DSD DAC Very Faint High Frequency Noise

Since upgrading to Yale firmware, DSD will output a very faint high frequency noise when not playing back anything. This applies to all inputs. If I turn off DSD via remote, this noise disappears.

Maybe Ted’s code is doing something unintended?

Have you tried going back to say 121 and then back to Yale

I always (on any firmware) from the tweeters is a quiet hissing sound when the ear to bring him.

If I disable the DSD - hiss disappears.

YAMAD, if you change the DS output level by pressing the “Filter” button on the remote when no music is playing, does the hissing sound change in level?

The DAC’s background noise floor is very low, but if you have a high sensitivity amp/speaker combination you might hear the noise floor when no music is playing and the output level is set to “high”. Switching to “low” level drops the overall output by approximately 20dB which is enough in most systems to put the DAC’s noise floor below the amp’s noise floor, and so make it inaudible.

Dvorak, thank you, I put a low output. The noise from the tweeters was many times quieter, but now has no reserve volume, at 100, sometimes a bit lacking. And I was scared I accidentally hit the filter button and my volume is 100, and turn on the music without knowing about it… blush_gif

And yet, it seems, on the quality of the sound output level is not affected.

Without this constant hiss, music was perceived much cleaner, more colorful, real and interesting. Thank you so much, Dvorak!

Seems to be a design flaw with DAD DAC hardware then? I would have expected passive LCL not to have any noise given input is Vcc/0V. Ted maybe able to comment? Unless FPGA is output something…

Single bit DSD based DACs have more random noise in their outputs than other DAC designs. That noise isn’t correlated to the material being played so it ignored very well by our ear/brain. That noise is low enough to typically be inaudible at realistic listening levels but high enough to be audible with the gain that some systems have when music isn’t playing.

The problem comes with very high gain (or very efficient speaker) systems. If the typical volume setting of the DS isn’t above say 60 or so then the analog noise floor of the DS can be audible at those levels. As mentioned above to address this we provide the 20dB attenuator, when engaged it lowers the noise floor by 20dB and allows using a volume setting that’s 40 ticks higher.

It is the case that many of us can hear the noise if we listen close to our speakers when the music is paused, but by either using an external preamp or by setting the 20dB attenuator to the “best” setting for a given system the noise shouldn’t be audible when playing at typical levels.

I noticed this as a hiss but now understand what is going on. I did notice that with the -20db setting and raising volume to full on the DS it seemed to squash dynamics and sound in general. Any thoughts as to why?

Since using or not using the 20dB attenuator changes the output impedance somewhat, the effects of cable capacitance and amp input impedance are a little different between the two settings. Ignoring levels (which of course we can’t) I’m sure that some prefer the sound with the 20dB attenuator engaged.

I have a serious problem with noise/hum.

I received my DS DAC, BHK 250 and PP 10 yesterday.

I have connected the DS DAC directly via XLR to the BHK, both plugged into the PP 10.

My loudspeakers provide a sensitivity of 90db/W/m (Chario Sovran).

At first power on of the system I noticed severe noise and hum from the speakers. I was shocked.

Nothing is connected to the DS DAC, only DS DAC and BHK.

The noise from the tweeter and the hum from the mid tone driver is so loud, that it is still noticeable at a distance of 10ft (3m).

I have activated the 20dB attenuator by setting the output level from high to low. The noise and hum are much lower, of course. But I can still hear noise and hum at a distance of 0,5m (1.5ft). But it is much lower.

If I power off the DS DAC, there is no hum or noise any more. If I disconnect the DS DAC from the BHK it is almost silent. I have to position my ear about 2 or 3 inches in front of the speakers to hear something (impressive).

I have used a high-end power bar instead of the PowerPlant 10. Only DS DAC and BHK connected. Nothing changed.

I have used different XLR cables. Nothing changed.

Sounds like the BHK is doing well and the problem is with DirectStream - though it may just be sensitivity mismatches. With the 20dB attenuator in DS on, as you have it, where are you with the DS volume control when it is playing loud?

