>I'm missing sound of some instruments or voice when playing CD's. Even duplicate CD's, when played, I'm missing some digital information or not having it picked up some where. For instance, the lead guitar part in a song may be totally missing or on other artists' recordings barely audible. It can be voice, horn, reed, string, etc., but it's always the same instrument even when played on another copy of the same CD.
>Maybe the laser in the CD is dirty? HELP. Thanks
No. That will get you static and perhaps rhythmic clicks as it fails to correct errors but can't remove individual frequencies let alone instruments.
The plausible explanations are that you're getting acoustic cancellation between multiple sources or are missing output from one or more drivers.
Polarity could be getting flipped in one place but not another. Maybe you have one channel out of phase with the other and are getting diffuse + quiet center images. Some amplifiers have the output terminals as mirror images of each other, some don't (makes it easy to use a dual banana plug for bridged operation). Maybe you have the connections reversed on one of the cable runs headed to one speaker and are getting cancellation in frequencies around the cross-over frequency. Maybe some one screwed up replacing a driver or at the factory and got the cross-over connections backwards inside (it's happened to review samples).
Perhaps you aren't getting enough gain from one tube so a set of drivers is quieter in one speaker. Maybe 12AU7/12AT7/12AX7 tubes have been substitute for one with more gain (same size, same pinouts, each one just has progressively more gain with mu of 20, 60, 100). Maybe a solder joint has broken in a cathode resistor bypass so you're getting local feedback in a tube which wasn't intended so there's less gain.
You need to measure (make a test CD, or hook a computer up to the stereo) and see what's going on.
Feed test tones > 200 Hz to each side separately and measure with your SPL meter. They should be about the same. Play them in stereo. They should be 3-6dB louder. Measure the output at the amplifier terminals with a DVM. For a given input level it should be about the same at all four outputs.
>Maybe the laser in the CD is dirty? HELP. Thanks
No. That will get you static and perhaps rhythmic clicks as it fails to correct errors but can't remove individual frequencies let alone instruments.
The plausible explanations are that you're getting acoustic cancellation between multiple sources or are missing output from one or more drivers.
Polarity could be getting flipped in one place but not another. Maybe you have one channel out of phase with the other and are getting diffuse + quiet center images. Some amplifiers have the output terminals as mirror images of each other, some don't (makes it easy to use a dual banana plug for bridged operation). Maybe you have the connections reversed on one of the cable runs headed to one speaker and are getting cancellation in frequencies around the cross-over frequency. Maybe some one screwed up replacing a driver or at the factory and got the cross-over connections backwards inside (it's happened to review samples).
Perhaps you aren't getting enough gain from one tube so a set of drivers is quieter in one speaker. Maybe 12AU7/12AT7/12AX7 tubes have been substitute for one with more gain (same size, same pinouts, each one just has progressively more gain with mu of 20, 60, 100). Maybe a solder joint has broken in a cathode resistor bypass so you're getting local feedback in a tube which wasn't intended so there's less gain.
You need to measure (make a test CD, or hook a computer up to the stereo) and see what's going on.
Feed test tones > 200 Hz to each side separately and measure with your SPL meter. They should be about the same. Play them in stereo. They should be 3-6dB louder. Measure the output at the amplifier terminals with a DVM. For a given input level it should be about the same at all four outputs.