 70KHz (can't tell if it makes a difference), but I asked Hypex, and they said the amp does not have an input filter. The C1-C4 in IVY does the same thing.

Next you should get an Arduino and program the internal registers of the DAC :-)

[dali05]

Originally Posted by glt

Next you should get an Arduino and program the internal registers of the DAC :-)

Thanks a lot glt!!!

As a matter of fact i have already ordered an Arduino Mega and a TFT color touchscreen (eDIPTFT43-atp). And that, is all your fault
Your blog got me really started.

Again, thank you!

Daniel

[rhester]

I have a maxxed out OPUS. All digi inputs feeding into mux into a metronome into a opus and finally to IVY. Also have a volumite to control volume digitally but can not get it to work. have tried every method of software control and get absolutely no sound when hooked in line. any help please?

[glt]

What do you mean by "every method of software control ". How is the Metro set up? If the Metronome is set to output 192K, then you cannot apply oversampling in the wm 8742 DAC (the OSR bits has to be 10)

[rhester]

Metro is set up to oversample to 192K. Does that mean I can't oversample and have a volumite. What If have music sources with different sampling rates (44.1, 48, 96)?