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Forum Index : Microcontroller and PC projects : Cute little 2.1 amp for your PC...

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Grogster

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Posted: 06:59am 09 Jan 2023
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I got one of these from AliExpress during the Christmas holidays, and I am very impressed with it!

Link to amplifier...

This one has both a standard 3.5mm analog audio input socket, and also Bluetooth 5 wireless audio.

Considering it's absurdly cheap US$12 price, it works VERY well indeed.  With a 13.8v DC supply, it blows the room apart, with very nice control of both the sub volume AND the crossover frequency - a feature most 2.1 amps DON'T have, especially at this price point.

Comes as a sort-of knock-down kit, requiring some simple assembly, but you get all the bits including the knobs and even a DC-to-terminal adaptor thing for power supply and even a cheap screwdriver!  All this comes packed inside a nice cardboard box.

Audio is via 3.5mm plug or wireless BT5 connection, but NOT BOTH - one or the other.

Excellent insulated terminals for the speaker connections, and very cute panels with labelling etc on it.  Very impressive for twelve bucks!  

Windoze sees it as a "Stereo headphones", with an ID of WUZHI, which matches the name of the amp itself, so finding it and connecting to it was dead easy - not always the case with cheap BT stuff out of China.

I don't know how much faith I would put in the 50W+50W+100W rating, but it sure has plenty of grunt for a set of modest PC speakers or perhaps for your gaming rig.



Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Joined: 05/10/2019
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Posted: 08:45am 09 Jan 2023
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I think that this will ust about fit in that little Hammond 1593 case that I've been using. Might need a dremel to take the pcb supports off the top half.  :)

It's a rather nice looking little amp. Might have a radiated interference problem as it stands though. It'll be bridged class D but the speaker outputs appear to be unfiltered.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
phil99

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Joined: 11/02/2018
Location: Australia
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Posted: 11:45am 09 Jan 2023
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" It'll be bridged class D but the speaker outputs appear to be unfiltered."

If so connect the speakers with microphone cable. Shielded twisted pair.
 
Mixtel90

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Posted: 12:01pm 09 Jan 2023
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... and instantly the hi-fi aficionados will throw up their hands in horror! :)

I see they also do a "hi-fi" version of the amp that includes output filters. Well, they refer to it in the ad, but there don't seem to be any.
Edited 2023-01-09 22:07 by Mixtel90
Mick

Zilog Inside! nascom.info for Nascom & Gemini
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Grogster

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Posted: 07:11am 10 Jan 2023
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  phil99 said  " It'll be bridged class D but the speaker outputs appear to be unfiltered."

If so connect the speakers with microphone cable. Shielded twisted pair.


Brilliant idea.    

I never bothered to measure it's EFI, but perhaps I should try to dig out my EFI probe thing.  Bah.  Who cares.  
Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Posted: 07:28am 10 Jan 2023
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Who cares? Every radio amateur within a 50 mile radius. :)
Mick

Zilog Inside! nascom.info for Nascom & Gemini
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TassyJim

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Posted: 08:39am 10 Jan 2023
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  Quote    Bah.  Who cares.

You will if it interferes with one of your wireless links.

Jim
VK7JH
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Grogster

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Posted: 02:15am 11 Jan 2023
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OK, OK.
I'll see if I can find my EMI probe thing and test it.  
Smoke makes things work. When the smoke gets out, it stops!
 
hitsware2

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Joined: 03/08/2019
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Posted: 02:32am 12 Jan 2023
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Stick with class AB so as to have no concerns  
http://www.hitswares.com/
 
Mixtel90

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Posted: 07:25am 12 Jan 2023
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Even better, stick to class A. You'll have a nice room heater thrown in. :)

(My little headphone amp uses a paralleled ECC82 followed by a source follower class A  MOSFET for the output stage on each channel. It's lovely in winter.)
Mick

Zilog Inside! nascom.info for Nascom & Gemini
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Bill.b

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Joined: 25/06/2011
Location: Australia
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Posted: 10:15am 12 Jan 2023
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This model appears to have output filtering.
Amp





Bill
Edited 2023-01-12 20:19 by Bill.b
In the interests of the environment, this post has been constructed entirely from recycled electrons.
 
Grogster

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Posted: 04:02am 14 Jan 2023
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Nice find, Bill.
Thanks.  

EDIT: Further searching revealed this amp with filters for NZ$25, so I think I will just get one of those as that one has the filters on-board also.  Same company, same features, same knob layout etc, just with the additional output filtering.
Edited 2023-01-14 14:15 by Grogster
Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Posted: 07:33am 14 Jan 2023
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That's a beast! Cheap too. :)
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
Grogster

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Posted: 07:48am 14 Jan 2023
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The $12 one I have here now, kicks ass, BUT it HAS revealed some issues with the BT connection.

Once connected to some long-ish speaker leads, although it sounds fine, the BT keeps getting SERIOUSLY corrupted, and the audio sounds like it it underwater most of the time.  

Connecting via a hardline 3.5mm lead totally fixes this problem, so perhaps we do indeed have an EMI radiation problem - the speaker leads acting as transmitting antennas to some extent, which then swamp the BT connection.

I have not yet found my EMI test probes, but that is what I am thinking.
But with the new version with built-in filtering, I am hoping that perhaps the BT connection will work better.  If not, I can still use the hardline AUX input.
Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Posted: 07:55am 14 Jan 2023
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I bet it's radiating like mad. A flourescent tube or a neon might light near the speaker leads. :)
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
Grogster

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Posted: 08:15am 14 Jan 2023
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LOL!!!!      
Perhaps I will see if I can find a neon.
Might be easier then finding my EMI probes at this point.
Smoke makes things work. When the smoke gets out, it stops!
 
phil99

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Posted: 11:34am 14 Jan 2023
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You could always knock up a filter on some strip-board. If it won't fit inside just attach it to the terminals.
 
Mixtel90

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Posted: 11:53am 14 Jan 2023
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Too easy, Phil. :)  Ferrite beads & little caps are all that's needed to get rid of AM band RFI according to the data sheet.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
hitsware2

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Posted: 03:57pm 14 Jan 2023
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The switching going on in a P.C. itself degrades
audio enough , without adding switching in the amplifier .
http://www.hitswares.com/
 
Mixtel90

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Posted: 06:03pm 14 Jan 2023
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Not a problem in many cases. It was already degraded when you got it. First at the mixing desk then it went progressively downhill...

I have a little Class D (although the chip manufacturer calls it something else) amp here that I've been using for several years. Built from one of the Chinese modules. With a pretty meaty power supply and some local caps on it it sounds pretty good into some B&W DM4 speakers. Well, it does to me anyway and that's what matters. :)  It's being hopelessly under-run so there's masses of headroom available, which might help.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
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