Hello,
i'm rookie in DIY-audio, so sorry for my maybe naive questions.

I'm planning to build a pair of 3-way active speakers,
with all signal processing in digital domain (FIR filters on DSP for x-over, EQ and enclosure+room resonanse correction).

Each speaker will contain 3 I2S mono inputs -> 3 mono DAC w/balanced out -> 3 mono amp w/balanced input -> 3 drive units (200W bass, 100W midrange, 50W treble).
My priorities are: wide dynamic range, low THD/IMD/N, and high clarity and smoothness for 24/96 HD loseless media playing.

So my questions are:

1) As i understand i need at least 2 * BuffaloII for each channel ?!?
1st - in stereo balanced mode (midrange and treble, for example), and 2nd - in mono balanced mode (bass, for example). Right?

2) Wich frequency band does require best dynamic range? I hope it's bass, as it produces more SPL. But it's question of psycho-acoustics, so it could be midrange, where human ear has better resolution... Any suggestions?

3) Can i drive the Hypex UcD400HG module directly from BuffaloII current output, without I/V stage? If so, what modifications needed?

4) In case of using IVY III, what power supply topology can you recommend?
Is it enough 1 transformer 15-0-15V + 1 Placid BP PSU for feeding 2 IVYs ?
Or 1 transformer + 2 Placid BP PSUs ?
Or 2 transformers + 2 Placid BP PSUs ?
Or may be the better choice is LCDPS instead of Placid ?

5) What power supplies and transformers do i need to feed 2 * BuffaloII ?
Is it enough 1 transformer 9-0-9V + 1 Placid PSU ?

6) Are the hitsinks on Placid PSUs insulated from electronics? Or grounded?
I would like to screw it on Alu case...

You could just use three Mono Opus DACs per speaker. That would give you I2S in, direct balanced voltage-out to your Hypex amps, excellent sound quality, and far simpler power supply requirements. Just my 2 cents.

Ideally one would use the volume control inside the DAC. But most DACs can only accommodate two I2C addresses. Question: Can two DACs with the same I2C address be controlled by one I2C controller?

The best solution would be a multi-channel DAC like buffalo: Instead of using it as a two channel device, it can be used as an 8 channel device.

Because volume control is independently set for every channel, you can adjust the gain for each channel to match the efficiency of each speaker, and because the Sabre DAC is also a volage out DAC, it can feed directly into balanced amps such as Hypex

Question: any plans to release a multi I2S in and multi-out configuration of Buffalo?

Opus/WM8741 is also a good solution. If I2C addresses can be shared, then you can use 3 OPUS boards to handle the 6 channels.

However, the Buffalo only supports two I2C addresses...

Brian, I haven't read the data sheets of specific devices in detail, but this is from the description of: http://ics.nxp.com/products/i2cmuxes/

"I2C Multiplexing
Some specialized devices have only one I2C address and sometimes several of these identical devices are needed in the same system. The multiplexers and switches split the I2C bus into several sub-branches and allow the I2C master to select and address one of multiple identical devices, thus resolving address conflict issues."

So in theory you can address multiple devices that can only have a single I2C address. And low cost solutions such as one based on WM8741 can be built to accommodate digital crossovers up the digital chain.

Here is a part that can be used to multiplex the I2C addresses: http://www.nxp.com/docum.../data_sheet/PCA9544A.pdf



The PCA9544A is a 1-of-4 bidirectional translating multiplexer, controlled via the I2C-bus. The SCL/SDA upstream pair fans out to four SCx/SDx downstream pairs, or channels. Only one SCx/SDx channel is selected at a time, determined by the contents of the programmable control register. Four interrupt inputs, INT0 to INT3, one for each of the SCx/SDx downstream pairs, are provided. One interrupt output, INT, which acts as an AND of the four interrupt inputs, is provided.