Headphone amplifier ground issue

[doug young]

I bought a little amp on Amazon a Pyle PLMP 35. I want to use it to amplify some headphones. I connected a 3.5mm stereo female jack to the speaker output terminals (one negative and one positive for each channel), which requires a common ground for both channels. When I do that, I get distortion and interruptions at low volume, and pretty poor quality at higher volumes. The power LED also flashes at low volumes. If I connect only one channel at a time, it sounds OK, not great, but OK on that channel. Shouldn't I be able to connect the grounds in common to the speaker outputs?

If not, what do you recommend? I cannot separate the grounds on the headphones because they are wired together at the male 3.5mm jack.

Incidentally, the input for this amp is a 3.5mm stereo female, which of course has common grounds for the stereo channels.

This is the 2d one I have tried with the same results, so I don't think the amp is defective.

Thanks
Doug

[mod note ... image deleted as it didn't show any information]

 

[dorke]

Welcome to EP,
Please post a diagram showing what you did.
Why on earth would you connect a 3.5mm plug to the output?

 

[doug young]

Why on earth would you connect a 3.5mm plug to the output?

so I can plug headphones into it. It is intended to be a headphone amplifier, like the title says.

I can't post a picture right now, but the output side of the amplifier has four terminals, a plus and a minus for each output channel. I soldered the wires that plug in to the minus terminals together and to a common ground on the female 3.5 mm plug, and soldered each of the other two wires to its own lug on the female plug. It's just like what you would find if you took the headphone jack apart.

 

[dorke]

Sounds like it is a Power Amplifier to drive speakers.
You can't connect headphones directly to a speaker output,
you will damage the headphones !
Please post the datasheet or direct link to it.

 

[BobK]

That is likely a bridged amplifier, neither of the speaker terminals is at ground, so they cannot be connected together.

And it is WAY overkill for a headphone amp unless you want to shake your brain loose.

Headphone amps are typically under 1W.

Bob

 

[CDRIVE]

Is this is what you purchased for headphones??
PYLE PLMPA35

Chris