Sorround Sound distorted sound issue

[Juako]

Hi.

I have a problem with sourround sound. Every time I turn the option of sorround sound on, sounds segments like big explosions or heavy sounds get distorted. But that happens only when I turn on the 7 band graphic stereo equalizer for better sound. I just want to know if I can use an equalizer when I use sorround sound or I just can't because Dolby Pro Logic sorround its already equalized?

My equipment is pretty outdated, it's from around 1996. I have a Technics stereo receiver SA-GX690 and a Technics Stereo Graphic Equalizer SH-G50 plus a Stereo Cassette Deck to be able to connect the equalizer.

The only time I can use the graphic equalizer with perfect sound is when I use only the two main speakers to listen to normal music that is not sorround sound.

If any sound expert can clarify me of why I get distorted sound when using a graphic equalizer plus sorround sound, it will be gladly appreciated.

Thanks

[JimJohnD]

Dolby Pro Logic depends on the "Phase" of the audio from a stereo signal. Your EQ is most likely messing it up to the point the decoder dosn't know what to do with it. It has to do with the way ProLogic is mixed into a stereo signal. Some EQ circuits adds a slight delay to the signal as it passes through the filters. If the delay isn't exactly even (or close to it) for both the left and right channels it will degrade the signal to the point where the ProLogic steering logic will turn it into mush.

[Kurt S]

Another problem is that many/most EQ's can really clip the preamp levels and that's what is causing the distortion. Instead of boosting the quiter frequencies, try the subtraction method and reduce the predominent frequencies.

[Juako]

By reducing the predominent frequencies, you mean adjusting the 7 band EQ to 0 or below (meaning -DB)?

[Kurt S]

Yes, adjust the louder frequencies to be softer instead of boosting the quiter ones.

In other words, let's say you are listening to audio that doesn't have enough bass to it. Instead of boosting the bass, try cutting the midrange and treble frequencies a little.

Some equalizers also have a master volume control for each channel. If you have that option on yours, try turning down the master volume a little.