• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Did I get a faulty Unit from Douk Audio M1 Pro? Tear Down with Pictures; too much GLUE?

neptune134

Member
Joined
Jul 4, 2022
Messages
19
Likes
7
Hello ASR members this is my first post and I really hope to become more active in here as my audiophile quest continues.

I recently bought a DoukAudio M1 Pro bluetooth amp/dac, and when I connect to my JBL HLS Center speaker, no sound comes out. I have used this same speaker with my SMSL 50 and I know the problem isnt the speaker, or even the banana clip/wires im using. I took pictures of my set up with the M1, and also opened up the inside to get some good pictures of the inner components.

The M1 powers on fine, and is able to pair the bluetooth via my iphone and Fiio M15 without issue with the BT finding my devices (shows up right on my phone detected BT devices and it shows up quickly) however NO SOUND comes out of the speakers.

Im wondering if its something im doing wrong, or if the unit is faulty. The power supply seems legit, but I'll add that when I plug the power adapter into the device, there is a minor electric spark noise (without any sparks).

I also tried to add my SMSL 50 into the mix as a pre amp, and daisy chained the cables from the SMSL to the speaker outputs of the M1 Pro, but nothing, still no sound. Im wondering if this was a soldering issue, or maybe way too much glue on the copper coils inside, or something maybe in the pictures attached that Im not privvy enough to know of due to my clearly lacking electronic skills. I do have a brand new multimeter from Harbor Frieght, its a cheap $5 one, but I have no idea how to use it or apply it to see if the speaker outputs on the M1 have any current running through them.

Thanks in advance for your help, tips, advice and participation in helping me figure this out.
 

Attachments

  • IMG_2289.jpg
    IMG_2289.jpg
    18.7 KB · Views: 109
  • IMG_2290.jpg
    IMG_2290.jpg
    21 KB · Views: 105
  • IMG_2291.jpg
    IMG_2291.jpg
    25.3 KB · Views: 97
  • IMG_2292.jpg
    IMG_2292.jpg
    22.9 KB · Views: 107
  • IMG_2299.jpg
    IMG_2299.jpg
    17.3 KB · Views: 124
  • IMG_2298.jpg
    IMG_2298.jpg
    24.6 KB · Views: 830
  • IMG_2297.jpg
    IMG_2297.jpg
    22 KB · Views: 130
  • IMG_2296.jpg
    IMG_2296.jpg
    21.3 KB · Views: 99
  • IMG_2295.jpg
    IMG_2295.jpg
    23.1 KB · Views: 94
  • IMG_2294.jpg
    IMG_2294.jpg
    19.8 KB · Views: 93
  • IMG_2293.jpg
    IMG_2293.jpg
    20.7 KB · Views: 90
  • IMG_2300.jpg
    IMG_2300.jpg
    15 KB · Views: 99
  • IMG_2301.jpg
    IMG_2301.jpg
    25.5 KB · Views: 86
  • IMG_2302.jpg
    IMG_2302.jpg
    19.3 KB · Views: 87
  • IMG_2303.jpg
    IMG_2303.jpg
    261 KB · Views: 72
  • IMG_2306.jpg
    IMG_2306.jpg
    13.2 KB · Views: 74
  • IMG_2305.PNG
    IMG_2305.PNG
    223.2 KB · Views: 72
  • IMG_2304.PNG
    IMG_2304.PNG
    208.5 KB · Views: 78
  • IMG_2307.jpg
    IMG_2307.jpg
    12.7 KB · Views: 63
  • IMG_2308.jpg
    IMG_2308.jpg
    13.8 KB · Views: 75
  • IMG_2314.jpg
    IMG_2314.jpg
    15.9 KB · Views: 82
  • IMG_2313.jpg
    IMG_2313.jpg
    19.2 KB · Views: 87
  • IMG_2312.jpg
    IMG_2312.jpg
    17 KB · Views: 83
  • IMG_2311.jpg
    IMG_2311.jpg
    19.8 KB · Views: 92
  • IMG_2310.jpg
    IMG_2310.jpg
    20.4 KB · Views: 103
  • IMG_2309.jpg
    IMG_2309.jpg
    24.3 KB · Views: 94
  • IMG_2319.jpg
    IMG_2319.jpg
    16.6 KB · Views: 88
  • IMG_2318.jpg
    IMG_2318.jpg
    25.7 KB · Views: 87
  • IMG_2316.jpg
    IMG_2316.jpg
    21.1 KB · Views: 84
  • IMG_2315.jpg
    IMG_2315.jpg
    17.4 KB · Views: 79
  • IMG_2320.jpg
    IMG_2320.jpg
    20 KB · Views: 76
  • IMG_2321.jpg
    IMG_2321.jpg
    18.8 KB · Views: 71
  • IMG_2322.jpg
    IMG_2322.jpg
    17.1 KB · Views: 78
  • IMG_2323.jpg
    IMG_2323.jpg
    15.7 KB · Views: 108

NTK

Major Contributor
Forum Donor
Joined
Aug 11, 2019
Messages
2,657
Likes
5,820
Location
US East
Don't know if the Douk M1 Pro is designed so that it can operate with both channels driving the same load connected together (in parallel).

