DirectStream DAC Output Level


#1

Why is the DS DAC’s output level so low?

Was it designed this way so that it wouldn’t be too loud for people who are using the DS directly feeding a power amp?


#2

The PWD actually is higher than standard DAC and there were some complaints about it being too hot for some preamps (I can’t quantify the relative complains about the PWD being hot vs. the DS being too low.) The balanced output of the DS is only about 3dB or 4dB lower than the PWD - most people should have at least that kind of headroom in their systems.

The pragmatic reason it’s lower is so that it could use the spare 12V supply in a PWD chassis for the DS analog card and hence allow field upgrades of PWDs to the DS. (As it turns out we changed the power transformer on the power supply and we didn’t need to design a new power supply card, but… Hindsight is a harsh mistress.)


#3
Ted Smith said The balanced output of the DS is only about 3dB or 4dB lower than the PWD - most people should have at least that kind of headroom in their systems.
And the PWD is a hotter than nominal for a source.

The DS is only a tad quieter than a nominal source.


#4
Ted Smith said The PWD actually is higher than standard DAC and there were some complaints about it being too hot for some preamps (I can't quantify the relative complains about the PWD being hot vs. the DS being too low.) The balanced output of the DS is only about 3dB or 4dB lower than the PWD - most people should have at least that kind of headroom in their systems.

The pragmatic reason it’s lower is so that it could use the spare 12V supply in a PWD chassis for the DS analog card and hence allow field upgrades of PWDs to the DS. (As it turns out we changed the power transformer on the power supply and we didn’t need to design a new power supply card, but… Hindsight is a harsh mistress.)


oh I see…so no hope for a future higher gain toilet-2_gif

“too hot” shouldn’t be a big problem if two different settings (high/low) are available as on the DS. But if the economic field upgrade reasons were the point, well…


#5

Ted, one question, as for those who can’t use balanced out, the lower output of the DS than of the PWD together with the inability to make use of the +6dB of balanced mode can stop one from using it without preamp:

Could it be an option to offer a kind of upgrade kit with i.e. an add. transformer to help that situation?


#6

From a technical point of view a transformer with a different turn ratio could up the output a little - at the expense of more sensitivity to cable capacitance, etc. From a pragmatic point of view it’s not simple to use a different transformer without also changing a lot of passive components to match as well as probably drilling holes thru the board to detach some audio routing that’s on the inside of the board. From a sound quality point of view, if your system is so close to the edge that a few dB makes the difference then you don’t have much headroom anyway and your system probably would be better off with a good preamp - in most cases the music would be more dynamic and would have more ease…


#7

Yes, that’s it, if you want to hear reasonably loud, covering the partly huge level differences between recordings, a preamp mostly has clear advantage in dynamics, punch and headroom. Preamps wouldn’t exist if every source with a volume regulator could replace it in every aspect aside of the source select feature. If a for most cases sufficient level would be possible, I guess many would be ok with a reasonable price increase for it.


#8

I have a pretty resolving system and coming from a DAC w volume control feeding my power amp directly, I had hoped that the DS would have enough output to do the same. Setting to HIGH causes an very audible hiss in my DS that I never experienced with the other DAC (Lampi). Is that an anomaly?

In my system either the volume is barely enough (normal setting) or I get enough volume (in high setting) but need to live with the loud hissing during pause and silent passages.

Any suggestions?


#9

Polyglot, my suggestion would be to try a preamp, preferably a very good one that works well with your amps. A preamp certainly could introduce more gain. Personally, I don’t use a preamp because the one I had, Audio Research LS-25, seemed to degrade the sound compared to direct. There are a lot of folks here who prefer a preamp, Paul McGowan being the most prominent. PS Audio is working on a preamp to go with the BHK 250, but I’m sure it will work with your amps. No idea when it will become available or the cost. One other thing, not sure if this was mentioned in response to you, but Ted Smith has said that improper loading of the DS operating system can be a source of noise. My DS makes essentially no noise, whereas the LS-25 had a low level hum.


