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smsl 1955+ DAC....opamp eatting monster

post #1 of 37
Thread Starter 

Well....I am sorry to say but my smsl 1955+ dac that I have been running has started to eat opamps.  I am not sure if it has anything to do with the quality of the opamps that came with it (Chinese copies.) or that the design is bad.  I am not an electrical engineer but from what I have been researching and from the advice I get from my electrical engineer friend the opamps seem to be cooking themselves.  I am assuming that if the circuits are not optimized for the opamps, they begin to oscillate and generate heat and also noise.  For me it was a ringing in the background.  Initially the JRC 5532DD burned up..noticed the edge formed a white power deposit.  So I replaced it with a LM4562.  Ringing went away and sounded great for a while.  Then after I forgot to shut off the DAC one night and woke up the next morning to find the ringing had returned.  I opened up the unit again to find that all three opamps, LM4562 and the pair of AD 275 with white deposits along the edge.  The sound was terrible.....basically I knew at that point that all three were trashed.  My next step now is to order replacement opamps from Arrow electronics(sugguested supplier from TI website)  here in the US.   I also have samples direct from TI (LM4562).  So I try a pair of AD 275 and also see what a pair of bb2134 will do.  As for third single opamp on the board I will try the lm4582 sourced from TI and compare with the BB2604 to see what happens. Anyone out there with similar problems?  Any other electrical engineers out there with ideas?  Keep you all update as soon as I get my opamps in and trial them out.  Thanks.

post #2 of 37

Hi, mine might have done the same. Few days ago it started to distort sound when cold but the problem went away. The next day the problem came back for good.


Trying to figure out if its something worth fixing. I cannot find any components which are obviously broken (no bulges, leaks, clearly visible residue). But as I have many times left the unit on for days I suspect my problem is pretty much same as yours.


Oh, wait...when really zooming into the op amps there might be some miniscule white powderish stuff on one end of the op amp chips...maybe... can hardly see it with naked eye.


What do you think, does this look like yours? http://oi46.tinypic.com/30j44k2.jpg


Do you think drilling coolig holes to the case or even adding some kind of cooling fins to the amps might help?




post #3 of 37


I  bought a SMSL SD 1955, I'm waiting to receive it.

Did you resolved the opamps problems?
On a forum I have seen that some units had problems with psu eek.gif



post #4 of 37

Hi again


Many people talk about psu and...




-Diferents email (seller) copy from forum-



We all feel unimaginable, even going crazy.

Our shipping to Spain's SD-1955 all the problems!!But other countries do not have a problem!!

I urgently need to know a problem now: if you make any changes to DAC? Or power adapter?

SD-1955+, we sold a total of 3000+PCS last year, other countries all normal, but every time the shipping to Spain will happen.

Maybe it is not appropriate to sell to spain.

But I will settle this matter as soon as possible.



SD-1955 +, we finally know where the problems.

SANYO provide the capacitance to us, one packaged goods happen problem.

But this is a high-end capacitance, it can be run in the case of failure, a week's time. This gives us debug very confusing.

Now, SANYO has formally apologized to us and to replace all the goods.

This loss has brought us is enormous. The future there will be no similar problems.

best regards



This problem has plagued us for months.

Has done numerous experiments last only conclusion: Maybe in December last year, that batch capacitor compatibility issues may arise.

Production in December 2012 DAC, and we all archived.

Since January, all the materials are to undergo a rigorous acceptance, future will absolutely not allow this to happen.

When receive the DAC you send back, we will study all the problems that may occur.

Anyway, we will be re-shipping to your. Just send DAC (WITHOUT power supply), OK?

best regards


post #5 of 37

Good to see that they are replacing the unit without any arguing.  

post #6 of 37
Thread Starter 

Just an update.  I sent my unit back to where I bought it from kidultdiagnostic.com and they shipped the unit back to the smsl factory.  Waiting to on the unit to be repaired and sent back.

post #7 of 37



I have the unit for two weeks and works perfectly.
Very good for the price.
I wish you will enjoy the new unit.

Edited by fuens - 5/17/13 at 11:01am
post #8 of 37
Thread Starter 

Well...just an update on the repair of my smsl 1955+ DAC.  Emailed kidultdiagnostic a few days ago.  Haven't heard back from them.  I think at this point I will be lucky to get something back.  There is a chinese saying..."Throw into the big salt ocean.....".  In other words...money down the drain.  I think I may try emailing SMSL directly to see what happens....otherwise pretty disappointing.  I the mean time I picked up the Modi from Schitt audio.  Should have known better...made in the USA all the way.

post #9 of 37


I'm so sad...
So tell to us your experience with Modi Schitt.
Best wishes
post #10 of 37
Thread Starter 

Well..tried to contact SMSL-audio.com.  No reply...guess I would avoid their products if you are not willing to take a gamble.  I still have one of the sapIII desktop amps that is performing nicely.  Would have been a good head to head review with the 1955+ dac with the sapIII amp vs the schitt audio modi and magni stack.  Anyone out there with any good or bad experiences with SMSL products?

Edited by hchanrn - 6/7/13 at 7:43pm
post #11 of 37

Hi hchanrn.

My experience is very good, but apparently this is a lottery... eek.gif
post #12 of 37

I think that thing is broken by design. I measure +7.5 and -6.5 supply voltage at the opamps, so they are overdriven regularly. I built a +-15V external supply for them. Sounds much better now. 


Or do you measure other voltages? I wonder how you can reasonably power the opamps from a single 9V supply.

post #13 of 37

Sorry double posting

Edited by lkazutwgef - 7/19/13 at 12:18pm
post #14 of 37
Thread Starter 

I have given up on this brand...emailed the company and no one replied on the status of my repair.  I did purchase the sap III headphone amp and have been experimenting with different op amps.  So far the amp has been holding up well.

post #15 of 37

They don't read any datasheets


DIR9001: "if the DIR9001 is used only for recovering the clock and decoding data from the biphase input signal, an XTI clock source is not required. In this case, the XTI pin must be connected to the DGND pin. (The DIR9001 does not have a selection pin for using an XTI clock source or not using one.)"


Is it connected? No 

Edited by lkazutwgef - 7/21/13 at 8:14am
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