simple stereo audio amplifier for streaming video box

[johnsmith123]

Hello everyone,
I hope you are all staying safe.
I have been watching more TV these days than I would like to admit.

I have a media player that uses composite inputs on my TV.

Sometimes streamed video audio output is extremely low, even with the TV volume at MAX.
Sometimes downloaded videos have the same problem.

I have been able to get around this by connecting
computer desktop speakers to the output of the media player and using the headphone jack to connect the cables going to the TV.
This way the sound is muted in my computer speakers going directly to the TV.

In other words, I am using the amplifier in the computer speakers to boost the audio before it gets to the TV by increasing the volume
on the computer speakers to MAX. It works, however I don't want the clutter of all of the wires, speakers, etc near the TV.

I don't want a sound bar.

I tried these modules and they work, but if both channels are connected (right and left), the module gives a clipping sound even when using a 2A power supply.
Works great if only one input is connected, so I would need two of these.

Anyone have any advice?
I am looking for a very small, very simple and very INexpensive inline amplifier (or preamp) for my composite audio output.

For now I just removed the small amplifier board from the computer speakers and it works.
I am hoping to get something smaller to fit behind the media player or some small module that I can hide inside the cable.
I don't want an amplifier that uses a large power supply.

Any friendly advice is greatly appreciated.

 

[AnalogKid]

You don't need a speaker amplifier per se, just something that will take line level in and give you boosted line level out. Do you want to buy or build?

To build, the circuit would be one 8-pin dual opamp chip plus some resistors, capacitors, a dual-gang volume control, and either connectors of direct-soldered input and output wires. The whole thing for both channels would be the area of a matchbook. With the right chip it will run on a single 5 v supply, but it will be happier with 12 V. For either a purchased or home-built device, what power sources (wall warts) do you have available?

If you want to buy, are you looking for just the pc board assembly, or something fully packaged with a box, knob, input and output jacks, etc?

AND - ebay has a ton of "audio preamp" modules based on the LM386 chip. The 386 is a low power speaker amplifier, with very low sound quality in a preamp application. I recommend staying away from these.

ak

HEY - lookee what I found:
**broken link removed**

 

[johnsmith123]

thanks for responding,

I am looking for a pre built unit or module, I don't want to build one or assemble a kit.
The ebay link looks good however the seller does not ship to Canada (I'm in Canada)

I have lots of walwarts and USB (5V) power supplies.

what do you think of this DC 5V-15V 12V AD828 Stereo Preamp Power Amplifier Board Preamplifier Module?

 

[AnalogKid]

The link was to a used one. New ones are available on ebay and Amazon. More money, but available to you.

The module uses a part intended for video applications, but it should be fine for you. Note that it has no provision for adjustable gain. That can be worked around, but the design intends for gain to be set by adding resistors in the pads near R5 and R7.

ak

 

[johnsmith123]

The module uses a part intended for video applications, but it should be fine for you. Note that it has no provision for adjustable gain. That can be worked around, but the design intends for gain to be set by adding resistors in the pads near R5 and R7.

thanks again, i can adjust the volume on the TV. It did work ok with the PAM8403 module without an adjustable gain control, only not on both channels.

 

[AnalogKid]

I misunderstood. I thought you wanted to boost the signal only when it is too low. Now it sounds like you want to boost all signals, then turn down the extra-loud ones with the TV volume control. If so, then a possible drawback is that the already-loud-enough signals might overdrive the TV audio input circuits and distort. No circuit damage, just an audio quality thing.

ak

 

[johnsmith123]

Yes I see your point. If there is distortion, a gain adjustment will be required.
So far there is no distortion with the other modules I have tried, however a louder video might cause problems.

thanks for your help

 

[Nigel Goodwin]

I imagine the issue is with 5.1 programmes?, when down-mixed to stereo they are always quiet, because you're squeezing 6 channels down to 2, so to avoid the chance of exceeding the output levels it's set quieter than you would wish.

It's always been a big problem with DVD Players, with the 5.1 versions having very quiet stereo output to a TV.

Presumably all he needs is a simple opamp preamplifier, to give some extra gain, rather than a small power amplifier.

 

[audioguru]

The cheap preamp module from AliExpress has absolutely NO detailed spec's. The sales sheet does not say if it has ANY gain.
You might need to add the optional resistors to give it some gain.

 

[AnalogKid]

It looks like it has two locations for externally-added through-hole resistors, either in parallel or in series with SMT resistors at the same locations.

ak

 

[johnsmith123]

thanks to everyone for responding.
I did order the RED preamp boards from the link above. I will post my results when they arrive.

 

[johnsmith123]

Received the red preamp modules. Just want to update my post.

They are working with just the factory installed 1K resistors for gain control.
The only thing I had to do was solder in RCA plugs on both ends and a USB plug for power supply.

So the preamp takes power from the media players USB jack.
There is no distortion, i can adjust the volume on the TV.

Thanks to everyone for responding to my post.