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Old 2nd September 2013, 06:17 AM   #1
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Default Modding a modi... Oh Schiit..

Hi,

The schiit modi is US$99 without shipping. That puts it in the same category as many ebay board DACs out there. And this already includes a nice case...

Has anybody though about buying one just to mod?

Schiit Audio Modi review - $99 killer | Digital Audio Review by John Darko

It already has a CM6631 USB chip, a AKM4396 DAC and a AD8616 output chip.

If you have modded one, share your experience modding the DAC, (better caps, Direct out etc).

I am thinking about using a simple pass B1 pre amp for the output stage with a low pass filter. And I guess giving it an external 5V power supply

Any thoughts on that?

Thanks...

Oon
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Old 2nd September 2013, 02:29 PM   #2
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http://schiit.com/products/modi

Forgot to add the link to the main website..

Oon
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Old 13th September 2013, 01:14 AM   #3
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Any thoughts anyone?

Oon
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Old 16th September 2013, 01:50 AM   #4
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Just from looking at the DS for the AD8616, its CMOS with rail-to-rail input. If its being used non-inverting this means it might be swapping input pairs as the common mode voltage varies. If its function is as a LPF, worth checking to see if its being used in a Sallen-Key or MFB form.

Usual suggestions for a DAC - the chip has internal opamps so bound to be lacking in the PSRR department. Lower noise and lower output impedance supply would be my first mod.
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Old 6th April 2014, 10:14 PM   #5
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For a few weeks I own the Modi's DSD brother - the Loki.

From what I understand both are very similar. They share the same CM6631 USB chip, same
AKM4396 DAC and the same AD8616 on output. Probably they also share the same PCB. The
only differences then are the Loki's pass-through switch and DSD-specific output filtering.

Unfortunately there is little chance to get hold of a schematic. So I'm not quite sure if the
two 2.2 F Wimas are output caps and if the inductors near the USB connector are there for
analog PSU filtering purposes (L6 & L7).
For now I started to replace C49/50/63/67 (470 F 10 V) with Pana FCs 1000 F / 35 V (not
on the photos) and bypassed the Wimas with 3.3 nF KPs. If the Wimas prove to be part of the
signal path, I'll replace them with these:

MKS-2 4,7 - WIMA Folienkondensator, Rm 5mm, 4,7F bei reichelt elektronik

before modding:

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After this I plan to build an external CLC filtered 5 V PSU.

Any ideas?
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Old 7th April 2014, 10:40 PM   #6
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Old 7th April 2014, 10:44 PM   #7
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Possible to remove and jumper the signal bypass switch?
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Old 8th April 2014, 12:04 AM   #8
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Quote:
Originally Posted by junker View Post
Possible to remove and jumper the signal bypass switch?
Certainly. Two wires will do the job.
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Old 8th April 2014, 02:16 PM   #9
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Quote:
Originally Posted by ticktock View Post
For a few weeks I own the Modi's DSD brother - the Loki.

From what I understand both are very similar. They share the same CM6631 USB chip, same
AKM4396 DAC and the same AD8616 on output. Probably they also share the same PCB.
I have been wrong with this.

Different PCB, fewer parts on the Modi's board. Many active devices are still the same though.
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Old 15th April 2014, 08:54 PM   #10
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As a second step I replaced the two remaining lytics with Pana FRs of same
470 F as stock (but 25 V instead of 10). No space to fit anything bigger there.
The output coupling caps (2.2 F) were replaced by 6.8 F, again Wima MKS.
When I did the first four lytics, I already placed small value FKP across the MKSs.

Sound? Hard to say as I've been on a (pretty loud) concert last weekend.
There's probably no such obvious difference as with the four 1000 F Pana FCs.

I will update here when I there's any change, but at the moment I'd primarily
recommend to fit 1000 F Pana FC/FM/FR or similar for C50/63/64/67 and call it
a day. Retrofitting an external linear PSU is (will be) another story. Coming soon.



Not what I call beauty:

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