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smsl 1955+ DAC....opamp eatting monster - Page 3

post #31 of 37

I today installed the LM4562 in place of the 5532DD. I also replaced the 4 unnamed caps with Nichicon KA-series. Sounds good already but I expect some change over next few weeks.




Ikazu, sorry didn't measure the voltages.

Edited by TonyCH - 8/13/13 at 9:49am
post #32 of 37
Thread Starter 

Well....I was pleasantly surprised yesterday when my dac arrived in the mail after a 5 month trip to China.  As I previously posted I didn't think I would ever see it again.  It came back with a different power supply and a silver (originally black.)  I am giving it a few days of listening before I post a review.  As for the smsl sapIII head phone amp...still running great.  So far no ringing or floor noise. Post more info in a few days.

post #33 of 37
Originally Posted by Argybargy View Post

My unit was defective on arrival. 7.5db channel imbalance. Currently awaiting an exchange. Fwiw, it sounded pretty good using an external psu. The stock wallwart is garbage.


The new unit arrived and no channel imbalance this time.


Stock, this  DAC sounds like utter crap... but there's potential there.


First, toss the useless power adapter.  Until I build a PSU, I'm using a cheap 2A regulated PS, ~$20 model from Parts Express.  Huge improvement right there.


Next, the stock OpAmps are garbage fakes.  I hear very noticeable clipping and when I up the PS voltage to 12V most of the distortion disappears but the SQ is still not there.  Obviously re-marked cheap fakes.  The single I swapped with a Opa827 and the pair with BB Opa2227P.  Now it gets interesting. 


The cheapO no-name big cap was swapped for 2x2200uf Nichicons with a 1uf polyester bypass = better bass response.


Similarly, the 4 no-name matching caps were swapped for Nichicons.  The small gold nichicons looked genuine so I left them as is.  There were reports in another forum that the Sanyo Oscons were defective in an early production run, so out they went.  While swapping the little one, I noticed that the polarity was reversed from what was shown on the PCB. So either the PCB is wrong or it was installed wrong.  Who knows, I just put in a bipolar nichicon Muse.


All the parts might be a little pricey considering this is a $99 DAC (I had all the parts except for 1 opamp so I actually only spent $10) but wow this thing sounds great!


The soundstage is big; nicely extended treble; excellent full bodied bass; and a clean detailed and dynamic sound.



post #34 of 37

I bypassed the supply pins (4 and 8) of the opamps with Wima 0.1uf polyester film caps (mounted on the bottom of the pcb) and the noise floor has dropped - a slightly cleaner sound with a blacker background.  Next is modding the case a bit to accommodate the taller caps, then adding an umbilical for an external PSU.

post #35 of 37

I bought one of these DACs as well. First impression was fine, But I noticed a lot of clipping when using the optical input when connected to a CD player. Sure enough setting the volume to 100% on a tablet or PC gave the same results on USB or optical input. Yes I can lower the volume on the tablet or pc, but I can not lower the volume on the CD player.


I am not too familiar with DACs but I don't think the output should clip at a 0db input.


Someone here asked so I measured the +/- voltages on the opamps. I got +7.5 and - 6.4vdc


The DC adapter is a steady 9Vdc


I will record some 100% signals with Audacity and I will try to scope out where the clipping starts.

post #36 of 37

Some doubts.  This thing really supports 32kHz @ 24-bit via SPDIF and/or Toslink ?


Also is possible to record/capture the audio to PC via USB (from SPDIF/Toslink to USB on PC) ?


I want to upsampling from 32kHz with this thing.  Is possible?

post #37 of 37

 I the mean time I picked up the Modi from Schitt audio.  Should have known better...made in the USA all the way.


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