Hacking Schiit

@Ksorota what resistance pot are you using? I assume a 50K Alps blue? I'll likely do a 10K TKD but I have an Alps 50K on hand for a quick dirty hack.

 

I am pretty sure it is a 10k pot. I would have to check to be sure though.

 

Quick and dirty Piety Squared while waiting on Mouser parts to arrive.

You get the spaciousness of Piety^2 but not the amazing bass, treble, or dynamics. Those will come with the lower impedance pot and PSU upgrades.

 

@Ksorota what uf value PSU caps did you use? I'm using the factory 1000uf but thinking of upping it.

 

The values are the same in the modded version. When it comes back I might swap them out for some diff. series caps, I have a bunch of Nichicon Muse caps that might sound nice.

I also have to start thinking about some nicer casework and figuring out how to get a dual set of Vali 1's into the circuit!

 

Hi all, it was fun to read the whole thread and I learned a lot from you, so thank you for that!

Since I'm a newb who is trying to get into some "quality listening" schiit, I have a Modi MB v1.1 (OG FW) which is fully stock and I use it with amplified speakers. I got inspired from this thread to mod it with OPA2156, but recently I've purchased a second hand Asgard 3 with MB card for my future headphone setup, and thought I would find under the hood the Schiit's Unison USB and a newer revision of OpAmps, but for my surprise it was the old CM6631A and OPA8512 (U12 & U13), same as inside my Modi.

I was thinking of changing the OPA8512 with OPA2156, and was wondering what's the purpose of U14&15, are those LME49724 that are being used as a servo? Is it worth "improving" as well? What other tweaks would you recommend to try on the Asgard 3? (which is already a very complete sounding piece of equipment for my ears, but I can't hold myself to play around with some IC swaps )

 

Yeah, the Modi card looks very different. It looks like the LME49724's are doing some LPF? I would also look under the board for some possible other op amps.

Which, if it was a filter op amp, you are not going to gain much by changing it. The AD8512's (note: not OPA) are the most offending part holding this DAC back IMHO.

Changing the servo is probably a bit overstated in this thread. Changing out the AD8512's are like 95%, the servo is maybe that last 5% of potential. Look at it that way.

 

Here’s how I got rid of transformer hum on my Yggdrasil A2:

This tiny gap next to the transformer standoff was causing the hum:


The fix was to secure it down:


Yggdrasil chassis is dead quit again!

 

@batriq - Did you drill those or were those mounting holes always there?

 

All the transformers have pre-drilled board holes corresponding to their mounting holes, but only one transformer had standoffs and only two of them. Adding a 3rd standoff there wouldn’t have helped unfortunately as the metal layer lifted only close to the other mounting hole.

 

So I bought a Gungnir MB A1 and sold it along; the new buyer gets it and it was DOA.

He sends it back to me and one of the transformers is completely detatched and rattling around inside. The DAC is now with Schiit for repair

For the life of me - it is pretty clear Schiit solders the Transformer to the Motherboard and calls it done - This means only the solder is supporting the entire weight of the transformer with no real mechanical connection to the motherboard (those transformers I have never seen one laying flat on the board!). I'm no engineer - but I guess it works.... most of the time? They obviously keep doing it like this - the standoff approach here costs too much money maybe?

 

Several thousand standoffs cost a quarter a piece. The 8 for an Yggdrasil would add $2 in cost. Power transformer mounting seems like a bad place to shave two bucks.

 

I totally respect that a business needs to turn a profit - also that Schiit team has the chops to design and build proper gear to a price. Would be interesting to know the reasons behind choices like this, pretty sure I'm not the only guy this has happened to or like @batriq with a transformer hum.

 

Same case with my Yiggy. No standoffs. I added them myself to stop my transformer humming. Schiit used to use them, so idk why they stopped. If you watch the original Yiggy assembly video on their YouTube channel you can see standoffs under the transformer.

 

Yes, I wish schiit installed all the standoffs. While this Yggdrasil is A2 with Unison, it used to be A1 with the pre Gen5 card. It’s one of the early original ones which is why it probably has some standoffs. If I had the right sized standoffs I would have installed them on all the transformers (it would require unmounting the main board though). In my case, the transformer with the standoffs had the hum — the other transformers have these longer metal strips that cover the seems and prevent what happened here from happening.

 

Would not the standoffs just mean the transformer is just further mounted to the circuit board? To me, it just seems this just distributes the load a little bit wider. Meaning, the standoffs should really be mounted TO the chassis. This would cause more complications in the way the chassis are designed with the board floating and the other stand offs for the board screw into the chassis from the top of the circuit board. Although, there could be the same way of doing the same thing with the transformers. Maybe they did in the past, which is why there are holes already in the circuit board.

 

The timing of the standoff install vs the solder of the transformer to the PCB seems very relevant in the grand scheme of things.

 

What conspiracy is this?

Thanks for this hack - that should save some RMAs, that is, if people don’t wreck their systems even further. To those who fear doing so: don’t read this thread then

 

@batriq how close did you had to be to hear that hum? I never noticed on mine but, when i come home, i am going to try to hear it.

 

I could hear it from 1 foot away, and at night when the house is quiet probably 2-3 feet away. The case amplifies the sound so when I first opened the case it sounded a lot more faint.

After the fix with the case in place, I hear nothing now.