speaker isolation
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Posted by Ivan Sedneff on January 30, 2006, 6:50 pm
Please log in for more thread options Hello, I made a portable enclosure for a car radio that has a negative ground but the left and right speaker outputs have isolated grounds from each other and the chassis. I needed to common out the (-) from the left and right speakers in order to attach them to the common connection on the headphone jack. I successfully connected each of the (-) outputs from the left and right speakers using non-polarized 47 uf electrolytic capacitors and joined the ends of the caps to the headphone jack. All is well when the jack is floating and un mounted, but when I mount the jack to the chassis, even though the audio output is great, I get annoying loud "clicks" and "pops" when I wiggle the headphone plug/jack, most likely because of the caps discharging/charging. Other than figuring a way to physically isolate the headphone jack from the chassis, is there a way to drain the charge using resistors, and if so, what values do you suggest? Thank you for your help, Ivan | |||||||||||||||||||
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Posted by Joseph2k on February 1, 2006, 1:35 am
Please log in for more thread options Ivan Sedneff wrote: The speaker outputs from the car stereo are H-bridge type, the return is not grounded but driven. Grounding any lead / part of it will eventually ruin the car stereo output amplifiers. The headphone jack is an even more exotic circuit. Float all the output terminals and just live with it. -- JosephKK Gegen dummheit kampfen Die Gotter Selbst, vergebens. --Shiller | |||||||||||||||||||
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Posted by Meindert Sprang on February 1, 2006, 1:56 am
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> Oh boy.
not
> The speaker outputs from the car stereo are H-bridge type, the return is > grounded but driven. Grounding any lead / part of it will eventually ruin
> the car stereo output amplifiers. The headphone jack is an even more > exotic circuit. Float all the output terminals and just live with it. If you only need to drive a headphone, you don't need the full power the brigde can deliver. What you can do is connect the each speaker "+" output through a electrolytic capacitor (+ to the output) to the L and R channel of the headphone and connect the common of the headphone to the *ground* of the radio (not to either "-" of the speaker outputs). This way, you only use half of each output bridge. Meindert | |||||||||||||||||||
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>
> I made a portable enclosure for a car radio that has a negative ground
> but the left and right speaker outputs have isolated grounds from each
> other and the chassis.
>
> I needed to common out the (-) from the left and right speakers in
> order to attach them to the common connection on the headphone jack. I
> successfully connected each of the (-) outputs from the left and right
> speakers using non-polarized 47 uf electrolytic capacitors and joined
> the ends of the caps to the headphone jack.
>
> All is well when the jack is floating and un mounted, but when I mount
> the jack to the chassis, even though the audio output is great, I get
> annoying loud "clicks" and "pops" when I wiggle the headphone
> plug/jack, most likely because of the caps discharging/charging.
>
> Other than figuring a way to physically isolate the headphone jack
> from the chassis, is there a way to drain the charge using resistors,
> and if so, what values do you suggest?
>
>
> Thank you for your help,
>
> Ivan