Author Topic: 38W x 2 stereo amplifiers  (Read 3931 times)

Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #60 on: August 29, 2017, 09:52:46 PM »
Does it make the noise with no input plugged in?
What power supply are you using, battery bank is the best.

My little chip amp cost around R70 and it sounds great, dead quiet other than the power on popping noise.
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Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #61 on: August 30, 2017, 07:12:59 AM »
Does it make the noise with no input plugged in?
What power supply are you using, battery bank is the best.

My little chip amp cost around R70 and it sounds great, dead quiet other than the power on popping noise.

It makes the noise with nothing plugged in, yes.  The Aux in I found out seems to be dead on the right-hand channel anyway.  The speaker plop is TERRIBLE - I already requested a refund as well.  It's currently running off a laptop charger modded to fit the amp.

Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #62 on: August 31, 2017, 12:21:14 AM »
I'd first try another power supply but with no input plugged in it should be very quiet, dodgy power supplies do typically come into play when an input is connected and some kind of ground loop starts causing hum etc.
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Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #63 on: August 31, 2017, 07:47:52 AM »
I'd first try another power supply but with no input plugged in it should be very quiet, dodgy power supplies do typically come into play when an input is connected and some kind of ground loop starts causing hum etc.

Nah I requested the refund and immediately got it.  They admitted it's not supposed to do this.  Check the speaker plop when switching it on, I made this video to show them what's happening:

https://www.youtube.com/watch?v=ec2stTVysgk

Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #64 on: September 01, 2017, 02:00:10 PM »
Did you make the case, looks great?

I built mine into a tupperware type container
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Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #65 on: September 01, 2017, 02:12:35 PM »
Did you make the case, looks great?

I built mine into a tupperware type container

Nah the little case came with the amp.  The order was supposed to come with additional heatsinks and heatsink compound and an assembly kit and everything, but most of this was all missing.  No instructions, no markings, nothing.  I had to guess to see what the stuff is, it's typical cheap Chinese manufacturing.

As a PS, does yours also make this noise that mine does?

Offline gov

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Re: 38W x 2 stereo amplifiers
« Reply #66 on: September 01, 2017, 06:28:10 PM »
Have the same board....there is a work around to get rid of the speaker plop....it doesn't make it perfect but its 95% gone.

Two of the smd resistors need to be changed.

Will post the link once I find it

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Offline gov

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Re: 38W x 2 stereo amplifiers
« Reply #67 on: September 01, 2017, 06:32:13 PM »
http://www.diyaudio.com/forums/showthread.php?t=290949

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Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #68 on: September 02, 2017, 02:15:11 PM »
Nah the little case came with the amp.  The order was supposed to come with additional heatsinks and heatsink compound and an assembly kit and everything, but most of this was all missing.  No instructions, no markings, nothing.  I had to guess to see what the stuff is, it's typical cheap Chinese manufacturing.

As a PS, does yours also make this noise that mine does?
Running off a power bank it's absolutely silent, using a power supply if I remember correctly did add some residual noise.
Music is in the Mind

Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #69 on: September 04, 2017, 07:06:41 AM »
http://www.diyaudio.com/forums/showthread.php?t=290949

That's awesome, thanks man, will give it a look!

Running off a power bank it's absolutely silent, using a power supply if I remember correctly did add some residual noise.

What kind of power bank are we talking about?  I'm running it off 18VDC since it wants something higher than 9V IIRC?

Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #70 on: September 06, 2017, 12:03:49 PM »
I got one of the ones Wolla recommended that can run off voltages down to 5v, I use a normal USB powerbank/5v
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Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #71 on: September 06, 2017, 01:26:30 PM »
I got one of the ones Wolla recommended that can run off voltages down to 5v, I use a normal USB powerbank/5v

I also have one of those, but it's completely different to the one I'm having issues with.  The one I'm having issues with is a 50W + 50W stereo Bluetooth amplifier that was reported to have "good quality audio" and all that.