Have you tried connecting your speaker to only one channel (you can test by disconnecting one of the channels, and make sure the dangling disconnected wires don't touch each other)?

Another question is how do you connect the Douk to its source signal?
 
OP
neptune134

neptune134

Member
Joined
Jul 4, 2022
Messages
19
Likes
7
Thanks for the quick response! I’m not sure what parallel means, but when you say to only use one channel, does that mean I should only plug 1 of the red and 1 of the black from the back of the DoukAudio M1 50? Would that be bottom two or top two? As far as the source I’ve used the Bluetooth feature, as well as the usb source.

I’m not sure what else to try. Am I not supposed to use all 4 of the speaker connectors in the back of the M1? The speaker says it’s JBL Center 8ohms. The documentation and video reviews show it powering more powerful and bigger type speakers.

What should I test or which part of the interior should I test with the multimeter to see if for some reason the speaker inputs in the back are maybe not working/not soldered properly and if it has any charge power to it?
 

NTK

Major Contributor
Forum Donor
Joined
Aug 11, 2019
Messages
2,657
Likes
5,820
Location
US East
Try to connect to your speakers with only the left channel. Disconnect the right channel and don't let the dangling wires touch each other.

No. You are not suppose to connect all 4 speaker connectors to a single speaker. The amplifier is designed to drive 2 separate speakers (stereo speakers).
douk.jpg
 
OP
neptune134

neptune134

Member
Joined
Jul 4, 2022
Messages
19
Likes
7
Awesome, I will try that when I get home. So connecting all 4 as I did (the wrong way) does that always result in absolutely zero sound coming out? Wouldn’t there be a distortion or at least some mumbled static? When I connect the smsl 50 pre amp/dac, I’ve been connecting it using all 4 and it does work perfectly.

Thanks for the advice, looking forward to trying that.

As far as in the inner circuitry, does any thing look off or questionable?

If I try your solution (and I hope that solves it cause it’s driving me crazy) and it still doesn’t work, what would my next trouble shooting step be?
 

NTK

Major Contributor
Forum Donor
Joined
Aug 11, 2019
Messages
2,657
Likes
5,820
Location
US East
When you connect the left and right output channels of amplifier together (to a single speaker), you don't get a summation of the two channels (i.e. you don't get a mono output from stereo). Unfortunately, it is not how amplifiers work.

If connecting you speaker to only one channel doesn't work, you probably have a dead amplifier.

BTW. Welcome to ASR :)
 
OP
neptune134

neptune134

Member
Joined
Jul 4, 2022
Messages
19
Likes
7
I appreciate the warm welcome. I’ve lurking for awhile, and reading reviews before I go in on anything. Was disappointed the FiiO Qs5 and the THX amp module AM3D didn’t really live up to the expectations on the graph.
 
OP
neptune134

neptune134

Member
Joined
Jul 4, 2022
Messages
19
Likes
7
...and no luck. This really sucks, its the first time I get burned on an item like this. I didnt spend a whole lot, and the reviews on Amazon should have strayed me off but i thought it was perfect for my needs from the advert. How the heck do they have the audacity to put 2 QA stickers on the thing?

Not sure what else to try, but just for kicks does anyone out there know how I can find the real issue with the use of a multimeter, and maybe I can re-solder this POS together?
 

sam_adams

Addicted to Fun and Learning
Joined
Dec 24, 2019
Messages
976
Likes
2,368
You see this:

index.php


as @NTK said above, you connected both the right and left channels together. That's not how this amplifier is supposed to be connected to speakers. You probably blew the amp.
 

NTK

Major Contributor
Forum Donor
Joined
Aug 11, 2019
Messages
2,657
Likes
5,820
Location
US East
...and no luck. This really sucks, its the first time I get burned on an item like this. I didnt spend a whole lot, and the reviews on Amazon should have strayed me off but i thought it was perfect for my needs from the advert. How the heck do they have the audacity to put 2 QA stickers on the thing?

Not sure what else to try, but just for kicks does anyone out there know how I can find the real issue with the use of a multimeter, and maybe I can re-solder this POS together?
Sorry to hear that. I was hoping the amplifier chip's (which I think is ST TDA7498E) protection circuit may be able to save itself. Apparently not.
 
Top Bottom