• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Fixing Hum/Buzz issues with Schiit Jotunheim Headphone Amplifier

Alcophone

Member
Joined
Jun 25, 2018
Messages
67
Likes
37
Location
San Francisco
Update from Jason:
None of the ones I've tested were like that. The paint is ground out of the chamfer during manufacturing specifically for that purpose.

In any case, the new test procedure checks for grounding in toto, and went into effect today. All shipping Jotunheims were checked and found to have proper grounding. Tomorrow we'll go through the rest of the stock just to be sure.

Again, if you have issues with your specific Jotunheim (or any other product), please contact us at [email protected] and we'll be happy to take care of it.
At the very least, not all products appear to be affected. That's good news for customers, and good news for Schiit.
 

derp1n

Senior Member
Joined
May 28, 2018
Messages
481
Likes
625
The fact they sell a mains-powered device in a metal case and didn't have basic safety QA in place from day 1 speaks volumes. If they QA is so lax here, it's no wonder at all that QA issues show up with their products all over the place. What a joke.
 

Jacona

Member
Joined
May 8, 2018
Messages
41
Likes
21
Jason acknowledging this problem is a nice step forward in "working" relationship.

I've always personally thought the goal of Amir's testing (especially Schiit products) is to help manufacturers improve their products with third party testing/a different perspective. I am just afraid that this will devolve into an "Us vs Them" tribal situation seen in so many other communities. We have had "third party" testing done on other sites, but not much commentary/direct comparison with other products to go along with the measurements.

People like Amir will keep manufacturers in check, while us as a community should keep Amir in check. I think it is a good thing to respectfully question and nitpick Amir's findings because he is just human....

Unless he's secretly a highly advanced Microsoft AI
:eek:
 

restorer-john

Master Contributor
Joined
Mar 1, 2018
Messages
8,947
Likes
25,182
Location
Gold Coast, Queensland, Australia
Schiit are doing the right thing, confirming and acknowledging the issue, and providing an immediate change in production going forward. I don't think you can ask for more than that.
 
Joined
Feb 26, 2018
Messages
2
Likes
2
Thanks for reviewing the jotunheim. I tested the grounding of mine with my Multimeter and got about 1 ohm for both the mains ground-top chasis and mains ground-analog input shielding. I've never noticed any hum or noise with it.
 

Alcophone

Member
Joined
Jun 25, 2018
Messages
67
Likes
37
Location
San Francisco
Schiit are doing the right thing, confirming and acknowledging the issue, and providing an immediate change in production going forward. I don't think you can ask for more than that.
They have neither confirmed, nor acknowledged the issue, just that it would be one if it indeed happened. They haven't changed how they produce their items, just how they test them, in order to rule out an issue that did not occur in any of their currently shipping units. They are also going to verify the amps currently in stock.

Those are absolutely the right steps, but Schiit has yet to claim that they ever produced an amp with that issue.
 

Blumlein 88

Grand Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
14,679
Likes
23,783
I wonder how they handle this. Does some guy with a file give it a rasp once in each hole for the lid? Seems the issue of hum crops up according to forum reports on the silver models more than the black case models. That makes sense as it is easier to see shiny metal from rasping off black paint than would be the case with silver.
 

restorer-john

Master Contributor
Joined
Mar 1, 2018
Messages
8,947
Likes
25,182
Location
Gold Coast, Queensland, Australia
"Effective" chassis earthing as I outlined in the previous post would solve it once and for all.

Two earth lugs, a pot shaft solder ring, a machine screw, star washer, flat washer, shake-proof split washer, a nut, and maybe 12" total of green/yellow earth wire.

Maybe 10 cents all up?
 

Alcophone

Member
Joined
Jun 25, 2018
Messages
67
Likes
37
Location
San Francisco
I wonder how they handle this. Does some guy with a file give it a rasp once in each hole for the lid? Seems the issue of hum crops up according to forum reports on the silver models more than the black case models. That makes sense as it is easier to see shiny metal from rasping off black paint than would be the case with silver.
Jason was talking about masking, i.e. some mask is supposed to prevent the paint from reaching the inside of the keyhole, precisely to prevent this issue from happening. Not sure about the specifics, but there shouldn't be any rasping involved.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
37,982
Likes
162,520
Location
Seattle Area
"Effective" chassis earthing as I outlined in the previous post would solve it once and for all.

Two earth lugs, a pot shaft solder ring, a machine screw, star washer, flat washer, shake-proof split washer, a nut, and maybe 12" total of green/yellow earth wire.

