ISD4003 Noise Problem

[mister_e]

bah, to make things simple, try few capacitor values in parallel with your LM386 input first. Try a range on 0.01-0.1 uF. You may find something interesting is this range.

Low-Pass between 6Khz-10Khz will remove most hiss noises... and more

A scope will be useless in this case, you need a Spectrum analyser (hardware or software)

[JoelMurphy]

I've played around with the ISD series a bit for a client. They are amazing chips, but the audio quality is not so good if you get it right out of the can. Filtering is crucial. A good source for that and more [so much more] is Paul Sherz's book: Practical Electronics for Inventors. Widely available. But note, there are some amazingly emberassing typos.

[Agent36]

Hi,
Thanks for the reply. I will try and source that book, it sounds like I can use it for other projects and problems.
I am still having problems with noise, do you have any info on the filter part of your isd4000 designs. i.e what type of filter and values, basicly anything will help. I solved every other problem i've had on this project, it does every thing I want.

thanks for your time

Nick

Found that book!! just ordered it, thanks...

[Agent36]

Hi,
Is there anyone that has access to a Spectrum analyser? I still have noise issues with the isd4002. If possible can someone look at the wav file using a Spectrum analyser then tell me what frequencys I need to filter. I am unable to upload the file. If you can pm me with your email i'll email the wav file.

kind regards
Nick

[mister_e]

Yup i have few of those here. You could still try some Software solutions too.

try TrueRTA and Visual Analyser, to me, they look good for some freeware.

Visual Analyser
http://www.sillanumsoft.com/

TrueRTA
http://www.trueaudio.com/

I didn't used them, i use Smaart Pro, SpectraLab and/or a good ol' Klark-Teknik DN60 RTA for my studio or on the field PA rig tune-up.

[Agent36]

Thanks for the links, I have downloaded the visual prog, going to try it later this week when I have time.

Regards
Nick