amp board for 2x15w 6Ω speakers

oppressor

Member
2019-12-16 3:17 am
Hello everyone,

I salvaged 2 speakers (SX-JN1) from an old AIWA CX-JN1 sound system (probably more than 15 years old) and I want to use them connected to my laptop at home.

The speakers are rated 15w RMS 6Ω and they work fine, they sound a lot better than the laptop's built-in speakers.
Need advice in choosing a cheap (€10-12) amp board from Aliexpress, something that will require as little soldering as possible.

But I don't know what audio IC should look for, I've seen most cheap amp boards built with PAM8610, someone recommended NE5532 and TDA7492P.

What do you guys think?
 

oppressor

Member
2019-12-16 3:17 am
I looked at that amp board and it's stated: "Output power: 5W 2Ω 5V /3W 4Ω 5V /1.8W 8Ω 5V"
My speakers are rated 6Ω, that means the output from the amplifier will be a little over 2W/channel ?

Can you please recommend something closer to 10-15W ? It doesn't have to be USB powered, external power supply will be fine.
 

oppressor

Member
2019-12-16 3:17 am
Thank you for your recommendations.

How do I prevent the amp board from burning my speakers, since the recommended boards are more powerful than the 15W rating of my speakers?

This may sound silly, but is the amp board's output linear ? For example if I turn its volume to 30% will that output only 30% of the watt rating of the amp (taking into consideration the impedance of the speakers and the voltage of the power-source) ?
 

oppressor

Member
2019-12-16 3:17 am
@asuslover plug & play would be nice, maybe the only soldering I would have to do will be attaching speaker and power-source wires to the board.
I also have at home several power sources of 12V/1A (left-over from some surveillance cameras kits).

I think Lm1875 or LM3886 boards are outside my budget (or not ?) of 10-12 EUR.

I don't want to spend more than this since this is my first DIY project and if it's successful (no smoke from either the board or speakers) I will probably donate the speakers to the local charity and just go an grab myself a pair of these: R980T - Powered Bookshelf Speakers - Edifier International
I can get them for 44EUR new.

I just want to feel good about salvaging those old speakers (that still work after so many years) and don't want to do a half-*** job.
 
@asuslover plug & play would be nice, maybe the only soldering I would have to do will be attaching speaker and power-source wires to the board.
I also have at home several power sources of 12V/1A (left-over from some surveillance cameras kits).

I think Lm1875 or LM3886 boards are outside my budget (or not ?) of 10-12 EUR.

....


here is a 2 $ kit per channel = 4 $
eBay mono LM1875 kit


chris
 

oppressor

Member
2019-12-16 3:17 am
@rabbitz thanks for advice.

I did a quick search on Aliexpress for "TPA3116D2", lots of results, I assume many are using fake chips?

Any advice on how to recognize them?
Or what should I avoid / look for, to increase my chances in getting a good board ?

Or if you can, please, provide a few links from Aliexpress/eBay with cheap-ish TPA3116D2 boards that seem (at least from pictures & description) to have a decent implementation.
 

pitbul

Member
2011-07-29 9:34 am
@oppressor; TPA3116 AMP, if you use 12V/5A power supply you will not produce declared output power, so You are in safe margin, don't worry.
With 12V You will have 6W on 8 ohm speaker or about 12W on 4 ohm speaker.
If amplifier will not clip, your tweeters are safe...
 

Yes, that's the one. There are others around with yellow caps and SMD resistors that are used instead of the MF resistors, not as good as the original.

I run mine at times with a 12VDC 2A power supply and had no issues and supplied plenty of power so it's tolerant of low power supplies.

There's also the lower power TPA3118 but I have no experience with it.
 
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So, the LM1875T board I noticed it is mono, not stereo.
How should I connect the speakers to the amp board? In series or in parallel ?

For stereo sound I would need 2 mono boards ?
One for right channel, one for left channel and both connected to stereo ground ?


hi oppresor


yes -you would need 2 boards a transformer, a rectifier..to power up these LM1875 boards. yes you have to connect the right and the left channel to the signal ground. but to be honest - the TPA3116 is a very good chip for that price - and i have modded 2 amps and its a buck for the money and as rabbitz wrote it is much easier to connect this amp to a single power supply and you get a power amp. just do not operate this class D boards without load connected - the output filter could ring excessively and you will destroy the amp.


chris