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Review and Measurements of PS Audio PerfectWave DirectStream DAC

Rja4000

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Yes. Here is the amount of "FFT gain" (measurement noise reduction) for different number of audio samples used:

32K = 42 dB
256K = 51 dB
1 million = 57 dB

The actual dB is a few dB different since it also includes the effect of the FFT Window. But is not material in grand scheme of things.
Hi

This "gain" is the level drop for noise in the display (or for the distortion analysis).
But it's not impacting SNR or SINAD, or does it ?

Actually, I see some impact of FFT size on SNR, but that's nowhere near linear.
And I have no clue what's causing that.
Example of a Loopback FFT Size/SNR

SNRvsFFTSize.PNG


And this looks quite random, on top of it: I've seen 128k being higher than 32k for other configurations, as an example.

Does anyone know why ?
At lower FFT size, it looks like there is high low frequency noise, due to the fuzzy frequency resolution.
But why do we see variation above 16k points ?

Notes: sampling frequency in this example was 48kHz
I get the same figures for the same config anytime
I also read the exact same values from Multi Instrument and from REW
 
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Hugo9000

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Dammit it all. And I thought I was being clever and making up something original. I guess they beat me to it. But that proves my point. Just use your imagination. It won't matter, since you'll be playing them. And they won't know it.

Use something from '50s sci-fi. That would work. How about, "I'm using custom made Phlogiston free Interocitor cables, the one's with a Cathermin tube termination, and with an Indium complex of +4. You know, the one's designed by Cal Meacham. Very expensive."
Sci-Fi might be too close to their own pseudoscience, and they might become suspicious. Since their attitude is obviously centered on their snobbery rather than actual experience with every possible cable brand and combination, it might be instructive to look to academia, and adopt a little German?

How about the following:

I use a full Gesamtkunstwerk Lebensraum® cable loom, consisting of Gemütlichkeit interconnects, Weltanschauung speaker cables with Schrödinger articulation tuning boxes, cable cradles crafted of genuine Waldsterben, and Schadenfreude power cables and conditioning devices.

For lesser systems (a kitchen radio, say), one can use Ersatz interconnect cables, Weltschmerz speaker cables, and Zugzwang power cables.

Don't forget the subtle nose lift as you speak the above.

Here's the rest of the system, incidentally:
Klangfarbenmelodie CD transport
Musikalisches Würfelspiel streamer
Zeitgeber master clock
Zwischenzug USB cable
Stockhausen Ausmultiplikation DAC
Affektenlehre control amplifier/preamplifier
Bereitschaftspotential amplifier

All of the above will make such miraculous improvements and yield such perfect synergy that the actual transducers are almost beside the point.

Edited to add: The above will only work in the U.S. I haven't a clue how to one-up the snobs in Europe or Asia or anywhere else.
 

AudioSceptic

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Sci-Fi might be too close to their own pseudoscience, and they might become suspicious. Since their attitude is obviously centered on their snobbery rather than actual experience with every possible cable brand and combination, it might be instructive to look to academia, and adopt a little German?

How about the following:

I use a full Gesamtkunstwerk Lebensraum® cable loom, consisting of Gemütlichkeit interconnects, Weltanschauung speaker cables with Schrödinger articulation tuning boxes, cable cradles crafted of genuine Waldsterben, and Schadenfreude power cables and conditioning devices.

For lesser systems (a kitchen radio, say), one can use Ersatz interconnect cables, Weltschmerz speaker cables, and Zugzwang power cables.

Don't forget the subtle nose lift as you speak the above.

Here's the rest of the system, incidentally:
Klangfarbenmelodie CD transport
Musikalisches Würfelspiel streamer
Zeitgeber master clock
Zwischenzug USB cable
Stockhausen Ausmultiplikation DAC
Affektenlehre control amplifier/preamplifier
Bereitschaftspotential amplifier

All of the above will make such miraculous improvements and yield such perfect synergy that the actual transducers are almost beside the point.

Edited to add: The above will only work in the U.S. I haven't a clue how to one-up the snobs in Europe or Asia or anywhere else.
Love those. German tends to sound techie, doesn't it?
 

Eirikur

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If you're wife can't distinguish DACs from the kitchen I would consider leaving her no matter how cute and intelligent she is - she simply isn't audiophille wife material. :D
In all honesty she's more of an audiophilistine, but putting up with my stupid hobbies more than makes up for that!

My wife, for example, can tell from our kitchen when our neighbours are switching their DACs. :D
Do they black-out the whole neighborhood?
 
OP
amirm

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Hi

This "gain" is the level drop for noise in the display (or for the distortion analysis).
But it's not impacting SNR or SINAD, or does it ?
Correct. This is post-processing in an analyzer which naturally does not exist in a real life when you are using the DAC.
 

GrimSurfer

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Sci-Fi might be too close to their own pseudoscience, and they might become suspicious. Since their attitude is obviously centered on their snobbery rather than actual experience with every possible cable brand and combination, it might be instructive to look to academia, and adopt a little German?

