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
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
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.
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.
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 µF 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 µF 10 V) with Pana FCs 1000 µF / 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 4,7µ - WIMA Folienkondensator, Rm 5mm, 4,7µF bei reichelt elektronik
before modding:
After this I plan to build an external CLC filtered 5 V PSU.
Any ideas? 😕
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 thetwo 2.2 µF 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 µF 10 V) with Pana FCs 1000 µF / 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 4,7µ - WIMA Folienkondensator, Rm 5mm, 4,7µF bei reichelt elektronik
before modding:
After this I plan to build an external CLC filtered 5 V PSU.
Any ideas? 😕
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.
As a second step I replaced the two remaining lytics with Pana FRs of same
470 µF as stock (but 25 V instead of 10). No space to fit anything bigger there.
The output coupling caps (2.2 µF) were replaced by 6.8 µF, 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 µF Pana FCs.
I will update here when I there's any change, but at the moment I'd primarily
recommend to fit 1000 µF 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:
470 µF as stock (but 25 V instead of 10). No space to fit anything bigger there.
The output coupling caps (2.2 µF) were replaced by 6.8 µF, 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 µF Pana FCs.
I will update here when I there's any change, but at the moment I'd primarily
recommend to fit 1000 µF 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:
I will, mate !!
Currently, I just can say it's better than stock - smoother, more extended
at both frequency extremes, deeper bass, more detailed upper treble with
more and sweeter "glitter".
There are also Panasonic ECWF 2.2 µF with a lead spacing of 7.5 mm, which
likely fit for C61/62 and are worth a try. Available at Digikey.
Currently, I just can say it's better than stock - smoother, more extended
at both frequency extremes, deeper bass, more detailed upper treble with
more and sweeter "glitter".
There are also Panasonic ECWF 2.2 µF with a lead spacing of 7.5 mm, which
likely fit for C61/62 and are worth a try. Available at Digikey.
Cool, I am way too busy tied up with other things...
I was thinking of transformer outputs one day...
Oon
I was thinking of transformer outputs one day...
Oon
A LL1684 would probably be a good idea, but I don't see any way to fit one inside the chassis
of these little Modi and Loki DACs.
However, if you have such a transformer at the input of your pre-amp, it seems worthwhile to
remove the output caps of the DAC.
of these little Modi and Loki DACs.
However, if you have such a transformer at the input of your pre-amp, it seems worthwhile to
remove the output caps of the DAC.
You remind me I wanted to build and linear PSU. I should have all the required
parts in my spare box, just need some time and get off my backside.
🙂
parts in my spare box, just need some time and get off my backside.
🙂Hey guys, looking at getting a normal Schiit Modi 2 for all around usb dac duties, mainly for my mid-fi, two channel HTPC system, but it could see use in the PA.
From reading reviews, it seems a bit bass challenged, possibly because the whole thing runs off a +5v USB supply. The computer's usb may not always supply a clean solid 5v. I'd probably do a USB y-cable to boost power supply, plugged in to a low noise usb wall charger I have around.
Test/Review index of all tested usb chargers, any comments? | BudgetLightForum.com <--usb charger, pretty nice actually.
Looking at the available information and pictures, it seems like the dac and USB chip run on separate 3.3V supplies, while the output op amp AD8616 appears to run on filtered but internally un-regulated usb +5V.........?
What is the big 2200uf cap doing? Have to figure it is on the +5V somewhere, but it's pretty far in? Is it safe to beef up the PS caps on a +5V line connected to USB? What about the 10uf input capacitance for usb? How would you beef up the PS caps like you normally would to get better bass?
Can somebody take high res pics of the board? Is it a 2-layer board? 4 layer, etc?
It seems that the AD8616 op amp could be swapped for others with minor stability tweaks, or none. Keep in mind this is a +5V single supply, SOIC op amp. It clips at somewhere less than 2.5V peak, and the unit is rated for 1.5V RMS max.
AD8656 - 50% more output current possible.
AD8652 - about half the settling time
OPA2836 - 1/10th settling time
https://audiofilifiorentini.wordpre...i-quando-le-prestazioni-superano-ogni-dubbio/
http://cdn.audiostream.com/images/12813modi3.jpg
From reading reviews, it seems a bit bass challenged, possibly because the whole thing runs off a +5v USB supply. The computer's usb may not always supply a clean solid 5v. I'd probably do a USB y-cable to boost power supply, plugged in to a low noise usb wall charger I have around.
An externally hosted image should be here but it was not working when we last tested it.
Test/Review index of all tested usb chargers, any comments? | BudgetLightForum.com <--usb charger, pretty nice actually.
Looking at the available information and pictures, it seems like the dac and USB chip run on separate 3.3V supplies, while the output op amp AD8616 appears to run on filtered but internally un-regulated usb +5V.........?
What is the big 2200uf cap doing? Have to figure it is on the +5V somewhere, but it's pretty far in? Is it safe to beef up the PS caps on a +5V line connected to USB? What about the 10uf input capacitance for usb? How would you beef up the PS caps like you normally would to get better bass?
Can somebody take high res pics of the board? Is it a 2-layer board? 4 layer, etc?
It seems that the AD8616 op amp could be swapped for others with minor stability tweaks, or none. Keep in mind this is a +5V single supply, SOIC op amp. It clips at somewhere less than 2.5V peak, and the unit is rated for 1.5V RMS max.
AD8656 - 50% more output current possible.
AD8652 - about half the settling time
OPA2836 - 1/10th settling time
https://audiofilifiorentini.wordpre...i-quando-le-prestazioni-superano-ogni-dubbio/
http://cdn.audiostream.com/images/12813modi3.jpg
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