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  • Karaoke Lewinner-L699

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ID:	945056 To display my art of whistling to Mp3 music I bought Lewinner699 - It's great sounding! The only problem is that its noise reduction chops the music sound at low music volume levels. As soon the Mp3 music level increases the noise reduction stops chopping the music.
    It's OK for singers, yet I need to lower the Mp3 music level so that my whistling is clearly heard. Now its music level is far too high and at a low music level its noise reduction chops and cuts the sound. I contacted Lewinner technical service, but they refuse to help me, fearing I try to copy their circuit.
    One way I thought of, is inserting a resistor in the music path, which decreases the music power, but then allows increasing the music volume Pot (without increasing its loudness) so that it overrides the noise reduction.
    Sadly, I can only take a photo of the circuit and carefully search for the music path emanating from the TF-card driver.
    I have basic electronics hobby experience. All I need is a bit of guidance on how to search for the music path so that I don't destroy anything. I'll let you know how if I succeed. I thought of starting to search/probe with an earthed 100k resistor. Would that be OK?

  • #2
    To trace an audio signal I think I need to use a 0.1uF Cap and headphones. There must be somewhere a resistor near the DSP, which sets the noise gate level, and bridging this resistor with a small capacitor might do override the noise gate (?) - I was also thinking of another idea ...that of adding a low-frequency noise to the music so that the noise gate remains inactive. Any ideas?

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    • #3

      To trace an audio signal I think I need to use a 0.1uF Cap and headphones. There must be somewhere a resistor near the DSP, which sets the noise gate level, and bridging this resistor with a small capacitor might do override the noise gate (?) - I was also thinking of another idea ...that of adding a low-frequency noise to the music so that the noise gate remains inactive. Any ideas?

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      • #4
        Another idea would be to attenuate the power going to the speaker. Then you could have the volume up higher but control the speaker loudness. Not sure what kind of output power this machine is putting out though.
        "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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        • #5
          Thank you g1 for your idea. That would of course reduce the whistling loudness as well. - There must be alternative ways of reducing the fixed noise gate effect. It only affects the music; not the Mic. path.

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          • #6
            What is your music source for putting music on the TF card? My guess is that it is just MP3 files. I would try editing the files with an audio editor and use compression and normalization to get the music levels more consistent. Audacity is a freeware editor that might help you achieve what you're after without modifying the unit. Otherwise, this is going to be a difficult, if not impossible, task without a schematic.
            "Yeah, well, you know, that's just, like, your opinion, man."

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            • #7
              What numbers are on the DSP? Maybe there is a datasheet available.
              "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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              • #8
                The Nr. on the DSP is: DevantA 20200612

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                • #9
                  Originally posted by The Dude View Post
                  What is your music source for putting music on the TF card? My guess is that it is just MP3 files. I would try editing the files with an audio editor and use compression and normalization to get the music levels more consistent. Audacity is a freeware editor that might help you achieve what you're after without modifying the unit. Otherwise, this is going to be a difficult, if not impossible, task without a schematic.
                  Thank you for that idea TheDude. - Yes, it's Mp3 format. That's another way of tricking the noise gate into inaction.
                  Important: I also noticed that this noise gate doesn't hack the low-volume music of all songs Could it be, because their recorded volume level is too low?
                  Last edited by jjj; 11-19-2021, 08:36 AM.

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                  • #10
                    Originally posted by g1 View Post
                    Another idea would be to attenuate the power going to the speaker. Then you could have the volume up higher but control the speaker loudness. Not sure what kind of output power this machine is putting out though.
                    The speaker is incredibly loud (20W). I found it very compact; just the thing when I'm traveling. Three years ago, I whistled to a large group of people et a nature's thermal bath in Chile just holding an MP3 player. I wished I had this compact thing with me. -The only other way would be to use this L-699 only for whistling and a separate MP3 player. What a pity, for I hate to carry too many gadgets with me on travel. The great thing with this karaoke is that it got real reverb; not echo.

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                    • #11
                      Originally posted by g1 View Post
                      Another idea would be to attenuate the power going to the speaker. Then you could have the volume up higher but control the speaker loudness. Not sure what kind of output power this machine is putting out though.
                      The speaker has 20W (damn loud!) but attenuating the speaker would also attenuate the microphone input. Sure, the signals from Mic & music are fed and mixed to the Amp. So, there at the music signal input could be attenuated. The Amp's output leads to the speaker emerging from underneath the board and thus, invisible in the Pic. That indicates that the Amp is underneath the circuit board.

                      Question: I also noticed that this noise gate doesn't hack the low-volume music of all songs Could it be, because their recorded volume level is too low?
                      As I understand in this device the noise gate kicks in when the music volume is low, but I'm not sure if a higher recorded volume level Mp3 allows me to play the music at a lower volume level without noise gate interference?
                      Alternatively, I thought of injecting a low (almost inaudible) hum-type frequency into each recording to trick the noise gate into inaction. I have got Soundforge. - I guess, if there's no technical solution, I have to experiment with different volume levels, etc.
                      Last edited by jjj; 11-19-2021, 01:43 PM.

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                      • #12
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                        Here are the details of its 20W Amplifier.
                        Since there's no hope of disabling the noise gate, I'll try to resolve the problem via recording and testing different MP3 volume levels. Maybe a low-volume recording allows me to turn the music volume Pot higher without increasing the actual music volume level. If that fails I'll try the opposite. I that fails I'll try to add a low-frequency hum (from a Tinnitus Prg) to the MP3 to stop noise gate activation. Any other ideas, which could trick the noise gate?
                        Last edited by jjj; 11-20-2021, 01:13 PM.

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                        • #13
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ID:	946058 Click image for larger version

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ID:	946059 I think I partly resolved my problem this way:
                          The Lewinner699 has got 108FM for music & Mic output. So I bought one of those FM-Modules, connected it to 2-inch Speakers, and stuck it all into a flat plastic box, which I hang onto my neck.
                          I noticed that the FM-music output is luckily not controlled by the same noise gate and thus, bridges somewhat the gap created by the noise gate. The small speakers also favor my whistling.
                          So, in a way, I'm glad gotten away with avoiding adding more gadgets, for I could have used the Lewinner699 only for whistling and a separate 20W Mp3 player. Yet, this way it's still "compact" enough.

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