How about the following:

I use a full Gesamtkunstwerk Lebensraum® cable loom, consisting of Gemütlichkeit interconnects, Weltanschauung speaker cables with Schrödinger articulation tuning boxes, cable cradles crafted of genuine Waldsterben, and Schadenfreude power cables and conditioning devices.

For lesser systems (a kitchen radio, say), one can use Ersatz interconnect cables, Weltschmerz speaker cables, and Zugzwang power cables.

Don't forget the subtle nose lift as you speak the above.

Here's the rest of the system, incidentally:
Klangfarbenmelodie CD transport
Musikalisches Würfelspiel streamer
Zeitgeber master clock
Zwischenzug USB cable
Stockhausen Ausmultiplikation DAC
Affektenlehre control amplifier/preamplifier
Bereitschaftspotential amplifier

All of the above will make such miraculous improvements and yield such perfect synergy that the actual transducers are almost beside the point.

Edited to add: The above will only work in the U.S. I haven't a clue how to one-up the snobs in Europe or Asia or anywhere else.

LOL. This is exactly what I had in mind when I read an earlier post about how audiophile shops in NYC operate.

Winning a battle of bull$hit is almost as satisfying as slapping someone down with science. Almost.

Love those. German tends to sound techie, doesn't it?

Ja, eindeutig.
 

scott wurcer

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Well, the limit is your patience. :) At 44.1 khz, 256K points is already 8 seconds.

On what??? Numpy/Python does a million 128 bit complex points in a few seconds on my laptop. Also look at the benchmarks for BruteFIR's FFT based convolution.
 

highstream

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If I understand correctly, to some degree, especially with regard to the lower midrange on down, Amir's measurements in the OP parallel SQ criticisms some of us had of the 3.0.6 firmware update, one that lead to sticking with 3.0.0. I'm now using a Lampi Atlantic TRP dac, tubes rolled, and it's far superior in all respects. That said, PSA is coming out with a new firmware version Oct 2, one that they claim is far beyond anything they've done so far. To be heard...
 

Krunok

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That said, PSA is coming out with a new firmware version Oct 2, one that they claim is far beyond anything they've done so far. To be heard...

Issues that Amir measured cannot possibly be rectified with firmware upgrade - complete redesign is needed for that.
 

Miska

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View attachment 34657

And this looks quite random, on top of it: I've seen 128k being higher than 32k for other configurations, as an example.

For example ESS Sabre has fluctuating characteristics. This naturally disappears when you use longer FFT at same rate because it begins to fall into the window size. If you use shorter FFT, then the dynamic range in the result may not be enough to show it, although time resolution would.

Took me a little while to get hold of it. It is likely due to the DPLL/ASRC, since one older DAC running with "synchronous clock" (Mytek Stereo192-DSD DAC) doesn't seem to have the problem (not that I would have paid whole lot of time on this detail).

Overall, there is 10 - 20 dB fluctuation of THD+N/IMD over time and the cycle time is somewhere around ballpark of 10 seconds or so.

Another side-effect are similarly wandering noise bumps in the noise floor.
 
OP
amirm

amirm

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On what??? Numpy/Python does a million 128 bit complex points in a few seconds on my laptop. Also look at the benchmarks for BruteFIR's FFT based convolution.
You have to capture the data first before you can FFT it. 256K/44K = 6 seconds already. Then the FFT can begin for each channel. So even if the FFT computation takes zero time, it will still be 6 seconds for the results to capture the audio.
 

scott wurcer

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You have to capture the data first before you can FFT it. 256K/44K = 6 seconds already. Then the FFT can begin for each channel. So even if the FFT computation takes zero time, it will still be 6 seconds for the results to capture the audio.

OK, but that's not the way benchmarks are usually run, loading the queue is simply latency. I assume we are talking .wav or .flac files on a disk already.
 

BDWoody

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If you're wife can't distinguish DACs from the kitchen I would consider leaving her no matter how cute and intelligent she is - she simply isn't audiophille wife material. :D

My wife, for example, can tell from our kitchen when our neighbours are switching their DACs. :D

She must be very sensitive to plankton...

That's excellent... That way she can keep making your sandwich while listening.
 
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amirm

amirm

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OK, but that's not the way benchmarks are usually run, loading the queue is simply latency. I assume we are talking .wav or .flac files on a disk already.
Not in my case or live analysis. The analyzer starts to capture the audio and then performs the FFT.
 

Bmoze

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Off the current topic, but just wanted to say thank you to FredYves for sharing his impressions, a few pages back, of his incredible selection of DACs. I think the DAC measurements provided here are a public service and are a great starting point for anyone looking for a DAC. They show that you don’t have to spend a ton of dough for great performance. Still, everyone’s speakers/headphones, rooms, and ears are different and audible differences in DACs, as FredYves has said, can be subtle. My 65 year old ears, after too many Grateful Dead shows, (not too many, just a lot) are not what they used to be, but I still want a good DAC a a fair price, and will at least pretend to hear the difference.
 
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