Hi All,

As there are quite a few posts on here refering to the ISD4002/3 chips, some one must have had the same problem.

I am getting alot of hiss when the chip is in playback mode. I load clean audio onto the chip, when I play it back I get background hiss along with the audio.
I have been through most of the chipcorder application notes and carried out their tips. Such as, seperate digital and audio supplies, large ground planes, plenty of decoupling caps etc.

The components on the board are the recomended values in the isd4003 data sheets.
I am using a lm386 audio opamp which is one of their recommended audio amps into an 8ohm speaker. (I have the gain set to 20) I have built the amp circuit as per the lm386 data sheet, still cant get rid of the hiss.

I have also modified the pic software to remove the power up pops during the record mode.

The only other option I can see is to filter the hiss out. I dont have access to a scope, so I cant view the wave form. If it helps the hiss is like the noise you would get from a tape recording played very loud.

Any suggestions would be much appreciated.

Thanks for your time.

Nick