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View Full Discussion I've tried multiple outlets, different speakers, and just connecting earphones to the amp. Still getting the hiss. Guess I'll have to return this since no one else is getting the same issue.
Have you tried different outlets? Any devices nearby that may be causing interference?
I've tried outlets throughout the house and it's still happening. Since no one else has the problem, I'll try to return it.
I can also confirm that I am getting a very low hissing sound through the tweeters of my speakers (Classix II). Is this normal? The hissing noise is not noticeable once I play music, even at low volume. This did not seem to happen on my old amplifier (Marantz model 2226), but I will say that my old amp was most likely not giving my speakers enough power on the woofers after trying out the SMSL SA-160. The sound is a lot more balanced on the lows with the SMSL, indicating to me that they are now sufficiently powered. I will keep this amp unless someone with more knowledge confirms that this is indeed a hardware fault.
I do not get the hissing sound when I use headphones. Are you getting hissing through the headphone port as well?
I get the hissing sound just connecting earphones to the amp and only power adapter in the back.
How high volume is it when it hisses? Have u tried a different rca cable?
I can't give you an exact measurement but the hissing is only noticeable up to 3-4 feet away from the tweeter when nothing is playing. It is not loud, just noticeable (think Youtube video reduced to 2-8% sound), which gets completely drowned out once I play music.
The noise is not due to the rca cables, I believe. I have tried disconnecting the rca cables while still having the speakers connected, and the hissing remains. I'm being careful about passing judgement on the SMSL amp so quickly because the problem could very well be my speakers. Just this morning I was getting random sound drops ranging between 10-30 seconds when playing music. Very odd. I will comment if I discover anything new.
Only other thing I can think of, is my line in and other inputs on my sound card used to make my speakers hiss. I muted them. Good luck.
2 separate issues at hand possibly.
Ground loops from your DAC and or PC(usb DACs are very prone to ground loop issues by way of design) signal chain. Possibly EMI on your A/C power supply. I recommend at minimum a Furman SS6B power bar.
Then there is the high frequency response on an vintage amp (marantz 2226). Capacitors age with time and dry out and start filtering differently effectively creating frequency filter. Sometimes a great thing with music creation production but terrible for Listening reproduction.
As it turns out the SA-160 is extremely responsive to above 10khz energy. So maybe it has been there in your signal chain and now you can actually hear it.
I personally have had a few usb DACs introduce digital noise. It is clicky more so than just a solid white noise hiss. (classic high noise floor hiss).
Isolate , Isolate, Isolate! It is easy to blame the new piece so having other reference gear around helps. 99% of the time it is the new piece or other equipment issues now being exposed. Signal chain and very importantly ground chain factor.
Remember an amplifier physically amplifies what it receives electrically. We demand a lot of it.
With 87db per watt/meter efficiency speakers I get a audible 10k white noise hiss but below my 38db spl sound meters ability to measure at point blank 1mm . I have to be direct ear proximity of 3 inches or closer next to the tweeter to hear it. With 95db/watt spl or greater speakers this may push it beyond tolerable.
That being said, it seems to be on par with the aprox -98db SNR noise floor. The SA-160's Achilles heel. The TDS7498e chip has this inherent limitation. We sometimes get obsessed with the elusive -127db noise floor possible. -110db to -115db noise floor seems to be the accepted standard for not discernible. Granted some tests show -90db to -100db.
Always a compromise somewhere...
Turn it off when you are not listening to it?
The SA-160s sound quality more than makes up for this IMO.
Thank you for your fantastic input. I did a fair amount of troubleshooting to isolate the noise source. With only the headphone port and the power cord connected, while having the RCA + speaker cables disconnected, I was able to hear the same low hiss frequency I was previously experiencing with my speakers through the headphones (though not as pronounced as with my speakers because of their efficiency levels). So the issue is not the speakers but the amplifier itself or the power supply, as you stated.
I love the sound coming out of this device so not the biggest deal. I will be purchasing the power bar you suggested or the Tripp Lite (TLP1208TELTV). Would you say the Tripp Lite is just as good as the Furman? The product description mentions "EMI/RFI line noise filtering" just like the Furman -- I'm just not really sure how well it compares.
All in all, I'm loving my SMSL and it would be PERFECT if I could reduce the hissing noise.
Hey, don't mean to be chiming in on your and Sagacious' conversation but, I guess I am. Just wanted to say that I think you're on the right track, and are getting some righteous advice. Before I jumped onto this drop I did some research. The problem (hiss) isn't new or unique. Here's a link to the cure that seemed to make the most sense to me. http://www.hifivision.com/amplifiers/55218-my-experience-smsl-sa-160-a.html Hope it helps because I'm right behind you. Mine should be here at the end of the month. Lead on Captain!