#10

DarqueKnight, Polyglot and Ted Smith.

From the day I received my PS Audio Direct Stream I have been running it through a BSG QOL and then to my Pass Labs Amp. No preamp necessary. To me, with my ears, the QOL matches up so well with the Direct Stream Dac that Tim you should consider adding that circuitry to the Direct Stream. With the QOL I can play my Direct Stream Dac with the low output in the 90’s or use the high output in the 60’s for rocking high levels.

With the Direct Stream Dac bringing out added details that were buried in the mix and the QOL enhancing those details, the sum is much greater.


#11
Polyglot said

In my system either the volume is barely enough (normal setting) or I get enough volume (in high setting) but need to live with the loud hissing during pause and silent passages.

Any suggestions

That's a bummer. First, the noise is not likely intrinsic to the DS, the units are very quiet by design. I run balanced connections direct to my amp with high sensitivity speakers. Plenty of gain and black background. Not noisy in the least.

So where is the noise coming from in your setup? No expert here but could ground loop or cables be an issue? Or the amp and DS not partnering well (impedance a factor?)

Noise is often a pesky issue in unbalanced setups. Could you trial a balanced amp to assure you the DS is not producing the noise all on its own?

[formatting edited for clarity. Elk]


#12
ozzymilton said

From the day I received my PS Audio Direct Stream I have been running it through a BSG QOL and then to my Pass Labs Amp. No preamp necessary. To me, with my ears, the QOL matches up so well with the Direct Stream Dac that Tim you should consider adding that circuitry to the Direct Stream. With the QOL I can play my Direct Stream Dac with the low output in the 90’s or use the high output in the 60’s for rocking high levels.

With the Direct Stream Dac bringing out added details that were buried in the mix and the QOL enhancing those details, the sum is much greater.


Would love to hear a QOL/DS setup, very enticing.

#13

I got rid of my very good tube preamp so I would only have to deal with one DAC/preamp, saving cost and space and doubling down on better power cord and cables on fewer devices. The cost does not stop at the preamp but I am used to good power cord and interconnects (the CH Acoustics X-20, Stillpoints Ultra SS and High Fidelity Cables CT1-U were passed down from the Lampi L4 w volume control to the DS which does a very good job as DAC), add those ancillary cost for a new device to the acquisition of a preamp and I don’t see the rationale of keeping the DS in the equation.

As for audio, I am not sure the sum of the parts is always greater than the individual (I am not talking about system synergy here). From Dagogo “Finally, while the QOL’s effect created a much more defined performance venue and brought out previously repressed instruments, the instruments on the soundstage seemed to become a bit more amorphous – there seemed to be less “space” between each performer on the stage.” Not familiar with the QOL but with other tweak devices like the QOL, you always lose something. It would be different if the heart or logic of QOL is built in a future release of the DS. IMHO the audio industry is trending back to “more is less” with the deployment of multi function devices as software controlled FPGA, CPU and open platform OS to cater single source (wired/wireless streamers/bridges to NAS/cloud). Good preamps on the Gon do not fetch the prices they demanded just a year ago, I believe the innovative and disruptive DACs are driving this change.

I will issue a ticket with support and hope to find a way to get rid of the hiss (like coming from a vintage receiver/amp that needs service) with the setting on high which is the problem (all devices except the power amp are turned off, never had this before). No one else seems to have this issue here, right?


#14
MegaHz said
That's a bummer. First, the noise is not likely intrinsic to the DS, the units are very quiet by design. I run balanced connections direct to my amp with high sensitivity speakers.
A slight correction:

The noise in a one bit DAC is intrinsically higher than people are used to with a PCM DAC. However at any realistic listening level that noise is too quiet to hear. But it’s at a constant level independent of the volume so when the volume setting on the DS is low that noise will be higher relative to your typical listening levels. We added the 20dB attenuator for those people whose systems are more sensitive so that they could push that noise down another 20dB if they typically had the DS’s volume set lower than 66. There are definitely some people out there who have systems that are very sensitive that might like more than a 20dB attenuator and a few who’s systems are somewhere in the middle that could use some smaller attenuation. These sets of people may prefer to use a preamp and leave the DS set at 100 so the DS’s output noise is always at a minimum relative to it’s output. As was mentioned a balanced interconnect will provide another 6dB of S/N in most systems that can use it and may just make the difference for some people.


