Frequently Asked Questions

Bits - Are the first bits in a resistor ladder? No.

Question: In the iDSD Pro, are the first 4 bits in a resistor ladder? Do you have a numeric value of how much of the signal that is?

Answer: 6 bit.

Why 6? That is how it is designed.

However, in the iDSD Pro we are running 4 actual DAC's in parallel with interleaving, meaning the net result is closer to 8 bit via multi-bit.

What it means the top 36dB (6bit) / 48dB (8 bit) are handled by a multi-bit architecture.

As delta sigma modulators struggle at high levels we are removing the main disadvantage of DS and we are avoiding the need for high order modulators.

Now multi-bit systems have the opposite problem of delta sigma, meaning the are not very good at very low levels and multi-bit struggles most at very low levels (around zero crossing).

By splitting low level signals off into a low order delta sigma modulator, you get the best of both worlds.

So the top 6-8 bit in iFi gear are processed as multi-bit including the option to apply no digital filter. The lower bits are processed as delta sigma over-sampled to what is in effect DSD256 (11.2/12.3MHz) again, it is possible to not apply any digital filtering.

This whole topic was covered here:

Around half way down the page, search for:

"The DAC chip we use in the iDSD nano offers a rather unusual way to handle things."

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