Maybe 10 cents all up?
I want to emphasize this again. Neither my mod, nor process outlined by Schiit (which is the same as mine) are sufficient for safety! There has to be secure green wire to the chassis with the proper screw and washers.

This friction contact is OK for getting rid of hum but is not in any way sufficient for safety. You can't rely on the pressure of some folded metal for a secure, high current carrying surface.

Such a test will likely fail CE certification. So it is important to inquire if Schiit has used an independent lab to certify this unit. Or what test if any they have run to have ascertained that a bit of contact between the pin the the keyhole is sufficient.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
37,982
Likes
162,520
Location
Seattle Area
Thanks for reviewing the jotunheim. I tested the grounding of mine with my Multimeter and got about 1 ohm for both the mains ground-top chasis and mains ground-analog input shielding. I've never noticed any hum or noise with it.
Sounds like you are good to go as far as hum prevention is concerned. The safety issue may remain per my previous post however.
 

Wombat

Master Contributor
Joined
Nov 5, 2017
Messages
6,726
Likes
6,321
Location
Australia
I want to emphasize this again. Neither my mod, nor process outlined by Schiit (which is the same as mine) are sufficient for safety! There has to be secure green wire to the chassis with the proper screw and washers.

This friction contact is OK for getting rid of hum but is not in any way sufficient for safety. You can't rely on the pressure of some folded metal for a secure, high current carrying surface.

Such a test will likely fail CE certification. So it is important to inquire if Schiit has used an independent lab to certify this unit. Or what test if any they have run to have ascertained that a bit of contact between the pin the the keyhole is sufficient.
 

Wombat

Master Contributor
Joined
Nov 5, 2017
Messages
6,726
Likes
6,321
Location
Australia

Design, manufacture and testing - three strikes.

No more excuses.

I'd be checking CVs.
 

restorer-john

Master Contributor
Joined
Mar 1, 2018
Messages
8,947
Likes
25,182
Location
Gold Coast, Queensland, Australia
I'm not sure about the US, but the so-called double-insulated standard has been watered down or ignored by much of the product of the last decade from many manufacturers. Correct earthing of metal cased consumer electronic devices has left me scratching my head many times, wondering how it was ever approved for sale here in Australia.

That's why the closeup interior shots of ChiFi particularly are so useful- there's plenty of eagle-eyed people here that will spot potential safety issues very quickly. With people directly importing stuff that has not had electrical authority approvals, accidents will happen- it's only a matter of when.

I'm very focused on it, and let's not forget, the practices in the past weren't perfect either, so it's not just a recent thing.
 

Blumlein 88

Grand Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
14,679
Likes
23,783
I think the unit under discussion here meets the US rules for double insulation. You only need 4mm of air clearance and construction so no loose wiring or component slip could potentially cause contact with the metal case putting 42 volts or more onto the exterior. Looks like this Schiit meets that even though no certification appears on the unit.

I'm no expert in the field of such things so take it for what it is worth which might be nothing.
 

IdiotCustomer

Member
Joined
Jul 15, 2018
Messages
26
Likes
7
What would a suitable replacement amp/dac combo with the features of the jotunheim be? Sennheisers Hdvd 800 amp/dac seems promising but a bit out of my league. It goes for $2150 over here
 

Canook

New Member
Joined
Jul 23, 2018
Messages
2
Likes
0
Joined to ask some questions about this topic...

-Supposing that the top cover of the Yotunheim was insulated, how would this create a ground loop/hum? A hum is created when current has two separate paths to ground. Supposing that the top cover was insulated, it would not provide a path for current to flow to ground. How exactly was it creating the hum you measured?

Just on another note about the example of V=IR... the example seems misleading. Current and resistance do not “create” voltage. Voltage (push) over a certain resistance is required to produce a flow of current. It is entirely possible for 100V over 1 ohm to draw 100A, however the current is produced by the voltage, not the other way around. (Also, the “deadliest” shocks occur with current that is far less than even 1A... this has the potential to put our hearts into fibrillation. I also don’t discount that it may certainly surprise us to cut into a live wire and create a short circuit where 100A may flow for a split second. However, far less current is far more deadly, in terms of our health.)

Supposing that somehow, the top cover was insulated, and 120V made contact with the cover... nothing would happen until a well grounded piece of equipment, or person touched the cover. (And receive a shock).

Do you believe it’s plausible for any of the circuitry inside to ever make contact with the top cover? I just don’t see this happening, personally.

The hum is interesting though... interested in understanding how it was created!
 
Top Bottom