#15
Ted Smith said These sets of people may prefer to use a preamp and leave the DS set at 100 so the DS's output noise is always at a minimum relative to it's output. As was mentioned a balanced interconnect will provide another 6dB of S/N in most systems that can use it and may just make the difference for some people.
Thanks Ted for expanding on noise management with the DS. Very helpful. You suggest "DS set at 100" with a preamp but would not using the 20dB attenuation and volume set at 106 provide lower noise when using an active preamp that provides adequate gain? Or am I a bit off again?

#16

If you are using a preamp it’s probably not the best course of action to first attenuate the signal by about a factor of 100 and then to reamplify the signal with the preamp (and then attenuate it again with the preamp’s volume control.) Any preamp will be able to handle the DS at 100 without the DS’s 20dB attenuator engaged, then you’ll only have one attenuator (the preamp’s volume control.) Of course you can do what ever you think sounds the best, but almost always getting changing “attenuation -> amplification -> attenuation -> amplification” to just "“attenuation -> amplification” will sound better.


#17

Ted. Do you ever notice a difference when the DS volume control is set at a 100 versus being set at 99? At the 100 setting, the sound seems to be a little more to the point and precise or exact, where as at 99, it feels a bit more relaxed or organic and the overall sound quality improves,including depth of soundstage… Weird,I know.


#18

There’s nothing special about 100 or 99. They each map to a linear volume with lots of ones and zeros. Each different upsampling filter has many coefficients with many ones and zeros and further, depending on the sample rate, there’s a volume correction based on the upsampling factor, e.g. tho samples at 44.1k are scaled by 1.000976174753312 samples at 48k are multiplied by 1.089497877282516 (which comes from the squareroot of 6.143632880538761e-9 * 147 or 160 and binary shift.)… So there’s no input volume that has mostly ones or mostly zeros. Then the sigma delta modulator is chaotic and hence every possible DC level (even being muted) has a time varying pattern of ones and zeros.

Don’t get me wrong, I can believe that some people might hear a very subtle difference between different volume levels (even if corrected for with an analog volume control downstream.) It’s just that at that level of subtlety every different volume level and sample rate would be different and none of them would be special, e.g. more or less technically faithful to the source.

I’ve got to believe that the differences from different volume levels of analog distortion in your preamps, amps, and, say, the transformer in the DS are more significant.


#19
Ted Smith said There's nothing special about 100 or 99. They each map to a linear volume with lots of ones and zeros. Each different upsampling filter has many coefficients with many ones and zeros and further, depending on the sample rate, there's a volume correction based on the upsampling factor, e.g. tho samples at 44.1k are scaled by 1.000976174753312 samples at 48k are multiplied by 1.089497877282516 (which comes from the squareroot of 6.143632880538761e-9 * 147 or 160 and binary shift.)... So there's no input volume that has mostly ones or mostly zeros. Then the sigma delta modulator is chaotic and hence every possible DC level (even being muted) has a time varying pattern of ones and zeros.

Don’t get me wrong, I can believe that some people might hear a very subtle difference between different volume levels (even if corrected for with an analog volume control downstream.) It’s just that at that level of subtlety every different volume level and sample rate would be different and none of them would be special, e.g. more or less technically faithful to the source.

I’ve got to believe that the differences from different volume levels of analog distortion in your preamps, amps, and, say, the transformer in the DS are more significant.


Wow boy do I feel inadequate mathematically now. Holy cow Ted.

Odd


#20

Very, very interesting. Thank you, Ted!