DSJ Huron Hiss at low level issue


#1

Hi Everyone,

For a few days now I have noticed hiss spoiling the signal especially at low level.

I use my DSJ as a Preamp and dac, MacBook pro, Bluesound and Oppo BDP as sources.

This phenomenon happens on all the inputs (usb,coax,tos), and all the outputs (RCA and balanced)

I tried changing usb cable, xlr cables to my amp, switching between my two amps both balanced and unbalanced, changing power cord and the problem is still there.

The only thing that fixes the problem is downgrading to Torreys.

Anyone have encountered the same issue, any fix?

Thanks for your help.


DirectStream DAC produces audible hiss when connected directly to M700's
#2

One thing that we found in the initial release of Huron on the DS Jr was that there was a higher rate of failed updates than usual with that release (not related to the release itself, but to the upgrade process in the DS Jr.)

One of the failure modes what that some upgrades seemed to cause audio anomalies varying from the subtle to outright hash.

The “fix” for that problem was to reformat the USB stick (as FAT, which is a little more work on the MAC), reload the Torreys upgrade files to the USB stick, use the OS’s Eject function to remove the USB stick, do the normal upgrade on the DAC, check that the version page now says “Torreys”, then repeat the same procedure with Huron, then turn the DAC off and back on with the back switch before listening the first time.

It’s not as bad as it sounds to do that and not all steps may be necessary in a given case, but each of the steps is necessary in some cases.

This fixed many upgrade problems, but a few systems needed help from PS Audio to do a force load to get Torreys back on.


#3

Hi Ted - I appear to be suffering from this issue as well on a factory fresh DSJ I got in July. At anything but 100 volume setting there’s a consderable amount of hash noise on low signals. Should I try the Torreys-and-back procedure you outline?

Best,

Marc


#4

Hello Taww,

Exactly the same issue for me, the only volume setting the hiss is not present is 100, the lower the volume setting, the bigger the hiss is.

I tried the procedure explained by Ted with three different usb but not working…

And now the version displayed on my dsj gets stuck to Huron 0.0.0.

I have send an email to the support.


#5
Soundtaker said

I tried the procedure explained by Ted with three different usb but not working…

It wasn't for me either, but I found this "force update" firmware version:

http://updates.psaudio.com/dak/94force.zip

This will allow you to downgrade to Torreys and redo the Huron upgrade. It worked for me, I’m currently showing Torreys 3.3.3.

I’m going to listen to Torreys for a bit before retrying Huron. The hash noise issues at lower volume settings is much better, but not completely gone - still not as clean as setting the volume to 100 and using the preamp attenuator.

FYI the thread where I found that link: http://www.psaudio.com/forum/directstream-all-about-it/cannot-update-directstream-jr-to-torreys/

Hope that helps!


#6
taww said

Hi Ted - I appear to be suffering from this issue as well on a factory fresh DSJ I got in July. At anything but 100 volume setting there’s a consderable amount of hash noise on low signals. Should I try the Torreys-and-back procedure you outline?

Yes, you should try it: the symptoms of a bad upgrade are varied and often inexplicable. Still I'm not too confident that this is your problem.

If by “anything but 100” you mean, say, 20 or 40 then that’s expected behavior, if by “anything but 100” you mean, say, 99 or 101 then that just isn’t the way the FPGA is programmed: There’s absolutely nothing special about 100 vs any other setting. The volume settings are converted via a table to a linear level to send to the FPGA, FWIW 101 maps to 1321123, 100 maps to 1246974 and 99 maps to1176986 and no volume setting which in and of itself can make hash. There’s a low level analog noise floor in the DS and DS Jr and the quieter your signal is the louder the noise floor will appear by comparison, but the differences between 100 and 99 are minuscule, and the only likely difference would be if 100 caused the rest of your system to overload with very loud music but 99 didn’t, which is very unlikely and just the opposite of what you are describing.

The DS and DS Jr are designed to be used with higher volume settings most of the time (a level of 100 being about as loud as you’d ever want to listen.) If the loudest you’d ever want to listen is below 66 use the 20dB attenuator to get a better match with your system. If listening with neither setting is acceptable, then using a volume of, say, 100 and an external preamp might be the best approach.

[Edit - our posts crossed.]


#7

Hi Ted - after downgrading and re-flashing to Huron, I think things are about the same as before (still hearing the noise) But to your point, it is correlated with output level. I would say the point at which the noise becomes distracting is the 60 setting (-20dBFS?). Adjusting things up 12 and the preamp down by 6dB audibly reduces the noise by, well, half if I had to quantify it.

So this might be working as designed, which is understandable but a little disappointing as I’m really enjoying the software volume control in Roon. For serious listening I guess I will peg things at 100 and use the preamp.

It does seem like Torreys is slightly quieter than Huron in this regard. Any idea why that might be? [armchair]Possible running things at quad rate is introducing more noise in the output?[/armchair] I’ll try making a recording of it so you can hear what it sounds like.


#8

Here’s a 24/96 WAV clip of what the distortion sounds like at volume 60:

https://www.dropbox.com/s/0lndlsd1bis0kme/Z0000002.WAV?dl=0

Yes, this is with the recorder sitting a few inches from my speaker drivers, but it’s audible from the listening position as well.

Soundtaker is that what it sounds like for you as well?


#9

Some noise is indeed part of the design - the DS Sr specifically has 4 times as much hardware in certain places to lower the noise by 6dB compared to the Jr. Also the Sr uses some better quality parts, but they are (much) more expensive. There are certain compromises that had to be made to lower the cost of the DS Jr while keeping the overall presentation, ease, flow of the music from the DS Sr.

