Fixing Hum/Buzz issues with Schiit Jotunheim Headphone Amplifier

[Dana reed]

Just to add to this age old thread. I have the shiit saga that is buzzing. The buzzing is clearly audible through the speakers. Fist I thought it was the transformer, but is wasn't. Then i thought it is the grounding, but it wasn't. Then i noticed the buzzing was gone when i turned the volume to max and i knew what it is. It is the relay-based attenuator. The relays are controlled with 0 to 5 volt using an alps pot. The relays are buzzing when off and this is introduced into the audio. Nice! Gonna find a solution for this. Might just remove the relays and replace the pot with a 100k log and wire the audio directly from the pot.

Shouldn’t this still be under warranty? They only introduced this ~4 years ago and it has a 5 year warranty

 

[JoeKickass]

Just to add to this age old thread. I have the shiit saga that is buzzing. The buzzing is clearly audible through the speakers. Fist I thought it was the transformer, but is wasn't. Then i thought it is the grounding, but it wasn't. Then i noticed the buzzing was gone when i turned the volume to max and i knew what it is. It is the relay-based attenuator. The relays are controlled with 0 to 5 volt using an alps pot. The relays are buzzing when off and this is introduced into the audio. Nice! Gonna find a solution for this. Might just remove the relays and replace the pot with a 100k log and wire the audio directly from the pot.

Why not just buy a SYS for $50 if you're about to hack up a $400 pre and add a manual pot?

 

[nodiophile]

Shouldn’t this still be under warranty? They only introduced this ~4 years ago and it has a 5 year warranty

I tried to fix the buzzing with the grounding solution from this thread first. So there was some scraping involved. Can't return it anymore.

 

[nodiophile]

Why not just buy a SYS for $50 if you're about to hack up a $400 pre and add a manual pot?

I'll look into the SYS, but i wanted something with remote control. The remote will keep working because i'll replace the current pot that controls the voltage to de relays with another motorized pot that will directly control the volume

 

[Dana reed]

I tried to fix the buzzing with the grounding solution from this thread first. So there was some scraping involved. Can't return it anymore.

I had done the same with my Jotunheim, but I sent it in anyway. They noted that I’d opened it and scratched the paint on the bottom, but they still fixed the hum issue under warranty anyway, just not the scratches.
They said that part of the issue is that one or more of the RCA connectors had a problem causing the hum in my case, so they replaced those, and it’s been great since then.

 

[lordvader]

I had done the same with my Jotunheim, but I sent it in anyway. They noted that I’d opened it and scratched the paint on the bottom, but they still fixed the hum issue under warranty anyway, just not the scratches.
They said that part of the issue is that one or more of the RCA connectors had a problem causing the hum in my case, so they replaced those, and it’s been great since then.

Sorry for a massive bump, but do you recall what they did to fix the buzz? I've got my hands on a buzzing Saga S, and ideally, try to fix it only once

 

[Dana reed]

Sorry for a massive bump, but do you recall what they did to fix the buzz? I've got my hands on a buzzing Saga S, and ideally, try to fix it only once

They said they replaced the RCA jacks, which had some problem, and also reinforced the grounding of the chassis, likely per how it was described here. Been great ever since getting it back.

 

[bobross]

Can someone explain the last picture with the multimeter reading? I am a newbie with electronics.

I thought OL when measuring resistance means that there is "infinite" resistance (same as holding the leads apart in the air), and a measurement of 0 means there is no resistance (aka danger).

What is @amirm showing with the OL reading?

EDIT: After reading the post again, I think they are measuring the resistance between the ground wire and case, rather than the hot wire and case. So a measure of OL means there is no path between the case and ground pin in the power supply. Correct?

In my review of Schiit Jotunheim by chance I noticed that the upper part of the case is not grounded. As such, it allowed the transformer to induce hum into the output of the amplifier. Here are the measurements showing such:

A jumper between the drilled holes that are not insulated and the back RCA jack shield got rid of the noise:

This quick article is about accomplishing the same without said jumper.

Note that this is both a performance issue and potential shock hazard. Metal cases on a three-pronged outlet must be security connected to mains safety ground pin. While my fix will also help with the safety issue, it is insufficient. A proper screw and ground wire is necessary for proper safety grounding.

