AD1955 audio out and I/V

[matejS]

Hi, all!

I am studying AD1955 analog out and datasheet says:

For best THD + N performance over temperature, a reference voltage of 2.80V should be used with the I/V converters. For a lower parts count, the voltage at FILTR can be used.

From all the schematics I have seen until now (AD1955 evaluation board, Anagram Sonic2) they all use FILTR, which is ~2.39V. Did anyone sonically compared these solutions?

... I've been also thinking of using Zapfilter as active I/V (any better suggestion?). Any experience with Zapfilter and AD1955? Note that Zapfilter's GND should be 2.8V reference and not connected to the GND.
Did you change IREF resistor (at pin 14 for the AD1955) when using Zapfilter (i.e. to 5k6)?

Thanks,
Matej

[georgehifi]

Harman Kardon HD970 uses the AD1955 in the same way as the AD Eval Board, and I second Lance's description it is stunning.
http://www.diyaudio.com/forums/showt...27#post1261027

I have also have a AD1955 Eval board but not modded it yet.
http://www.diyaudio.com/forums/showt...02#post1382102

Cheers George

[matejS]

Originally posted by georgehifi
[B]Harman Kardon HD970 uses the AD1955 in the same way as the AD Eval Board, and I second Lance's description it is stunning.
http://www.diyaudio.com/forums/showt...27#post1261027

Yes, that config. looks great! I've just bought HK970 - very good player for the money if you know what is inside. Zapfilter is one way to go, but it rather pricey... and this is why I wanted to check before buying it. Do you use Zapfilter?

Cheers,
Matej

[analog_sa]

Originally posted by matejS


Zapfilter is one way to go, but it rather pricey...

It will stop being pricey if you build it yourself.

[matejS]

You are right
And if "customized" for AD1955 it can be even better and in DIY spirit

Still, I would not go and clone it ("stealing" intellectual property is my way; the author deserves to be given some credits and time is precious). I wonder how it could be improved/simplified...


Cheers,
Matej