I run Avantgarde Duo Omega’s ( approximately 106dB sensitive ) along with Atmasphere M60 OTL tube amps connected to the Direct Stream. ( no pre )

When I listen, the Direct Stream is set anywhere from 85 to 95 depending on the source material being played. ( sometimes 100 )

I do not use the 20dB attenuation provided by the Direct Stream.

I can only faintly detect a slight “whoosh” from the midbass horn and a slight “tizz” from the tweeter horn with my head in the midbass horn or my ear directly against the tweeter horn… Absolutely no audible noise from the listening position.

This has been the case with all firmware revisions, including the latest.

I am obsessively anal when it comes to noise and have gone to great lengths to keep it at a minimum.

I would suggest that you examine where your gain is actually coming from ( gain structure ) and try some adjustments.

Is it coming from the source? DS? pre-amp? or your amps?

I have my M60 tube amps set to provide the least gain possible.

Paul McGowan said Sounds like the BHK is doing well and the problem is with DirectStream - though it may just be sensitivity mismatches. With the 20dB attenuator in DS on, as you have it, where are you with the DS volume control when it is playing loud?

With 20db attenuator in DS ON (LOW) I have to use volume levels of 90 to 95 for playing loud. With some classical recordings 100.

I could measure the sound level with -3db pink noise, stereo (e.g. A or C rated). Please let me know.

Ok, then something doesn’t sound right. With the attenuator in there should be little to no noise. Where did you buy the DS?

For what it may be worth, this story may be relative.

Before the Omega’s I was listening with Reference 3A DeCappo I’s, 93dB sensitive I think.

Never heard any extraneous noise from the system.

Enter the Omega’s, I had hum and noise where non had existed before.

Finally found that I had removed a ground pin from the PS Audio cord that fed power to the head end.

Replaced the ground pin and all was right with the world once again.

Sometimes we cause our own problems.

qu@rk: Work on the hum first. This is a ground loop problem until proven otherwise. If you are in the USA, try a ground lift “cheater” plug on the DS DAC to see if the hum goes away. If the system only consists of a single power supply, DS DAC and BHK I think that this should kill a ground loop. If the hum is at 60Hz it is most likely a ground loop. If it is an octave up, at 120Hz, it may be inductive hum. In that case, try flipping one of the two components up on it’s side or just moving it farther away. If you have another component to swap for the DS DAC, then give that a try. Try to cross XLR cables at 90 degrees to power cabling if they do cross and don’t run them close and parallel. These maneuvers should at least give you some clues as to where the problem lies. I am assuming that your XLRs have standard pin out and shielding. Good luck!

Thanks to all for the good intentions.

I am an engineer for electronics and a retailer in Germany for many years.

The German distributor and his technical specialist suggested just to use the “LOW” (attenuator active) setting because it has to be a problem with my speakers - very interesting conclusion - but not acceptable. A new digital board could be ordered, but the distributor told me, most likely that would not change very much.

Because of the doubtable technical support I had to return everything - even for a retailer too much money, too much risk. I want to prevent a never ending story.

PS Audio are great products, astonishing quality. But without a competent and reliable support, the risk is too great. I am so sorry, that it did not work out.

I just got a new DirectStream yesterday, eventually “upgrading” from PerfectWave II. The noise floor indeed is very high compared with other DAC’s. PWII had none. Even after upgrading to Redcloud, the DirectStream still sounds worse than older DAC’s I have, including old Krell 707 processor (!) and Esoteric DAC’s. Attenuation does help with the noise floor, but seems a poor solution, and it does not help with the lack of instrument separation, clarity, or poor spaciousness of the sound, compared with other DAC’s. Looks like one needs to wait another couple of years before a solution is engineered.properly, as I was informed by PS technical support that high noise floor is considered normal. (???) That was normal in the 90’s. Wish I had read these threads before going for this “upgrade.”

You need to let the DAC burn in for a while. The sound will change and it will get a lot better.