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Schiit Magni 3+ Headphone Amp Teardown

amirm

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#1
This is a tear down of the Schiit Magni 3+ headphone amplifier which I just reviewed. Schiit has come a long way on objective performance. Question remains as to build quality.

Other than some really tight screws, taking the unit apart was easy and shows care in reducing cost. Putting all the components on one side helps a lot too.

Here is the main PC Board:
Schiit Magni 3+ Teardown.jpg


The architecture is quite simple. AC input becomes rectified, cleaned up with the caps and then regulated using the LM series variable regulators. High quality Japanese Nichicon capacitors are used here as well as the rest of the amplifier. Temperature rating is 85 degrees C as opposed to higher grade, 105. In this application though, I am fine with that as I did not detect the unit getting warm enough to cook the capacitors.

Input signal then goes into a couple of integrated opamps (OPA1678) so all is not discrete here. From there, matched pairs of transistors in those IC looking packages take care of increasing drive to power the final output stage which also uses matched pair transistor packages. I could not locate the matched pair transistors anywhere. However, they seem to be clones of the Nexperia dual BJT packages with the same series (e.g. 10035, 1003, etc.).

The devil is of course in the details which I can't get into.

Automated pick and place and soldering is used for most of the components with the exception of a few such as headphone jack. Sadly the past problems of solder splatter remain there:

Schiit Magni 3+ PCB Teardown.jpg

Here is a zoomed look:


Schiit Magni 3+ PCB Zoom Teardown.jpg

Solder balls are everywhere although not nearly as bad as some of the other Schiit products I have examined. The solder mask (in red) keeps them from shorting things out. Still, I wish hand soldering was much cleaner and left over solder brushed off.

There is some flux residue there but again, not as much as before. And likely is the "no clean" variety.

Conclusions
The construction of the Schiit Magni 3+ looks fine from the top with good choice of components in general. The hand soldering remains a weak point. If you are handy, you may want to open the unit and scrape off the solder balls/splatter. They should come off easy given the solder mask underneath.

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As always, questions, comments, corrections, etc. are welcome.

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trl

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#3
3A output stage transistors, quite impressive and definitely a new approach for a headamp!

https://assets.nexperia.com/documents/data-sheet/PHPT61003PY.pdf
https://assets.nexperia.com/documents/data-sheet/PHPT610035NK.pdf

Seems a very good price/perf. ratio. I wonder if swapping http://www.ti.com/lit/ds/symlink/opa1678.pdf with OPA1612 or with another opamp will do any better; although, the only thing to improve would be for output power >1W where the THD+N is a bit below THX headamp (inaudible anyway).
 

trl

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#5
I have already forwarded this to our Operations Manager. We will be speaking with our PCB assembly house tomorrow and I will send them this feedback directly.
Time to solder per PCB will definitely increase if we want this to be perfect, so probably price will go a bit up now. :(
 

Cahudson42

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#6
@amirm ,

Any chance of doing the same 9v 32ohm load thermal profile you did with the Heresy?

Really would be interesting to see those 100v 3a drivers under load..really..
 
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amirm

amirm

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Thread Starter #7
@amirm ,

Any chance of doing the same 9v 32ohm load thermal profile you did with the Heresy?
Oh gosh. I put the thing back together and it has super tight screws. Except the one for RCA which is now stripped. I will see....
 

solderdude

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#8
Input signal then goes into a couple of integrated opamps (OPA1678) so all is not discrete here.
Sssst... don't mention this... because the op-amp haters (elsewhere) thought the amp was completely discrete.
EDIT: is Probably a DC servo.

The electronic design is nicely symmetrical though.
 
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#9
Sssst... don't mention this... because the op-amp haters (elsewhere) thought the amp was completely discrete.
They were already convinced the 'better' sound quality came from the all discrete design and the all opamp sounded flat and boring.
They still have a trick up their sleeves so they can wiggle their way out of this... the sound difference comes from the current feedback technology.

The electronic design is nicely symmetrical though.
If we shove a Heresy board in a Magni 3+ case would it sound like a Magni 3+ or a Heresy?
 

solderdude

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#10
That would be a fun experiment... you would have to remove the red LED though...
It would have to be placed in the hands of people with better hearing than Amir.
And they must not be told it is a 'special' the amp should be sent to them as when handing it over the suppressed grin on the face of the experimenter might make them suspicious.

The 'Magni 3+' would measure slightly better though in such case.
 
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#15
Sssst... don't mention this... because the op-amp haters (elsewhere) thought the amp was completely discrete.
Perhaps Tyler Noble can clarify what the OPA1678s are doing in the circuit--are they in the signal path 100% of the time, or only for the line out but not headphone? Or is it being used as a DC Servo or some other not-in-the path application?
 
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#16
I have already forwarded this to our Operations Manager. We will be speaking with our PCB assembly house tomorrow and I will send them this feedback directly.

Thanks for the info, @amirm.
You'll never get a job at Ciunas with an attitude like that.
 

T.M.Noble

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#17
That is interesting. You heard differences?
I think I ended up spending around anywhere from 10 to 12 hours each with this units over a period of a week. Since Heresy is aptly named, I wanted to make sure I wasn't dogmatic so I had them both in unmarked chassis. I ended up liking both. For me, 3+ had a deep sound stage and was a bit darker, A heavier sound. Heresy Felt like a tighter room and a wall of sound but the vocals popped more for me. Granted, I have been listening to Schiit gear for five years, everyday of my life so I am rather used to the sound of our gear. In the blind tests we have done here I have a decent success rate. I guess I think I have a good ear but I imagine many people also think that.
 
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#19
I think I ended up spending around anywhere from 10 to 12 hours each with this units over a period of a week. Since Heresy is aptly named, I wanted to make sure I wasn't dogmatic so I had them both in unmarked chassis. I ended up liking both. For me, 3+ had a deep sound stage and was a bit darker, A heavier sound. Heresy Felt like a tighter room and a wall of sound but the vocals popped more for me. Granted, I have been listening to Schiit gear for five years, everyday of my life so I am rather used to the sound of our gear. In the blind tests we have done here I have a decent success rate. I guess I think I have a good ear but I imagine many people also think that.
Interesting. But, didn’t you see something red glowing through the vents of one of the unmarked cases?
 
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ZeDestructor

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#20
Oh gosh. I put the thing back together and it has super tight screws. Except the one for RCA which is now stripped. I will see....
And this crap right there is why I have a pathological hatred of most things not Torx, Allen/Hex or triple-square. Perhaps change to Torx, @T.M.Noble ?
 
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