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Dacmagic humming on one channel
Dacmagic humming on one channel
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Old 11th March 2019, 03:30 PM   #1
Jos301 is offline Jos301
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Join Date: Sep 2018
Default Dacmagic humming on one channel

I'm using a Dacmagic for many year now. I'm still love the sound of it. Recently the left channel is producing a humming sound lower than 60 Hz, hear attachment for details. This sound is independent of selected source and increases with amp volume. When playing music it is reduced to the background, but still audioable at slow passages. I can only test the RCA output. The right channel is oke.

Can anyone be so kind and point me in the direction of the possible problem of this humming.

Thanks in advance for you support.

Regards,

Jos
Attached Files
File Type: zip Dacmagic noise left channel.zip (113.6 KB, 4 views)
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Old 11th March 2019, 04:10 PM   #2
FauxFrench is offline FauxFrench  France
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Join Date: Dec 2017
Location: The mountains, calm and quiet.
Hi Jos,

Could it be the outer contact of your phono-plug that does not get in good contact with the outer contact surface of the phono connector on the DAC-Magic? I sometimes have to bend the (outer) phono contacts inwards and turn them around when inserted in the DAC-Magic in order to get a good contact.
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Old 11th March 2019, 06:51 PM   #3
Jos301 is offline Jos301
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Join Date: Sep 2018
Hi FauxFrench,

Thanks for this quick response. The RCA connection I did not check. I recently have a new interconnect with original WBT connectors. I put the old Atlas Elements interconnect back and this reduced the humming on the left channel. When I changed L and R cables on the DACmagic the humming changed from left to right as well. I put the new interconnect back with WBT connector and made the connection very tight. This give the same result as the old interconnects. Changing L and R cable on DACmagic give same result as with old interconnect.

Your advice reduced the humming, thanks for that. Put it’s still there.

Any other advice on this probleem ?

Thanks in advance.

Regards,

Jos
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Old 13th March 2019, 07:43 AM   #4
Jos301 is offline Jos301
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Join Date: Sep 2018
Default Update on resolving humming (poster)

I have posted the request and have done some investigation by my own to resolve the humming. I opened the DACmagic and I suspected the relay which mutes the outputs at power-up. I measure DC voltage over the closed relay contacts. I orderd in a Drop-in replacement of the MASSUSE relay. This is the Osram G5V-2-H1-9DV. This is can be ordered at Aliexpress. See pictures. This did not resolve the humming.

Because the humming is only on the left channel which is the top connector on the RCA plug I resoldered the connects on the PCB of this RCA plug. I could not reposition the centerpin of the RCA connector, because the connector is sealed.


If anyone have some more tips to look at please let me know.
Attached Images
File Type: jpg PCB.jpg (93.4 KB, 35 views)
File Type: jpg relay.jpg (55.0 KB, 33 views)
File Type: jpg top rca.jpg (72.8 KB, 34 views)
File Type: jpg bottom rca.jpg (58.4 KB, 34 views)
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Old 13th March 2019, 07:55 AM   #5
FauxFrench is offline FauxFrench  France
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Join Date: Dec 2017
Location: The mountains, calm and quiet.
I listened to your MP4 file on my laptop. Am I right in that it is more a wide-spectrum type noise than 50Hz humm? To me it sounded like it could be a capacitor leaking.

Last edited by FauxFrench; 13th March 2019 at 07:58 AM.
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Old 14th March 2019, 08:03 PM   #6
FauxFrench is offline FauxFrench  France
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Join Date: Dec 2017
Location: The mountains, calm and quiet.
Hi Jos, I tried with better speakers and to me it does not sound like humm (50 Hz entering the circuit). My guess is still a leaking capacitor.
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Old 18th March 2019, 09:48 AM   #7
Jos301 is offline Jos301
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Join Date: Sep 2018
FauxFrench,


Thanks for you thorough investigation.


My electronic equipment is limited to a multimeter. Furthermore my SMD (de)soldering skills are limited. This doesn't make it easy to find this leaking capacitor.


To determine the area where to look for I ordered a female XLR and female RCA for Aliexpress. I will connect pin 1 of XLR to ground of RCA and pin 2 to XLR to signal of RCA and not connect pin 3 of XLR.


When I have got the components I will report my findings.


To be continued.
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