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strange and distorted headphone output?

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strange and distorted headphone output?

Postby klagis » Sun Aug 09, 2015 11:29 am

Hello everyone,

I recently started getting strange issue in the headphone jack of my sub 37 where the sound would become very distorted and weak - this would get worse and more frequent the longer the unit was switched on.

It tends to come and go randomly, regardless of headphones used, ocassionaly the sound cuts out entirely!

I've noticed on this forum a few people had similar issues a while ago - but didn't want to necrobump anything.

Any advice would be appreciated!

Thanks very much.
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Joined: Sun Aug 09, 2015 11:24 am

Re: strange and distorted headphone output?

Postby pakmario » Fri Oct 09, 2015 1:49 am

I have exactly the same problem on my sub37... I´ll try to re-update the firmware via PC, because i did it with a MAC and i had some issues during the Updating process to 1.1
Anyways, if someone can help, it would be great.
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Joined: Fri Oct 09, 2015 1:39 am

Re: strange and distorted headphone output?

Postby amada13 » Mon Jan 02, 2017 4:42 am

Was there ever a solution to this issue?
I just discovered the same thing with my SUB 37.
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Joined: Mon Jan 02, 2017 4:39 am

Re: strange and distorted headphone output?

Postby aldred » Mon Mar 13, 2017 8:12 am

I just used the headphone jack on my Sub37 for the first time in a while, and I'm having similar trouble. I get noise, drops in level, and sometimes loss of signal completely. I've contacted support in Japan to get it seen to.
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Re: strange and distorted headphone output?

Postby electrowiz01 » Wed May 31, 2017 8:19 pm


I had the same crackling and noise on the SUB37 headphone jack. Additionally when I pressed on the case in that area it would vary the sound amplitude.
WARNING the following requires opening and changing the guts of your Sub37 which voids the warranty.
If you have decent solder skills and are careful you should be able to fix this. I use a headeyepiece magnifier and a good strong light.
1) Remove the screws from the wood end caps (Be very careful to note which type of screw came from which hole as there are wood type screws and machine screws. Put a soft cloth towel over the keys and lift up and out to get the front knob panel to turn over and reveal the circuit boards underneath.
2) Locate the white plastic connector on the board that goes to the headphone jack and has three wires (green = Ground, red and white are right and left channel). To me this connector is not solid enough, and when the case is assembled it can put pressure on the plastic connector. The circuit connected to this connector is expecting a relatively low headphone resistance as it drives signal into it, but when the connector makes poor contact it can drop the amplitude and create little crackles and sounds.
3) We are going to bypass the connector. look along the circuit board till you find a green wire with a spade lug, and a bolt holding it to the board. Unscrew the bolt and touch up the top PCB solder pad where the lug makes contact - this is ground and on mine there was corrosion on the pad. Add a second wire to the lug that is long enough to reach to the white headphone connector.
4) screw the ground lug securely in place on the board. Thread on some heatshrink to the open end of the wire you added.
5) OK this part is scary, clip the green wire coming from the headphone jack close to the little white connector. Solder the green wire coming from the headphone jack to the open end of the wire you added, make good solder connections, shrink down the heatshrink to insulate the connection.
6) Notice the three little solder pads on the top side of the board where the white connector is. Notice the red colored headphone wire goes to one pad, the white goes to another, the green went to the third but ignore this one.
7) Clip the red wire at the white connector and CAREFULLY solder the wire to the corresponding top PCB pad, be careful not to create a short between any of these pads. Make sure there is a little bit of extra solder to really bond the wire to the pad. Do the same for the white wire.
8) Add some hot melt glue to help keep the red and white wire held down flat to the board.
9) Along the length of the long wire you added to the ground lug, use hot melt glue to secure the loose wire to the board in a few places. Make sure this wire does not get placed on top of any sharp pointy component leads coming through the board or with pressure or vibration it could puncture the long wire you added.
10) Ok now the tough part - Bob Moog must be cussing in his grave over this - as putting the case back together is pitiful the screw holes are hard to line up. Use a bright light or flashlight to sight down the holes and see where things should line up. Remember there are wood screws and machine screws and if you get them mixed up you will chew up the internal threads. take your time, get it right.
Ok I can imagine you are nervous, if you got it wired securely and the case back together three cheers for you. With mine I had a nice solid headphone amplitude, no crackles, no noises, no volume drops. Good luck, and happy music making.
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Re: strange and distorted headphone output?

Postby aldred » Thu Jun 01, 2017 6:53 am

In the end I sent my Sub37 to support. They checked it out and couldn't reproduce the problem, so were unable to figure out the cause. But they did clean the headphone jack for me, and so far that seems to have solved it. I don't know exactly how they cleaned it, but it might be worth trying a cotton bud dipped in ethanol before attempting major surgery.

I have no idea how the headphone jack could have been dirty. I had problems with it from the very beginning. And I keep my stuff pretty clean anyway.
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Re: strange and distorted headphone output?

Postby bichuelo » Thu Jun 01, 2017 2:56 pm

The best bet is to speak to Moog support, always. There is a known issue on some units regarding the headphone output on the Sub 37. If this is the case, Moog will replace the entire PCB board for you without cost, sometimes after the usual warranty has expired
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