Start by disconnecting all cables, especially the power one. There are lethal voltages inside and you can easily shock and kill yourself. So check and double check that you have unplugged the mains cable.



The case is tricky to take apart and that actually contributes to the problem. First, take off the large volume control by unscrewing its tiny set screw (be careful to not round it). Behind it are a nut and washer which you need to remove with a pair of pliers Once there, you have this:

View attachment 13922

Now the hard part. Pull the case forward some. It will put up fair amount of resistance at first. Slide it forward with fair amount of force and it should move at least a quarter of an inch. It will then get stuck. The pins are in keyholes and if you slide the case too far, they will latch on the opposite side. I found that putting the case upside down on my lap, sliding it forward and back, and eventually tilting it to clear the volume control shaft works.

Don't be concerned if you can't get it off immediately. Go ahead and curse fair bit as I did every time i tried to open and close it. It is necessary and gets you refocused on getting it open. It will eventually come apart and you see the inside guts:
View attachment 13923

There are four pins in the top lid that slide into those keyholds. As luck would have it, they are not insulated like the rest of the case is. So what you need to do is sand/file off the narrow part of the keyhole where the pins seat when closed. I used a diamond file and kept the unit upside down to make sure nothing fell in there. Alternatively you can use a sharp pick and scrape off the paint.

Here, you need to have an ohmmeter to check that you have sufficiently exposed bare metal. Connect the probes to the different keyholes and you should get connectivity in the 1 ohm or less.

The powder coating or whatever they have used is very tough. It took fair amount of doing to get the paint exposed. A better solution is to take the entire unit apart and use a rotary tool to get in there and really clean up the paint. Better yet you could sand of the paint around the top of the keyholes to expose even more metal for good contact. Be sure to do the same in the lid. The issue here is that these components may rust. Use your own judgement.

Turns out that the above is NOT sufficient because even the bottom of the case is ungrounded! All that stays between you and electric shock is that powder coat. To fix that, you need to take out these screws and like above get rid of the pain that exists on the chamfer in the case:

View attachment 13924

Screw them back in and check with a multimeter that the keyhole area you sanded off now reads a low resistance with either the mains safety pin in the IEC connector or the outside of the RCA connectors. Keep sanding and exposing fresh metal until you get to a near short (1 ohm or less ideally).

Then put the lid back on following the reverse process (yeh right, as if it is that easy). Once you put the case all together and before putting the volume knob and screw back on, run this test to make sure there is good continuity:

Unlike the above picture where I tested before this mod, you should get a short/1 ohm or less resistance. I had to be careful with my loaned unit and I think I got it down to 2 ohms or so.

That's it.

I am hoping that Schiit responds and makes this fix for owners. But if not, you can improve things with this mod which takes 10 to 15 minutes.

Post here if you have this problem and the mod helps things.

As is always the case, you make these mods at your own risks. You can easily damage the unit once inside. So be careful.

 

[AdamG]

Can someone explain the last picture with the multimeter reading? I am a newbie with electronics.

I thought OL when measuring resistance means that there is "infinite" resistance (same as holding the leads apart in the air), and a measurement of 0 means there is no resistance (aka danger).

What is @amirm showing with the OL reading?

EDIT: After reading the post again, I think they are measuring the resistance between the ground wire and case, rather than the hot wire and case. So a measure of OL means there is no path between the case and ground pin in the power supply. Correct?

First off Welcome Aboard @bobross . Here is a link to Amir’s Learning Video Library. I believe you can find your answer to your question and many others you may have about how to interpret all the graphs and charts.

Master List of Instructional Teaching Video presentations (How to read and interpret/understand all the Graphs and Charts!

Collection of Amir’s instructional Videos for reference, refresher and new members: (“Behind the Curtain @ ASR University”) Welcome New and returning Members of ASR. Our Host Amir has put together a collection of comprehensive instructional videos that might help new and returning Members...

www.audiosciencereview.com

 

[Killingbeans]

EDIT: After reading the post again, I think they are measuring the resistance between the ground wire and case, rather than the hot wire and case. So a measure of OL means there is no path between the case and ground pin in the power supply. Correct?

Correct.