ZAPfilter instalation in Philips DVD963SA

[skza]

Hello,

I have tried to install ZAPfilter from LC Audio (http://www.lcaudio.com/index.php?page=6) in Philips DVD963SA according to connection diagram in LC Audio website (diagram 2, for differential current output DAC):
http://www.lcaudio.com/index.php?page=43

DAC is AD1955 (differential current output) in DVD963SA.

AD1955 data sheet:
http://www.analog.com/UploadedFiles/Data_Sheets/422968845AD1955_0.pdf

It seems to be OK, but signal output level from installed ZAPfilter is very low (comparing to original analogue stage).

Any ideas how to solve this problem?
Is it DAC mismatch with the connection offered in LC Audio website?

Original analogue stage in DVD963SA player is similar like shown in data sheet for AD1955 (fig.9).

Thank you beforehand.

Skirma

 

[skza]

... and yes, schematics of ZAPfilter mk2 used:
http://www.lcaudio.com/zf2dia.gif

Skirma

 

[tongwi]

Hi Skirma,

I installed the Zapfilter into my Philips 963SA 2 weeks ago. The output level is low for mine as well.

I guess the AD1955 is not quite compatible for the Zapfilter. However, the sound is very nice. It is more open, transparence, execllent image and tighter bass. You may need a larger gain preamp for it.

The other alternative might be connect the input of the Zapfilter to the output of the IV conversion op-amps (AD8022) in voltage mode. I did not try it because I want my player op-amps free.

William

 

[Extreme_Boky]

Hi guys,

You DAC is differential Iout type, so I presume you followed the instructions about shorting 1,3,4,5 and 7. You should also insert 33ohm resistor in series with + and with - current feeds to ZAPfilter.

The output of this filter is balanced and using only one half referenced to ground would mean 4 times less output (I'm a bit lazy today – Friday!!! but I think this is correct). You may have to consider balanced to single ended converters (balanced to unbalanced).

Good luck,
Extreme_Boky

 

[skza]

Hi William, Extreme_Boky.

Thank you for opinions and ideas.

1,3,4,5 and 7 are shortened.
I am using only one half of ballanced output refferenced to the ground. Ok, maybe, thats the reason for the low output signal.

By the way, I haven't inserted 33ohm resistors in series with + and with - current feeds to ZAPfilter. What is the meaning of these resistors?

Skirma

 

[Duck-Twacy]

Hi guys,

You DAC is differential Iout type, so I presume you followed the instructions about shorting 1,3,4,5 and 7. You should also insert 33ohm resistor in series with + and with - current feeds to ZAPfilter.

The output of this filter is balanced and using only one half referenced to ground would mean 4 times less output (I'm a bit lazy today – Friday!!! but I think this is correct). You may have to consider balanced to single ended converters (balanced to unbalanced).

Good luck,
Extreme_Boky

Just a little hijack of this old post.

I have a Zapfilter 2 installed is a Sony SACD555ES (European version, voltage out DAC) with the balanced output (didnt install it myself). However it seems to output 5V, which is a bit too much for my pre-amp.

What can be wrong?

 

[Extreme_Boky]

That's balanced out - not single ended output; therefore you'll have higher output between + and - signal wires.

You may have to use balanced to single-ended 'converter' or play with the gain either in ZAPFilter or in your pre-amp (amp?).

Why use ZAPFilter? They sound horrible (sorry, my opinion)... I puled out 2 so far installed by someone else, and replaced with AD826 / AD8066 / OP275 with high quality components around them, and straight (pure silver ribbon) wiring from IC's output to RCA's (XLR's) connectors. Can't get silver ribbons? Try copper ribbons! - cut them yourself. Copper does not need to be heat treated.

Cheers,
Extreme_Boky

 

[Duck-Twacy]

Thanks you for your reply. On the single ended output it is 3.9V PP

Still a bit too much imo.

 

[tongwi]

Trick for the Zapfilter installation on AD1955

Hi Skirma,

I have fixes the low output problem for my player. The AD1955 current outputs need bias current in order to work. The voltage for each current output (for the ad1955) to ground should have around +2V.

You need to connect a 6k8 ohm resistor between the pin 13 (filter R) for the AD1955 to the -8.5V of the power supply section for the Zapfilter. After the connection, you should have around 1.8V between each output (for the AD1955) to ground. It should fix the low output problem.

Before connecting pin 13 to the Zapfilter, the voltage for each output to gound is about 0.2V which is not enough, and that's why you have very low output volume.

Note: The Zapfilter takes around 20 second to start for this connection.

Please be careful about this connection. I have no responsibility for any possible damage you have made. I just want to share to others for what I have done that's work for me.

William

 

[tongwi]

Correction for the fixes!

Hi All,

I just got the response from Lars.

The bubbles 4 for the zapfilter should not be soldered, and then connect pin 13 of the AD1955 to the ground inputs for the Zapfilter. Not connecting the analog ground to the zapfilter.

Also change IREF resistor (at pin 14 for the AD1955) to 5k6.

Please forget about connecting the pin 13 of the AD1955 to the -8.5V power supply section for the zapfliter, this is not corrected!

William