Actually quad rate lowers the noise, both subjectively and objectively. But tho it isn’t a result of quad rate, the character of the noise is a little different between Torreys and Huron on very low levels of audio (especially long fadeouts). For the next release of the software I’ll try to keep the best from both releases. A few people have chosen to remain on Torreys because it better matches their systems and listening preferences. Most have chosen to stay on Huron for it’s other features compared to Torreys.

If you are having distortion at 60, you can use the attenuator to lower the noise by 20dB - that will then allow you to use 100 instead of 60 for the same volume level. Some people have found that the extra 6dB from using balanced connections may help, some have added, say, 10dB inline attenuators to their analog interconnects to lower the noise by 10dB and use a volume that’s 20 units higher. A preamp is the best solution if cost isn’t the major concern, and a few are happiest with upgrading to the DS Sr. I’m not trying to talk anyone into anything, just admitting that the noise is louder on the Jr than I’d like but that many don’t notice any noise problems with the Jr compared to the Sr and for others the trade off in price is worth it.


#10

I Understand what you’re saying but I switched to Huron the Day it was out for DSJ, then switched back to Torreys a few times and carefully listen on my different systems (Mc 275 and ARC Réf 75).

At the beginning the noise/hiss was not present I’m sure.

So I’m thinking of a different issue in my case.


#11

Indeed, I’ve just listened to the wave file posted by taww, and the noise shape is exactly the same.

When I bought DSJ I had different speakers, high efficiency, and was using DSJ as a preamp and never noticed that hiss…


#12
Ted Smith said

One thing that we found in the initial release of Huron on the DS Jr was that there was a higher rate of failed updates than usual with that release (not related to the release itself, but to the upgrade process in the DS Jr.)

Thank you Ted - I myself reverted back to Torreys a month ago because of the low level distorsion I heard with Huron, I will give it another try based on your instructions.

It seems that failed updates show themselves from “no update at all” to anomalies in the reproduced sound after what seems to be a sucessful update.

Is there no way to verify that an up- or downgrade went through exactly as intended when completed ?


#13

The updater itself was broken in the DS Jr so any checks we might have tried to use weren’t necessarily effective. To make things worse, it was much less likely to fail in a system that was updated often, like a development system. There are only a small number of DS Jr’s running at PS Audio that have been around for quite a while without having various software loads for various tests/experiments, etc. so the problem wasn’t seen in development. In the DS Sr there were a few people that had problems, but those were caused by corruptions on the SD card and could easily be fixed by a redownload/reupdate. The FPGA software is “protected” by two levels of checksum: the FPGA gives an error during load if the checksum of the bits sent isn’t right and we use another checksum around the FPGA load and validate it after reading from flash and before sending the bits to the FPGA, if that fails we reload the FPGA. Both of these mechanisms have been tested and seem to work fine. In all honesty, if we understood the problem exactly we’d fix it. The director of engineering at PS Audio is very interested in fixing the update problems but some of the issues may take a release or two to ring out.


#14

Ok, to be back to the original topic, not the update but the low level signal hiss issue, the answer is: it is normal with the DSJ/Huron combination?


#15

Have you tried the forced update outlined in post 5?

Have you tried engaging the 20dB attenuator?


#16
Soundtaker said

Ok, to be back to the original topic, not the update but the low level signal hiss issue, the answer is: it is normal with the DSJ/Huron combination?

I would say no to that, I just updated to Huron again following Teds instructions and the low level intermodulation noise I heard after the

Huron update i did just after release is not there anymore. Now it was just as good as Torreys from this perspective.

Background noise is a tiny bit more pronounced and has a somewhat more - how can I say - “harsh” character in Huron compared to Torreys.

I recorded a 1kHz sine at -60dB (44/16) and played it back (DSj at 100) , and yes there are some audible intermodulation when cranking up the

Hegel to a normal listening level. But I would consider that a rather extreme and mean test, it was just for fun.

I am not surprised and not worried, I know a little about how DS dacs work, so I would say what I heard was normal.

Just to compare - the H360 dac is dead silent in itself and did not reproduce any audible intermodulation with the test tone - still the DSj sounds

so much better. It is not all in the numbers.

After trying Huron according to above I went back to Torreys again, but that is another topic and not related to noise.


#17

Yes, I try the force update and it worked fine, shows Torreys 3.3.3 now.

I keep Torreys, it is more coherent with my system/setup… but as you said it’s a different topic.

I send 1K tone to the DSJ to, still have that intermodulation noise, when I use the attenuator and Torreys the hiss is below earring level.

The problem is classical music with huge dynamic range, the attenuator minus 20 Db is to low and without attenuator the hiss is to important at low level…

I’m using the DSJ as a preamp because the result is so much better compared to my preamp

So now I’m a bit disappointed about the hiss, I think I will see with PS Audio Dealer to trade for a DS Sr…


#18

This would be frustrating.

Please let us know if you get a DS Sr. and how this works out for you.


#19
Soundtaker said

I’m using the DSJ as a preamp because the result is so much better compared to my preamp

Interestingly, I've tried the DSJ with a tube preamp (Monarchy NM24 line stage/DAC, bit of a sleeper as a pre) between it and my integrated (Ayre AX7e) and really liked the way it sounded. Little surprised the LS27 didn't yield similar results.

#20

It is really dependent on your preamplifier. As I have said for years, DACs directly into the amplifier are better than most preamplifiers. It is the word MOST that matters here.