Researching The PS Audio Direct Stream DAC. Its Unusual.

Mister Pig

Pigamus Maximus
I have to say I have had a long and enjoyable run with my Audio Magic Kukama DAC. It functions well, and would make someone a great component. But I have been thinking awhile about replacing it, and seeing what is possible.

I came across some info on the PS Audio Direct Stream DAC while I was searching some other stuff. It seems I have somehow slid into PS Audio appreciation, as I now have a P10 AC Regenerator, the BHK 250 Signature amp, and have ordered the BHK pre amp. I never intended this to work out this way, but its my opinion that you get a whole lot of quality sound for the money spent, and while not cheap, the gear is not at the "are you insane" price level.

But the DAC is really intruiging for a couple of reasons, such as :
*I stole all the following text from reviews so I didn't try to write it and screw up the meaning. Plus I am a lazy pig.

1: does not have a traditional DAC chip built within; instead it uses a Field Programmable Gate Array (FPGA) which is an integrated circuit board that is programmed to serve whatever function it is commanded, including non-audio applications such as medical instruments and defence, distributed monetary systems and security systems.

2. There is no conventional analog output stage. The output of the DSD engine is fed directly into high-speed, high-voltage, high-current symmetrical video amplifiers and from there into the passive output filter. Rather than use an active output section, a balanced wideband transformer (which is part of the low-pass filter) drives either balanced or unbalanced interconnect cables.

3. All incoming data, PCM and DSD, are upsampled to 30 bits running at ten times the standard DSD rate and then back down again to double DSD for noise-shaping. The ten-times DSD sampling rate was the lowest common rate attainable through integer upsampling of 176.4 and 192kHz PCM files. An internal volume control maintains complete precision. Except for the sigma-delta modulation process itself there is no rounding; a full 50 bits are used. Consequently, there is no degradation from using the digital volume control. After the volume control, the signal is converted to DSD and downsampled to double-speed DSD (often referred to as DSD128). The double-speed DSD rate allows the low-pass filter to begin rolling off at 80kHz. A higher output rate would would have increased jitter.

I am not going to claim to understand all the subtle nuances to this design. To be honest all my digital library up until now is just 16 bit redbook. With this I will look to purchase high rez software, but really I would be a newb in this arena.

But once the BHK pre amp gets here and is integrated into the system, I think I will take a close look at buying one of these.

Cheers
Mister Pig
 
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Congratulations on the BHK preamp, and hopefully, the Direct Stream DAC. I've not yet read a negative review on any of that gear. All those pieces are reported to form a very synergistic system. I definitely look forward to your impressions when the next puzzle piece arrives.
 
Ted Smith (DAC) and Bascom King (amplification) are smart guys. King worked with Arnie Nudell on a number of Infinity projects. Good luck!

There are some videos of BK describing his design process on YouTube:

 
instead it uses a Field Programmable Gate Array (FPGA) which is an integrated circuit board

An FPGA is a chip, not a board. It allows them to create custom, high speed digital filters and conversion algorithms. This means they don't have to rely on the digital filter designs (either for upsampling, or for DSD conversion) that are built in to off-the-shelf DAC chips.

If they're any good at digital signal processing design, it could mean improved performance. If they're not, it could be worse...

Since an FPGA is programmable, it allows the design to be changed, to correct design errors, or to introduce new or improved features; for instance, to add new decoding schemes.

So it's somewhat future-proofed, although it does fundamentally rely on the their final digital to analogue conversion stage, which, as far as I can make out from the description, is some form of single bit pulse modulation, rather than a multibit PCM DAC.
 
An FPGA is a chip, not a board. It allows them to create custom, high speed digital filters and conversion algorithms. This means they don't have to rely on the digital filter designs (either for upsampling, or for DSD conversion) that are built in to off-the-shelf DAC chips.

If they're any good at digital signal processing design, it could mean improved performance. If they're not, it could be worse...

Since an FPGA is programmable, it allows the design to be changed, to correct design errors, or to introduce new or improved features; for instance, to add new decoding schemes.

So it's somewhat future-proofed, although it does fundamentally rely on the their final digital to analogue conversion stage, which, as far as I can make out from the description, is some form of single bit pulse modulation, rather than a multibit PCM DAC.


There is a porcine disclaimer....the verbage after it is stolen from other writers. I cannot be held responsible for their missteps. :)

Cheers
Mister Pig
 
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PS Audio is such an awesome company that has continuously blazed new trails for new and better audio solutions. A brave company. Could only imagine the potential of your new stack.
 
I got on the phone this afternoon and called PS Audio to check and see when my DAC would be done. I was told it would be the second half of April, but to call at the beginning of the month and check in. So that is what I did. What I found out was that the DAC is shipped, and its slated to arrive tomorrow! Now I just have to make sure someone is home to sign for it. So hopefully this weekend I will have it hooked up and breaking in.

Since the DAC was done, I inquired about my BHK pre amp. No word on that one shipping, even though I ordered it a week earlier than the DAC. So a request is in to see when it gets completed, and perhaps tommorow I will know when I can expect the pre amp here.

Now hopefully the turntable delivers here in the second half of April, like its estimated to be. That would be ultra awesome!

Cheers
Mister Pig
 
At least you can run the Direct Stream DAC, as a preamp, direct into you BHK amp. Get a feel for it's sound, before putting the new preamp into the signal chain. You'll get an idea of the sound quality of both components, as such. I look forward to updates too.
 
Unfortunately this did not work out for me. Designer claims that all DSD Dacs have conversion noise, and that in a higher efficiency system you will hear it. I have 93 dB efficient speakers and in the full output setting I could hear white noise, with the -20dB setting engaged I could only hear it at the speakers between tracks or at idle, but did not care for the presentation at that setting. I also had drop out issues if using the co-ax input. I felt the issues were enough to dissuade me, so its going back. I also am fortunate enough to recover my Kukama DAC, and love it on Redbook CD. So I have to return to ground zero, and consider what my options are, which include standing pat at Redbook with the Kukama. But I would still like to find a way to explore DSD, and wonder if noise is indeed inherent in this implementation.

Cheers
Mister Pig
 
Maybe I need more coffee.....But can you expand on this? Did the Direct Stream Dac not work out?
 
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