Distracted with my new AKG 7XX's. Furman is a leader in power conditioning equipment. Some units can cost in the 1000's. Tripplite is a reputable company but I didn't find any tests to support its EMI/RF filtering. A lot of UPS's have EMI/RF filtering but almost no one gives actual suppression technical info. I have previously used some of the older monster premium bars home theater with good results.
SMSL SA-160: I did pre-purchase read about the hiss issues in that forum thread but it seems the person had a defective board on the older SMSL version. I do have a second SA-160 coming and will A/B the 2 to see if noise floor is the same.
I have yet to test the SA-160 headphone amp section. (didn't buy it for the headphone amp) I did read (maybe this thread?) that the headphone amp is driven by the 5532 opamp. Maybe a NJ4562 or the NJM4556 (higher output) might be slight upgrade. Since the TDA7498e has a fixed gain the ALPS pot is likely all that is needed for volume control versus a inline pre-amp.
I might break it down after warranty or at least a few months to insure reliability first to determine if the POT is direct or to the 5532 for volume control..
I do retract the recommendation of the sparkolabs opamps as its phase accuracy isn't ideal despite its brilliant specs otherwise. The problem with opamp rolling is often when it is switched it actually creates anomalies that we find subjectively pleasing. (see tube amplifiers). Proper bench testing is the only way to verify an actual improvement.
Some are swappable as they can react similar in the same circuit others not. The tl072 is a notoriously bad op amp and I would generally recommend a swap for that one. (source of bad rep for opamps)
Gimmediscount said: "All in all, I'm loving my SMSL and it would be PERFECT if I could reduce the hissing noise."
An inevitable compromise so far with D-amp technology.(noise floor -105db-110db) The TDA7498E chip seems to be one of the best D-AMP (t-amp) versions for usability and is at its prime at 75db to 100db (typical 87db spkr 1m/w) range listening level. To be fair, it would be nice to bench test the SMSL SA-160 iteration of design to see how close it reaches the actual noise floor limit of the TDA7498E. SMSL states -98db SNR. Circuit layout, components and power supply do greatly influence the noise floor.
There is always a dynamic to what sounds best versus what is technically best. Subjective versus the scientific objective. I see subjective preference often equating to what effects (eq, compression, reverb, harmonic manipulation etc) one wants to apply to their playback reproduction. Objective use scientific measurements to describe results. One of the hardest thing to quantify is resolution and quality. It generally takes all tests combined to do so. Even to this day, there have been 1000's of pieces of audio gear all trying to do the same and yet still no set of extensive standards of testing.
Hence 35 years later I am still buying "Gear".
The audiophile industry is being nebulous for a reason.
Hey, my only point was that I thought you were on the right track. Particularly supported (in my opine) by the last post in the thread where it was stated that by switching to a universal power adapter set to 24v the high frequency noise "became much less noticeable". Of all the posts in all the threads that I read about this problem, it was the only experiment where someone came out and said that they got a positive outcome (albeit subjective). I have no idea weather the locus of that positive outcome had to with over powering, brand build, filtering or a defect in the stock power. What I am fairly confident of is that most people won't end up needing 160 watts to drive the speakers that will be hooked up to this amp. So, if dropping the power input down to 24v does truly reduce the hiss, little else will be lost.
I also agree with your objective/subjective statement. For years I used nothing but David Hafler amps and preamps (solid state) extremely flat and clean, until I bought my first New York Audio Labs amp (Hafler modified to tube hybrid). Technically not as linear and darker but to my ears, a more pleasing sound. I guess that's why a timbre adjustment knob was standard fare on 'truly vintage' vintage pre amps and integrated amps. Or maybe it's simply that triodes rule, as a friend of mine is prone to avow.
any updates on using the new power bar?
I received the afformentioned tripp lite surge protector yesterday. End result: Hissing noise is still there. Am I willing to purchase a lower powered power brick to see if the hissing noise is reduced? Not sure yet.
Here's a video example of my experience: https://vid.me/tToZ
It will sound a lot more exaggerated than it really is if you have the volume of the video all the way up.
Not sure if I have a defective device since I am also getting occasional sound muting that last 4-12 seconds. Are you returning yours?
Sorry for the late response. I tried contacting the manufacturer but they havent responded at all. I'll see what massdrop has to say about it, but it might be too late to return.